Radiology Illustrated: Spine [2 ed.]
 9819966116, 9789819966110

Table of contents :
Preface
Contents
Part I: Basic Step: Common Spinal Disorders
1: Anatomic Considerations of the Spine
1.1 Osseous Structure and Facet (Zygapophyseal) Joints
1.2 Intervertebral Disk
1.3 Uncovertebral Joint (Joint of Luschka)
1.4 Central Canal and Neural Foramen
1.5 Spinal Cord, Conus Medullaris, Cauda Equina, and Spinal Nerve Roots
1.6 Ligaments
1.7 Illustrations: Anatomic Considerations of the Spine
1.7.1 Normal Anatomy of the Spine
1.7.2 Intervertebral Disk and Ligamentous Anatomy on MR
1.7.3 Cervical Spine Anatomy
1.7.4 Spinal Cord and Nerve Root Anatomy
References
2: Common Spine Disorders Associated with Back Pain
2.1 Lumbar Spine MR in Patients with Back Pain: What Should We Focus on?
2.2 Herniated Intervertebral Disk
2.3 Spinal Stenosis
2.4 Alignment Disorders (Spondylolisthesis, Scoliosis, Kyphosis)
2.5 Degenerative Changes of the Posterior Elements (Facet Joint Arthrosis, Baastrup’s Phenomenon)
2.6 Illustrations: Common Spine Disorders Associated with Back Pain
2.6.1 Schematic Illustrations of the Nomenclature for Disk Herniation
2.6.2 Herniated Intervertebral Disk
2.6.3 Lumbar Central Canal Stenosis
2.6.4 Lumbar Foraminal Stenosis
2.6.5 Spondylolysis/Spondylolisthesis
2.6.6 Degenerative Changes of the Posterior Elements
References
3: Common Spine Disorders Associated with Neck Pain
3.1 Cervical Spine Imaging in Patients with Neck Pain: What Should We Focus on?
3.2 Cervical Spondylotic Myelopathy
3.3 Cervical Spondylotic Radiculopathy
3.4 Herniated Intervertebral Disk
3.5 Illustrations: Common Spine Disorders Associated with Neck Pain
3.5.1 Cervical Spondylotic Myelopathy
3.5.2 Cervical Spondylotic Radiculopathy
3.5.3 Herniated Intervertebral Disk
References
4: Common Traumatic Disorders of the Thoracolumbar Spine
4.1 Stable and Unstable Spinal Injuries
4.2 Major Thoracolumbar Injury: Denis Classification
4.3 Benign Osteoporotic Versus Malignant Compression Fractures
4.4 Sacral Insufficiency Fractures
4.5 AO Classification
4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine
4.6.1 Compression Fractures
4.6.2 Burst Fractures
4.6.3 Distraction Injury
4.6.4 Malignant Spine Fracture Due to Metastasis
4.6.5 Sacral Insufficiency Fracture
References
5: MR Imaging of Spinal Bone Marrow
5.1 Marrow Conversion in the Spine
5.2 Inhomogeneous Marrow Signal on MR Images
5.3 Marrow Infiltrative Disorders: Proliferative, Replacement, Depletion Disorders
5.4 Illustrations: MR Imaging of Spinal Bone Marrow
5.4.1 Marrow Conversion
5.4.2 Inhomogeneous Bone Marrow Signal
5.4.3 Marrow Infiltrative Disorders
References
6: Common Normal Structures and MR Imaging Artifacts of the Spine that May Mimic Pathology
6.1 Common Normal Structures and Variants Mimicking Spinal Disorders on MRI
6.2 Common MR Artifacts on Spinal Imaging
6.2.1 Chemical Shift Artifact
6.2.2 Susceptibility Artifacts Due to Metallic Implants
6.2.3 Truncation Artifacts
6.2.4 Aliasing Artifacts
6.2.5 Motion-Related Artifacts
6.2.6 Saturation Artifact
6.2.7 Artifacts Due to Radio-Frequency Interference
6.2.8 Artifacts Due to Incomplete Fat Saturation
6.3 Illustrations: Common Normal Structures and MR Imaging Artifacts of the Spine that May Mimic Pathology
6.3.1 Common Normal Structures and Variants Mimicking Spinal Disorders on MRI
6.3.2 Chemical Shift Artifact
6.3.3 Susceptibility Artifact Due to Metallic Implants
6.3.4 Truncation Artifact
6.3.5 Aliasing Artifact
6.3.6 Motion-Related Artifacts
6.3.7 Saturation Artifact
6.3.8 Artifacts Due to Radio-Frequency Interference
6.3.9 Artifacts Due to Incomplete Fat Saturation
References
7: Postoperative Imaging
7.1 Immediate Postoperative MR Findings After Decompression Surgery
7.2 Normal Post-Diskectomy Changes Versus Residual Disk Herniation
7.3 Normal Postoperative Change Versus Early Postoperative Infection
7.4 Postoperative Scarring Versus Recurrent Disk Herniation
7.5 Postoperative Pseudomeningocele Versus Postoperative Fluid Collection
7.6 Fusion Versus Pseudoarthrosis
7.7 Adjacent Segment Degeneration
7.8 Illustrations: Postoperative Imaging
7.8.1 Normal Postoperative Changes
7.8.2 Postoperative Infection
7.8.3 Postoperative Scarring Versus Recurrent Disk Herniation
7.8.4 Postoperative Pseudomeningocele Versus Postoperative Fluid Collection
7.8.5 Fusion Versus Pseudoarthrosis
7.8.6 Miscellaneous Postoperative Complications
References
Part II: Intermediate Step: Critical Spinal Disorders
8: Infectious Spondylitis
8.1 Pathophysiology
8.2 Pyogenic Spondylitis
8.3 Tuberculous Spondylitis
8.4 Fungal Infections
8.5 Brucellar Spondylitis
8.6 Illustrations: Infectious Spondylitis
8.6.1 Pyogenic Spondylitis
8.6.2 Tuberculous Spondylitis
8.6.3 Fungal Spondylitis
8.6.4 Brucellar Spondylitis
References
9: Cervical Trauma
9.1 Upper Cervical Spine (Occiput (C0)–C1–C2)
9.1.1 Atlanto-Occipital Dislocation
9.1.2 Atlas Fracture
9.1.3 Atlantoaxial Rotatory Fixation
9.1.4 Odontoid Process (Dens) Fractures
9.1.5 Hangman’s Fracture
9.2 Lower (Subaxial) Cervical Spine (C3–C7)
9.2.1 Flexion Injuries
Simple Wedge Compression Fracture
Flexion Teardrop Fracture
Anterior Subluxation
Bilateral Facet Dislocation
Clay Shoveler Fracture
9.2.2 Flexion-Rotation Injuries (Unilateral Facet Dislocation)
9.2.3 Extension Injuries
9.2.4 Vertical Compression Injuries
9.3 Subaxial Cervical Spine Injury Classification System (SLICS)
9.4 AO Classification
9.5 Spinal Cord Injury
9.6 Epidural Versus Subdural Hematoma
9.7 Subarachnoid Hemorrhage
9.8 Illustration: Cervical Trauma
9.8.1 Atlanto-Occipital Dislocation
9.8.2 Atlas Fracture
9.8.3 Atlantoaxial Rotatory Fixation
9.8.4 Odontoid Process Fractures
9.8.5 Hangman’s Fractures
9.8.6 Hyperflexion Injury of Cervical Spine
9.8.7 Hyperextension Injury of Cervical Spine
9.8.8 Subaxial Cervical Spine Injury Classification System (SLICS)
9.8.9 AO Classification
9.8.10 Spinal Cord Injury
9.8.11 Intraspinal Hemorrhage
References
10: Spinal Cord Disorder
10.1 Spinal Cord Tumors Versus Nonneoplastic Myelopathies
10.2 Common Neoplasms of the Spinal Cord
10.2.1 Ependymoma Versus Astrocytoma
10.2.2 Hemangioblastoma
10.3 Acute Transverse Myelitis Versus Multiple Sclerosis
10.4 Neuromyelitis Optica Spectrum Disorder
10.5 Myelitis Associated with Myelin Oligodendrocyte Glycoprotein Autoantibody (MOG-IgG)
10.6 Acute Disseminated Encephalomyelitis (ADEM)
10.7 Acute Spinal Cord Infarction
10.8 Syringomyelia
10.9 COVID-19 Associated Spinal Neurologic Complications
10.10 Illustration: Spinal Cord Disorder
10.10.1 Common Neoplasms of the Spinal Cord
10.10.2 Acute Transverse Myelitis
10.10.3 Multiple Sclerosis
10.10.4 Neuromyelitis Optica Spectrum Disorder
10.10.5 Myelitis Associated with Myelin Oligodendrocyte Glycoprotein Autoantibody (MOG-IgG)
10.10.6 Acute Disseminated Encephalomyelitis
10.10.7 Acute Spinal Cord Infarction
10.10.8 Subacute Combined Degeneration
10.10.9 Compressive Myelopathy
10.10.10 Syringomyelia
10.10.11 COVID-19 Associated Spinal Neurologic Complications
References
11: Spinal Tumor
11.1 Diagnosis for Spinal and Spinal Cord Tumors
11.1.1 Compartment Approach
Extradural Vs Intradural Tumor
Intradural Extramedullary Vs Intramedullary Tumor
11.1.2 Pathologic Approach
Fat Component
Red Marrow Component
Vascular Component
High Cellularity
Hemorrhagic Component
Calcification/Ossification
11.1.3 Multiplicity
11.1.4 Clinical Information
11.1.5 Location
11.1.6 Margins
11.1.7 Pattern of Morphology
11.1.8 Signal Intensity
11.2 Osseous Tumors
11.2.1 Most Common Osseous Tumors
Hemangioma
Metastasis
Hematologic Malignancy (Multiple Myeloma/Leukemia/Lymphoma)
11.2.2 Primary Spinal Benign Osseous Tumor
Bone Island
Osteoid Osteoma
Osteoblastoma
Aneurysmal Bone Cyst (ABC)
Benign Notochordal Cell Tumor (BNCT)
Giant Cell Tumor (GCT)
Osteochondroma (Exostosis)
11.2.3 Primary Spinal Malignant Tumor
Chordoma
Chondrosarcoma
Osteosarcoma
Ewing Sarcoma and Primitive Neuroectodermal Tumor (PNET)
11.3 Extradural Non-osseous Tumor
11.3.1 Common Extradural Non-osseous Tumor
Peripheral Nerve Sheath Tumor (Schwannoma, Neurofibroma)
11.3.2 Other Extradural Non-osseous Tumor
Angiolipoma
11.4 Intradural Extramedullary Tumor
11.4.1 Common Intradural Extramedullary Tumor
Peripheral Nerve Sheath Tumor (Schwannoma, Neurofibroma)
Meningioma
11.4.2 Other Intradural Extramedullary Tumor
Intradural Lipoma
Myxopapillary Ependymoma
Paraganglioma
Leptomeningeal Seeding
11.5 Intramedullary Tumor
11.5.1 Common Intramedullary Tumor
Ependymoma
Astrocytoma
Hemangioblastoma
11.5.2 Other Intramedullary Tumor
Cavernous Hemangioma
Intramedullary Metastasis
11.6 Illustration: Tumor
11.6.1 Diagnosis for Spinal and Spinal Cord Tumors
11.6.2 Osseous Tumors
Hemangioma
Metastasis
Hematologic Malignancy (Multiple Myeloma/Leukemia/Lymphoma)
Multiple Myeloma
Leukemia
Lymphoma
Bone Island
Osteoid Osteoma
Osteoblastoma
Aneurysmal Bone Cyst (ABC)
Benign Notochordal Cell Tumor (BNCT)
Giant Cell Tumor (GCT)
Fibrous Dysplasia
Osteochondroma (Exostosis)
Langerhans Cell Histiocytosis
Chordoma
Chondrosarcoma
Osteosarcoma
Ewing Sarcoma and Primitive Neuroectodermal Tumor (PNET)
11.6.3 Extradural Non-osseous Tumor
Peripheral Nerve Sheath Tumor (Schwannoma, Neurofibroma)
Angiolipoma
11.6.4 Intradural Extramedullary Tumor
Peripheral Nerve Sheath Tumor (Schwannoma, Neurofibroma)
Meningioma
Intradural Lipoma
Myxopapillary Ependymoma
Paraganglioma
Leptomeningeal Seeding
11.6.5 Intramedullary Tumor
Ependymoma
Astrocytoma
Hemangioblastoma
Cavernous Hemangioma
Intramedullary Metastasis
References
12: Congenital Disorder
12.1 Embryology
12.2 Myelocele/Myelomeningocele
12.3 Lipomyelocele/Lipomyelomeningocele
12.4 Meningocele
12.5 Myelocystocele
12.6 Intradural Lipoma/Fibrolipoma of the Filum Terminale
12.7 Dorsal Dermal Sinus
12.8 Diastematomyelia
12.9 Neurenteric Cyst
12.10 Caudal Regression Syndrome
12.11 Tethered Cord Syndrome
12.12 Congenital Vertebral Anomalies
12.13 Illustration: Congenital Disorder
12.13.1 Myelocele/Myelomeningocele
12.13.2 Lipomyelocele/Lipomyelomeningocele
12.13.3 Intradural Lipoma/Lipoma of the Filum Terminale
12.13.4 Dorsal Dermal Sinus
12.13.5 Diastematomyelia
12.13.6 Neurenteric Cyst
12.13.7 Caudal Regression Syndrome
12.13.8 Congenital Vertebral Anomalies
References
13: Uncommon Degenerative Disorder
13.1 Ossification of the Posterior Longitudinal Ligament (OPLL)
13.2 Ossification of the Ligamentum Flavum (OLF)
13.3 Diffuse Idiopathic Skeletal Hyperostosis (DISH)
13.4 Scheuermann’s Disease
13.5 Baastrup’s Disease
13.6 Epidural Lipomatosis
13.7 Illustration: Uncommon Degenerative Disorder
13.7.1 Ossification of Posterior Longitudinal Ligament (OPLL)
13.7.2 Ossification of Ligamentum Flavum
13.7.3 Diffuse Idiopathic Skeletal Hyperostosis (DISH)
13.7.4 Scheuermann’s Disease
13.7.5 Baastrup’s Disease
13.7.6 Epidural Lipomatosis
References
14: Inflammatory Arthritis
14.1 Spondyloarthropathy
14.1.1 Ankylosing Spondylitis
Sacroiliac Joint
Spine
14.1.2 Psoriatic Arthritis
14.2 SAPHO Syndrome
14.3 Rheumatoid Arthritis
14.4 Illustrations: Inflammatory Arthritis
14.4.1 Ankylosing Spondylitis
14.4.2 Psoriatic Arthritis
14.4.3 SAPHO Syndrome
14.4.4 Rheumatoid Arthritis
References
15: Spinal Vascular Malformation
15.1 Vascular Anatomy and Imaging Modalities
15.2 Dural Arteriovenous (AV) Fistula
15.3 Spinal Cord Arteriovenous Malformation (AVM)
15.4 Juxtamedullary (Perimedullary) AV Fistula
15.5 Intramedullary Cavernous Hemangioma
15.6 Illustrations: Inflammatory Arthritides
15.6.1 Normal Vascular Anatomy and Schematic Diagrams
15.6.2 Dural Arteriovenous Fistula
15.6.3 Spinal Arteriovenous Malformation
15.6.4 Spinal Perimedullary Arteriovenous Fistula
15.6.5 Spinal Cord Cavernous Angioma
References
Part III: Rare But Characteristic Spinal Disorders
16: Rare but Characteristic Spinal Disorders: Musculoskeletal
16.1 Neuropathic Arthropathy of the Spine
16.2 Abdominal Aortic Aneurysm Causing Vertebral Body Destruction
16.3 Benign Notochordal Cell Tumor
16.4 Os Odontoideum/Ossiculum Terminale
16.5 Condylus Tertius
16.6 Paget Disease
16.7 Rhabdomyolysis of the Back Muscles
16.8 Calcific Tendinitis of Longus Colli
16.9 Neural Arch Clefts
16.10 Serous Atrophy of Bone Marrow
16.11 Illustrations: Rare but Characteristic Spinal Disorders: Musculoskeletal
16.11.1 Neuropathic Arthropathy of the Spine
16.11.2 Abdominal Aortic Aneurysm Causing Vertebral Body Destruction
16.11.3 Benign Notochordal Cell Tumor
16.11.4 Os Odontoideum/Ossiculum Terminale
16.11.5 Condylus Tertius
16.11.6 Paget Disease
16.11.7 Rhabdomyolysis of the Back Muscles
16.11.8 Calcific Tendinitis of Longus Colli
16.11.9 Neural Arch Clefts
16.11.10 Serous Atrophy of Bone Marrow
References
17: Rare but Characteristic Spinal Disorders: Neural
17.1 Idiopathic Spinal Cord Herniation
17.2 Hirayama Disease
17.3 Subacute Combined Degeneration
17.4 Radiation Myelitis
17.5 Spinal Visceral Larva Migrans of Toxocara Canis
17.6 Conjoined Nerve Root
17.7 Guillain–Barré Syndrome
17.8 Hereditary Motor and Sensory Neuropathies (HMSN)
17.9 Surfer’s Myelopathy
17.10 Wallerian Degeneration of the Spinal Cord
17.11 Illustrations: Rare but Characteristic Spinal Disorders: Neural
17.11.1 Idiopathic Spinal Cord Herniation
17.11.2 Hirayama Disease
17.11.3 Subacute Combined Degeneration
17.11.4 Radiation Myelitis
17.11.5 Spinal Visceral Lava Migrans of Toxocara Canis
17.11.6 Conjoined Nerve Root
17.11.7 Guillain–Barré Syndrome
17.11.8 Hereditary Motor and Sensory Neuropathies
17.11.9 Surfer’s Myelopathy
17.11.10 Wallerian Degeneration of the Spinal Cord
References
18: Rare but Characteristic Spinal Disorders: Miscellaneous
18.1 Neurofibromatosis
18.2 Marfan Syndrome
18.3 Idiopathic Hypertrophic Pachymeningitis
18.4 Spontaneous Intracranial Hypotension
18.5 Superficial Siderosis Caused by Spinal Tumor
18.6 Spinal Arachnoid Cysts
18.7 Renal Osteodystrophy
18.8 Extramedullary Hematopoiesis
18.9 Rosai–Dorfman Disease of the Spine
18.10 Tumoral Calcinosis
18.11 Illustrations: Rare but Characteristic Spinal Disorders: Miscellaneous
18.11.1 Neurofibromatosis
18.11.2 Marfan Syndrome
18.11.3 Idiopathic Hypertrophic Pachymeningitis
18.11.4 Spontaneous Intracranial Hypotension
18.11.5 Superficial Siderosis Caused by Spinal Tumor
18.11.6 Spinal Arachnoid Cysts
18.11.7 Renal Osteodystrophy
18.11.8 Extramedullary Hematopoiesis
18.11.9 Rosai–Dorfman Disease of the Spine
18.11.10 Tumoral Calcinosis
References
Part IV: Similar Spinal Disorders
19: Practical Tips for Differential Diagnosis
19.1 Introduction
19.2 Herniated Disk (Sequestration) Versus Schwannoma
19.3 Spondylolytic Spondylolisthesis Versus Degenerative Spondylolisthesis
19.4 Focal Red Marrow Versus Metastasis
19.5 Postoperative Scar Versus Recurrent Disk Herniation
19.6 Benign Vertebral Fracture Versus Malignant Vertebral Fracture
19.7 Os Odontoideum Versus Odontoid Process Fracture
19.8 Neurofibromatosis Type 1 Versus Type 2
19.9 Infectious Spondylitis Versus Modic Type 1
19.10 Spinal Cord Herniation Versus Intradural Arachnoid Cyst
19.11 Spinal Arteriovenous Fistula Versus Hypervascular Tumor with Intratumoral Shunt
19.12 Ankylosing Spondylitis (AS) Versus Diffuse Idiopathic Skeletal Hyperostosis (DISH)
19.13 Pyogenic Spondylitis Versus Tuberculous Spondylitis
19.14 Spinal Cord Tumor Versus Nonneoplastic Myelopathy
19.15 Acute Transverse Myelitis Versus Multiple Sclerosis
19.16 Ependymoma Versus Astrocytoma
19.17 Schwannoma Versus Meningioma
19.18 Sacral Tumors: Chordoma Versus Giant Cell Tumor
19.19 Vertebral Hemangioma Versus Paget Disease
19.20 Sacroiliitis of Spondyloarthropathy Versus Osteitis Condensans Ilii
19.21 Sacral Insufficiency Fracture Versus Sacral Osteomyelitis
19.22 Osteochondroma Versus Osteophyte
Index

Citation preview

Joon Woo Lee Eugene Lee Heung Sik Kang

Spine Second Edition

Radiology Illustrated

The open series ‘Radiology Illustrated’ is a comprehensive, up-to-date and richly illustrated visual reference designed specifically to be of value in clinical practice. It provides a practical guide to the diagnostic imaging in real clinical situations and covers current imaging modalities. Every volume is written by experts in the field, and it has covered following topics so far: Uroradiology, Gynecologic Imaging, Pediatric Radiology, Hepatobiliary and pancreatic radiology, Spinal Imaging and Chest Radiology.

