Spinal Imaging E-Book

• Herausgeber: Thieme
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 243

Veröffentlichungsjahr: 2007

Beschreibung

Dx-Direct is a series of eleven Thieme books covering the main subspecialties in radiology. It includes all the cases you are most likely to see in your typical working day as a radiologist. For each condition or disease you will find the information you need -- with just the right level of detail.

Whether you are a resident or a trainee, preparing for board examinations or just looking for a superbly organized reference: Dx-Direct is the high-yield choice for you!

The series covers the full spectrum of radiology subspecialties including:

• Brain
• Gastrointestinal
• Cardiac
• Breast
• Urogenital
• Vascular
• Spinal
• Head and Neck
• Musculoskeletal
• Pediatric
• Thoracic

Dx-Direct gets to the point: Definitions, Epidemiology, Etiology, and Imaging Signs Typical Presentation, Treatment Options, Course and Prognosis Differential Diagnosis, Tips and Pitfalls, and key References ... all combined with high-quality diagnostic images.

Leseprobe

Direct Diagnosis in Radiology

Spinal Imaging

Professor Herwig Imhof, MD

Department of RadiologyDivision of OsteoradiologyMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

With contributions by

Benjamin Halpern, Andreas M. Herneth, Klaus M. Friedrich,Michael Matzner, Christina Mueller-Mang, Iris-Melanie Noebauer-Huhmann,Daniela Prayer, Oliver Sommer, Florian Wolf

327 Illustrations

ThiemeStuttgart • New York

Library of CongressCataloging-in-Publication Data

Wirbelsäule. English.

Spinal imaging/[edited by] Herwig Imhof;with contributions by Benjamin Halpern…[et al.; translator: John Grossman;illustrator, Emil Wolfgang Hanns].

p.; cm.

Includes bibliographical references and index.

ISBN 978-3-13-144071-6 (TPS: alk. paper) – ISBN 978-1-58890-560-4 (TPN: alk. paper)

1. Spine–Imaging. 2. Spinal cord–Imaging. 3. Spine–Diseases–Diagnosis. 4. Spinal cord–Diseases–Diagnosis. I. Imhof, H. (Herwig) II. Halpern, Benjamin. III. Title.

[DNLM: 1. Spinal Diseases–diagnosis–Handbooks. 2. Diagnostic Imaging–methods–Handbooks. 3. Spinal Cord Diseases–diagnosis–Handbooks. WE 39 W798s 2007a] RD768.W5513 2007

617.4'8207548–dc22                 2007023541

This book is an authorized and revised translation of the German edition published and copyrighted 2006 by Georg Thieme Verlag, Stuttgart, Germany. Title of the German edition: Pareto-Reihe Radiologie: Wirbelsäule.

Translator: John Grossman,Schrepkow, Germany

Illustrator: Emil Wolfgang Hanns,Schriesheim, Germany

© 2008 Georg Thieme Verlag KGRüdigerstrasse 14,70469 Stuttgart, Germanyhttp://www.thieme.deThieme New York, 333 Seventh Avenue,New York NY 10001, USAhttp://www.thieme.com

Cover design: Thieme Publishing GroupTypesetting by Ziegler + Müller,Kirchentellinsfurt GermanyPrinted by APPL, aprinta Druck,Wemding, Germany

ISBN 978-3-13-144071-6(TPS, Rest of World)

ISBN 978-1-58890-560-4(TPN, The Americas)                        1 2 3 4 5 6

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Nevertheless, this does not involve, imply, or express any guarantee or responsibility on the part of the publishers in respect to any dosage instructions and forms of applications stated in the book. Every user is requested to examine carefully the manufacturers’ leaflets accompanying each drug and to check, if necessary in consultation with a physician or specialist, whether the dosage schedules mentioned therein or the contraindications stated by the manufacturers differ from the statements made in the present book. Such examination is particularly important with drugs that are either rarely used or have been newly released on the market. Every dosage schedule or every form of application used is entirely at the user's own risk and responsibility. The authors and publishers request every user to report to the publishers any discrepancies or inaccuracies noticed. If errors in this work are found after publication, errata will be posted at www.thieme.com on the product description page.

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List of Contributors

Benjamin Halpern, MDDepartment of RadiologyDivision of OsteoradiologyMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

Andreas M. Herneth, MDProfessorDepartment of RadiologyDivision of OsteoradiologyMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

Klaus Friedrich, MDDepartment of RadiologyDivision of OsteoradiologyMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

Michael Matzner, MDDepartment of OrthopedicsMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

Christina Mueller-Mang, MDDepartment of RadiologyDivision of NeuroradiologyMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

Iris-Melanie Noebauer-Huhmann, MDDepartment of RadiologyDivision of OsteoradiologyMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

Daniela Prayer, MDProfessorDepartment of RadiologyDivision of NeuroradiologyMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

Oliver Sommer, MDCentral Department of RadiologyLainz HospitalVienna, Austria

Florian Wolf, MDDepartment of RadiologyDivision of OsteoradiologyMedical University ViennaVienna General Hospital (AKH)Vienna, Austria

Contents

1 Congenital Malformations

Christina Mueller-Mang, Daniela Prayer, Klaus M. Friedrich, Michael Matzner

Arnold–Chiari Malformation

Lumbarization and Sacralization

Diastematomyelia

Tethering

Sacrococcygeal Teratoma

Meningocele, Myelomeningocele

Vertebral Malformations

Klippel–Feil Syndrome

Kyphosis

Scheuermann Disease

Scoliosis

Malrotation

2 Trauma

Christina Mueller-Mang, Daniela Prayer, Klaus M. Friedrich, Florian Wolf, Michael Matzner, Herwig Imhof

Spinal Injury—Magerl Classification

Vertebral Fractures—Causes

Dens Fracture

Flexion Fracture of the Cervical Spine

Burst Fracture of the Spine

Chance Fracture (Seat Belt Fracture)

Jefferson Fracture

Hangman's Fracture

Spinal Cord Trauma

Syringohydromyelia

Anterior Subluxation

Insufficiency Fracture of the Sacrum

Stress Phenomena in the Spine

Stress Fractures in Ankylosing Spondylitis

3 Degenerative Disorders

Iris-Melanie Noebauer-Huhmann, Benjamin Halpern, Michael Matzner, Herwig Imhof

Disk Degeneration

Degenerative Disk Disease—Modic I

Degenerative Disk Disease—Modic II

Spondylosis Deformans—Modic III

Disk Herniation

Bulge, Protrusion, Extrusion, Sequestration

Disk Calcification and Vacuum Phenomenon

Facet Joint Degeneration

Uncovertebral Osteoarthritis

Synovial Cyst

Hypertrophy of the Ligamenta Flava

Baastrup Disease

Spondylolisthesis and Pseudospondylolisthesis

Degenerative Spinal Stenosis

Diffuse Idiopathic Skeletal Hyperostosis

4 Inflammatory Disorders

Christina Mueller-Mang, Daniela Prayer, Andreas M. Herneth, Oliver Sommer, Michael Matzner, Herwig Imhof

Rheumatoid Arthritis

Rheumatoid Arthritis—Chronic Trauma

Psoriatic Spondyloarthropathy

Reiter Syndrome

Ankylosing Spondylitis

Ankylosing Spondylitis—Ligament Calcification and Bamboo Spine

Ankylosing Spondylitis—Fractures

Acute Bacterial Spondylitis

Tuberculous Spondylitis

Epidural Abscess

Granulomatous Inflammations of the Spinal Cord

Arachnoiditis

Acute Transverse Myelitis

Spinal Multiple Sclerosis

5 Tumors

Andreas M. Herneth, Christina Mueller-Mang, Daniela Prayer, Michael Matzner, Herwig Imhof

Hemangioma

Osteoid Osteoma

Osteoblastoma

Osteochondroma

Aneurysmal Bone Cyst

Giant Cell Tumor

Langerhans Cell Histiocytosis

Malignant Tumors

Bone Metastases

Multiple Myeloma

Chordoma

Ewing Sarcoma

Lymphoma

Nerve Sheath Tumors

Leptomeningeal and Intramedullary Metastases

Meningioma

Ependymoma

Astrocytoma

Hemangioblastoma

6 Vascular Disorders

Christina Mueller-Mang, Daniela Prayer

Epidural Hematoma

Arteriovenous Malformation

Arterial Spinal Cord Infarction

7 Postoperative Disorders

Andreas M. Herneth, Michael Matzner, Herwig Imhof

Failed Back Surgery Syndrome

CSF Fistula

Peridural Fibrosis

Rapidly Progressive Osteoarthritis (After Intersegmental Fusion)