Joon Woo Lee • Eugene Lee • Heung Sik Kang

Radiology Illustrated: Spine Second Edition

Joon Woo Lee Department of Radiology Seoul National University Bundang Hospital Seongnam, Kyonggi-do, Korea (Republic of)

Eugene Lee Department of Radiology Seoul National University Bundang Hospital Seongnam, Kyonggi-do, Korea (Republic of)

Heung Sik Kang Department of Radiology Seoul National University Bundang Hospital Seongnam, Kyonggi-do, Korea (Republic of)

ISSN 2196-114X     ISSN 2196-1158 (electronic) Radiology Illustrated ISBN 978-981-99-6611-0    ISBN 978-981-99-6612-7 (eBook) https://doi.org/10.1007/978-981-99-6612-7 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2014, 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore Printed on acid-free paper

Preface

Spinal disorders constitute one of the most commonly encountered ailments, affecting up to 80% of the population worldwide, and are a major cause of disability and economic loss. The prevalence of spinal problems has increased significantly with a growing proportion of elderly people in the general population. Correspondingly, many physicians and radiologists face a large workload of spinal imaging as part of their daily practice. There is however a limited number of textbooks available for clinicians and radiology trainees who are interested in embarking on a self-learning course in spinal imaging interpretation. With this point in mind, Radiology Illustrated: Spine, first edition, was published in 2014. Radiology Illustrated: Spine aims to cover most of the common and critical spinal disorders by presenting numerous representative cases and providing practical tips. This book also addresses many of the common questions that have been asked of the authors by their clinical colleagues over the course of their years of practice. There are two characteristic features of Radiology Illustrated: Spine. First, this book is aimed to facilitate self-learning. To enhance the reader’s understanding of key concepts, many tables, figures, and schematic illustrations are included. We provide essential practical tips from three experienced radiologists and present up-to-date information of critical and distinctive spinal disorders. Second, this book focuses on entities that would expectedly be seen in the course of routine practice rather than the esoteric. The book starts off by presenting the common spinal disorders and concludes by describing differential points between similar spinal disorders. Radiology Illustrated: Spine, second edition, incorporates concepts of spinal disorders that have evolved or newly emerged over a span of approximately 10 years. The second edition covers updated knowledge on spine imaging interpretation, including disc nomenclature version 2.0, AO classification for spine trauma, neuromyelitis optica spectrum disorders, COVID-­19 vaccine-related spine disorder, and more. The third part of the book includes a variety of interesting cases that demonstrate characteristic imaging features. In particular, the chapter related to spinal tumors has undergone significant revisions and additions in content. This book is intended for all physicians and radiologists caring for patients with spinal problems. We hope readers will be as richly rewarded on this self-learning journey from the first through to the last case as it has been for the authors over the course of preparation of this book. Finally, we thank Dr. Jiyoung Suh and Hyo Jin Kim for their assistance in preparing of the manuscript. Seongnam, Kyonggi-do, Korea, South Korea Seongnam, Kyonggi-do, Korea, South Korea  Seongnam, Kyonggi-do, Korea, South Korea 

Joon Woo Lee Eugene Lee Heung Sik Kang

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Contents

Part I Basic Step: Common Spinal Disorders 1 Anatomic  Considerations of the Spine���������������������������������������������������������������������   3 1.1 Osseous Structure and Facet (Zygapophyseal) Joints�����������������������������������������   4 1.2 Intervertebral Disk�����������������������������������������������������������������������������������������������   4 1.3 Uncovertebral Joint (Joint of Luschka)���������������������������������������������������������������   4 1.4 Central Canal and Neural Foramen���������������������������������������������������������������������   5 1.5 Spinal Cord, Conus Medullaris, Cauda Equina, and Spinal Nerve Roots�����������   5 1.6 Ligaments�������������������������������������������������������������������������������������������������������������   5 1.7 Illustrations: Anatomic Considerations of the Spine�������������������������������������������   6 1.7.1 Normal Anatomy of the Spine�����������������������������������������������������������������   6 1.7.2 Intervertebral Disk and Ligamentous Anatomy on MR���������������������������   9 1.7.3 Cervical Spine Anatomy �������������������������������������������������������������������������  11 1.7.4 Spinal Cord and Nerve Root Anatomy ���������������������������������������������������  12 References���������������������������������������������������������������������������������������������������������������������  15 2 Common  Spine Disorders Associated with Back Pain���������������������������������������������  17 2.1 Lumbar Spine MR in Patients with Back Pain: What Should We Focus on?�����������������������������������������������������������������������������������������������������������������������  17 2.2 Herniated Intervertebral Disk������������������������������������������������������������������������������  18 2.3 Spinal Stenosis�����������������������������������������������������������������������������������������������������  19 2.4 Alignment Disorders (Spondylolisthesis, Scoliosis, Kyphosis)��������������������������  19 2.5 Degenerative Changes of the Posterior Elements (Facet Joint Arthrosis, Baastrup’s Phenomenon)�������������������������������������������������������������������������������������  20 2.6 Illustrations: Common Spine Disorders Associated with Back Pain�������������������  21 2.6.1 Schematic Illustrations of the Nomenclature for Disk Herniation����������  21 2.6.2 Herniated Intervertebral Disk �����������������������������������������������������������������  25 2.6.3 Lumbar Central Canal Stenosis���������������������������������������������������������������  39 2.6.4 Lumbar Foraminal Stenosis���������������������������������������������������������������������  43 2.6.5 Spondylolysis/Spondylolisthesis�������������������������������������������������������������  47 2.6.6 Degenerative Changes of the Posterior Elements �����������������������������������  56 References���������������������������������������������������������������������������������������������������������������������  60 3 Common  Spine Disorders Associated with Neck Pain���������������������������������������������  61 3.1 Cervical Spine Imaging in Patients with Neck Pain: What Should We Focus on?�������������������������������������������������������������������������������������������������������������  61 3.2 Cervical Spondylotic Myelopathy�����������������������������������������������������������������������  62 3.3 Cervical Spondylotic Radiculopathy�������������������������������������������������������������������  62 3.4 Herniated Intervertebral Disk������������������������������������������������������������������������������  63 3.5 Illustrations: Common Spine Disorders Associated with Neck Pain�������������������  64 3.5.1 Cervical Spondylotic Myelopathy�����������������������������������������������������������  64 3.5.2 Cervical Spondylotic Radiculopathy�������������������������������������������������������  70 3.5.3 Herniated Intervertebral Disk �����������������������������������������������������������������  79 vii

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References���������������������������������������������������������������������������������������������������������������������  83 4 Common  Traumatic Disorders of the Thoracolumbar Spine���������������������������������  85 4.1 Stable and Unstable Spinal Injuries���������������������������������������������������������������������  85 4.2 Major Thoracolumbar Injury: Denis Classification���������������������������������������������  86 4.3 Benign Osteoporotic Versus Malignant Compression Fractures�������������������������  87 4.4 Sacral Insufficiency Fractures�����������������������������������������������������������������������������  87 4.5 AO Classification�������������������������������������������������������������������������������������������������  88 4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine���������  91 4.6.1 Compression Fractures����������������������������������������������������������������������������  91 4.6.2 Burst Fractures�����������������������������������������������������������������������������������������  93 4.6.3 Distraction Injury�������������������������������������������������������������������������������������  97 4.6.4 Malignant Spine Fracture Due to Metastasis������������������������������������������� 101 4.6.5 Sacral Insufficiency Fracture������������������������������������������������������������������� 105 References��������������������������������������������������������������������������������������������������������������������� 113 5 MR  Imaging of Spinal Bone Marrow����������������������������������������������������������������������� 115 5.1 Marrow Conversion in the Spine������������������������������������������������������������������������� 115 5.2 Inhomogeneous Marrow Signal on MR Images ������������������������������������������������� 116 5.3 Marrow Infiltrative Disorders: Proliferative, Replacement, Depletion Disorders ������������������������������������������������������������������������������������������������������������� 116 5.4 Illustrations: MR Imaging of Spinal Bone Marrow��������������������������������������������� 118 5.4.1 Marrow Conversion��������������������������������������������������������������������������������� 118 5.4.2 Inhomogeneous Bone Marrow Signal����������������������������������������������������� 130 5.4.3 Marrow Infiltrative Disorders ����������������������������������������������������������������� 136 References��������������������������������������������������������������������������������������������������������������������� 139 6 Common  Normal Structures and MR Imaging Artifacts of the Spine that May Mimic Pathology����������������������������������������������������������������������������������������� 141 6.1 Common Normal Structures and Variants Mimicking Spinal Disorders on MRI ����������������������������������������������������������������������������������������������� 142 6.2 Common MR Artifacts on Spinal Imaging ��������������������������������������������������������� 142 6.2.1 Chemical Shift Artifact ��������������������������������������������������������������������������� 142 6.2.2 Susceptibility Artifacts Due to Metallic Implants����������������������������������� 142 6.2.3 Truncation Artifacts��������������������������������������������������������������������������������� 142 6.2.4 Aliasing Artifacts������������������������������������������������������������������������������������� 143 6.2.5 Motion-Related Artifacts������������������������������������������������������������������������� 143 6.2.6 Saturation Artifact����������������������������������������������������������������������������������� 143 6.2.7 Artifacts Due to Radio-Frequency Interference��������������������������������������� 143 6.2.8 Artifacts Due to Incomplete Fat Saturation��������������������������������������������� 143 6.3 Illustrations: Common Normal Structures and MR Imaging Artifacts of the Spine that May Mimic Pathology ������������������������������������������������������������� 145 6.3.1 Common Normal Structures and Variants Mimicking Spinal Disorders on MRI ����������������������������������������������������������������������������������� 145 6.3.2 Chemical Shift Artifact ��������������������������������������������������������������������������� 147 6.3.3 Susceptibility Artifact Due to Metallic Implants������������������������������������� 148 6.3.4 Truncation Artifact����������������������������������������������������������������������������������� 152 6.3.5 Aliasing Artifact��������������������������������������������������������������������������������������� 153 6.3.6 Motion-Related Artifacts������������������������������������������������������������������������� 154 6.3.7 Saturation Artifact����������������������������������������������������������������������������������� 161 6.3.8 Artifacts Due to Radio-Frequency Interference��������������������������������������� 162 6.3.9 Artifacts Due to Incomplete Fat Saturation��������������������������������������������� 163 References��������������������������������������������������������������������������������������������������������������������� 164

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7 Postoperative Imaging ����������������������������������������������������������������������������������������������� 165 7.1 Immediate Postoperative MR Findings After Decompression Surgery��������������� 166 7.2 Normal Post-Diskectomy Changes Versus Residual Disk Herniation����������������� 166 7.3 Normal Postoperative Change Versus Early Postoperative Infection ����������������� 166 7.4 Postoperative Scarring Versus Recurrent Disk Herniation ��������������������������������� 166 7.5 Postoperative Pseudomeningocele Versus Postoperative Fluid Collection��������� 167 7.6 Fusion Versus Pseudoarthrosis����������������������������������������������������������������������������� 167 7.7 Adjacent Segment Degeneration������������������������������������������������������������������������� 167 7.8 Illustrations: Postoperative Imaging ������������������������������������������������������������������� 169 7.8.1 Normal Postoperative Changes��������������������������������������������������������������� 169 7.8.2 Postoperative Infection ��������������������������������������������������������������������������� 175 7.8.3 Postoperative Scarring Versus Recurrent Disk Herniation ��������������������� 178 7.8.4 Postoperative Pseudomeningocele Versus Postoperative Fluid Collection������������������������������������������������������������������������������������������������� 183 7.8.5 Fusion Versus Pseudoarthrosis����������������������������������������������������������������� 187 7.8.6 Miscellaneous Postoperative Complications������������������������������������������� 192 References��������������������������������������������������������������������������������������������������������������������� 199 Part II Intermediate Step: Critical Spinal Disorders 8 Infectious Spondylitis������������������������������������������������������������������������������������������������� 203 8.1 Pathophysiology��������������������������������������������������������������������������������������������������� 203 8.2 Pyogenic Spondylitis������������������������������������������������������������������������������������������� 204 8.3 Tuberculous Spondylitis ������������������������������������������������������������������������������������� 205 8.4 Fungal Infections������������������������������������������������������������������������������������������������� 206 8.5 Brucellar Spondylitis������������������������������������������������������������������������������������������� 206 8.6 Illustrations: Infectious Spondylitis��������������������������������������������������������������������� 208 8.6.1 Pyogenic Spondylitis������������������������������������������������������������������������������� 208 8.6.2 Tuberculous Spondylitis ������������������������������������������������������������������������� 214 8.6.3 Fungal Spondylitis����������������������������������������������������������������������������������� 223 8.6.4 Brucellar Spondylitis������������������������������������������������������������������������������� 226 References��������������������������������������������������������������������������������������������������������������������� 227 9 Cervical Trauma��������������������������������������������������������������������������������������������������������� 229 9.1 Upper Cervical Spine (Occiput (C0)–C1–C2)����������������������������������������������������� 230 9.1.1 Atlanto-Occipital Dislocation ����������������������������������������������������������������� 230 9.1.2 Atlas Fracture������������������������������������������������������������������������������������������� 230 9.1.3 Atlantoaxial Rotatory Fixation ��������������������������������������������������������������� 230 9.1.4 Odontoid Process (Dens) Fractures��������������������������������������������������������� 230 9.1.5 Hangman’s Fracture��������������������������������������������������������������������������������� 231 9.2 Lower (Subaxial) Cervical Spine (C3–C7)��������������������������������������������������������� 231 9.2.1 Flexion Injuries ��������������������������������������������������������������������������������������� 231 9.2.2 Flexion-Rotation Injuries (Unilateral Facet Dislocation) ����������������������� 232 9.2.3 Extension Injuries ����������������������������������������������������������������������������������� 232 9.2.4 Vertical Compression Injuries����������������������������������������������������������������� 232 9.3 Subaxial Cervical Spine Injury Classification System (SLICS) ������������������������� 233 9.4 AO Classification������������������������������������������������������������������������������������������������� 233 9.5 Spinal Cord Injury����������������������������������������������������������������������������������������������� 235 9.6 Epidural Versus Subdural Hematoma ����������������������������������������������������������������� 236 9.7 Subarachnoid Hemorrhage����������������������������������������������������������������������������������� 236 9.8 Illustration: Cervical Trauma������������������������������������������������������������������������������� 237 9.8.1 Atlanto-Occipital Dislocation ����������������������������������������������������������������� 237

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9.8.2 Atlas Fracture������������������������������������������������������������������������������������������� 238 9.8.3 Atlantoaxial Rotatory Fixation ��������������������������������������������������������������� 240 9.8.4 Odontoid Process Fractures��������������������������������������������������������������������� 241 9.8.5 Hangman’s Fractures������������������������������������������������������������������������������� 244 9.8.6 Hyperflexion Injury of Cervical Spine����������������������������������������������������� 247 9.8.7 Hyperextension Injury of Cervical Spine ����������������������������������������������� 253 9.8.8 Subaxial Cervical Spine Injury Classification System (SLICS) ������������� 255 9.8.9 AO Classification������������������������������������������������������������������������������������� 257 9.8.10 Spinal Cord Injury����������������������������������������������������������������������������������� 259 9.8.11 Intraspinal Hemorrhage��������������������������������������������������������������������������� 265 References��������������������������������������������������������������������������������������������������������������������� 271 10 Spinal Cord Disorder������������������������������������������������������������������������������������������������� 273 10.1 Spinal Cord Tumors Versus Nonneoplastic Myelopathies��������������������������������� 274 10.2 Common Neoplasms of the Spinal Cord����������������������������������������������������������� 274   10.2.1 Ependymoma Versus Astrocytoma ������������������������������������������������������� 274   10.2.2 Hemangioblastoma ������������������������������������������������������������������������������� 275 10.3 Acute Transverse Myelitis Versus Multiple Sclerosis��������������������������������������� 275 10.4 Neuromyelitis Optica Spectrum Disorder��������������������������������������������������������� 276 10.5 Myelitis Associated with Myelin Oligodendrocyte Glycoprotein Autoantibody (MOG-IgG)��������������������������������������������������������������������������������� 276 10.6 Acute Disseminated Encephalomyelitis (ADEM)��������������������������������������������� 277 10.7 Acute Spinal Cord Infarction����������������������������������������������������������������������������� 277 10.8 Syringomyelia ��������������������������������������������������������������������������������������������������� 277 10.9 COVID-19 Associated Spinal Neurologic Complications��������������������������������� 277 10.10 Illustration: Spinal Cord Disorder��������������������������������������������������������������������� 278 10.10.1 Common Neoplasms of the Spinal Cord������������������������������������������� 278 10.10.2 Acute Transverse Myelitis����������������������������������������������������������������� 286 10.10.3 Multiple Sclerosis ����������������������������������������������������������������������������� 289 10.10.4 Neuromyelitis Optica Spectrum Disorder����������������������������������������� 292 10.10.5 Myelitis Associated with Myelin Oligodendrocyte Glycoprotein Autoantibody (MOG-IgG)������������������������������������������� 294 10.10.6 Acute Disseminated Encephalomyelitis ������������������������������������������� 296 10.10.7 Acute Spinal Cord Infarction������������������������������������������������������������� 297 10.10.8 Subacute Combined Degeneration���������������������������������������������������� 302 10.10.9 Compressive Myelopathy ����������������������������������������������������������������� 303 10.10.10 Syringomyelia����������������������������������������������������������������������������������� 305 10.10.11 COVID-19 Associated Spinal Neurologic Complications����������������� 309 References��������������������������������������������������������������������������������������������������������������������� 310 11 Spinal Tumor��������������������������������������������������������������������������������������������������������������� 311 11.1 Diagnosis for Spinal and Spinal Cord Tumors ������������������������������������������������� 312 11.1.1 Compartment Approach����������������������������������������������������������������������� 312 11.1.2 Pathologic Approach���������������������������������������������������������������������������� 312 11.1.3 Multiplicity������������������������������������������������������������������������������������������� 313 11.1.4 Clinical Information����������������������������������������������������������������������������� 313 11.1.5 Location����������������������������������������������������������������������������������������������� 313 11.1.6 Margins������������������������������������������������������������������������������������������������� 314 11.1.7 Pattern of Morphology������������������������������������������������������������������������� 314 11.1.8 Signal Intensity������������������������������������������������������������������������������������� 314 11.2 Osseous Tumors������������������������������������������������������������������������������������������������� 314 11.2.1 Most Common Osseous Tumors���������������������������������������������������������� 314 11.2.2 Primary Spinal Benign Osseous Tumor����������������������������������������������� 316

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11.2.3 Primary Spinal Malignant Tumor��������������������������������������������������������� 319 11.3 Extradural Non-osseous Tumor������������������������������������������������������������������������� 320 11.3.1 Common Extradural Non-osseous Tumor ������������������������������������������� 320 11.3.2 Other Extradural Non-osseous Tumor������������������������������������������������� 320 11.4 Intradural Extramedullary Tumor ��������������������������������������������������������������������� 320 11.4.1 Common Intradural Extramedullary Tumor����������������������������������������� 320 11.4.2 Other Intradural Extramedullary Tumor����������������������������������������������� 321 11.5 Intramedullary Tumor ��������������������������������������������������������������������������������������� 322 11.5.1 Common Intramedullary Tumor����������������������������������������������������������� 322 11.5.2 Other Intramedullary Tumor����������������������������������������������������������������� 323 11.6 Illustration: Tumor��������������������������������������������������������������������������������������������� 324 11.6.1 Diagnosis for Spinal and Spinal Cord Tumors������������������������������������� 324 11.6.2 Osseous Tumors����������������������������������������������������������������������������������� 326 11.6.3 Extradural Non-osseous Tumor ����������������������������������������������������������� 372 11.6.4 Intradural Extramedullary Tumor��������������������������������������������������������� 376 11.6.5 Intramedullary Tumor��������������������������������������������������������������������������� 384 References��������������������������������������������������������������������������������������������������������������������� 394 12 Congenital Disorder��������������������������������������������������������������������������������������������������� 395 12.1 Embryology������������������������������������������������������������������������������������������������������� 396 12.2 Myelocele/Myelomeningocele��������������������������������������������������������������������������� 396 12.3 Lipomyelocele/Lipomyelomeningocele ����������������������������������������������������������� 397 12.4 Meningocele������������������������������������������������������������������������������������������������������� 397 12.5 Myelocystocele ������������������������������������������������������������������������������������������������� 397 12.6 Intradural Lipoma/Fibrolipoma of the Filum Terminale����������������������������������� 397 12.7 Dorsal Dermal Sinus ����������������������������������������������������������������������������������������� 397 12.8 Diastematomyelia ��������������������������������������������������������������������������������������������� 397 12.9 Neurenteric Cyst ����������������������������������������������������������������������������������������������� 398 12.10 Caudal Regression Syndrome ��������������������������������������������������������������������������� 398 12.11 Tethered Cord Syndrome����������������������������������������������������������������������������������� 398 12.12 Congenital Vertebral Anomalies ����������������������������������������������������������������������� 398 12.13 Illustration: Congenital Disorder����������������������������������������������������������������������� 399 12.13.1 Myelocele/Myelomeningocele������������������������������������������������������������� 399 12.13.2 Lipomyelocele/Lipomyelomeningocele����������������������������������������������� 404 12.13.3 Intradural Lipoma/Lipoma of the Filum Terminale����������������������������� 409 12.13.4 Dorsal Dermal Sinus����������������������������������������������������������������������������� 413 12.13.5 Diastematomyelia��������������������������������������������������������������������������������� 415 12.13.6 Neurenteric Cyst����������������������������������������������������������������������������������� 417 12.13.7 Caudal Regression Syndrome��������������������������������������������������������������� 418 12.13.8 Congenital Vertebral Anomalies����������������������������������������������������������� 419 References��������������������������������������������������������������������������������������������������������������������� 421 13 Uncommon Degenerative Disorder��������������������������������������������������������������������������� 423 13.1 Ossification of the Posterior Longitudinal Ligament (OPLL)��������������������������� 423 13.2 Ossification of the Ligamentum Flavum (OLF) ����������������������������������������������� 424 13.3 Diffuse Idiopathic Skeletal Hyperostosis (DISH)��������������������������������������������� 424 13.4 Scheuermann’s Disease������������������������������������������������������������������������������������� 425 13.5 Baastrup’s Disease��������������������������������������������������������������������������������������������� 425 13.6 Epidural Lipomatosis����������������������������������������������������������������������������������������� 425 13.7 Illustration: Uncommon Degenerative Disorder����������������������������������������������� 426 13.7.1 Ossification of Posterior Longitudinal Ligament (OPLL)������������������� 426 13.7.2 Ossification of Ligamentum Flavum ��������������������������������������������������� 429 13.7.3 Diffuse Idiopathic Skeletal Hyperostosis (DISH) ������������������������������� 431