Complications of Spinal Instrumentation

8 Metabolic Disorders

Andreas M. Herneth, Herwig Imhof

Senile and Postmenopausal Osteoporosis

Paget Disease

Spinal Epidural Lipomatosis

Index

Abbreviations

ACE

Angiotensin converting enzyme

ADEM

Acute disseminated encephalomyelitis

AFP

Alpha-fetoprotein

A-P

Anterior-posterior

AVF

Arteriovenous fistula

C-ANCA

Cytoplasmic antineutro-phil cytoplasmic antibody

CSF

Cerebrospinal fluid

CT

Computed tomography, computed tomogram

DD

Differential diagnosis

DEXA

Dual-energy x-ray absorption

DISH

Diffuse idiopathic skeletal hyperostosis

DSA

Digital subtraction angiography

DWI

Diffusion-weighted imaging

FDG-PET

Fluoro-18-deoxyglucose positron emission tomography

HIV

Human immunodeficiency virus

MRI

Magnetic resonanceimaging

NSAID

Nonsteroidal anti-inflammatory drug

P-A

Posterior-anterior

PCR

Polymerase chain reaction

PD

Proton density

PET

Positron emission tomography

PNET

Primary neuroectodermal tumor

Q-CT

Quantitative CT

SPECT

Single photon emission computed tomography

STIR

Short tau inversion recovery

TNF-α

Tumor necrosis factor α

TSE

Turbo spin echo

1 Congenital Malformations

Arnold–Chiari Malformation

Definition

Epidemiology

Rare malformation of the posterior cranial fossa and craniocervical junction (underdevelopment of the endochondral occiput) Autosomal inheritance pattern.

Etiology, pathophysiology, pathogenesis

Chiari I: Displacement of the cerebellar tonsils caudal to the foramen magnum (McGregor line) Associated with cervical syringomyelia (syringohydromyelia) and atlantooccipital fusion (25–50% of cases) May occur in combination with scoliosis and kyphosis (42% of cases).

Chiari II: Small posterior cranial fossa Portions of the cerebellum, fourth ventricle, and medulla oblongata are caudally displaced Hypoplastic pons associated with spinal dysraphism (most often lumbar myelomeningocele).

Chiari III: Very rare Type II malformation combined with an occipital or high cervical encephalocele.

Chiari IV: Very rare Aplasia or severe hypoplasia of the cerebellum Small brainstem Enlarged CSF spaces in the posterior cranial fossa.

Caution: In published literature, the term “Arnold–Chiari” is used for both Chiari I and Chiari II malformations.

Imaging Signs

Modality of choice

– MRI: Sagittal Axial CSF flow measurement (Chiari I).

– Prenatal ultrasound or fetal MRI.

MRI findings

Chiari I: Descent of the cerebellar tonsils (> 5 mm caudal to the foramen magnum) Malformation of the bony skull base is common (shortened clivus) The fourth ventricle appears normal or elongated The posterior cranial fossa is not too small There are no associated cerebral malformations Secondary hydrocephalus may result from blockage of CSF drainage in the foramen magnum Syringomyelia is present in 50–75% of cases Abnormal CSF pulsation (CSF flow measurement).

Chiari II: Early diagnosis on fetal MRI (associated malformations) Closed or open dysraphism (more often lumbar than cervical) Portions of the cerebellum and medulla oblongata are displaced into the spinal canal Hypoplasia of the posterior cranial fossa with parietooccipital microgyria Callosal dysgenesis Hypoplastic, flattened pons Enlargement of the prepontine cisterns Beaklike extension of the quadrigeminal plate Hydrocephalus Syringomyelia (hydromyelia) extending past C1.

Prenatal and postnatal ultrasound findings

Chiari II: Caudal displacement of the cerebellum Hydrocephalus.

Fig. 1.1 A 57-year-old man with a history of pain in both upper extremities for many years, now accompanied by sensory deficits on the left side. MR image of the craniocervical junction (sagittal, T2). The image shows elongation and cervical descent of the cerebellar tonsils accompanied by cervical hydromyelia (Arnold–Chiari I).

Fig. 1.2 Fetal MR image (sagittal, T2, single-shot fast-spin echo). A small posterior cranial fossa with caudal displacement of the cerebellum, enlarged ventricles, and lumbar myelomeningocele (Chiari II).

Clinical Aspects

Typical presentation

Chiari I: Up to 50% of all cases are asymptomatic Herniation > 12 mm is almost invariably symptomatic Pain on movement of the head and neck Gait ataxia Caudal cranial nerve symptoms Sleep apnea.

Chiari II: Myelomeningocele Paralysis of the lower extremities Sphincter dysfunction Obstructive hydrocephalus Brainstem compression.

Therapeutic options

Chiari I: Patients with symptoms require suboccipital craniotomy or dorsal resection of C1 to decompress the spinal cord Conservative treatment is indicated in the absence of syrinx.

Chiari II: Hydrocephalus is treated by shunting Surgical closure of the myelo-meningocele (sometimes this may be done prenatally, in which case there will be near normal development of the posterior cranial fossa).

Differential Diagnosis

Acquired hydromyelia from another cause

Descent of the cerebellar tonsils

– Basilar invagination (osteogenesis imperfecta, Paget disease, acromegaly, Klippel–Feil syndrome)

– Chronic petrosal vein shunt, elevated intracranial pressure

Selected References

Gammal TE, Mark EK, Brooks BS. MR imaging of Chiari II malformation. Am J Röntgenol 1988; 150: 163–70

Osborn AG. Diagnostic Neuroradiology. Philadelphia: Mosby 1994; 15–24,66

Lumbarization and Sacralization

Definition (Transitional Lumbosacral Vertebra)

Sacralization: The border between the sacrum and lumbar spine is shifted one segment cranially.

Lumbarization: The first sacral vertebra develops as a lumbar vertebra.

Cranial shifts are more common than lumbarization. Sacralization can also occur unilaterally. A full-spine radiograph is required to clearly identify the malformation as lumbarization or sacralization. Wherever this is not feasible or not indicated, the term “transitional lumbosacral vertebra” is preferred.

Imaging Signs

Modality of choice

– Conventional radiographs or CT.

– MRI (when neurologic symptoms are present).

Clinical Aspects

Typical presentation

Asymmetric transitional lumbosacral vertebrae, in particular, are often accompanied by spinal symptoms.

Therapeutic options

Physical therapy.

Selected References

Brossmann J, Czerny C, Freyschmidt J. Grenzen des Normalen und Anfänge des Pathologischen in der Radiologie des kindlichen und erwachsenen Skeletts, 14th ed. Stuttgart: Thieme 2001

Fig. 1.3 Conventional radiograph of the lumbosacral junction (A-P, detail). Asymmetrical transitional lumbosacral vertebra.

Fig. 1.4a,b Schematic diagram: Sacralization (a); lumbarization (b).

Diastematomyelia

Definition

Epidemiology

Rare closed spinal dysraphism Most common in the lumbar and thoracic spine More common in men than in women (4:1).

Etiology, pathophysiology, pathogenesis

Characterized by development of a sagittal cleft in the spinal cord.

Type I (diastematomyelia with a septum): The spinal cord is split by a bony or cartilaginous septum or “spur” extending between the vertebral body and arch Each hemicord has its own dural tube and separate subarachnoid space The hemicords may be asymmetrical.

Type II (diastematomyelia without a septum): The two hemicords are contained in a single dural tube, occasionally separated by a fine cartilaginous septum.

Cutaneous stigmata: Hypertrichosis, hemangioma, lipoma, dermal sinus Associated with bony malformations (85% of cases): Fused vertebrae, hemivertebrae, “butterfly” vertebrae, scoliosis (up to 60% of cases) Associated hydromyelia (30–40% of cases), especially with type I Associated myelomeningocele.

Imaging Signs

Modality of choice

MRI:

– Sagittal: T1, T2 (skin surface also visualized).

– Coronal: With severe scoliosis.

– Transverse: T2-TSE with 3-mm slice thickness in the region of the bony defects, slice thickness of 5–10 mm over the rest of the spinal cord (associated hydromyelia); T1 with 3-mm slice thickness over the bony defects.

– Contrast administration is indicated when intraspinal soft tissue components are present (cartilaginous structures can develop into fibromatous tumors) or for postoperative imaging (to exclude inflammation): Sagittal and transverse T1-weighted sequences with fat suppression.

– Cerebral MRI to identify associated anomalies.

MRI findings

The two hemicords are visualized with their common or separate dural tubes and/or a bony spur Associated hydromyelia or adherent lipomas are seen Vertebral dysplasia is visualized The precise craniocaudal extent of the malformation is seen Prenatal examination is also possible.

CT findings

Three-dimensional visualization of the bony anomalies CT myelography can demonstrate the cleft spinal cord when MRI is contraindicated Useful for visualizing associated bony malformations and reconstruction in all planes.

Ultrasound findings

Prenatal diagnosis and postnatal examination through the bony aperture.

Conventional radiography findings

A bony spur and vertebral dysplasia may be seen.

Fig. 1.5 A 25-year-old patient with a history of scoliosis since childhood presented with increasing sensory deficits and weakness in the right hand, and beltlike bands of pain. MR image of the cervicothoracic region (coronary, T2). Two narrow hemicords are separated by a bony septum (type I diastematomyelia with septum).