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13.7.4 Scheuermann’s Disease ����������������������������������������������������������������������� 435 13.7.5 Baastrup’s Disease������������������������������������������������������������������������������� 437 13.7.6 Epidural Lipomatosis��������������������������������������������������������������������������� 440 References��������������������������������������������������������������������������������������������������������������������� 441 14 Inflammatory Arthritis����������������������������������������������������������������������������������������������� 443 14.1 Spondyloarthropathy����������������������������������������������������������������������������������������� 443 14.1.1 Ankylosing Spondylitis ����������������������������������������������������������������������� 444 14.1.2 Psoriatic Arthritis��������������������������������������������������������������������������������� 445 14.2 SAPHO Syndrome��������������������������������������������������������������������������������������������� 445 14.3 Rheumatoid Arthritis����������������������������������������������������������������������������������������� 445 14.4 Illustrations: Inflammatory Arthritis ����������������������������������������������������������������� 447 14.4.1 Ankylosing Spondylitis ����������������������������������������������������������������������� 447 14.4.2 Psoriatic Arthritis��������������������������������������������������������������������������������� 459 14.4.3 SAPHO Syndrome������������������������������������������������������������������������������� 464 14.4.4 Rheumatoid Arthritis ��������������������������������������������������������������������������� 467 References��������������������������������������������������������������������������������������������������������������������� 471 15 Spinal Vascular Malformation����������������������������������������������������������������������������������� 473 15.1 Vascular Anatomy and Imaging Modalities������������������������������������������������������� 473 15.2 Dural Arteriovenous (AV) Fistula ��������������������������������������������������������������������� 474 15.3 Spinal Cord Arteriovenous Malformation (AVM)��������������������������������������������� 475 15.4 Juxtamedullary (Perimedullary) AV Fistula������������������������������������������������������� 475 15.5 Intramedullary Cavernous Hemangioma����������������������������������������������������������� 476 15.6 Illustrations: Inflammatory Arthritides ������������������������������������������������������������� 477 15.6.1 Normal Vascular Anatomy and Schematic Diagrams��������������������������� 477 15.6.2 Dural Arteriovenous Fistula����������������������������������������������������������������� 480 15.6.3 Spinal Arteriovenous Malformation����������������������������������������������������� 483 15.6.4 Spinal Perimedullary Arteriovenous Fistula����������������������������������������� 485 15.6.5 Spinal Cord Cavernous Angioma��������������������������������������������������������� 486 References��������������������������������������������������������������������������������������������������������������������� 488 Part III Rare But Characteristic Spinal Disorders 16 Rare  but Characteristic Spinal Disorders: Musculoskeletal����������������������������������� 491 16.1 Neuropathic Arthropathy of the Spine��������������������������������������������������������������� 492 16.2 Abdominal Aortic Aneurysm Causing Vertebral Body Destruction ����������������� 492 16.3 Benign Notochordal Cell Tumor����������������������������������������������������������������������� 492 16.4 Os Odontoideum/Ossiculum Terminale������������������������������������������������������������� 492 16.5 Condylus Tertius ����������������������������������������������������������������������������������������������� 493 16.6 Paget Disease����������������������������������������������������������������������������������������������������� 493 16.7 Rhabdomyolysis of the Back Muscles��������������������������������������������������������������� 493 16.8 Calcific Tendinitis of Longus Colli������������������������������������������������������������������� 493 16.9 Neural Arch Clefts��������������������������������������������������������������������������������������������� 494 16.10 Serous Atrophy of Bone Marrow����������������������������������������������������������������������� 494 16.11 Illustrations: Rare but Characteristic Spinal Disorders: Musculoskeletal��������� 496 16.11.1 Neuropathic Arthropathy of the Spine����������������������������������������������� 496 16.11.2 Abdominal Aortic Aneurysm Causing Vertebral Body Destruction����������������������������������������������������������������������������������������� 497 16.11.3 Benign Notochordal Cell Tumor������������������������������������������������������� 498 16.11.4 Os Odontoideum/Ossiculum Terminale��������������������������������������������� 499 16.11.5 Condylus Tertius ������������������������������������������������������������������������������� 502 16.11.6 Paget Disease������������������������������������������������������������������������������������� 504

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16.11.7 Rhabdomyolysis of the Back Muscles����������������������������������������������� 508 16.11.8 Calcific Tendinitis of Longus Colli��������������������������������������������������� 509 16.11.9 Neural Arch Clefts����������������������������������������������������������������������������� 513 16.11.10 Serous Atrophy of Bone Marrow������������������������������������������������������� 514 References��������������������������������������������������������������������������������������������������������������������� 515 17 Rare  but Characteristic Spinal Disorders: Neural ������������������������������������������������� 517 17.1 Idiopathic Spinal Cord Herniation��������������������������������������������������������������������� 518 17.2 Hirayama Disease ��������������������������������������������������������������������������������������������� 518 17.3 Subacute Combined Degeneration��������������������������������������������������������������������� 518 17.4 Radiation Myelitis��������������������������������������������������������������������������������������������� 519 17.5 Spinal Visceral Larva Migrans of Toxocara Canis��������������������������������������������� 519 17.6 Conjoined Nerve Root��������������������������������������������������������������������������������������� 519 17.7 Guillain–Barré Syndrome ��������������������������������������������������������������������������������� 520 17.8 Hereditary Motor and Sensory Neuropathies (HMSN)������������������������������������� 520 17.9 Surfer’s Myelopathy������������������������������������������������������������������������������������������� 520 17.10 Wallerian Degeneration of the Spinal Cord������������������������������������������������������� 521 17.11 Illustrations: Rare but Characteristic Spinal Disorders: Neural������������������������� 522 17.11.1 Idiopathic Spinal Cord Herniation����������������������������������������������������� 522 17.11.2 Hirayama Disease ����������������������������������������������������������������������������� 526 17.11.3 Subacute Combined Degeneration���������������������������������������������������� 528 17.11.4 Radiation Myelitis����������������������������������������������������������������������������� 531 17.11.5 Spinal Visceral Lava Migrans of Toxocara Canis����������������������������� 534 17.11.6 Conjoined Nerve Root����������������������������������������������������������������������� 536 17.11.7 Guillain–Barré Syndrome����������������������������������������������������������������� 539 17.11.8 Hereditary Motor and Sensory Neuropathies ����������������������������������� 542 17.11.9 Surfer’s Myelopathy ������������������������������������������������������������������������� 545 17.11.10 Wallerian Degeneration of the Spinal Cord��������������������������������������� 546 References��������������������������������������������������������������������������������������������������������������������� 547 18 Rare  but Characteristic Spinal Disorders: Miscellaneous ������������������������������������� 549 18.1 Neurofibromatosis��������������������������������������������������������������������������������������������� 550 18.2 Marfan Syndrome ��������������������������������������������������������������������������������������������� 550 18.3 Idiopathic Hypertrophic Pachymeningitis��������������������������������������������������������� 550 18.4 Spontaneous Intracranial Hypotension ������������������������������������������������������������� 550 18.5 Superficial Siderosis Caused by Spinal Tumor������������������������������������������������� 551 18.6 Spinal Arachnoid Cysts������������������������������������������������������������������������������������� 551 18.7 Renal Osteodystrophy��������������������������������������������������������������������������������������� 551 18.8 Extramedullary Hematopoiesis������������������������������������������������������������������������� 552 18.9 Rosai–Dorfman Disease of the Spine ��������������������������������������������������������������� 552 18.10 Tumoral Calcinosis ������������������������������������������������������������������������������������������� 552 18.11 Illustrations: Rare but Characteristic Spinal Disorders: Miscellaneous������������ 554 18.11.1 Neurofibromatosis����������������������������������������������������������������������������� 554 18.11.2 Marfan Syndrome ����������������������������������������������������������������������������� 560 18.11.3 Idiopathic Hypertrophic Pachymeningitis����������������������������������������� 561 18.11.4 Spontaneous Intracranial Hypotension ��������������������������������������������� 564 18.11.5 Superficial Siderosis Caused by Spinal Tumor��������������������������������� 566 18.11.6 Spinal Arachnoid Cysts��������������������������������������������������������������������� 567 18.11.7 Renal Osteodystrophy����������������������������������������������������������������������� 573 18.11.8 Extramedullary Hematopoiesis��������������������������������������������������������� 575 18.11.9 Rosai–Dorfman Disease of the Spine ����������������������������������������������� 577 18.11.10 Tumoral Calcinosis ��������������������������������������������������������������������������� 578 References��������������������������������������������������������������������������������������������������������������������� 579

xiv

Part IV Similar Spinal Disorders 19 Practical  Tips for Differential Diagnosis������������������������������������������������������������������� 583 19.1 Introduction������������������������������������������������������������������������������������������������������� 584 19.2 Herniated Disk (Sequestration) Versus Schwannoma��������������������������������������� 585 19.3 Spondylolytic Spondylolisthesis Versus Degenerative Spondylolisthesis��������� 586 19.4 Focal Red Marrow Versus Metastasis ��������������������������������������������������������������� 587 19.5 Postoperative Scar Versus Recurrent Disk Herniation��������������������������������������� 588 19.6 Benign Vertebral Fracture Versus Malignant Vertebral Fracture����������������������� 589 19.7 Os Odontoideum Versus Odontoid Process Fracture����������������������������������������� 590 19.8 Neurofibromatosis Type 1 Versus Type 2����������������������������������������������������������� 591 19.9 Infectious Spondylitis Versus Modic Type 1����������������������������������������������������� 592 19.10 Spinal Cord Herniation Versus Intradural Arachnoid Cyst ������������������������������� 593 19.11 Spinal Arteriovenous Fistula Versus Hypervascular Tumor with Intratumoral Shunt��������������������������������������������������������������������������������������������� 594 19.12 Ankylosing Spondylitis (AS) Versus Diffuse Idiopathic Skeletal Hyperostosis (DISH)����������������������������������������������������������������������������������������� 595 19.13 Pyogenic Spondylitis Versus Tuberculous Spondylitis ������������������������������������� 596 19.14 Spinal Cord Tumor Versus Nonneoplastic Myelopathy������������������������������������� 597 19.15 Acute Transverse Myelitis Versus Multiple Sclerosis��������������������������������������� 598 19.16 Ependymoma Versus Astrocytoma ������������������������������������������������������������������� 599 19.17 Schwannoma Versus Meningioma��������������������������������������������������������������������� 600 19.18 Sacral Tumors: Chordoma Versus Giant Cell Tumor����������������������������������������� 601 19.19 Vertebral Hemangioma Versus Paget Disease��������������������������������������������������� 602 19.20 Sacroiliitis of Spondyloarthropathy Versus Osteitis Condensans Ilii ��������������� 603 19.21 Sacral Insufficiency Fracture Versus Sacral Osteomyelitis������������������������������� 604 19.22 Osteochondroma Versus Osteophyte����������������������������������������������������������������� 605 Index������������������������������������������������������������������������������������������������������������������������������������� 607

Contents

Part I Basic Step: Common Spinal Disorders

1

Anatomic Considerations of the Spine

Contents 1.1   Osseous Structure and Facet (Zygapophyseal) Joints 

 4

1.2   Intervertebral Disk 

 4

1.3   Uncovertebral Joint (Joint of Luschka) 

 4

1.4   Central Canal and Neural Foramen 

 5

1.5   Spinal Cord, Conus Medullaris, Cauda Equina, and Spinal Nerve Roots 

 5

1.6   Ligaments 

 5

1.7   Illustrations: Anatomic Considerations of the Spine  1.7.1  Normal Anatomy of the Spine  1.7.2  Intervertebral Disk and Ligamentous Anatomy on MR  1.7.3  Cervical Spine Anatomy  1.7.4  Spinal Cord and Nerve Root Anatomy 

 6  6  9  11  12

References 

 15

Abstract

Keywords

Each vertebra is composed of a vertebral body, vertebral arch, and bony appendages. The superior and inferior articular processes make up the zygapophyseal (facet) joint. Each vertebra has two sets of facet joints. The pars interarticularis is the narrowed portion of the vertebral arch between the superior and inferior articular processes. The neural foramen is bounded by the pedicles of the corresponding upper and lower vertebral levels. Normally, the intervertebral disk shows central T2 hyperintensity and peripheral T2 hypointensity. The spinal nerve roots are named with respect to the corresponding lower vertebral level from C1 to C7 and to the corresponding upper vertebral level from T1 to S5, due to the C8 nerve root situated between the C7 and T1 vertebrae.

Vertebral body · Nerve root · Intervertebral disk · Nucleus pulposus · Facet joint

Each vertebra is composed of a vertebral body, vertebral arch, and bony appendages. The superior and inferior articular processes make up the zygapophyseal (facet) joint. Each vertebra has two sets of facet joints. The pars interarticularis is the narrowed portion of the vertebral arch between the superior and inferior articular processes. The neural foramen is bounded by the pedicles of the corresponding upper and lower vertebral levels. Normally, the intervertebral disk shows central T2 hyperintensity and peripheral T2 hypointensity. The spinal nerve roots are named with respect to the

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 J. W. Lee et al., Radiology Illustrated: Spine, Radiology Illustrated, https://doi.org/10.1007/978-981-99-6612-7_1

3

4

corresponding lower vertebral level from C1 to C7 and to the corresponding upper vertebral level from T1 to S5, due to the C8 nerve root situated between the C7 and T1 vertebrae.

1.1 Osseous Structure and Facet (Zygapophyseal) Joints The spine is made up of 32 or 33 vertebral segments, with 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 3–4 coccygeal vertebrae. Each vertebra is composed of a vertebral body, vertebral arch, and bony appendages. The vertebral body is comprised of outer cortical and inner trabecular bone, with bone marrow within the vertebral body. The vertebral arch is situated posterior to the vertebral body and made up of two pedicles anteriorly (one on each side) and the lamina posteriorly. The pedicle is composed of cortical bone and connects the vertebral body with the lamina. The transverse process and superior and inferior articular processes arise near the junction of the pedicle and lamina (LaMasters and Dorwart 1985). The pars interarticularis is the narrowed portion of bone between the superior and inferior articular processes. Spondylolysis refers to a defect of the pars interarticularis and mostly involves the lower lumbar spine (most frequently at L5) (Grogan et al. 1982; Grenier et al. 1989). The articulations of the spinal motion segment consist of the intervertebral disk in the anterior column and the zygapophyseal joints in the posterior column (Del Grande et al. 2012). The superior and inferior articular processes make up the zygapophyseal joint (Z-joint, or the so-called facet joint). Each vertebra has two sets of facet joints, one on each side. Facet joints are hinge-like and link adjacent vertebrae together. The facet joint is a true synovial joint containing hyaline cartilaginous articular surfaces and synovial fluid and is bounded by a joint capsule. The cervical facet joints are aligned mainly in a horizontal direction, while the thoracic and lumbar facet joints are mainly in a vertical direction. The thoracic facet joints are oriented in the coronal plane; the lumbar facets are orientated in the sagittal plane, with the upper lumbar facet joints in the parasagittal plane and the lower lumbar facet joints in an oblique sagittal plane directed anteromedially. In reality, most facet joints are oriented between the horizontal and vertical planes, thus allowing for some movement in each direction. The joint spaces and synovium of the lumbar facet joints extend beyond the margins of the articular surfaces in the majority of adults. Extensions of the synovium and joint space along the superior and inferior articular processes, under the ligamentum flavum and into the ligamentum flavum, may be recognized on MR and CT.  On the ventral aspect of the lumbar facet joint, MR images showed regions of T2 hyperintensity where the joint space extends into the ligamentum flavum or

1  Anatomic Considerations of the Spine

between the ligamentum flavum and lamina. On the dorsal aspect of the joint, MR demonstrates prominence of the fibrous joint capsule with the joint space extending under it along the inferior articular process or superior articular process (Xu et al. 1990).

1.2 Intervertebral Disk The major components of the intervertebral disk space are the hyaline cartilaginous endplates of the adjacent vertebral bodies, the gelatinous core of the intervertebral disk (nucleus pulposus), and its circumferential thick fibrous ring (annulus fibrosus) (Rumboldt 2006). The nucleus pulposus has high water content (85–90%) and performs the role of a shock absorber to distribute axial loading evenly to the outer annulus. Proteoglycans constitute about 65% of the dry weight of the nucleus with collagen comprising 15–20% (Del Grande et al. 2012). The annulus fibrosus is composed of about 20 fibrocartilaginous circular lamellae, containing part of the nucleus pulposus. The annulus fibrosus resists radial tension caused by axial loading, as well as resisting torsion and flexion. The normal intervertebral disk in adults is of slightly lower signal intensity than the bone marrow on T1-weighted images, with higher signal on T2-weighted images (Castillo et al. 1990). Normally, the intervertebral disk shows central T2 hyperintensity and peripheral T2 hypointensity. The central T2 hyperintensity area reflects the central nucleus pulposus and inner annulus fibrosus. A dark horizontal signal zone within the central high signal of the disk represents early degeneration of the nucleus pulposus, which is a common finding after the third decade of life (termed the “intranuclear cleft”) (Aguila et  al. 1985). The cartilaginous endplate is between 0.6 and 1.0 mm thick and composed of hyaline cartilage and fibrocartilage. As the disk degenerates, the fibrocartilage dominates. The endplate is tightly bound to the disk and less firmly fixed to the underlying subchondral bone. The intimate contact of the endplate with subchondral bone marrow is critical in nutrient diffusion of the disk through the cartilaginous endplate and nuclear matrix.

1.3 Uncovertebral Joint (Joint of Luschka) The intervertebral articulation consists of the intervertebral disk space and the two posterior facet (zygapophyseal) joints. In the cervical spine, there are additional lateral articulations between the vertebral bodies bilaterally known as the uncovertebral joints (joints of Luschka) (Rumboldt 2006). Each uncovertebral joint is composed of the uncinate process of the lower vertebral body and the lower surface of the upper vertebral body and is not a true synovial joint. The

1.6 Ligaments

uncinate process is a bony process projecting superiorly from posterolateral surface of the vertebral body. The uncovertebral joint is a special feature of the cervical spine from C3 to C7.

1.4 Central Canal and Neural Foramen The central canal is a tubular passage within the vertebrae along the length of the spine, surrounded by the vertebral bodies and neural arches. Within the central canal, there is a dural sac surrounded by the epidural space. The dural sac is a fluid-filled sac containing the cerebrospinal fluid, spinal cord, and spinal nerve roots. The epidural space is the space outside the dural sac and is composed of fatty tissue, venous plexus, and traversing nerve roots. The neural foramen (intervertebral foramen) is the bony opening through which the nerve roots exit the spine. There are two neural foramina located between each adjacent pair of vertebrae, one on each side. The neural foramen is bounded by the pedicles of the corresponding upper and lower vertebral levels. Within the neural foramen, the exiting nerve root is protected by surrounding perineural fat tissue. In the cervical spine, the neural foramen is orientated in an anterolateral direction, thus an ipsilateral oblique view will show the cervical neural foramen in its widest extent. The neural foramen opens up on the oblique view between the ipsilateral pedicles which are shown as a bridge-like configuration, while the contralateral pedicles are shown on end. In the thoracic and lumbar spine, the neural foramen is directed laterally; as such, the lateral view will show the neural foramen to its best advantage.

1.5 Spinal Cord, Conus Medullaris, Cauda Equina, and Spinal Nerve Roots The spinal cord represents the central nervous system within the dural sac. The spinal cord starts from the level of the foramen magnum and ends near the L1 to L2 level where it has a cone-shaped configuration known as the “conus medullaris.” There are two areas of spinal cord enlargement: the cervical enlargement and the lumbar enlargement. The cauda equina (“horse’s tail”) is the name given to the collection of nerve fibers located below the level of the conus medullaris. Each spinal nerve root is named with respect to the corresponding lower vertebral level from C1 to C7 (e.g., C6 nerve above C6 vertebra) and to the corresponding upper vertebral level from T1 to S5 (e.g., L4 nerve below L4 vertebra), due to the C8 nerve root between the C7 and T1 verte-

5

brae. In the lumbar spine, the descending nerve root is situated in the epidural space at the vertebral level above its exit. The lumbar nerve root then descends along the medial side of the pedicle of the same numbered vertebra and exits below the pedicle of same vertebra. For example, the L5 nerve root is located in the epidural space at the L4–5 disk level, descends along the medial side of the L5 pedicle, and finally exits below the L5 pedicle through the L5–S1 neural foramen. On MR, the spinal cord can be differentiated from CSF by its intermediate signal intensity on T1-weighted and T2-weighted images. The spinal cord normally terminates at the L1–L2 vertebral levels. The spinal nerve roots can be distinguished from surrounding fat as linear low signal intensity structures on either T1-weighted or T2-weighted images.