Fig. 1.6 MR image of T1 (axial, GRE). Hemicords are visualized. Adhesions to the bony septum are seen on the right.

Clinical Aspects

Typical presentation

Often only becomes symptomatic in adults Scoliosis Discrete atrophy or weakness in one or both lower extremities Progressive paraparesis Bladder and bowel dysfunction.

Therapeutic options

Surgical intervention immediately after the diagnosis to avoid irreversible damage to the nerve tissue Resection of a bony spur or fibrous septum Correction of a tethered cord.

Differential Diagnosis

Hydromyelia

– May present a similar picture where axial and coronal slices are not obtained

Selected References

Pang D et al. Split cord malformation. Part I: A unified theory of embryogenesis for double spinal cord malformations. Part II: Clinical syndrome. Neurosurgery 1992; 31: 214–217, 481–500

Songio-Cohen P et al. Prenatal diagnosis of diastematomyelia. Childs Nerv Syst 2003; 19: 555–566

Tortori-Donati P et al. Magnetic Resonance Imaging of Spinal Dysraphism. Topics Mag Res Im 2001; 12: 375–409

Tethering

Definition

Epidemiology

Almost always congenital Most commonly occurs in preadolescence (7–12 years) Predilection: lumbosacral region.

Etiology, pathophysiology, pathogenesis

“Tethered cord” is not a morphologic symptom but a clinical syndrome consisting of:

– Pain and/or sensory deficits in the lower extremity.

– Spastic gait.

– Muscle atrophy.

– Occasionally bladder and bowel dysfunction.

– Occasionally club foot.

Etiology

Adherence of the spinal cord to the dura prevents the cord from ascending normally and results in increasing traction Intradural lipoma or lipomyelomenin-gocele Split cord malformation (diastematomyelia) Dermal sinus Fibrotic lipomatosis (“fatty filum”) Myelomeningocele Arachnoiditis Posttraumatic condition.

Imaging Signs

Modality of choice

MRI:

– Sagittal: T1, T2 (skin surface also visualized).

– Coronal: With severe scoliosis.

– Transverse: T2-TSE with 3-mm slice thickness in the region of the bony defects Slice thickness of 5–10 mm over the rest of the spinal cord (associated hydromyelia, diastematomyelia; T1 with 3-mm slice thickness over the bony defects).

– Contrast administration is indicated where intraspinal soft tissue components are present (cartilaginous structures can develop into fibromatous tumors) or where there is postoperative inflammation: Sagittal and transverse T1-weighted sequences with fat suppression.

– Cerebral MRI to exclude associated malformations.

– CSF flow study.

– Fetal MRI: To assess the prognosis.

Fig. 1.7 A 4-year-old boy with spastic gait and bladder dysfunction. MR image of the lumbar spine (sagittal, T2). There is no typical conus medullaris, the spinal cord is elongated and fixed within a lipoma at the level of S2.

Fig. 1.8 MR image of the lumbar spine (sagittal, T1). Lipoma fused with the short, thick fibers of the cauda equina (“thickened fatty filum”).

Fig. 1.9 MRI of SI (axial, T1). Neural structures are fixed within the lipoma.

MRI findings

Descent of the conus medullaris (normal position at 8–10 weeks after birth is approximately L1–L2) Changes in the shape of the conus medullaris: Elongated and thinned without the physiologic bulb-shaped expansion of the spinal cord at the level of the conus medullaris Filum terminale: Thickened and shortened Underlying pathology is visualized.

CT findings

Three-dimensional reconstruction to visualize associated bony malformations Urodynamic study Evaluation of compromised bladder function CT myelography: Evaluation of descent of the conus medullaris when MRI is contraindicated.

Ultrasound findings

Fetal examination to assess prognosis In the presence of instability in a newborn (when MRI is not feasible) Prenatal detection of dysraphism Direct visualization of tethering (through a bone aperture after a laminectomy).

Radiographic findings

Visualization of associated bonyanomalies: Spina bifida, fused vertebrae, rib malformations Evaluation of scoliosis.

Clinical Aspects

Typical presentation

Increasing muscle weakness Heightened muscle tone, spasticity Unsteady gait Rapidly progressive scoliosis Increasing bladder and bowel dysfunction Back and leg pain Leg deformity.

Therapeutic options

Surgical intervention is indicated only in worsening neurologic symptoms or pain resistant to therapy Primary goal: Prevention of further neurologic deficits; postoperative improvement of neurologic function is a secondary aim that is often not achieved Mobilization of the fixed spinal cord Resection of scar tissue Laminectomy where indicated Surgical complication rate: 1–2% (infection, bleeding, worsening of neurologic symptoms) Tethering recurs in 10–20% of all cases, especially where the initial surgery is performed at an early age (growth of spinal column).

Differential Diagnosis

Drop metastases

– History (underlying malignancy)

– Difference in patient age

Associated malformations with tethering

Selected References

Cornette L et al. Closed spinal dysraphism: a review on diagnosis and treatment in infancy. Eur J Paediatr Neurol 1998; 2: 179–185

Gupta SK et al. Tethered cord syndrome in adults. Surg Neurol 1999; 52: 362–370

Kim MJ et al. Tethered spinal cord with double spinal lipomas. J Korean Med Sci 2006; 21: 1133–1135

Sarwark JF et al. Tethered cord syndrome in low motor level children with myelomeningocele. Pediatr Neurosurg 1996; 25: 2

Yamada S, Won DJ. What is the true tethered cord syndrome? Childs Nerv Syst 2007; 23: 371–375

Sacrococcygeal Teratoma

Definition

Epidemiology

Most common congenital neoplasm, usually diagnosed before birth Benign in 80–85% of cases Mortality: 15–35% Localization: Lesions are usually intradural and extramedullary, rarely intramedullary (2% of cases) More common in females than males (3:1); malignant subtype is more common in males.

Etiology, pathophysiology, pathogenesis

Mixed tumor with tissue components from all three germ layers Arises from pluripotent cells of the node of Hensen The tissue components exhibit varying degrees of maturation.

Staging classification:

– Type I: Spreads beyond the fetus.

– Type II: External and presacral spread.

– Type III: Small external component, primarily intrapelvic and intraabdominal tumor spread.

– Type IV: Completely presacral tumor.

Currarino triad:

– Sacral anomaly.

– Anal atresia or stenosis.

– Presacral tumor (benign teratoma in 40% of all cases, anterior meningocele in 47%).

Imaging Signs

Modality of choice

MRI:

– Sagittal: T1, T2, STIR.

– Coronal: T2.

– Axial: T2.

Abdominal study (CT or MRI): Evaluation of ventral spread (into the abdominal cavity).

General

Inhomogeneous solid-cystic mass in the region of the sacrum and distal lumbar spine, occasionally extending into the intrapelvic and intraabdominal regions Secondary hydronephrosis due to compression Polyhydramnios.

MRI findings

Cysts: Homogeneously hyperintense (T1 and T2) with high protein content, or hypointense (T1) and hyperintense (T2) with serous content, occasionally septate Solid nodules: Enhance with contrast Fatty components: Fat suppression with a STIR sequence Calcified deposits: Markedly hypointense on T1 and T2.

Ultrasound findings

Hyperechoic (solid) areas with inclusions of or peripheral anechoic (cystic) components Calcifications: Hyperechoic foci with acoustic shadows.

Fig. 1.10 Newborn with a known a sacrococcygeal mass detected by prenatal ultrasound. Pelvic MR image (sagittal, T2). Mass with a larger component anterior to the spine than posterior to the spine, exhibiting inhomogeneous signal; the caudal spine is completely present.

Fig. 1.11 MR image of the sacrum (coronal, T2). Tumor spread is visible in the sacrum.

Clinical Aspects

Typical presentation

Hydrops fetalis: Results from intrauterine complications such as polyhydramnios and tumor hemorrhage. Fatal prognosis where hydrops occurs prior to the 30th week of pregnancy (93 % mortality) Postpartum morbidity resulting from associated congenital anomalies (10% of cases), compression of adjacent organs (such as the urogenital tract), recurrent tumor, intraoperative and postoperative complications.

Therapeutic options

In cases of hydrops, birth should be induced as soon as the lungs are sufficiently mature Radical resection of the tumor including the coccyx is indicated prior to birth or within the first week of life Fetal interventions: Tumor resection, cyst aspiration, reduction of the amnion.

Differential Diagnosis

External tumors: myelomeningocele

– Spina bifida located higher and further dorsal

Intrapelvic tumors

– Ovarian, mesenteric cysts

– Bowel dilation or duplication

– Cystic neuroblastoma

Solid tumors

– Chordoma

– Neurogenic tumors

– Lipoma

– Hemangioma

– Malignant melanoma

Selected References

Avni FE et al. MR imaging of fetal sacrococcygeal teratoma: diagnosis and assessment. AJR Am J Roentgenol 2002; 178: 179–183

Feldman M et al. Neonatal sacrococcygeal teratoma: multiimaging modality assessment. J Pediatr Surg 1990; 26: 675–678

Hedrick HL et al. Sacrococcygeal teratoma: prenatal assessment, fetal intervention, and outcome. J Pediatr Surg 2004; 39: 430–438

Meningocele, Myelomeningocele

Definition

Spinal dysraphism: Developmental anomaly with incomplete closure of the neural tube A third of dysraphic anomalies are open and two-thirds are closed.