1.6 Ligaments The anterior longitudinal ligament covers the anterior portion of the vertebral bodies from the occipital base to S1. The anterior longitudinal ligament is tightly bounded to the vertebral bodies and intervertebral disks. The posterior longitudinal ligament covers the posterior portion of the vertebral bodies from C2 to S1 levels and continues proximally to form the tectorial membrane. The posterior longitudinal ligament is loosely attached to the vertebral bodies and tightly attached to the intervertebral disks. There is a venous plexus with epidural fatty tissue located between the vertebral bodies and posterior longitudinal ligament. The ligamentum flavum (yellow ligament) is a fibroelastic ligament which connects the anterior portion of the lamina of each vertebral level above to the posterior portion of the lamina of the corresponding vertebral level below. The ligamentum flavum is directed laterally toward the anterior capsule of the facet joints. The interspinous ligament spans between the spinous processes. The supraspinous ligament connects the posterior surfaces of the spinous processes, transitioning as the nuchal ligament from the C7 level superiorly. Forget Me Nots! • The intervertebral disk normally shows central T2 hyperintensity and peripheral T2 hypointensity. • The neural foramen is bounded by pedicles from the corresponding upper and lower vertebral levels. • Each spinal nerve root is named with respect to the corresponding lower vertebral level from C1 to C7 and to the corresponding upper vertebral level from T1 to S5 due to the C8 nerve root situated between the C7 and T1 vertebrae.

6

1  Anatomic Considerations of the Spine

1.7 Illustrations: Anatomic Considerations of the Spine 1.7.1 Normal Anatomy of the Spine See Figs. 1.1, 1.2 and 1.3. a

b

VB

SAP TP

TP P VB

SAP

L IAP L SP

SP

c

d SAB

TP VB L

TP

L

SP

SP

Fig. 1.1 (a–d) Schematic illustrations of the spine. Each vertebra is composed of the vertebral body (VB), vertebral arch, and bony appendages. The vertebral arch consists of the pedicles (P) anteriorly and laminae (L) posteriorly. Each pedicle is composed of cortical bone connecting the vertebral body with each lamina. The transverse process

(TP), superior articular process (SAP), and inferior articular process (IAP) arise near the junction of the pedicle and lamina. The spinous process (SP) is located in the midline between the laminae and projects posteriorly (Published with kind permission of © HealthWave 2014. All Rights Reserved)

1.7 Illustrations: Anatomic Considerations of the Spine

b

a

IVD

7

c

d

IVD

VB

VB

SAP

SAP SP

TP

Fig. 1.2  Schematic illustrations of the lumbar spine. The vertebral bodies (VB) as seen on frontal (a) and lateral views (b). The intervertebral disks (IVD) are located between the vertebral bodies. In the lumbar spine, the neural foramen (dot) is directed laterally. The superior articular process (SAP) and inferior articular process (IAP) make up the zygapophyseal joint (Z-joint, so-called facet joint, circle in the figure) and are well demonstrated on the posterior oblique view (c). The pars interarticularis (PI) is the narrowed segment of the bone between the supe-

IAP PI

IAP TP

L

SP L

TP

rior and inferior articular processes and is also well visualized on the posterior oblique view (c). In the posterior view (d), the laminae (L), transverse processes (TP), spinous process (SP) as well as the superior and inferior articular processes are shown. In between the laminae, there is a space (interlaminar space, dotted arrow) which may be used as a route for spinal tapping or epidural injection (Published with kind permission of © HealthWave 2014. All Rights Reserved)

8

1  Anatomic Considerations of the Spine

a

b

c

d e

f

Fig. 1.3  Facet joint orientation. The cervical facet joints are oriented mainly in a horizontal direction and in the coronal plane (b, c). The thoracic and lumbar facet joints are primarily directed vertically. The thoracic facet joints are oriented in the coronal plane (d, e) while the

g

lumbar facets are orientated in the oblique sagittal plane anteromedially (f, g), predisposing degenerate lumbar facets to anterior displacement (a, b, d, f) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

1.7 Illustrations: Anatomic Considerations of the Spine

9

1.7.2 Intervertebral Disk and Ligamentous Anatomy on MR See Fig. 1.4.

b

a

ISL ISL

LF

SSL

LF

SSL

Fig. 1.4  Normal intervertebral disk and ligaments shown on schematic illustrations (a, c) and T2-weighted MR images (b, d). The intervertebral disks (arrows) are fibrocartilaginous structures found between the vertebral bodies. The ligamentum flavum (LF) is located just anterior to the lamina. The interspinous ligament (ISL) spans across the spinous processes, while the supraspinous ligament (SSL) connects the posterior surfaces of the spinous processes. The intervertebral disk is composed of an inner nucleus pulposus ligaments shown on schematic illustration (NP) and an outer annulus fibrosus. Normally, the intervertebral disk

shows central hyperintensity (dotted arrow) and peripheral hypointensity on T2-weighted MR images. The central T2-hyperintensity reflects the nucleus pulposus (NP) and inner annulus fibrosus. The ligamentum flavum (= yellow ligament, LF) is a fibroelastic ligament connecting the anterior portion of the lamina of the upper level to the posterior portion of the lamina of the lower level, and is directed laterally toward the anterior capsule of the facet joint (a, c) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

10

1  Anatomic Considerations of the Spine

d

c

LF

NP

LF

Fig. 1.4 (continued)

1.7 Illustrations: Anatomic Considerations of the Spine

11

1.7.3 Cervical Spine Anatomy See Fig. 1.5. b

a

c

UP UP UP

d

e

f

VA NF

NF

VA

Fig. 1.5  Cervical spine anatomy as demonstrated on anterior (a–c) and right oblique views (d–f) of the schematic illustrations (a, d), plain radiographs (b, e), and CT angiogram (c, f). The uncinate process (UP) is a bony projection arising superiorly from the posterolateral surface of the cervical vertebral body. The cervical neural foramen (NF) is directed anteromedially and is well shown on oblique views (d–f). The ipsilateral neural foramen (NF) is shown en face on oblique views between the ipsilateral pedicles (open arrows) which appear as bony bridges. The contralateral pedicles are shown on end (dots) on the oblique radio-

graph (e). The uncovertebral joint (circle) is formed by the uncinate process of the lower vertebral body and the inferior surface of the upper vertebral body. The uncovertebral joint (circle) is situated along the anterior aspect of the neural foramen, as such hypertrophy of the uncovertebral joint can lead to neural foraminal narrowing, predisposing to nerve root compression. The vertebral artery (VA) courses through the vertebral foramen of the transverse processes from C6 to C1 and is located in the anterior half of the neural foramen (a, d) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

12

1  Anatomic Considerations of the Spine

1.7.4 Spinal Cord and Nerve Root Anatomy See Figs. 1.6, 1.7 and 1.8.

a

b

c

SC

CM

CE

Fig. 1.6  Spinal cord and nerve roots as demonstrated on schematic illustration (a), T2-weighted sagittal MR image (b), and T1-weighted sagittal MR image (c). The spinal cord is the continuation of the central nervous system within the dural sac of the spine. The spinal cord (SC) ends as a cone-shaped structure at the L1 level, known as the conus

medullaris (CM). There are two areas of spinal cord enlargements: the cervical enlargement and the lumbar enlargement. The cauda equina (CE, “horse’s tail”) refers to the collection of nerve fibers distal to the conus medullaris (a) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

1.7 Illustrations: Anatomic Considerations of the Spine Fig. 1.7 Schematic illustration of the nerve roots. Each spinal nerve root is named with respect to the corresponding lower vertebral level from C1 to C7 and to the corresponding upper vertebral level from T1 to S5, as a result of the C8 nerve root between the C7 and T1 vertebrae (a). For example, the C6 nerve root exits through the C5/6 neural foramen above the C6 vertebra (b), while the L4 nerve root exits through the L4/5 neural foramen below the L4 vertebra (c) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

13

a

b

C1 nerve

C5

C1

C6 C6 nerve C8 nerve

C5 C6 C7

C6 nerve

T1 T1 nerve

c

L4

L4 nerve T12 L1 nerve

L4 nerve

L4 L5

L5 nerve

S1 nerve

S1

L5

14

1  Anatomic Considerations of the Spine

b a L4

L5

L4

L5

c

L5

Fig. 1.8  Exiting and descending nerve roots of the lumbar spine. On the schematic illustration (a), the exiting L4 nerve root is located in the L4/5 neural foramen while the descending L5 nerve root is seen outside the dura coursing along the medial side of the L5 pedicle, finally exiting distal to the L5 pedicle through the L5/S1 neural foramen. On the T1-weighted axial MR image at the L4/5 disk level (b), the L4 nerve

root is situated in the neural foramen and the L5 nerve root is just outside the dural sac. At the level just inferior to the L4/5 disk, the L5 nerve root is shown to descend along the medial side of the L5 pedicle (c) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

References

References

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Grenier N, Kressel HY, et al. Isthmic spondylolysis of the lumbar spine: MR imaging at 1.5 T. Radiology. 1989;170(2):489–93. Grogan JP, Hemminghytt S, et al. Spondylolysis studied with computed Aguila LA, Piraino DW, et al. The intranuclear cleft of the intervertebral tomography. Radiology. 1982;145(3):737–42. disk: magnetic resonance imaging. Radiology. 1985;155(1):155–8. LaMasters DL, Dorwart RH.  High-resolution, cross-sectional comCastillo M, Malko JA, et al. The bright intervertebral disk: an indirect puted tomography of the normal spine. Orthop Clin N Am. sign of abnormal spinal bone marrow on T1-weighted MR images. 1985;16(3):359–79. AJNR Am J Neuroradiol. 1990;11(1):23–6. Rumboldt Z. Degenerative disorders of the spine. Semin Roentgenol. Del Grande F, Maus TP, et  al. Imaging the intervertebral disk: age-­ 2006;41(4):327–62. related changes, herniations, and radicular pain. Radiol Clin N Am. Xu GL, Haughton VM, et al. Lumbar facet joint capsule: appearance at 2012;50(4):629–49. MR imaging and CT. Radiology. 1990;177(2):415–20.

2

Common Spine Disorders Associated with Back Pain

Contents 2.1   Lumbar Spine MR in Patients with Back Pain: What Should We Focus on? 

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2.2   Herniated Intervertebral Disk 

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2.3   Spinal Stenosis 

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2.4   Alignment Disorders (Spondylolisthesis, Scoliosis, Kyphosis) 

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2.5   Degenerative Changes of the Posterior Elements (Facet Joint Arthrosis, Baastrup’s Phenomenon) 

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2.6   Illustrations: Common Spine Disorders Associated with Back Pain  2.6.1  Schematic Illustrations of the Nomenclature for Disk Herniation  2.6.2  Herniated Intervertebral Disk  2.6.3  Lumbar Central Canal Stenosis  2.6.4  Lumbar Foraminal Stenosis  2.6.5  Spondylolysis/Spondylolisthesis  2.6.6  Degenerative Changes of the Posterior Elements 

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References 

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Abstract

In this chapter, we will introduce tips to aid in lumbar spine MR interpretation. We will also explain imaging findings of common spine disorders associated with back pain and lumbar radiculopathy, such as herniated intervertebral disk, spinal stenosis, spondylolysis, facet joint arthrosis, as well as alignment disorders such as spondylolisthesis, kyphosis, and scoliosis. Keywords

Nerve root · Intervertebral disk · Spinal stenosis · Degenerative spondylolisthesis · Synovial cyst

In this chapter, we will introduce tips to aid in lumbar spine MR interpretation. We will also explain imaging findings of common spine disorders associated with back pain and lumbar radiculopathy, such as herniated intervertebral disk, spi-

nal stenosis, spondylolysis, facet joint arthrosis, as well as alignment disorders such as spondylolisthesis spondylolisthesis, kyphosis, and scoliosis.

2.1 Lumbar Spine MR in Patients with Back Pain: What Should We Focus on? To interpret spine MR in patients complaining of pain, it is best to start by screening the sagittal images. On T2-weighted sagittal images, the three anatomic areas of the central canal, spinal cord, and intervertebral disks should be reviewed carefully. On T1-weighted sagittal images, bone marrow signal abnormality should be carefully reviewed with reference to the signal of the intervertebral disks. Any focal or diffuse low signal intensity of the bone marrow on T1-weighted sagittal images could suggest bony pathology. Following the sagittal images, the axial images are then reviewed from cau-

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 J. W. Lee et al., Radiology Illustrated: Spine, Radiology Illustrated, https://doi.org/10.1007/978-981-99-6612-7_2

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2  Common Spine Disorders Associated with Back Pain

dal to cranial and vice versa, comparing with the corresponding levels on the sagittal images. On T2-weighted axial images, the relationship of the posterior margin of the intervertebral disks with the dural sac and nerve roots should be carefully defined to identify a herniated disk. Common ­mistakes include missing superior migration of herniated disks into the foraminal or extraforaminal zones and inferior migration of herniated disks into the subarticular zones. On T1-weighted axial images, the course of the descending nerve roots from the dural sac to the neural foramina should be traced, to identify nerve root anomalies such as a conjoined nerve root (Song et al. 2008) (Table 2.1). Recent articles suggest that lumbar imaging for low back pain without clinical evidence of a serious underlying condition does not improve clinical outcome (Modic et  al. 2005; Chou et al. 2009). One prospective study showed no cases of malignancy in 1170 patients under the age of 50 presenting without a history of cancer, weight loss, an evidence of systemic illness, or a history of failure to improve with conservative therapy (Deyo and Diehl 1988). The American College of Radiology considers spine imaging appropriate only when there are red flag features that suggest an underlying systemic disease, in the face of progressive neurologic deficits, or cauda equina syndrome (Bradley Jr 2007). The American Pain Society and American College of Physicians further emphasize that imaging should be recommended only when the patient with radiculopathy is a candidate for therapeutic intervention, such as epidural steroid injection or surgery (Chou et al. 2007). Common spine disorders associated with back pain or lumbar radiculopathy include herniated intervertebral disks, spinal stenosis, spondylolysis, spondylolisthesis, kyphosis, scoliosis, facet joint arthrosis, and Baastrup’s phenomenon (Table 2.2). Table 2.1  Special areas to focus on lumbar spine MR interpretation T2-weighted sagittal images T1-weighted sagittal images T2-weighted axial images

Central canal, spinal cord, intervertebral disks Bone marrow signal alteration

Posterior margin of intervertebral disks, central canal, subarticular zones, foraminal– extraforaminal zones T1-weighted axial Course of nerve roots, posterior margin of images intervertebral disks Table 2.2  Common spine disorders associated with back pain and lumbar radiculopathy Herniated intervertebral disks Spinal stenosis Alignment disorders such as spondylolisthesis, kyphosis, and scoliosis Facet joint arthrosis Baastrup’s phenomenon Annular fissure, disk degeneration

2.2 Herniated Intervertebral Disk A combined task force of the American Society of Spine Radiology, the American Society of Neuroradiology, and the North American Spine Society presented recommendations defining terminology of herniated intervertebral disks in the lumbar spine (Fardon and Milette 2001). According to the recommendations, a herniated intervertebral disk is defined as a “localized displacement of disc material beyond the disc space.” “Localized” is defined as displaced disk material involving less than half of the circumference of the disk on axial images. The margin of the disk is determined by the outline of the adjacent vertebral bodies excluding osteophytes. The nomenclature was revised as “disc nomenclature version 2.0” in 2010. According to the revised nomenclature, “localized” is defined as displaced disk material involving less than one fourth (90°) of the disk on axial images. Therefore, herniated disc was defined as a displacement of disc material beyond disc space less than one fourth (90°) of the disc margin on axial images. Herniated intervertebral disks are further divided into protrusions and extrusions based upon the shape of the displaced disk. A protrusion is a disk herniation where the distance between the edges at the base of the displaced disk material is larger in all planes than the maximal distance between the edges of the displaced disk. An extrusion refers to a disk herniation where the maximal distance between the edges of the displaced disk is larger than the distance between the edges at its base in any plane. According to the revised nomenclature, the shape of the herniated disc can be defined as the relationship with posterior longitudinal ligaments as subligamentous or transligamentous, which would be better clinical impact than protrusion or extrusion. The location of the displaced disk material is classified as central, subarticular, foraminal, or extraforaminal (far lateral) zones on the axial plane. The central and subarticular zones are divided in the sagittal plane by the medial edge of the facet joint. The subarticular and foraminal zones are divided in the sagittal plane by the medial edge of the pedicle. The foraminal and extraforaminal zones are divided in the sagittal plane by the lateral edge of the pedicle. In the sagittal or coronal planes, the location of disk material may also be classified as being at the suprapedicular, pedicular, infrapedicular, or disk levels. In some cases, the herniated disk material may show higher signal on T2-weighted images than the parent disk, which can be a cause of decreased detectability; thus careful tracing of the posterior margin of the intervertebral disk is required to locate the herniated disk. According to the revised nomenclature, herniated disc with T2-hyperintensity or peridiscal enhancement can be described as a “acute disc herniation.”

2.4 Alignment Disorders (Spondylolisthesis, Scoliosis, Kyphosis)

If the herniated disk is sequestrated from the parent disk, it can be misdiagnosed as an epidural tumor. The features differentiating a herniated disk from an epidural tumor include (1) associated protrusion involving the base of the adjacent intervertebral disk, (2) T2 low signal intensity within the disk material, and (3) rim-like enhancement of the disk material. The relationship of the herniated disk and adjacent nerve roots can be described as being in contact, deviated, or compressed (Pfirrmann et al. 2004). The numbering of the nerve roots may be confusing in the lumbar spine, as the descending root in the epidural space will exit through the neural foramen of the lower vertebral level. For example, at the L4–5 disk level, there are two pairs of nerve roots outside the dural sac; the L4 nerve roots are located in the foraminal or extraforaminal zones bilaterally, while the L5 nerve roots are located in the central or subarticular zones bilaterally. Thus a herniated disk located at the L4–5 central or subarticular zones may compress upon the L5 nerve roots (and not L4 nerve roots), while a herniated disk at the L4–5 foraminal or extraforaminal zones may compress upon the L4 nerve roots. Radiculopathy is mainly caused by perineural inflammation due to the herniated disk, rather than from nerve root compression itself. Radiculopathy implies the presence of objective signs of neural dysfunction including motor weakness, hypesthesia/paresthesia, or diminished deep tendon reflexes. Radiculopathy is typically accompanied by intermittent, lancinating, electrical, or burning radiating pain (Del Grande et al. 2012).

2.3 Spinal Stenosis Spinal stenosis is a degenerative disorder where there is narrowing of the central canal, lateral recesses, or neural foramina, with resultant nerve root or spinal cord compression. The most common symptoms in patients with lumbar spinal stenosis are back pain (95%), claudication (91%), leg pain (71%), weakness (33%), and voiding disturbances (12%) (Amundsen et al. 1995). Claudication is a clinical condition where patients experience lower leg pain and the feeling of weakness during walking. Spinal stenosis is a common cause of claudication (neurogenic claudication). Vascular compromise (especially arterial insufficiency to the legs) can be another cause of claudication (vascular claudication). Common descriptors used for determining central canal stenosis include the dural sac anteroposterior (AP) dimension and the dural sac cross-sectional area. Dural sac AP dimensions of less than 10 mm or dural sac cross-sectional areas of less than 100 mm2 constitute stenosis (Maus 2012). Currently, Lee grading (Lee et  al. 2011) is a widely used grading system for central canal stenosis in the lumbar spine based on MR.  According to Lee grading, lumbar central

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canal stenosis can be diagnosed when there is obliteration of the ventral subarachnoid space on axial and sagittal images and may be graded as mild, moderate, or severe according to the degree of CSF obliteration and nerve root clumping. With mild central canal stenosis, the nerve roots remain separate inside the dura without clumping. In moderate central canal stenosis central canal stenosis, there is some clumping of the nerve roots inside the dural sac. Severe central canal stenosis occurs when there is a single bundle of nerve roots visualized inside the dural sac due to severe clumping. For lumbar foraminal stenosis, Lee grading is a universally accepted grading system based on MR (Lee et al. 2011). Lumbar foraminal stenosis can be graded according to the obliteration of perineural fat in the neural foramen and associated nerve root compression (Lee et al. 2011). Mild, moderate, and severe lumbar foraminal stenoses are defined as follows: mild foraminal stenosis when there is perineural fat obliteration in one direction such as AP or superior–inferior, moderate foraminal stenosis when perineural fat obliteration occurs in two or more directions, and severe foraminal stenosis when there is nerve root compression or morphological changes of the nerve root due to compression.

2.4 Alignment Disorders (Spondylolisthesis, Scoliosis, Kyphosis) Alignment disorders such as spondylolisthesis, scoliosis, and kyphosis can be a source of back pain and occasionally a cause of radiating pain or claudication due to resultant spinal stenosis. Spondylolisthesis is a condition where there is anterior displacement of a vertebral body relative to the vertebral body below, while retrolisthesis refers to the condition in which the vertebral body is displaced posteriorly relative to the vertebral body below. Spondylolisthesis can be graded as follows: the anteroposterior (AP) diameter of the superior surface of the lower vertebral body is divided into quarters, with grades I–IV spondylolisthesis assigned to slips involving up to one, two, three, or four quarters of the upper vertebra, respectively. The causes of lumbar spondylolisthesis are congenital (dysplastic), isthmic (spondylolytic), degenerative, traumatic, pathological, and iatrogenic (Butt and Saifuddin 2005). The two most common causes of spondylolisthesis are spondylolysis (spondylolytic spondylolisthesis) and facet joint degeneration (degenerative spondylolisthesis). Spondylolysis is a disorder where there is a defect involving the pars interarticularis. The pars interarticularis is the part of vertebral posterior element between the superior and inferior articular processes. Spondylolysis is most commonly seen at the L5 level and can be a cause of spondylolisthesis in cases of bilateral involvement. In spondylolytic spondylolisthesis,

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both neural foramina can often be narrowed, but the central canal is usually widened as the lamina and spinous processes are not displaced anteriorly. On the contrary, in degenerative spondylolisthesis caused by facet joint degeneration, the central canal is severely narrowed in most cases. Degenerative spondylolisthesis is thought to be the end result of segmental instability. Degenerative lumbar scoliosis refers to the condition in which asymmetric disk degeneration and facet arthrosis result in abnormal curvature of the lumbar spine. In such cases, patients can complain of low back pain and radiculopathy due to foraminal stenosis. In degenerative lumbar scoliosis, foraminal stenoses can be unilateral and asymmetric, e.g., involving left L1–2, left L2–3, right L4–5, and right L5–S1. Atrophy of the back muscles and facet arthrosis can also result in lumbar kyphosis (lumbar degenerative kyphosis = LDK). Standing lateral plain radiographs are essential for diagnosing LDK, with kyphotic alignment of the lumbar spine curvature demonstrated. On MR, there is severe fatty atrophy of the back muscles.

2.5 Degenerative Changes of the Posterior Elements (Facet Joint Arthrosis, Baastrup’s Phenomenon) The facet joint is a true synovial joint and like other joints is susceptible to the same degenerative changes, namely joint space narrowing, osteophyte formation, subchondral sclerosis, subchondral cyst formation, joint effusion, and synovial cyst formation. Facet joint degeneration (facet arthrosis) is a common source of back pain in the elderly; it is the main cause of degenerative spondylolisthesis with central canal stenosis causing radiating pain and claudication and occasionally a cause of lateral recess stenosis due to osteophytes. Ventral synovial cysts from the facet joints can compress upon the descending nerve roots, which can be a cause of radiculopathy. In case of epidural cystic mass, the clues to

2  Common Spine Disorders Associated with Back Pain

consider synovial cyst are (1) degenerative change in the adjacent facet joint, (2) communication with joint effusion or joint space, and (3) old age. Interspinous pseudoarthrosis and cyst formation can also occur secondary to close approximation of the spinous processes. This formation has been termed Baastrup’s phenomenon (Malfair and Beall 2007). Redundancy of the interspinous ligament may extend into the posterior aspect of the central spinal canal, resulting in effacement of the retrothecal fat pad and posterior narrowing of the spinal canal because of the redundant posterior ligamentous soft tissues. When the posterior degenerative changes are severe, an adventitial bursa may form and occasionally may communicate with the facet joints. Interspinous bursae or hypertrophic degenerative changes can extend anteriorly from the interspinous space and result in canal stenosis. Forget Me Nots! • On T2-weighted sagittal images, the three anatomic areas of the central canal, spinal cord, and intervertebral disks should be reviewed carefully. • On T1-weighted sagittal images, evaluation of bone marrow signal abnormality should be carefully reviewed with reference to the signal of the intervertebral disks. • Features differentiating herniated disks from epidural tumor include (1) protrusion at the base of the adjacent intervertebral disk, (2) T2 low signal intensity of the disk material, and (3) rim-like enhancement of the disk material. • Spinal stenosis of the lumbar spine can be graded by the degree of CSF obliteration (for central canal stenosis) and perineural fat obliteration (for foraminal stenosis). • The two most common causes of spondylolisthesis are spondylolysis (spondylolytic spondylolisthesis) and facet joint degeneration (degenerative spondylolisthesis). • The facet joint can show similar degenerative features to other synovial joints, including joint space narrowing, osteophytes, subchondral sclerosis, subchondral cyst, joint effusion, and synovial cyst formation.

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

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2.6 Illustrations: Common Spine Disorders Associated with Back Pain 2.6.1 Schematic Illustrations of the Nomenclature for Disk Herniation See Figs. 2.1, 2.2, 2.3 and 2.4.

a

b

c

Fig. 2.1  Schematic illustrations for defining disk herniation. A herniated intervertebral disk is defined as a “localized displacement of disk material beyond the disk space.” The disk space is delineated by the outline of the adjacent vertebral bodies excluding osteophytes. “Localized” refers to displaced disk material involving less than one fourth (90°) of the circumference of the disk as seen on axial images;

thus (a, b) are not disk herniations, but represent bulging disks. (c) Schematic illustration of disk herniation with displaced disk material involving less than one fourth (90°) of the circumference of the disk on axial images. (Published with kind permission of © HealthWave 2014. All Rights Reserved)

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a

Protrusion

Extrusion

b

d

c

Protrusion

e

Extrusion

Fig. 2.2  Schematic illustrations of disk protrusion and extrusion. A herniated intervertebral disk is further classified as a protrusion or extrusion depending on the shape of the displaced disk. A protrusion is defined as when the distance between the edges at the base of the herniated disk is larger than the maximal distance between the edges of the

Extrusion

displaced disk material in both axial and sagittal planes (a, c). An extrusion refers to a disk herniation where the maximal distance between the edges of the displaced disk is larger than the distance between the edges at its base in either axial or sagittal planes (b, d, e) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

a

Fig. 2.3  Transligamentous extension of the herniated disc between the posterior longitudinal ligament and the dural sac. T2-weighted sagittal (a) and axial (b) images demonstrate the herniated disc (yellow arrow) extending toward the central zone (left > right) and exhibiting inferior

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b

migration (extrusion). The disc material is positioned between the posterior longitudinal ligament (red arrows) and the dural sac, indicating a transligamentous extension

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a

Fig. 2.4  (Schema A11). Schematic illustrations describing the location of herniated disks. The location of disk material is classified as central, subarticular (lateral recess), foraminal (pedicular), or extraforaminal (far lateral) zones in the axial plane (a). The central and subarticular zones are divided by a sagittal plane along the medial edge of the facet joint. The subarticular and foraminal zones are divided by a sagittal

2  Common Spine Disorders Associated with Back Pain

b

plane along the medial edge of the pedicle. The foraminal and extraforaminal zones are divided by a sagittal plane along the lateral edge of the pedicle. On the sagittal or coronal planes, the location of disk material may also be described as being at the suprapedicular, pedicular, infrapedicular, or diskal levels (b) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

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2.6.2 Herniated Intervertebral Disk See Figs. 2.5, 2.6, 2.7, 2.8, 2.9, 2.10, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.19 and 2.20.

a

b

Left S1 nerve root

Fig. 2.5  Focal disk protrusion in the central zone in a 20-year-old man. There is a focal herniation (involving less than one quarter of the disk circumference in the axial plane) of the L5/S1 disk (arrow) (a, b). Because the width (line) at the base of the herniated disk is larger in both axial and sagittal planes than the displaced disk material, this is defined as a protrusion. The location of the herniated disk is medial to the medial edge of the facet joint, and thus is located in the central zone.

In the central zone, the disk herniation is situated to the left of midline and can be described as involving the left central zone. The herniated disk at L5/S1 compresses the descending left S1 nerve root (dashed arrow). The final radiological report can be written as follows: “Herniated disk (protrusion) at the left central zone of L5/S1 with left S1 nerve root compression”

26 Fig. 2.6  Herniated disk in a 38-year-old woman. There is a herniated disk (protrusion) at the L4/L5 central zone (arrows) (a, c). Modic type 2 endplate degenerative changes (high signal on both T2-weighted (a) and T1-weighted images (b) suggestive of fatty infiltration) are also noted at the L4/L5 level (dashed arrows)

2  Common Spine Disorders Associated with Back Pain

a

c

b

2.6 Illustrations: Common Spine Disorders Associated with Back Pain Fig. 2.7  Herniated disk in a 73-year-old man. Herniated disk (arrows) at the left central zone of L4/L5 with inferior migration (a–c)

a

27

b

c

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2  Common Spine Disorders Associated with Back Pain

a

a

b b Left L5 nerve root

Right L4 nerve root

Fig. 2.8  Herniated disk in a 72-year-old man. Herniated disk (extrusion, arrow) at the right central and right subarticular zone of L3/L4 with inferior migration, resulting in right L4 nerve root compression (a, b)

Fig. 2.9  Herniated disk in a 66-year-old man. Herniated disk (extrusion) at the left central and left subarticular zone of L4/L5 with inferior migration to the L5 pedicle level, resulting in compression of the left L5 nerve root (dashed arrow) (a, b). We can see the intact right L5 nerve root medial to the right L5 pedicle (in the circle). The lumbar nerve root is located medial to the similarly numbered pedicle (e.g., L5 nerve root is medial to the L5 pedicle). The linear line (open arrow) on the T2 axial image posteriorly is a saturation artifact (this will be discussed subsequently)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain Fig. 2.10  Herniated disk in a 54-year-old man. There is a lumbosacral transitional vertebra (L5 sacralization) (a). We can see the herniated intervertebral disk (arrow) at the right subarticular zone of L3/L4 (lateral to the sagittal plain of medial edge of facet joint) with inferior migration and resultant right L4 nerve root compression (b, c)

a

29

b

c

L5

30 Fig. 2.11  Small herniated disk at the subarticular zone with severe nerve root compression in a 67-year-old woman. A herniated disk is seen at the right subarticular zone of L4/L5 (arrows) with inferior migration, the herniated disk compresses upon the right L5 nerve root (medial to the right L5 pedicle) (a–c). Small herniated disks at the subarticular zoned can be missed on MR, and nerve root compression in this region can be a source of severe radicular pain

a

2  Common Spine Disorders Associated with Back Pain

a

b

c

b

Left S1 nerve root

Fig. 2.12  Herniated disk in a 56-year-old man. Herniated disk (arrows) at the left subarticular zone of L5/S1 with inferior migration and left S1 nerve root compression (a, b)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

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a

b

c

d

Fig. 2.13  Herniated disk (extrusion) at the left foraminal zone of L3/ L4 with superior migration in a 71-year-old man. On the sagittal T2-weighted (a) and sagittal T1 contrast-enhanced images (b), there is focal disk herniation (arrows) into the neural foramen with peripheral enhancement. At a level above the L3/L4 disk on axial T2-weighted (c) and axial T1 contrast-enhanced images (d), the migrated disk material

(arrows) is seen at the left foraminal zone as a low signal mass on the T2-weighted image with peripheral enhancement. The foraminal zone is an easily overlooked area in the detection of herniated disks; thus readers should carefully scrutinize the foraminal zones on sagittal and axial images

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a

c

b

d

Fig. 2.14  Herniated disk in a 72-year-old man shown on T2-weighted MR images (a–d). Herniated disk (arrows, extrusion) at the right foraminal and extraforaminal zones of L4/L5 with superior migration and right L4 nerve root compression

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

a

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b

Fig. 2.15  Herniated disk in a 69-year-old woman. There is a herniated intervertebral disk at the right L5/S1 extraforaminal zone (arrow) with right L5 nerve root (dotted arrow) compression (a, b). A herniated disk

at the extraforaminal zone is harder to delineate on sagittal images, but is well defined on axial images, as such the extraforaminal zones should be assessed on axial images to locate disk herniations

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a

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b

Fig. 2.16  Easily missed disk herniation with T2 hyperintensity in a 66-year-old man. The herniated disk (arrows) shows high signal on T2-weighted images, different in signal to the parent disk (a, b). In such cases, a herniated disk can be missed

a

Fig. 2.17  Herniated disk mimicking an epidural tumor in a 69-year-­ old man. There is a herniated disk (sequestration) in the left posterior epidural space. This appears similar to an epidural tumor but shows T2 hypointensity (a) and peripheral rim enhancement on follow-up at 2 weeks (b), which can be clues indicative of a disk herniation. Contrast-­

b

enhanced images were again acquired 2 weeks later (b). The shape and location of the herniated disk on the contrast-enhanced image shows interval change from the initial T2-weighted image, which is also a pointer to a herniated disk rather than a tumor

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

a

c

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b

d

Fig. 2.18  Herniated disk in a 73-year-old man. There is a herniated disk (arrows, sequestration) in the left central zone, demonstrating T2 hypointensity (a, c) and peripheral enhancement (b, d)

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2  Common Spine Disorders Associated with Back Pain

a

b

c

d

Fig. 2.19  Herniated disk mimicking a paravertebral mass in a 72-year-­ old man. On abdominal CT (a), a round mass (arrow) is detected in the right paravertebral area. Spinal MR was performed for the evaluation of this mass. On MR images, the mass (arrows) shows heterogeneous high and low T2 signal (b) with peripheral enhancement (c). CT discography

was performed in view of the suspicion of a disk herniation on the basis of the MR findings. This showed (d) contrast leakage into the mass (arrow) from the parent L4/L5 disk, confirming the diagnosis of disk herniation

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

a

37

b

c

Fig. 2.20  Herniated disk (sequestration) at the left epidural space in a 61-year-old man. On the T2-weighted sagittal image (a), there is an ovoid hyperintense mass (arrow) in the posterior epidural space. On the T2-weighted axial images (b, c), the mass (arrow) occupies the left posterior epidural space; at the disk level (c), there is a linear high signal area (dotted arrow) in the posterior annulus of the disk near the

epidural mass, which can be a clue to a disk herniation. On the T1-weighted axial image (d), the mass (arrow) shows intermediate signal intensity. Following contrast enhancement (e), peripheral rim enhancement is noted of the mass (arrow), suggestive of a disk herniation

38

d

Fig. 2.20 (continued)

2  Common Spine Disorders Associated with Back Pain

e

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

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2.6.3 Lumbar Central Canal Stenosis See Figs. 2.21, 2.22, 2.23, 2.24, 2.25, 2.26 and 2.27. No stenosis

Mild central canal stenosis

a

b

c

d

Moderate central canal stenosis

Fig. 2.21  Schematic illustrations of lumbar central canal stenosis. Central canal stenosis of the lumbar spine can be diagnosed when there is obliteration of the ventral subarachnoid space on axial and sagittal images and graded as mild, moderate, or severe depending on the degree of CSF obliteration and nerve root clumping (a–d). With mild central canal stenosis, the nerve roots remain separate within the dura

Severe central canal stenosis

without clumping (b). In moderate central canal stenosis, there is some clumping of the nerve roots inside the dural sac (c). Severe central canal stenosis occurs when there is a single bundle of nerve roots visualized inside the dural sac due to severe clumping (d) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

40 Fig. 2.22  Mild central canal stenosis at L4/L5 in a 62-year-old woman. The ventral subarachnoid space at L4/L5 level is obliterated, in keeping with central canal stenosis (a, b). However, the nerve roots of the cauda equina are separately identified at the L4/L5 level without clumping and are indicative of mild central canal stenosis

Fig. 2.23  Moderate central canal stenosis at L4/L5 in a 65-year-old woman. There is some clumping (arrow) of the cauda equina at the L4/L5 level, in keeping with moderate stenosis (a, b)

2  Common Spine Disorders Associated with Back Pain

a

a

b

b

2.6 Illustrations: Common Spine Disorders Associated with Back Pain Fig. 2.24  Moderate central canal stenosis at L4/L5 in a 74-year-old woman (a, b). The cauda equina proximal to the stenotic level shows redundancy (dotted arrow) suggestive of long-standing stenosis (a)

Fig. 2.25  Moderate central canal stenosis at L3/L4 (arrow)in a 52-year-old man (a, b)

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a

a

b

b

42 Fig. 2.26  Severe central canal stenosis at L4/L5 in a 74-year-old woman. The cauda equina at the L4/L5 level shows a single bundle-like appearance (arrow) in keeping with severe stenosis (a, b). The cauda equina distal to the stenotic level is redundant (dotted arrow) secondary to the stenosis (a)

Fig. 2.27  Severe central canal stenosis in a 64-year-old man. There is a severe central canal stenosis at L4/L5 with redundant nerve roots (dotted arrows) distally (a, b)

2  Common Spine Disorders Associated with Back Pain

a

b

a

b

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

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2.6.4 Lumbar Foraminal Stenosis See Figs. 2.28, 2.29, 2.30 and 2.31. a

No stenosis

b

c

Mild foraminal stenosis

d

Mild foraminal stenosis

e

Moderate foraminal stenosis

Fig. 2.28 Schematic illustrations of lumbar foraminal stenosis. Lumbar foraminal stenosis is graded according to the degree of obliteration of the perineural fat in the neural foramen (a–e). Mild, moderate, severe lumbar foraminal stenoses are defined as follows: mild foraminal stenosis when there is perineural fat obliteration in one direction such as anteroposteriorly or superior-inferiorly (b, c), moderate

Severe foraminal stenosis

foraminal stenosis when perineural fat obliteration in present in two or more directions (d), and severe foraminal stenosis when there is nerve root compression or morphological changes of the nerve root due to the compression (e) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

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2  Common Spine Disorders Associated with Back Pain

a

Fig. 2.29  Mild foraminal stenosis in a 58-year-old woman. There is mild left foraminal stenosis at L5/S1 as shown on T1-weighted sagittal (a) and T2-weighted sagittal images (b). The perineural fat around the L5 nerve root is obliterated in one direction (superior-inferiorly, arrows) without significant nerve root deformity. The intact L3/L4 neural fora-

b

men is also observed with preservation of perineural fat. The L4/L5 neural foramen is not considered stenotic as perineural fat obliteration is only seen at one point (superiorly, dotted arrow) without inferior involvement (preservation of perineural fat at the opposite side inferior to the nerve root)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

a

Fig. 2.30  Moderate left foraminal stenosis at L5/S1 on T1-sagittal (a) and T2-sagittal images (b) in a 68-year-old woman. The perineural fat around the L5 nerve root is obliterated in two directions [anteroposteri-

45

b

orly (dotted arrows) and superior-inferiorly (arrows)], but the nerve root is not deformed

46

2  Common Spine Disorders Associated with Back Pain

a

b

Fig. 2.31  Severe right foraminal stenosis at L5/S1 on T1-weighted sagittal (a) and T2-weighted sagittal images (b) in a 65-year-old man. The L5 nerve root is severely compressed in the foramen (arrows). Spondylolysis is also identified of the L5 pars interarticularis (dotted arrow)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

47

2.6.5 Spondylolysis/Spondylolisthesis See Figs. 2.32, 2.33, 2.34, 2.35, 2.36, 2.37, 2.38, 2.39, 2.40 and 2.41.

a

b

c

d SP

TP

PI L

IP

Fig. 2.32  Scotty dog appearance on an oblique view of the lumbar spine demonstrated on schematic illustrations (a, c, d) and oblique radiograph (b). The components of the posterior elements contributing to the Scotty dog appearance are well visualized on the magnified images without (c) or with spondylolysis (d): eye = ipsilateral pedicle, nose = transverse process (TP), ear = superior articular process (SP), leg  =  inferior articular process (IP), neck  =  pars interarticularis (PI), body = lamina (L). The pars interarticularis is the narrowed part of the

posterior element between the superior and inferior articular processes, i.e., the part (“pars”) between (“inter-”) the facet joints (“articularis”). A defect of the pars interarticularis is well visualized as a defect in the neck of the Scottie dog (arrow, a, b, d). On the oblique radiograph (b), a linear defect is noted involving the L5 pars interarticularis in keeping with spondylolysis (a, c, d) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

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a

2  Common Spine Disorders Associated with Back Pain

b

Fig. 2.33  Scotty dog appearance on a lumbar spine oblique radiograph in a 55-year-old woman. The linear defects involving both L5 pars interarticularis (arrows) are in keeping with spondylolysis (a, b)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

a

49

b

c

Fig. 2.34  Spondylolytic spondylolisthesis of L4/L5  in a 50-year-old man. Spondylolisthesis is a condition where there is anterior displacement of a vertebral body relative to the vertebral body below. Two most common causes of spondylolisthesis are spondylolysis (spondylolytic spondylolisthesis = isthmic spondylolisthesis) and facet joint degenerative changes (degenerative spondylolisthesis). Spondylolytic spondylolisthesis at L4/L5 is well demonstrated on the lateral radiograph in

flexion (a). On the midsagittal T2-weighted image (b), the central canal is widened at L4/L5 level. Spondylolytic spondylolisthesis can often show central canal widening. On the parasagittal T1-weighted image (c), spondylolysis at L4 is evident (arrow) and also seen on plain radiography, whereas the spondylolysis of L5 (dotted arrow) was not well demonstrated on plain radiography

50

2  Common Spine Disorders Associated with Back Pain

a

b

c

d

Fig. 2.35  Spondylolysis on plain radiography in a 60-year-old man. Bilateral spondylolysis of L4 and L5 (arrow) is seen on plain lateral radiographs in the neutral position (a), in flexion (b), and in both

oblique views (c, d). Flexion radiographs are usually more useful in identifying spondylolysis compared to neural or extension radiographs as the bony defect of the pars interarticularis is exaggerated

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

51

b

a

c

B C D

d

Fig. 2.36 Spondylolytic spondylolisthesis of L5/S1 on CT in a 67-year-old man (a–d). While evaluating the course of the spine on consecutive images, spondylolysis is identified as a defect (arrows in c) in the posterior arch between the upper (b) and lower facet joints (d). On CT axial images, spondylolysis can mimic and be mistaken for a

facet joint due to similar appearances. Differentiating features are as follows: (1) the cortices of the facet joints are of high attenuation on CT with smooth margins (dotted arrows); (2) on the axial level where both pedicles are visualized as in (c), the normal facet joints should not be visible; thus any bony defect at this level represents spondylolysis

52 Fig. 2.37 Degenerative spondylolisthesis at L4/L5 shown on schematic illustration (a), plain lateral radiograph (b), CT (c), and MR T2-weighted sagittal image (d) in a 74-year-old man. Spondylolysis of L4 was not identified on the plain radiograph (dot on figure b). The central canal was narrowed (left-right arrow) at L4/L5 level on CT (c) and on the MR sagittal image (d). The L4 spinous process was also anteriorly displaced (arrow, dashed lines), which is a sign suggestive of degenerative spondylolisthesis with spondylolytic spondylolisthesis (Published with kind permission of © HealthWave 2014. All Rights Reserved)

2  Common Spine Disorders Associated with Back Pain

a

b

d c

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

a

Fig. 2.38  Pars interarticularis on MR sagittal image. There is no spondylolysis in this case as the pars interarticularis (arrows) could be traced on the two consecutive parasagittal images (a, b). As the pars

53

b

interarticularis is oriented obliquely, it can be mistaken for spondylolysis on a single sagittal image. Therefore, the pars interarticularis should be evaluated on at least two consecutive parasagittal images

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2  Common Spine Disorders Associated with Back Pain

a

b

c

d

e

Fig. 2.39  Degenerative spondylolisthesis at L4/L5  in a 52-year-old woman. On the plain lateral radiograph (a) and MR T2-sagittal image (d), spondylolisthesis is observed at the L4/L5 level. There is severe central canal stenosis at the L4/L5 level on MR T2-weighted sagittal (b)

f

and axial images (c). On the plain oblique radiograph (d), the pars interarticularis is sclerotic (dotted arrow), and spondylolysis is not ruled out. However, the pars interarticularis (arrows) is shown to be intact on two consecutive parasagittal T1-weighted MR images (e, f)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain Fig. 2.40 Degenerative spondylolisthesis at L4/L5 with severe central canal stenosis in a 75-year-old man (a). Facet joint effusion is also noted with hyperintense signal (dotted arrows) on the axial T2-weighted image (b). Degenerative changes of the facet joint are the main cause of degenerative spondylolisthesis. In degenerative spondylolisthesis, the central canal can be severely narrowed

a

a

55

b

b

Fig. 2.41  Degenerative spondylolisthesis at L4/L5 with severe central canal stenosis in a 58-year-old woman (a, b)

56

2  Common Spine Disorders Associated with Back Pain

2.6.6 Degenerative Changes of the Posterior Elements See Figs. 2.42, 2.43, 2.44, 2.45 and 2.46.

d

a

c

b

Fig. 2.42  Bilateral synovial cysts arising from the facet joints in an 82-year-old man. Facet joint degeneration can result in effusions with synovial cyst formation in the anterior or posterior aspects of the joint (c). A synovial cyst anterior to the joint can compress upon the descending nerve roots and be a cause of radiculopathy. On MR T2-weighted

e

axial (a, d) and T1-weighted axial images (b, e), synovial cysts (arrows) are seen anterior to the facet joint communicating with the joint. The right-sided synovial cyst (dotted arrow) shows T1 hyperintensity (b) suggestive of a hemorrhagic synovial cyst (c) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

2.6 Illustrations: Common Spine Disorders Associated with Back Pain Fig. 2.43  Synovial cyst (arrows) arising from the left L4/L5 facet joint in a 59-year-old man (a, b). As synovial cysts are degenerative in etiology, other degenerative features such as osteophytes, joint space narrowing, joint hypertrophy, and joint effusion are usually also present of the adjacent facet joints. With an epidural cystic mass, features that point to a synovial cyst include (1) degenerative changes of the adjacent facet joint, (2) communication with a joint effusion or joint space, and (3) old age

a

Fig. 2.44  Synovial cyst (arrow) originating from the right L5/S1 facet joint in a 47-year-old woman. Degenerative changes such as joint space narrowing and subchondral sclerosis are also noted of the L5/S1 facet joint. The cyst is located near the ventral aspect of the right facet joint. The ventral synovial cyst can compress upon the adjacent descending nerve root and dural sac

57

b

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2  Common Spine Disorders Associated with Back Pain

a

b

c

Fig. 2.45  Baastrup’s phenomenon in a 69-year-old man. A midline fluid collection (arrows) is present in the posterior epidural space due to interspinous bursitis at the L3/L4 level on T2-weighted sagittal (a) and T2-weighted axial images (b). There are erosions of the spinous pro-

d

cesses of L3 and L4 with interspinous narrowing (dotted arrows) on T2-weighted (a) and T1-weighted sagittal images (c). On CT (d), interspinous narrowing, erosions, and sclerosis of the spinous processes (dotted arrow) are evident

2.6 Illustrations: Common Spine Disorders Associated with Back Pain

a

59

b

Fig. 2.46  Baastrup’s phenomenon in a 67-year-old woman. The interspinous distance between L4 and L5 is narrowed (arrow, a) with associated enhancement (dotted arrow, b). There are also erosions of the L4 and L5 spinous processes

60

References Amundsen T, Weber H, Lilleas F, Nordal HJ, Abdelnoor M, Magnaes B. Lumbar spinal stenosis. Clinical and radiologic features. Spine (Phila Pa 1976). 1995;20(10):1178–86. Bradley WG Jr. Low back pain. AJNR Am J Neuroradiol. 2007;28(5):990–2. Butt S, Saifuddin A.  The imaging of lumbar spondylolisthesis. Clin Radiol. 2005;60(5):533–46. https://doi.org/10.1016/j. crad.2004.07.013. Chou R, Qaseem A, Snow V, Casey D, Cross JT Jr, Shekelle P, et al. Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society. Ann Intern Med. 2007;147(7):478–91. Chou R, Fu R, Carrino JA, Deyo RA.  Imaging strategies for low-back pain: systematic review and meta-analysis. Lancet. 2009;373(9662):463–72. https://doi.org/10.1016/S0140-­ 6736(09)60172-­0. Del Grande F, Maus TP, Carrino JA. Imaging the intervertebral disk: age-related changes, herniations, and radicular pain. Radiol Clin N Am. 2012;50(4):629–49. https://doi.org/10.1016/j.rcl.2012.04.014. Deyo RA, Diehl AK.  Cancer as a cause of back pain: frequency, clinical presentation, and diagnostic strategies. J Gen Intern Med. 1988;3(3):230–8. Fardon DF, Milette PC. Nomenclature and classification of lumbar disc pathology. Recommendations of the combined task Forces of the

2  Common Spine Disorders Associated with Back Pain North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology. Spine (Phila Pa 1976). 2001;26(5):E93–113. Lee GY, Lee JW, Choi HS, Oh KJ, Kang HS. A new grading system of lumbar central canal stenosis on MRI: an easy and reliable method. Skelet Radiol. 2011;40(8):1033–9. https://doi.org/10.1007/s00256-­ 011-­1102-­x. Malfair D, Beall DP.  Imaging the degenerative diseases of the lumbar spine. Magn Reson Imaging Clin N Am. 2007;15(2):221–38. https://doi.org/10.1016/j.mric.2007.04.001. Maus TP.  Imaging of spinal stenosis: neurogenic intermittent claudication and cervical spondylotic myelopathy. Radiol Clin N Am. 2012;50(4):651–79. https://doi.org/10.1016/j.rcl.2012.04.007. Modic MT, Obuchowski NA, Ross JS, Brant-Zawadzki MN, Grooff PN, Mazanec DJ, et  al. Acute low back pain and radiculopathy: MR imaging findings and their prognostic role and effect on outcome. Radiology. 2005;237(2):597–604. https://doi.org/10.1148/ radiol.2372041509. Pfirrmann CW, Dora C, Schmid MR, Zanetti M, Hodler J, Boos N.  MR image-based grading of lumbar nerve root compromise due to disk herniation: reliability study with surgical correlation. Radiology. 2004;230(2):583–8. https://doi.org/10.1148/rad iol.23020212892302021289. Song SJ, Lee JW, Choi JY, Hong SH, Kim NR, Kim KJ, et al. Imaging features suggestive of a conjoined nerve root on routine axial MRI.  Skelet Radiol. 2008;37(2):133–8. https://doi.org/10.1007/ s00256-­007-­0403-­6.

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Common Spine Disorders Associated with Neck Pain

Contents 3.1   Cervical Spine Imaging in Patients with Neck Pain: What Should We Focus on? 

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3.2   Cervical Spondylotic Myelopathy 

 62

3.3   Cervical Spondylotic Radiculopathy 

 62

3.4   Herniated Intervertebral Disk 

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3.5   Illustrations: Common Spine Disorders Associated with Neck Pain  3.5.1  Cervical Spondylotic Myelopathy  3.5.2  Cervical Spondylotic Radiculopathy  3.5.3  Herniated Intervertebral Disk 

 64  64  70  79

References 

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Abstract

3.1 Cervical Spine Imaging in Patients with Neck Pain: What Should In this chapter, we will describe some tips in the assessWe Focus on? ment of cervical spine imaging in patients presenting with neck pain and/or cervical radiculopathy. We will also detail imaging findings of cervical spondylotic myelopathy, cervical spondylotic radiculopathy, and cervical herniated intervertebral disks. Keywords

Intervertebral disk · Cervical spondylotic myelopathy · Ligamentum flavum · Cervical radiculopathy · Foraminal stenosis

In this chapter, we will describe some tips in the assessment of cervical spine imaging in patients presenting with neck pain and/or cervical radiculopathy. We will also detail imaging findings of cervical spondylotic myelopathy, cervical spondylotic radiculopathy, and cervical herniated intervertebral disks.

Common spinal disorders associated with neck pain include cervical spondylotic myelopathy (CSM), cervical spondylotic radiculopathy (CSR), and cervical herniated intervertebral disks (HIVD). A routine plain radiograph series may consist of up to six images: anterior-posterior (AP), lateral, lateral with flexion and extension, and both oblique views. On AP radiographs, careful evaluation for uncovertebral hypertrophy on both sides of the upper vertebral endplates should be made. On the lateral view, alignment disorders, ossification of the posterior longitudinal ligament (OPLL), and posterior osteophytes may be observed. On flexion/ extension views, segmental instability should be determined by assessing for a change of angulation and displacement. On oblique views, the ipsilateral neural foramen is best demonstrated, and foraminal stenosis caused by uncovertebral hypertrophy can be observed. For example, in the left anterior oblique view, the left neural foramen is imaged en face and appears widest due to its anterolateral course.

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 J. W. Lee et al., Radiology Illustrated: Spine, Radiology Illustrated, https://doi.org/10.1007/978-981-99-6612-7_3

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Table 3.1  Cervical spine imaging in patients with neck pain: what should we focus on? AP radiograph Lateral radiograph

Lateral radiographs in flexion and extension Oblique radiographs CT T2-weighted MR images T1-weighted MR images

Uncovertebral hypertrophy on both sides of the upper endplate Alignment disorders, ossified posterior longitudinal ligament (OPLL), posterior osteophytes Segmental instability Ipsilateral neural foraminal stenosis from uncovertebral hypertrophy Osteophytes, uncovertebral hypertrophy, OPLL Herniated disk, central canal stenosis, spinal cord pathology Bone marrow signal change, soft disk herniation

With three-dimensional CT, endplate osteophytes, uncovertebral hypertrophy, and OPLL are easily visualized, while soft disk herniation may be diagnosed by adjusting window level and width settings. MR is the best method to evaluate spinal pathology including that of the spinal cord. On T2-weighted images, apart from screening the central canal for any pathology obliterating the cerebrospinal fluid space around the cord such as a herniated disk or central canal stenosis due to a bulging disk or ligamentum flavum buckling, it is also important to carefully evaluate the spinal cord. Most pathology involving the spinal cord shows high signal change on T2-weighted images. On T1-weighted images, the signal intensity of the bone marrow should be carefully assessed. Soft disk herniation and osteophytes can be differentiated on T1-weighted images, as disk herniation is usually of isointense signal to the parent disk while osteophytes are usually of lower signal intensity (Table 3.1).

3.2 Cervical Spondylotic Myelopathy Cervical spondylotic myelopathy (CSM) is a condition in which degenerative changes of the cervical spine result in myelopathy from spinal cord compression. The common mechanical compressive factors contributing to CSM include bulging disks, buckling of the ligamentum flavum, posterior osteophytes, or ossification of the posterior longitudinal ligament. These mechanical compressive factors both directly injure neural tissue and initiate secondary ischemia, inflammation, and apoptosis. The histologic characteristics of CSM include cystic cavitation and gliosis of the central gray matter and demyelination of the medial portions of the white matter long tracks. There is Wallerian degeneration of the posterior columns and posterolateral tracts cephalad to the

site of compression, with loss of anterior horn cells and corticospinal tract degeneration at and caudal to the site of compression (Baptiste and Fehlings 2006; Maus 2012). The diagnosis of cervical central canal stenosis and grading of its severity can be made by assessing for cerebrospinal fluid (CSF) obliteration around the spinal cord, spinal cord deformity, and intramedullary T2 high signal change. In grade 1 central canal stenosis, there is central canal narrowing resulting in more than 50% obliteration of the subarachnoid space around the spinal cord anteriorly and/or posteriorly without spinal cord deformity. Central canal narrowing with deformity of the spinal cord is defined as grade 2 central canal stenosis. Central canal narrowing with intramedullary T2 high signal change is defined as grade 3 central canal stenosis (Kang et al. 2011). In patients with CSM, T2 hyperintensity in the spinal cord represents edema, demyelination, gliosis, and cystic necrosis. The observed changes may be reversible or irreversible. Faint and indistinct T2 hyperintensity in the spinal cord is more likely to reflect reversible edema, but intense and well-­ defined T2 hyperintensity more likely represents fixed gliosis or cystic necrotic changes. T1 hypointensity in the spinal cord represents irreversible necrosis and myelomalacia (Al-Mefty et  al. 1988; Ohshio et  al. 1993; Ramanauskas et  al. 1989; Takahashi et  al. 1989; Taneichi et  al. 1994). Contrast enhancement with Gd is not typical for patients with CSM with low prevalence. But contrast enhancement can reveal areas of blood–spinal cord barrier disruption and relate to inferior recovery potential after decompression surgery. It was suggested recently that a pancake-like Gd enhancement of the spinal cord on sagittal images immediately below the area of compression and circumferential enhancement on axial images in patients with intramedullary lesions found with T2WI is strongly indicative of CSM rather than other inflammatory or tumorous condition of the spinal cord (Flanagan et al. 2014).

3.3 Cervical Spondylotic Radiculopathy In the cervical spine, uncovertebral hypertrophy with foraminal stenosis is a more common cause of radiculopathy than HIVD, in contrast to the lumbar spine. The term “cervical spondylotic radiculopathy” (CSR) refers to degenerative narrowing of the cervical neural foramen causing nerve root compression and subsequent radiculopathy. The primary imaging finding of cervical spondylotic radiculopathy is cervical foraminal stenosis mainly caused by uncovertebral hypertrophy or facet osteophytes. Uncovertebral hypertrophy is seen on AP radiographs as laterally orientated bony projections of the uncovertebral

3.4 Herniated Intervertebral Disk

joints (especially from the uncinate processes). On lateral radiographs, uncovertebral hypertrophy can be seen as a double line just above the lower cortical margin of the vertebral body. On oblique views with the ipsilateral neural foramen shown en face, the uncovertebral joint is situated anterior to the neural foramen. On CT images, uncovertebral hypertrophy can be easily identified on axial and oblique sagittal reconstructed images. However, optimal window settings are required in proper evaluation of the neural foramen because the margins of the uncovertebral joints may be obscured and result in exaggeration of foraminal stenosis under different window settings. It is important to set the window level and width settings to display the bony cortical margins sharply. On MR images, axial images are better than sagittal images in evaluating the neural foramina. On axial images, both the disk level and the level at the inferior aspect of the vertebral body above the disk are important in assessing neural foraminal stenosis because (1) the nerve root exits through the inferior portion of the neural foramen at the disk level and at the inferior aspect of the vertebral body above the disk (in contrast to the lumbar spine where the nerve roots exit through the superior portion of the neural foramina) and (2) uncovertebral hypertrophy is best seen at these two levels as the uncinate processes project superiorly. As such, on axial T2-weighted images, the AP diameter of the neural foramen at both the disk level and inferior aspect of the vertebral body above the disk should be carefully reviewed for narrowing from uncovertebral or facet hypertrophy. The Lee grading system (Kim et al. 2015) for cervical neural foraminal stenosis suggests the use of axial T2-weighted images to avoid overestimation of stenosis. The narrowest width of the neural foramen is narrower than that of the extraforaminal nerve root, which indicates the presence of cervical neural foraminal stenosis. If the width of the neural foramen is less than half the width of the extraforaminal nerve root, it indicates “severe” neural foraminal stenosis (grade 2). If the width of the neural foramen is more than half, but narrower than the width of the extraforaminal nerve root, it indicates “non-­ severe” neural foraminal stenosis (grade 1). If the narrowest width of the neural foramen is greater than the width of the extraforaminal nerve root at the level of the anterior margin of the superior articular process, it indicates normal (grade 0). Occasionally, the extraforaminal nerve root is not clearly visible. In such cases, the width of the contralateral extraforaminal nerve root or the distance between the posterior margin of the vertebral artery and anterior margin of the superior articular process can be used as an alternative.

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Even though oblique sagittal MR images show the patency of the neural foramen best, the orientation angle of the cervical neural foramen varies from C2–3 to C7–T1. Therefore, obtaining images in a plane perfectly perpendicular to all levels of the cervical neural foramina course is impossible.

3.4 Herniated Intervertebral Disk In many cases, it is not easy to differentiate HIVD from endplate osteophytes on MR. CT images can help in the differentiation of HIVD from osteophytes. On MR, careful review of the T1-weighted sagittal images may provide a clue in identifying HIVD, as HIVD is seen as intermediate signal intensity isointense and in contiguity with the parent disk, in contrast to posterior osteophytes or a thickened PLL. Posterior osteophytes are of low signal intensity similar to the vertebral cortex, while thickened PLL is also of low signal intensity on T1-weighted images. On gradient-echo T2-weighted images, cervical HIVDs are of high signal intensity similar to the central portion of the intervertebral disk, compared to the low signal seen in osteophytes. Schmorl’s nodes refer to areas where the intervertebral disk herniates into the vertebral body through endplate defects. In the acute stage, the vertebral body around the intravertebral disk herniation shows bone marrow edema. In this situation, differential diagnoses to consider include focal metastasis and early infectious spondylitis. On CT sagittal images or T1-weighted sagittal MR images, discontinuity of the endplate is a clue to the diagnosis of a Schmorl’s node. Forget Me Nots! • On oblique radiographs, the ipsilateral neural foramen is presented in its widest profile. • Common mechanical compressive factors contributing to CSM include bulging disks, buckling of the ligamentum flavum, posterior osteophytes, and ossified posterior longitudinal ligament. • In patients with CSM, T2 hyperintensity in the spinal cord represents a mixture or combination of edema, demyelination, gliosis, and cystic necrosis. • On axial images, both the disk level and the level at the inferior aspect of the vertebral body above the disk are important in evaluation of neural foraminal stenosis. • HIVD is seen as intermediate signal intensity isointense to and in contiguity with the parent disk on T1-weighted images and as high signal intensity on gradient-echo T2-weighted images.

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3  Common Spine Disorders Associated with Neck Pain

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain 3.5.1 Cervical Spondylotic Myelopathy See Figs. 3.1, 3.2, 3.3, 3.4, 3.5, 3.6 and 3.7. a

c

b

No stenosis

Grade 2 central canal stenosis

Fig. 3.1  Schematic illustrations of cervical central canal stenosis (a– d). Diagnosis and grading of cervical central canal stenosis are made on the basis of the degree of cerebrospinal fluid (CSF) obliteration around the spinal cord, spinal cord deformity, and intramedullary T2-high signal change. Central canal narrowing with more than 50% obliteration of the subarachnoid space around the spinal cord anteriorly or posteriorly

d

Grade 1 central canal stenosis

Grade 3 central canal stenosis

(either or both) without spinal cord deformity is defined as grade 1 central canal stenosis (b). Central canal narrowing with deformity of the spinal cord is defined as grade 2 central canal stenosis (c). Central canal narrowing with intramedullary T2-high signal change is defined as grade 3 central canal stenosis (d) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

a

65

b

Grade 1 central canal stenosis Grade 1 central canal stenosis

c

Grade 1 central canal stenosis

Fig. 3.2  Grade 1 central canal stenosis in a 51-year-old man. Grade 1 central canal stenosis at C5/C6 and C6/C7 shown on T2-weighted sagittal (a) and T1-weighted sagittal images (b). Subarachnoid space oblit-

eration is noted involving more than 50% of its width at these levels, but without cord deformity (c) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

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a

3  Common Spine Disorders Associated with Neck Pain

b

Grade 2 central canal stenosis Grade 2 central canal stenosis

Fig. 3.3  Grade 2 central canal stenosis in a 64-year-old man (a, b). Grade 2 central canal stenosis at C4/C5 and C5/C6, with spinal cord deformity secondary to the stenosis (dotted line) (a) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

a

67

b

Grade 3 central canal stenosis

c

Grade 3 central canal stenosis

Fig. 3.4  Grade 3 central canal stenosis in a 64-year-old man. Grade 3 central canal stenosis at C4/C5. There is cord compression with intramedullary T2-hyperintensity (arrow) at C4/C5 (a). Newer MR tech-

niques like diffusion tensor imaging shows fiber indentation (dotted arrow) without fiber disruption at that level (b, c) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

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a

3  Common Spine Disorders Associated with Neck Pain

b

c

Grade 2 central canal stenosis

Grade 3 central canal stenosis

Grade 1 central canal stenosis

Fig. 3.5  Multilevel central canal stenoses of the cervical spine in a 57-year-old man. Multilevel central canal stenoses are evident at C3/C4 (grade 2), C4/C5 (grade 3), C5/C6 (grade 1), C6/C7 (grade 1), and C7/

a

b

Fig. 3.6  Ossification of the posterior longitudinal ligament (OPLL) as a cause of central canal stenosis in a 57-year-old man. OPLL (arrow) is seen at the C3/C4 level on plain lateral radiography (a). OPLL can be a cause of central canal stenosis with cord compression and compressive

T1 (grade 1) (a–c) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

c

myelopathy. OPLL shows variable signal intensity on MR (b, c). Most cases of OPLL show low signal intensity (arrow) on T1-weighted sagittal images, but sometimes high T1 signal intensity may be present due to presence of fatty marrow within

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

a

Fig. 3.7  Contrast enhancement with Gd in a patient with cervical spondylotic myelopathy. (a, b) On T2- and contrast enhanced T1-weighted sagittal images, a pancake-like Gd enhancement of the spinal cord (red arrow) immediately below the area of compression

69

b

with increased T2 signal intensity (yellow arrow) suggests cervical spondylotic myelopathy, possibly combined dynamic cord compression

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3  Common Spine Disorders Associated with Neck Pain

3.5.2 Cervical Spondylotic Radiculopathy See Figs. 3.8, 3.9, 3.10, 3.11, 3.12 and 3.13.

a

c

Fig. 3.8  Uncovertebral hypertrophy as depicted on schematic illustrations (a, c, e) and plain radiography (b, d, f) in a 47-year-old man. Right C5/C6 uncovertebral hypertrophy is present on plain radiographs in the anterior-posterior (b), lateral (d), and oblique projections (f). To identify uncovertebral hypertrophy on the AP view, the outline of the uncinate process (dotted lines on b) should be carefully evaluated. On plain

b

d

lateral radiography (d), the double line (dotted arrows) separate from the inferior endplate suggests uncovertebral hypertrophy. On the oblique view (e, f), uncovertebral hypertrophy (arrow) can be easily identified anterior to the neural foramen (a, c, e) (Published with kind permission of © HealthWave 2014. All Rights Reserved)

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

e

Fig. 3.8 (continued)

f

71

72

a

Fig. 3.9  Right C5/C6 uncovertebral hypertrophy in a 57-year-old woman. On the AP radiograph (a), the right C5/C6 uncovertebral joint is hypertrophied (dotted circle). On the lateral radiograph (b), the double line (dotted arrows) separate from the inferior endplate is suggestive of uncovertebral hypertrophy. On the right oblique view, the right

3  Common Spine Disorders Associated with Neck Pain

b

C5/C6 neural foramen is narrowed by uncovertebral hypertrophy (c, dotted circle). The left neural foramen shows normal patency on the left oblique view (d). On MR T2-weighted oblique (e) and axial images (f), right C5/C6 uncovertebral hypertrophy causing neural foraminal stenosis (dotted circle) is well demonstrated

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

c

Fig. 3.9 (continued)

d

73

74

e

Fig. 3.9 (continued)

3  Common Spine Disorders Associated with Neck Pain

f

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

a

75

b

c

d

e

f

g

B,C

D,E F,G

Fig. 3.10  Foraminal stenoses evaluated by MR axial images in a 74-year-old man. Foraminal stenosis can be evaluated on T2-weighted spin echo axial images (b, d, f) and gradient-echo axial images (c, e, g)

at the level near the lower endplate just above the intervertebral disk (dotted lines on a). There are foraminal stenoses at both C3 and C4, both C4 and C5, and left C5/C6 levels (circles)

76

a

3  Common Spine Disorders Associated with Neck Pain

c

d

b

Fig. 3.11  Right C6/C7 foraminal stenosis due to uncovertebral hypertrophy in a patient presenting with right arm pain in a 59-year-old man. On axial images (a, b), the right neural foramen is narrowed (circles) relative to the normal left side. On sagittal images (c, d), uncovertebral hypertrophy can be differentiated from disk herniation, the cortical line in the former (uncovertebral hypertrophy) continues to the uncinate process and demonstrates internal low signal (due to sclerosis) or high

signal (due to internal marrow fat) on T1-weighted sagittal images (d), whereas the latter (disk herniation) reveals intermediate signal intensity on T1-weighted images without a cortical outline (which will be shown later). In this case, uncovertebral hypertrophy can be identified on sagittal images on the basis of its cortical outline (arrow) on the T2-weighted sagittal image (c), with internal high signal (dotted arrow) due to fatty marrow on the T1-weighted sagittal image (d)

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

a

d

b

e

Fig. 3.12  The Lee grading system for cervical neural foraminal stenosis (a, d) Grade 0 (normal) cervical neural foraminal stenosis. (b, e) Grade 1 (non-severe) cervical neural foraminal stenosis (yellow arrows). The width of the neural foramen is more than half, but nar-

77

c

f

rower than the width of the extraforaminal nerve root. (c–f) Grade 2 (severe) cervical neural foraminal stenosis (red arrows). The width of the neural foramen is less than half the width of the extraforaminal nerve root

78

3  Common Spine Disorders Associated with Neck Pain

a

b

c

d

Fig. 3.13  Oblique sagittal MR image of the cervical spine. (a, b) oblique sagittal T2-weighted MR image shows the patency of the cervical neural foramen with foraminal stenosis at C5/6 and C6/7 (yellow arrows). (c, d) However, the orientation angle of the cervical neural

foramen varies from C2–3 (c) to C6/7 (d). Therefore, obtaining images in a plane perfectly perpendicular to all levels of the cervical neural foramina course is impossible

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

79

3.5.3 Herniated Intervertebral Disk See Figs. 3.14, 3.15, 3.16, 3.17 and 3.18.

a

b

c

d

Fig. 3.14  Herniated disk (arrows) at the C4/C5 central zone in a 59-year-old woman (a–d). The herniated disk at the central zone is well visualized on the T1-weighted images (a, d) demonstrating intermedi-

ate signal intensity, with high signal intensity on the gradient-echo T2-weighted axial image (c)

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3  Common Spine Disorders Associated with Neck Pain

a

b

c

d

Fig. 3.15  Herniated disk (arrow) in the foraminal zone on T2-weighted oblique sagittal (a), T1-weighted sagittal (b), T2-weighted axial (c) and gradient-echo axial images (d) in a 74-year-old man. The foraminal disk herniation is shown as a focus of intermediate signal on the

a

b

T1-weighted image (similar to the signal of the disk, b) and slightly hyperintense on the gradient-echo axial image (d); these are different from the low signal found in osteophytes or uncovertebral hypertrophy

c

d

Fig. 3.16  Foraminal disk herniations in a 51-year-old man. On sagittal T2-weighted (a) and T1-weighted images (b), the disk herniation (arrows) in the foraminal zone is barely defined. However on axial

images (c, d) the disk herniation (arrows) in the foraminal zone is clearly demonstrated

3.5 Illustrations: Common Spine Disorders Associated with Neck Pain

a

c

81

d

b

Fig. 3.17  Herniated disk in the right C6/C7 subarticular and foraminal zones in a 75-year-old man (a–d). On the T2-weighted axial image (a), the disk herniation is of hypointense signal (arrow) and cannot be differentiated from uncovertebral hypertrophy. However, on the gradient-­

echo axial image (b), the disk herniation is of hyperintense signal (arrow), different from uncovertebral hypertrophy which are of low signal on gradient-echo images. On the T1-weighted sagittal image (c), the disk herniation shows intermediate signal intensity (arrow)

82

a

3  Common Spine Disorders Associated with Neck Pain

b

c

d

e

f

Fig. 3.18  Acute Schmorl’s node in the patient present with neck pain in a 37-year-old man. There is a round nodular area (arrow) in the upper aspect of the C4 vertebral body of low signal on T2-weighted (a, d) and T1-weighted sagittal images (b). The nodular area shows enhancement (arrow) following intravenous contrast administration (c). Surrounding this is an area of bone marrow edema manifest as T2 hyperintensity, T1 hypointensity with associated enhancement (arrowheads in c). On CT, the C4 upper endplate is not well defined (dotted arrow) around the nodular area (arrow) (e). These findings are suggestive of an acute Schmorl’s node. A Schmorl’s node occurs when part of the interverte-

g

bral disk herniates into the vertebral body through an endplate defect. In the acute stage, the vertebral body around the intravertebral disk herniation shows bone marrow edema. On sagittal CT or T1-weighted sagittal images, the finding of endplate discontinuity is a clue to the presence of a Schmorl’s node. Differential diagnoses include focal metastasis and early infectious spondylitis. The finding of endplate discontinuity is an important feature in the diagnosis of a Schmorl’s node. At follow-up MR 6 months later (f, g), the bone marrow edema (T1-hypointensity and enhancement) around the Schmorl’s node has disappeared, although some areas of enhancement persist

References

References Al-Mefty O, Harkey LH, Middleton TH, Smith RR, Fox JL.  Myelopathic cervical spondylotic lesions demonstrated by magnetic resonance imaging. J Neurosurg. 1988;68(2):217–22. https://doi. org/10.3171/jns.1988.68.2.0217. Baptiste DC, Fehlings MG.  Pathophysiology of cervical myelopathy. Spine J. 2006;6(6 Suppl):190S–7S. https://doi.org/10.1016/j. spinee.2006.04.024. Flanagan EP, Krecke KN, Marsh RW, Giannini C, Keegan BM, Weinshenker BG: Specific pattern of gadolinium enhancement in spondylotic myelopathy. Ann Neurol. 2014;76:54–65. https://doi. org/10.1002/ana.24184. Kang Y, Lee JW, Koh YH, Hur S, Kim SJ, Chai JW, et  al. New MRI grading system for the cervical canal stenosis. AJR Am J Roentgenol. 2011;197(1):W134–40. https://doi.org/10.2214/ AJR.10.5560. Kim S, Lee JW, Chai JW, Yoo HJ, Kang Y, Seo J, et al. A new MRI grading system for cervical foraminal stenosis based on axial

83 T2-weighted images. Korean J Radiol 2015;16:1294-302. https:// doi.org/10.3348/kjr.2015.16.6.1294. Maus TP.  Imaging of spinal stenosis: neurogenic intermittent claudication and cervical spondylotic myelopathy. Radiol Clin N Am. 2012;50(4):651–79. https://doi.org/10.1016/j.rcl.2012.04.007. Ohshio I, Hatayama A, Kaneda K, Takahara M, Nagashima K.  Correlation between histopathologic features and magnetic resonance images of spinal cord lesions. Spine (Phila Pa 1976). 1993;18(9):1140–9. Ramanauskas WL, Wilner HI, Metes JJ, Lazo A, Kelly JK. MR imaging of compressive myelomalacia. J Comput Assist Tomogr. 1989;13(3):399–404. Takahashi M, Yamashita Y, Sakamoto Y, Kojima R.  Chronic cervical cord compression: clinical significance of increased signal intensity on MR images. Radiology. 1989;173(1):219–24. Taneichi H, Abumi K, Kaneda K, Terae S.  Monitoring the evolution of intramedullary lesions in cervical spinal cord injury. Qualitative and quantitative analysis with sequential MR imaging. Paraplegia. 1994;32(1):9–18. https://doi.org/10.1038/sc.1994.3.

4

Common Traumatic Disorders of the Thoracolumbar Spine

Contents 4.1   Stable and Unstable Spinal Injuries 

 85

4.2   Major Thoracolumbar Injury: Denis Classification 

 86

4.3   Benign Osteoporotic Versus Malignant Compression Fractures 

 87

4.4   Sacral Insufficiency Fractures 

 87

4.5   AO Classification 

 88

4.6   Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine  4.6.1  Compression Fractures  4.6.2  Burst Fractures  4.6.3  Distraction Injury  4.6.4  Malignant Spine Fracture Due to Metastasis  4.6.5  Sacral Insufficiency Fracture 

 91  91  93  97  101  105

References 

 113

In this chapter, we will describe radiologic findings suggestive of an unstable spinal injury. We also explain Denis’ In this chapter, we will describe radiologic findings sugthree-column theory and the four major injury types of comgestive of an unstable spinal injury. We also explain pression fractures, burst fractures, seat-belt-type injuries, Denis’ three-column theory and the four major injury and fracture–dislocations. We will present recently introtypes of compression fractures, burst fractures, seat-belt-­ duced classification systems for thoracolumbar and cervical type injuries, and fracture–dislocations. We will present injuries. In addition, differential features between benign recently introduced classification systems for thoracoosteoporotic and malignant compression fractures will be lumbar and cervical injuries. In addition, differential feadiscussed. Tips to aid in identifying sacral insufficiency fractures between benign osteoporotic and malignant tures will be also presented. compression fractures will be discussed. Tips to aid in identifying sacral insufficiency fractures will be also presented. Abstract

4.1 Stable and Unstable Spinal Injuries

Keywords

Compression fracture · Burst fracture · Posterior ligamentous complex · Distraction injury · Vertebral body collapse

Daffner et al. reported five radiographic signs indicative of vertebral instability: displacement, widened interlaminar space, widened facet joint, disrupted posterior vertebral body line, and widened vertebral canal (Daffner et  al. 1990) (Table 4.1).

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 J. W. Lee et al., Radiology Illustrated: Spine, Radiology Illustrated, https://doi.org/10.1007/978-981-99-6612-7_4

85

86 Table 4.1  Five radiographic signs indicative of vertebral instability Sign Displacement

Significance Injury to major ligamentous and articular structures Widened interlaminar space Injury to the posterior ligamentous structures and the facet joint Widened facet joint Injury to the posterior ligamentous structures Disrupted posterior vertebral Burst injury with disruption of body line the anterior bony and posterior ligamentous structures Widened vertebral canal (increase Injury to the entire vertebra in the sagittal plane in the interpedicular distance of more than 2 mm)

The three-column theory of Denis divides the spinal column into anterior (anterior half of the vertebral body), middle (posterior half of the vertebral body including its posterior wall), and posterior columns (posterior bony elements including the pedicles, lamina, facet joints, and spinous processes and the ligamentous structures including the ligamentum flavum, interspinous and supraspinous ligaments, as well as the facet joint capsule) (Denis 1983). When only one column is disrupted, the injury is considered mechanically stable. When two or more columns are disrupted, the injury is considered unstable (Denis 1983). The Thoracolumbar Injury Classification and Severity (TLICS) score has been described recently, focusing on clinical decision-making by scoring of three major variables (Vaccaro et al. 2005). The three major variables are injury morphology (compression = 1, burst = 2, translation/ rotation = 3, distraction = 4), integrity of the posterior ligamentous complex (intact = 0, suspected/indeterminate = 2, injured = 3), and neurologic status (intact = 0, nerve root injury  =  2, complete cord injury  =  2, incomplete cord injury  =  3, cauda equina injury  =  3). The injury severity score is obtained by summing up the scores of each major variable. A total score of more than 4 is an indication for surgery. More recently, the Subaxial Cervical Spine Injury Classification (SLIC) scale has been described for the cervical spine (Vaccaro et al. 2007). In SLIC, the three major variables are injury morphology (compression  =  1, burst = 2, distraction = 3, rotation/translation = 4), integrity of the disco-ligamentous complex (intact  =  0, indeterminate = 1, disrupted = 2), and neurologic status (intact = 0, root injury = 1, complete cord injury = 2, incomplete cord injury = 3) (Tables 4.2 and 4.3).

4  Common Traumatic Disorders of the Thoracolumbar Spine Table 4.2  Thoracolumbar Injury Classification and Severity (TLICS) scoring Points Morphology  Compression fracture  Burst fracture  Translational/rotational  Distraction Neurology  Intact  Nerve root  Complete cord injury  Incomplete cord injury  Cauda equina injury Posterior ligamentous complex  Intact  Injury suspected/indeterminate  Injured

1 2 3 4 0 2 2 3 3 0 2 3

A total score of more than 4 is an indication for surgery Table 4.3  Subaxial Cervical Spine Injury Classification (SLIC) scale Points Morphology  Compression fracture  Burst fracture  Distraction  Translational/rotational Neurology  Intact  Nerve root  Complete cord injury  Incomplete cord injury  Continuous cord compression in setting of neuro deficit Disco-ligamentous complex  Intact  Injury suspected/indeterminate  Injured

1 2 3 4 0 1 2 3 +1 0 1 2

A total score of more than 4 is an indication for surgery

4.2 Major Thoracolumbar Injury: Denis Classification Denis classified thoracolumbar trauma into four major injury types: compression fractures, burst fractures, seat-belt-type injuries, and fracture–dislocations (Denis 1983). A compression fracture is defined as anterior vertebral body collapse without posterior vertebral body wall involvement; this is indicative of anterior column failure by a compressive force without middle column failure. A burst fracture involves anterior and posterior vertebral body collapse with posterior

4.4 Sacral Insufficiency Fractures Table 4.4  Criteria for chance-type flexion–distraction injury 1. Disruption of the posterior elements of the spine 2. Longitudinal separation of the disrupted posterior elements 3. Minimal or no decrease in the anterior vertical height of the vertebral body 4. Minimal or no forward displacement of the superior vertebral fragment 5. Minimal or no lateral displacement of this fragment or of the superior vertebra 6. Height of posterior aspect of affected vertebral body equal to or greater than that of the adjacent inferior vertebral body

vertebral body wall disruption resulting in retropulsion, reflecting anterior and middle column failure by a compressive force. A seat-belt-type injury represents failure of both the posterior and middle columns under tension forces generated by flexion and distraction, with preserved hinge function of the anterior column (if the anterior column loses this hinge function, it is classified as a fracture–dislocation flexion–distraction subtype injury). A seat-belt-type injury is also known as a Chance fracture in cases involving bony disruption. The seat-belt-type injury is also known as a flexion– distraction injury, a term more commonly used currently. A flexion–distraction injury is diagnosed if there is widening of the interspinous distance representing posterior ligamentous complex injury, along with horizontal fractures of the pedicles and articular processes. The accurate diagnosis of a flexion–distraction injury is important because it can be a cause of delayed neurologic deficits due to progressive kyphosis if left untreated. Gloves et  al. described six criteria for a Chance-type flexion–distraction injury (Table  4.4) (Groves et  al. 2005). Finally, the fracture–dislocation injury represents failure of all three columns leading to subluxation or dislocation. It can be also classified into three subtypes: flexion–rotation, shear, and flexion–distraction. However, flexion burst fracture and flexion–distraction injury are hard to differentiate if there is posterior ligamentous injury because flexion–distraction injury can have burst subtype (flexion–distraction burst injury) according to current classification system such as TLICS. There are no criteria to differentiate flexion burst fracture with PLC injury from flexion–distraction injury with burst subtype (flexion– distraction burst injury) on TLICS. We think that if there is definite PLC injury with widened interspinous space, that type of injury can be classified as flexion–distraction burst injury although there is a burst component.

4.3 Benign Osteoporotic Versus Malignant Compression Fractures In osteoporotic patients, compression or burst fractures are commonly encountered without a corresponding history of an acute traumatic episode. Acute osteoporotic compression

87 Table 4.5 Benign osteoporotic versus malignant compression fractures Benign osteoporotic compression fracture Preservation of normal bone marrow signal in the fractured vertebra Mild low-signal change in the vertebral body on T1-weighted images Less intense bone marrow enhancement Linear or box-like non-­ enhancing areas Retropulsion of posterior vertebral body Fluid- or air-filled cavity Evidence of other old compression fractures

Malignant compression fracture Bone marrow signal change involving the whole vertebral body Marked low T1 signal change in the vertebral body on T1-weighted images Intense bone marrow enhancement Small irregular non-enhancing areas Convex posterior vertebral body margin Paravertebral and epidural mass Evidence of remote metastases

or burst fractures can be diagnosed by MRI. On MRI, bone marrow edema in the fractured vertebral body (low signal on T1-weighted images, high signal on fat-suppressed T2-weighted and contrast enhancement T1-weighted images) is a clue indicative of an acute stage of the injury. Absence of bone marrow edema with fatty marrow replacement strongly suggests an old healed compression fracture. Metastasis can be also a cause of compression fracture without an episode of trauma; this is known as a malignant compression fracture. Differentiating a malignant compression fracture from a benign osteoporotic compression fracture is important. Clues that suggest a malignant compression fracture include bone marrow signal change involving the entire vertebral body, convex margin of the posterior vertebral body, strong bone marrow enhancement, associated paravertebral mass, and evidence of remote metastases. Findings more suggestive of a benign osteoporotic compression fractures include preservation of normal bone marrow signal in the fractured vertebra, less intense bone marrow enhancement, fluid- or air-filled cavity within the vertebral body, and evidence of other old healed compression fractures. T1-weighted axial image is good for evaluating epidural tumor extension because epidural vein can be engorged and can be enhanced in hypervascular bone metastasis without epidural extension. In such cases, low signal on T1-weighted axial image in the epidural space suggests epidural extension of metastasis (Table 4.5).

4.4 Sacral Insufficiency Fractures Sacral insufficiency fractures usually occur in elderly patients with osteoporosis without a definite history of recent trauma. These are difficult to diagnose at an early stage as

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there is usually no significant history of recent trauma upon presentation and are often accompanied by concurrent lower lumbar degenerative pathology, as well as difficult depiction of these fractures on routine sacral radiographs. On T1-weighted sagittal MR images, the fracture is seen as a low-signal area within the sacral body and ala. Because in the routine lumbar spine MR, fat suppression T2-weighted image, contrast-enhanced image, and axial scans for the sacrum are not usually obtained, sacral insufficiency fracture should be found on T1-weighted sagittal image. Sacral insufficiency fractures are sometimes missed on routine spinal MR images performed without fat suppression and contrast-­ enhanced image, so careful evaluation of the T1-weighted sagittal images to identify any bone marrow signal change in the sacral body and ala is required. On contrast-enhanced T1-weighted axial images performed with fat suppression, extensive bone marrow enhancement containing low-signal linear densities within (representing the acute fracture lines) is seen. The extensive bone marrow enhancement can be sometimes mistaken for tumor or infection; however, the typical location (bilateral sacral ala and sacral body) and linear low-signal areas within (representing the fractures) are clues that suggest an acute sacral insufficiency fracture.

4.5 AO Classification The AO Spine Knowledge Forum Trauma presented a new classification system based on Magerl classification. They considered both fracture morphology and clinical factors relevant for clinical decision making like TLICS and SLIC. They presented five classification on their websites as follows:

upper cervical injury classification system, subaxial injury classification system, thoracolumbar injury classification system, sacral injury classification system, and osteoporotic fracture classification system. AO classifications are presented on AO websites as follows: www.aospine.org/classification. In the AO spine thoracolumbar injury classification system, tension band injury is important for the classification. Anterior tension band represents anterior longitudinal ligaments and anterior intervertebral disc. Posterior tension band represents posterior ligamentous complex and bony posterior elements. For each classification, they are composed of three components: morphological description, neurologic status, and modifiers (Tables 4.6, 4.7 and 4.8). Forget Me Nots! • Five radiographic signs indicative of vertebral instability are displacement, widened interlaminar space, widened facet joint, disrupted posterior vertebral body margin, and widened vertebral canal. • A flexion–distraction injury involves widening of the interspinous distance representing posterior ligamentous complex injury, with horizontal fractures of the pedicles and articular processes. • Features suggestive of a malignant compression fracture include bone marrow signal change involving the entire vertebral body, convex posterior vertebral body margin, strong bone marrow enhancement, associated paravertebral mass, and evidence of remote metastases. • Careful assessment of the T1-weighted sagittal images for abnormal bone marrow signal change in the sacral body and sacral ala is required to identify acute sacral insufficiency fractures.

Table 4.6  AO spine thoracolumbar injury classification system (www.aospine.org/classification) Type A  A0  A1  A2  A3

Compression injuries Minor nonstructural fractures Wedge compression Split Incomplete burst

 A4

Complete burst

Type B  B1

Distraction injury Transosseous tension band disruption (chance fracture) Posterior tension band disruption Hyperextension

 B2  B3

Type C  C

Translation injuries Displacement or dislocation

Fractures, which do not compromise the structural integrity of the spinal column such as transverse process or spinous process fractures Fracture of a single endplate without involvement of the posterior wall of the vertebral body Fracture of both endplates without involvement of the posterior wall of the vertebral body Fracture with any involvement of the posterior wall; only a single endplate fractured. Vertical fracture of the lamina is usually present and does not constitute a tension band failure Fracture with any involvement of the posterior wall and both endplates. Vertical fracture of the lamina is usually present and does not constitute a tension band failure Monosegmental pure osseous failure of the posterior tension band. The classical chance fracture Bony and/or ligamentary failure of the posterior tension band together with a type A fracture Type A fracture should be classified separately Injury through the disc or vertebral body leading to a hyperextended position of the spinal column Commonly seen in ankylotic disorders. Anterior structures, especially the ALL are ruptured but there is a posterior hinge preventing further displacement There are no subtypes because various configurations are possible due to dissociation/ dislocation. Can be combined with subtypes of A or B

4.5 AO Classification

89

Table 4.6 (continued) Neurology  N0 = neurology intact, N1 = transient neurologic deficit, N2 = radiculo symptoms, N3 = incomplete spinal cord injury or any degree of cauda equine injury, N4 = complete spinal cord injury, Nx = cannot be examined, + = continued spinal cord compression Modifiers  M1 This modifier is used to designate fractures with an indeterminate injury to the tension band based on spinal imaging with or without MRI. This modifier is important for designating those injuries with stable injuries from a bony standpoint for which ligamentous insufficiency may help determine whether operative stabilization is a consideration  M2 Is used to designate a patient-specific comorbidity, which might argue either for or against surgery for patients with relative surgical indications. Examples of an M2 modifier include ankylosing spondylitis or burns affecting the skin overlying the injured spine Classification nomenclature  Primary injury level: type (secondary injury level: type; neurology; modifier)  Example Displacement injury of the segment T 8/9 with an incomplete burst fracture of T9, incomplete spinal cord injury,    T8–9:C ankylosing spondylitis (T9:A3; N3;M2)    L1:A4 Complete burst fracture of L1, neurologically intact, PLC status unclear (N0;M1) Table 4.7  AO Spine sacral injury classification system (www.aospine.org/classification) Type A  A1  A2  A3 Type B  B1  B2  B3 Type C  C0  C1

 C2  C3

Lower sacrococcygeal injuries Coccygeal or compression vs ligamentous avulsion fractures Non-displaced transverse fractures below the S-I joint Displaced transverse fractures below the S-I joint Posterior pelvic injuries Central fracture—involves spinal canal Transalar fracture—does not involve foramina or spinal canal Transforaminal fracture—involves foramina but not spinal canal Spino-pelvic injuries Non-displaced sacral U-type variant Sacral U-type variant without posterior pelvic instability Bilateral complete type B injuries without transverse fracture Displaced U-type sacral fracture

No impact on posterior pelvic or spino-pelvic instability

 •  No implications on stability  •  Low likelihood of cauda equina injury  •  Higher likelihood of neuro injury than A1 or A2 (displacement)  •  May possibly benefit from reduction and stabilization Primary impact is on posterior pelvic stability  •  Longitudinal injuries only-rare type of Denis zone III injuries  •  Low likelihood of neurological injury  •  Unilateral Denis zone I injury  •  Denis zone II injury Spino-pelvic instability  •  Commonly seen low-energy insufficiency fracture  •  Any unilateral B-subtype where ipsilateral superior S1 facet is discontinuous with medial part of sacrum  •  May impact spino-pelvic stability (Isler)  •  More unstable and higher likelihood of neuro injury than C1  •  Worst combination of instability and likelihood of neuroinjury  •  Displaced transverse sacral fracture = canal compromise

Neurology  N0 = neurology intac, N1 = transient neurologic deficit, N2 = radiculo symptoms, N3 = incomplete spinal cord injury or any degree of cauda equine injury, N4 = complete spinal cord injury, Nx = cannot be examined, + = continued spinal cord compression Modifiers  M1 = soft tissue injury, M2 = metabolic bone disease, M3 = anterior pelvic bone injury, M4 = sacroiliac joint injury Classification nomenclature  Primary injury; neurology, modifiers  Example    B3; N1, M3 Transforaminal fracture (B3) high energy injury associated with transient neurological deficit (N1) and anterior pelvic ring injury (M3)

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Table 4.8  AO spine—DGOU osteoporotic fracture (OF) classification system (www.aospine.org/classification) OF 1 OF 2

OF 3 OF 4

OF 5

No deformation (vertebral body edema in MRI-STIR) Deformation of one endplate without or with only minor posterior wall involvement Deformation of one endplate with distinct posterior wall involvement Deformation of both endplates with/ without posterior wall involvement

 •  Typically not visible on X-rays: chance to find on MRI  •  With posterior wall 1/5 involved  •   •   •   •   • 

Loss of vertebral frame structure Vertebral body collapse Pincer type fracture Injuries with signs of distraction, rotation, or translation Hyperextension with anterior tension band failure

Injuries with anterior or posterior tension band failure Modified score for therapeutic decision-making in OF 0–5 points = conservative therapy; 6 points = conservative therapy or surgery; >6 points = surgery Parameter Grade Points Morphology (OF 1–5) 1–5 2–10 Severity of osteoporosis 1 T-score 2, anticoagulation Each −1, maximum −2

5-Item modified frailty index (mFI) = COPD, or recent pneumonia; congestive heart failure; functional status (not independent); hypertension requiring medication; diabetes mellitus

a

4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine

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4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine 4.6.1 Compression Fractures See Figs. 4.1, 4.2 and 4.3. a

c

b

T1-weighted image

T2-weighted fat suppression image

Fig. 4.1  Benign compression fractures of L1, L3, and L4 in a 62-year-­ old woman (a–d). Among these levels, the L4 compression fracture (arrows) shows no internal bone marrow edema which suggests an old healed compression fracture, whereas the L1 and L3 compression fractures are associated with extensive bone marrow edema (dotted arrows) as depicted by the low signal on the T1-weighted image (a), high signal on the T2-weighted fat-suppressed image (b), and associated contrast

d

T2-weighted image

Contrastenhanced fat suppression image

enhancement (d), which are all features of acute fractures. The acute compression fractures of L1 and L3 show preserved normal marrow signal (arrowheads) of the vertebral bodies, with band-like signal changes and mild enhancement containing an internal low-signal band (dots on d, suggestive of the fractured area), features of which favor benign over malignant compression fractures

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4  Common Traumatic Disorders of the Thoracolumbar Spine

a

b

Fig. 4.2  Benign compression fracture of L1 in a 51-year-old man. On plain radiography (a), the acute compression fracture would be easily missed (dotted arrow) unless the radiograph was carefully reviewed. Cortical disruption (arrows) of the upper endplate with band-like bone

a

b

T1-weighted

c

marrow edema is seen on T2-weighted images without (b) and with (c) fat suppression. There is also preservation of normal marrow in the fractured vertebral body, suggestive of a benign compression fracture rather than a malignant compression fracture

c

T2-weighted image

Fig. 4.3  Acute benign compression fracture of L1  in a 59-year-old man (a–d). The features of benign fractures are well demonstrated: preservation of normal fatty marrow on T1-weighted images, marrow edema signal with mild hypointense signal on T1-weighted images,

d

T2-weighted fat suppression image

Contrastenhanced fat suppression image

mild hyperintense signal on T2-weighted images, and mild vertebral enhancement less than usually encountered with tumors, as well as a band-like internal low-signal area (arrow, suggestive of fracture line) on the postcontrast enhanced images

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4.6.2 Burst Fractures See Figs. 4.4, 4.5, 4.6 and 4.7.

a

b

T1-weighted image

c

T2-weighted fat suppression image

Fig. 4.4  Burst fracture of T12 in an 81-year-old man (a–c). In a burst fracture, both the anterior and posterior aspects of the vertebral body (representing the anterior and middle columns according to the three-­ column theory of Denis) are collapsed, in contrast to a compression fracture in which there is preservation of the posterior vertebral body. The height of the posterior wall (arrow) of the fractured vertebral body is reduced, which is a hallmark of a burst fracture. More extensive acute

Contrast-enhanced fat suppression image

bone marrow edema is noted, but there is still preservation of normal fatty marrow in some portion of the fractured vertebral body (arrowheads), which again suggests a benign over a malignant fracture. The fractured area (fracture site with surrounding hemorrhage) is seen as a low-signal area (dotted arrows) within the area of enhancement, in keeping with the acute stage of the fracture

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4  Common Traumatic Disorders of the Thoracolumbar Spine

a

b

d

c

T1-weighted image

e

T2-weighted fat suppression image

Fig. 4.5  Axial burst fracture of L3 in a 34-year-old man. On the CT image (a, b) there is a fracture of the L3 vertebral body with loss of height in both anterior and posterior aspects of the vertebral body including its posterior wall, consistent with a burst fracture. In a burst

T2-weighted image

fracture, there is retropulsion (arrow) of the fractured posterior vertebral body wall. On MR images (c–e), central canal compromise with dural sac compression by the burst fracture is easily identified

4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine

a

c

Fig. 4.6  Flexion burst fracture of L1 without posterior ligamentous complex injury in an 18-year-old woman (a–d). The posterior ligament complex structures including the ligamentum flavum (arrow), interspinous ligament (dotted arrow), and supraspinous ligaments (arrow-

95

b

d

heads) are intact. A burst fracture is differentiated from a flexion distraction injury by decreased height of the posterior vertebral body in the former

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4  Common Traumatic Disorders of the Thoracolumbar Spine

a

b

T1-weighted image

c

T2-weighted image

d

T2-weighted fat suppression image

Fig. 4.7  Axial burst fracture of L1 with concomitant fracture of the T12 spinous process in a 67-year-old woman. The spinous process fracture (arrows) can be missed on MR (a–c), whereas the spinous process fracture (arrow) is easily detected on the sagittal reconstructed CT images (d)

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4.6.3 Distraction Injury See Figs. 4.8, 4.9, 4.10 and 4.11. a

b

Fig. 4.8  Flexion distraction injury on CT in a 46-year-old woman (a– c). The horizontal fracture line extends from the spinous process, through the articular process, pedicle, and into the lower posterior corner of the vertebral body (dotted arrows). The height of the vertebral body posterior wall is preserved (arrow). The differentiating feature

c

between a flexion distraction injury and a burst fracture depends upon the height of the posterior vertebral body wall; a loss of height suggests a burst fracture, whereas preserved or increased height favors a flexion distraction injury

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a

b

c

Fig. 4.9  Flexion distraction injury on MR in a 46-year-old woman (a–c). The horizontal fracture (dotted arrows) line extends from the spinous process, through the articular process and pedicle, to involve the lower posterior corner of the vertebral body. The height of the posterior

vertebral body wall is preserved. With flexion distraction injuries, overlying subcutaneous edema (arrows) is usually seen. Flexion distraction injuries should be surgically fixated in most cases, as it can be a cause of delayed neurology due to kyphosis

4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine

a

b

c

d

Fig. 4.10  Flexion distraction burst injury of T12 with posterior ligamentous complex (PLC) injury in a 28-year-old man (a–d). There is disruption of the PLC structures involving the ligamentum flavum (arrow), interspinous ligament (dotted arrow), and supraspinous ligament (arrowheads) on MR (b–d). The PLC is composed of the supraspinous ligament, interspinous ligament, ligamentum flavum, and the anterior capsular ligament of the facet joint. Posterior ligamentous complex injuries are common in flexion distraction injuries and should be carefully evaluated for. The integrity of the PLC is important in thoracolumbar trauma because it has a major role in spinal stability and can be a cause of kyphosis with resultant delayed neurology if injured. Although the differentiating feature between a burst fracture and a flex-

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ion distraction fracture depends upon the height of the posterior vertebral body wall (height loss suggests a burst fracture, whereas preserved or increased height favors a flexion distraction injury), distinguishing a flexion burst fracture from a flexion distraction injury with burst subtype (flexion distraction burst injury) is difficult in the presence of posterior ligamentous injury. According to the current thoracolumbar injury severity classification system (TLICS), there is no strict criteria differentiating a flexion burst fracture with PLC injury from a flexion distraction injury with burst subtype (flexion distraction burst injury). We suggest that for a definite PLC injury with associated widened interspinous distance that this injury be classified as a flexion distraction burst injury, although there is a burst component

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a

4  Common Traumatic Disorders of the Thoracolumbar Spine

b

c

Fig. 4.11  Extension distraction injury in a 72-year-old man (a–c). There is disruption of the anterior portion of the intervertebral disk (arrows) with a widened anterior intervertebral distance, which suggests an extension distraction injury

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4.6.4 Malignant Spine Fracture Due to Metastasis See Figs. 4.12, 4.13 and 4.14.

a

b

c

d

Fig. 4.12  Malignant fracture due to metastasis in a 45-year-old man (a–d). There is a malignant fracture (arrow) of the L5 vertebral body secondary to bony metastatic involvement. A pathological malignant fracture typically shows no preservation of normal fatty marrow,

marked hypointense signal on T1-weighted image, intense enhancement, as well as associated epidural or paravertebral masses (arrowheads), and distant metastases (dotted arrows)

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a

Fig. 4.13  Malignant burst fracture at T6 (arrows) in a 40-year-old woman. The convex bulging of the posterior vertebral body wall (arrowheads) is one of the signs suspicious for a malignant fracture (a–c). Diffuse marrow signal change with marked low signal on

b

T1-weighted images (a) and strong enhancement (d) are also suggestive of a malignant fracture. Extensive remote metastases also favor a malignant fracture

4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine

c

Fig. 4.13 (continued)

d

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a

b

c

d

e

f

Fig. 4.14  Malignant fracture at L1 due to metastasis from hepatocellular carcinoma in a 79-year-old man. Entire bone marrow signal change of L1 vertebral body is abnormal (a–c). Posterior wall of the L1 vertebral body shows convex bulging. The L1 vertebral body shows very low signal on T1-weighted image (b, d) and intense enhancement (c–f). Epidural and paravertebral masses (arrows) are also noted.

T1-weighted axial image is good for evaluating epidural tumor extension because epidural vein can be engorged and can be enhanced in hypervascular bone metastasis without epidural extension. In such cases, low signal on T1-weighted axial image in the epidural space suggests epidural extension of metastasis

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4.6.5 Sacral Insufficiency Fracture See Figs. 4.15, 4.16, 4.17, 4.18, 4.19, 4.20 and 4.21.

a

b

c

d

Fig. 4.15  Sacral insufficiency fracture in a 60-year-old woman. On the T1-weighted midsagittal image (a), there is a low-signal area of the S2 vertebral body with anterior cortical buckling (arrow) in keeping with a fracture. On the T1-weighted parasagittal image (b) and T2-weighted parasagittal image with fat suppression (c), acute bone marrow edema (arrows) is seen in the sacral ala as low T1 and high T2 signal areas. On the contrast-enhanced T1-weighted axial image with fat suppression (d), extensive enhancement with an irregular low-signal linear line within (arrowheads) is noted representing the acute fracture line

(arrowheads). Sacral insufficiency fractures are sometimes missed on routine MR images performed without fat suppression or without contrast enhancement; thus careful evaluation of the T1-weighted sagittal images for any area of abnormal bone marrow signal change of the sacral body and ala is required. Extensive enhancement can sometimes be mistaken for tumor or infection. The typical location (bilateral sacral ala and sacral body) and internal linear low-signal area (representing the fracture) are features indicative of a sacral insufficiency fracture

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a

4  Common Traumatic Disorders of the Thoracolumbar Spine

b

Fig. 4.16  Sacral insufficiency fracture in a 76-year-old woman. On the T1-weighted midsagittal image (a), there is a low-signal area (arrow) of the S2 vertebral body in keeping with a fracture. On the T1-weighted parasagittal images (b, c), there is a low-signal area (arrows) in the sacral ala suggestive of acute bone marrow edema. On T2-weighted images with fat suppression (d, e), acute bone marrow edema is seen in the sacral body and both sacral ala. On the contrast-enhanced T1-weighted axial image with fat suppression (f), extensive enhancement with an irregular low-signal linear line within (dotted arrows) is

c

noted representing the acute fracture line. Because in the routine lumbar spine MR, fat suppression T2-weighted image, contrast-enhanced image, and axial scans for sacrum are not usually obtained, sacral insufficiency fracture should be found on T1-weighted sagittal image. Sacral insufficiency fractures are sometimes missed on routine MR images performed without fat suppression or without contrast enhancement; thus careful evaluation of the T1-weighted sagittal images for any area of abnormal bone marrow signal change of the sacral body and ala is required

4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine

d

e

f

Fig. 4.16 (continued)

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a

4  Common Traumatic Disorders of the Thoracolumbar Spine

c

b

Fig. 4.17  Translation injury at L2 in a 19-year-old man after fall from the third floor of a building. MR image (c) shows acute burst fracture at T12 VB and acute compression fracture at L3 upper endplate corner. Posterior dislocation of fractured upper body of L2 (c) and, combined widening of left facet joint (a), suggestive of translation injury (type C injury). Fracture line also, extending to the lamina and transverse pro-

cess. (b) Fat-suppressed T2-weighted MRI image shows diffuse cord signal change at conus medullaris and lower thoracic spinal cord, compressed by dislocated T2 upper body. Ligamentum flavum, interspinous, and supraspinous ligament injury with signal change at L2/3 level (arrow), suggestive of posterior ligament complex injury. He had severe weakness on both legs (N3) without modifiers

4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine

a

Fig. 4.18  Compression injury at L3  in a 25-year-old man after fall down from a fence. Plain radiograph shows acute burst fracture at L3 with anterior cortical step-off. (a) There is a burst fracture at upper end-

109

b

plate at L2 vertebra (type A3 injury), without posterior tension band injury on MRI (b). He presented with acute back pain without neurologic deficit (N0) without any modifiers

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a

4  Common Traumatic Disorders of the Thoracolumbar Spine

d

b

c

Fig. 4.19  Sacral injury in a 54-year-old man who crushed by a fallen oak tree. Axial and coronal CT scan (a–d) shows right sacral ala and lateral mass fracture, involving right S3 neural foremen (arrows) but not

e

spinal canal (Denis zone II). He had anterior pelvic ring fracture (M3, both pubic bones) without neurologic symptoms (N0) (e)

4.6 Illustrations: Common Traumatic Disorders of the Thoracolumbar Spine

a

b

Fig. 4.20  Osteoporotic fracture at L1  in a 70-year-old woman, presented with chronic low back pain. Plain radiograph and MRI images show wedge compression fracture at upper endplate of L1 vertebral body with only minor posterior wall involvement (