Meningocele: Accounts for 2.4% of all closed dysraphic anomalies Herniation of a CSF-filled sac lined with dura and arachnoid through a posterior spina bifida Completely covered by skin Incomplete dysraphism with incomplete closure of the vertebral arch (spina bifida) is common. Often there is associated superficial skin pathology (indentation, hypertrichosis, etc.) Spina bifida is usually clinically insignificant Lesion usually does not contain any nerve structures (rarely nerve roots of the filum terminale will pass through a large meningocele) Not an indication for immediate surgery.

Meningomyelocele: Most common type of open spinal dysraphism (98.8% of cases) Herniation of the incompletely developed spinal cord and meninges through a bony defect in the posterior vertebral structures with projection of these neural structure above the surface of the skin (neural placode) Often combined with an abnormally small posterior cranial fossa, caudal herniation of cerebellar tissue, and hydrocephalus (= Chiari II malformation) Imaging studies are useful primarily for postoperative follow-up and visualizing associated malformations; hydrocephalus in the setting of a Chiari II malformation may develop only after closure of the meningomyelocele Neurosurgical emergency: Surgical closure is indicated within 48 hours to avoid infection of the exposed spinal cord and an increase in neurologic dysfunction Lumbar and lumbosacral regions are most often affected More common in women than in men.

Imaging Signs

Modality of choice

MRI:

– Sagittal: T1, T2 (skin surface also visualized).

– Coronal: With severe scoliosis.

– Transverse: T2-TSE with 3-mm slice thickness in the region of the bony defects. Slice thickness of 5–10 mm over the rest of the spinal cord (associated hydromyelia, diastematomyelia); T1 with 3-mm slice thickness over the bony defects.

– Contrast administration is indicated when an intraspinal soft tissue component is present (cartilaginous structures can develop into fibromatous tumors) or when there is postoperative inflammation: Sagittal and transverse T1-weighted sequences with fat suppression.

– Cerebral MRI to exclude associated malformations.

– CSF flow study where tethering is suspected.

– Fetal MRI: To assess the prognosis.

Fig. 1.12 Conventional radiograph of the lumbosacral junction (A-P, detail). Spina bifida at L5.

Fig. 1.13 Findings at birth included a sacral mass. Motor function in the child's legs was normal. MR image of the lumbosacral region (sagittal, T2). Myelocele sac containing CSF but otherwise empty. Intraspinal descent of the conus medullaris with short straight cauda equina fibers that are fixed to the caudal end of the dural sac.

Fig. 1.14 MR image of L5 (axial, T2). Bony defect is occluded by a connective tissue structure (operative report) through which a CSF-filled sac has herniated. Septa are present but there are no neural structures. These structures lie entirely within the spine. The anterior CSF spaces are not enlarged. The myelocele sac is covered by a thin layer of skin along its margins.

Fig. 1.15 Ultrasound examination in the 20 th week of pregnancy detected spina bifida. MR image of the fetus and pelvis (coronal, T2). Sacral myelocele sac with neural structures coursing along its apex. The axial T2-weighted sequence shows the broad-based bony defect and neural structures within the myelocele (arrow).

MRI findings

Clinical indication Preoperative evaluation Anatomic characterization of the constituent components of the malformation and their relation to the nerve roots Identification of morphology and entity Identification of coexisting diastematomyelia (such as hemimyelomeningocele) Postoperative visualization of complications Hydrocephalus: 48–72 hours postoperatively Recurrent tethering: Strands of scar tissue fix the spinal cord to the dura Arachnoid cysts: Sequela of postoperative adhesions Slightly hyperintense to CSF (elevated protein content) Fine wall No flow artifacts in contrast with CSF Dermoid and epidermoid cysts: Occur as a result of intraoperative inclusion of epidermal cells, as a primary lesion, or in association with a dermal sinus Slightly hyperintense to CSF on T1- and T2-weighted images Superinfection enhances with contrast Caution: Rupture leads to toxic meningitis Syringomyelia (syringohydro-myelia): Primarily responsible for worsening postoperative neurologic symptoms, leads to rapidly progressive clinical scoliosis.

CT findings

Three-dimensional reconstruction to visualize associated bony malformation.

Conventional radiographs

Visualization of bony defect (spina bifida) Evaluation of scoliosis.

Ultrasound findings

Prenatal detection of dysraphism Fetal ultrasound to assess the prognosis To evaluate the conus medullaris and filum terminale in newborns with instability (where MRI is not feasible) Amniocentesis Elevated AFP.

Clinical Aspects

Typical presentation

Meningocele: Usually clinically asymptomatic (no primary spinal cord lesion) Caution: Pressure sores can ulcerate to form open lesions Tethered cord syndrome with progressive neurologic symptoms.

Meningomyelocele: Reddish raised exposed nerve tissue in the middle of the back Sensorimotor deficits in the lower extremity Bladder and bowel dysfunction Rarely psychomotoric retardation Severity of the different symptoms varies.

Therapeutic options

Meningocele: Immediate closure of the meningocele where ulcerating pressure sores are present Elimination of a tethered cord syndrome.

Meningomyelocele: Neurosurgical emergency Mobilization of the placode Closure of the soft tissue defect Fetal surgical procedures are being tested.

Differential Diagnosis

Open spinal dysraphism

– Myeloschisis (= myelocele): Very rare. Because the subarachnoid space does not extend to the level of the defect, the neural placode lies at skin level or slightly recessed.

– Hemicord with myelocele or myelomeningocele: Malformation affects only one hemicord

Closed spinal dysraphism

– Lipomyeloschisis: Subcutaneous intraspinal lipoma adhering to the neural placode

– Lipomyelocele: Subcutaneous extraspinal lipoma adhering to the neural placode

– Lipomyelomeningocele: Subcutaneous lipoma, usually adhering asymmetrically to the neural placode. Myelocele on the contralateral side

– Terminal myelocystocele: Central canal expanded to form a terminal cyst (syringocele)

– Cervical myelocystocele: Dorsal wall of the central canal is displaced and communicates with a meningocele

– Cervical myelomeningocele: Fibrous neurovascular cord is displaced into a meningocele through a posterior wall defect

Selected References

Rossi A et al. Imaging in spine and spinal cord malformations. Eur J Radiol 2004; 50: 177–200

Schijman E. Split cord malformation: report of 22 cases and review of literature. Childs Nerv Syst 2003; 19: 106–108

Tortori-Donati P et al. Magnetic Resonance Imaging of Spinal Dysraphism. Topics Mag Res Im 2001; 12: 375–409

Vertebral Malformations

Definition

Partial or complete malformation of the vertebrae Abnormal vertebral segmentation and fusion.

Total aplasia: Absence of both ossification centers. Very rare.

Lateral hemivertebra: Failure of ossification of one of the two ossification centers. A distinction is made between the primordium of a hemivertebra exhibiting a vertebral arch of normal length (hemisoma) and the primordium of a hemivertebra with half an arch (hemispondylus). This is often associated with scoliosis and deformities of the bony thorax.

Butterfly vertebra (partial ventral or dorsal cleavage): Failure of fusion of the individual ossification centers.

Persistent notochord: The remnant divides the vertebral body into two halves; the clefts of the ventral and dorsal halves extend to the notochord canal.

Total sagittal cleavage: This very rare deformity is incompatible with life.

Congenitally fused vertebrae: Partial or total fusion of adjacent vertebrae due to failure of segmentation; partial fusion anomaly type A: Fusion in the anterior third of the vertebral body; type B: Fusion in the posterior third of the vertebral body with or without fusion of the vertebral arches and facet joints.

Imaging Signs

Modality of choice

– MRI: Multiplanar T1-weighted and T2-weighted sequences Coronal slices are particularly important in severe scoliosis.

– CT: Three-dimensional reconstructions can be obtained for preoperative planning.

General

Radiographic signs of butterfly vertebra: Viewed in the coronal plane, the two halves of the vertebra taper toward the unfused center to produce a shape resembling a butterfly.

Radiographic signs of lateral hemivertebra: Viewed in the coronal plane, one half of the vertebra tapers toward the center while the other half is absent, producing a nearly triangular or wedge shape.

Radiographic signs offused vertebrae: The A-P diameter of the fused vertebrae is diminished, often in combination with narrowing in the area of the disk interspace, which is either absent or underdeveloped. Fused vertebrae are about as high as two normal vertebrae including the interspace. In 50% of cases, the facets joints are also fused. The spinous processes can be malformed or fused as well. Localization: