Magnetic resonance imaging of intraspinal cystic lesions: A pictorial review☆
Section snippets
Syringohydromyelia
Syringohydromyelia refers to the presence of longitudinally orientated cerebrospinal fluid (CSF)-filled cavities within the cord. Traditionally, when the cavity represents dilatation of the central canal, the term hydromyelia is used, whereas the term syringomyelia is used to refer to single or multiple longitudinally orientated cavities lying lateral to the central canal, which may or may not connect to it. In practice, however, it is often difficult to distinguish these pathologic findings on
Trauma and spinal cord injury
After significant spinal cord injury, there is initially microcyst formation and later gliosis at the site of injury (myelomalacia) resulting in an end stage of tissue loss and cord atrophy.8 Microcysts may coalesce to form a true spinal cord cyst or syrinx, which may occur as frequently as in 59% of cases.9, 10 Progressive enlargement of the cavity may occur if there is direct transmission of CSF pulsation into the cavity via the central canal.
On MRI myelomalacia can usually be distinguished
Intramedullary tumors
The commonest spinal cord tumors are astrocytomas and ependymomas, which make up more than 70% of cases.11 Other spinal tumors include hemangioblastoma (associated with von Hippel-Lindau syndrome in approximately 30% of cases), primitive neuroectodermal tumors, and metastases.
The differentiation of the various primary spinal cord tumors is often difficult on imaging features alone.11 It is, however, more important to accurately identify the level and extent of the tumor and to differentiate the
Neurenteric cysts
Neurenteric cysts, also known as enterogenous cysts, result from persistence of endodermal elements within the spinal canal. They are lined by alimentary tract mucosa and have a definite connection with the spinal canal. They most commonly present in adolescence and occur most frequently at the cervicothoracic junction or in relation to the conus.21 Ninety percent lie in an intradural, extramedullary position within the canal, although there have been rare reports of intramedullary lesions.22
Arachnoid/dural cysts
Arachnoid/dural cysts may arise as congenital or acquired abnormalities and may be intradural or extradural. The extradural type may result from a congenital or acquired dural defect allowing arachnoid and CSF to herniate through the dural layer.24 The intradural type may also be congenital or can result from adhesions caused by spinal trauma, infection, or intervention. The Nabors classification25 divides these lesions into 3 types. Type I includes extradural cysts without nerve root
Dermoids and epidermoids
Dermoid and epidermoid tumors are classically described as arising from the inclusion of ectodermal elements during neural tube development. They may also result from iatrogenic implantation at the time of surgery or after spinal instrumentation such as lumbar puncture.28 They are unilocular or multilocular tumors that are frequently cystic.
Dermoid cysts are lined by a squamous epithelium and the supporting dermal components such as hair follicles and sebaceous and sweat glands, whereas
Synovial cysts
Intraspinal synovial cysts or ganglion cysts are uncommon lesions usually associated with degenerative disease of the spine or post-trauma.31 They communicate with the facet joint and are lined by synovium. They are most common at the L4/5 and L5/S1 level.32 They can result in thecal sac, spinal cord, or nerve root compression and contribute to central canal stenosis.
Diagnosis on MRI is usually made by lateral location of mass and its relationship to the facet joint (Fig 14).
Infection
Intraspinal infection usually results from blood borne spread or, less commonly, direct extension of spinal osteomyelitis.34 Most commonly this results in extradural collections or empyemas.35, 36 Infection can also take the form of extramedullary cysts (such as in tuberculosis or hydatid disease) and even more rarely, intramedullary cysts, most notably caused by cysticercosis.1 Infected extramedullary collections are usually limited to the dorsal aspect of the canal in blood- borne infection
Meningoceles and myelomeningoceles
Most myelocoeles and myelomeningoceles are congenital lesions resulting from neural tube closure anomalies or associated with caudal regression syndromes.5 There may be a variety of other anomalies present including associated dermal sinuses, diastematomyelia (Fig 16), or syringohydromyelia, and imaging should include the whole spine for this reason.
Conclusion
In conclusion, MRI is the modality of choice for the evaluation of spinal cystic disease. It provides an accurate and noninvasive means of localizing and characterizing the lesion without the use of radiation. MRI appearances have been shown to correlate well with both surgical and histologic findings. Although in some cases the imaging findings may be nonspecific, with knowledge of the typical MRI characteristics on both standard sequences and those after gadolinium enhancement, it is
Acknowledgements
We acknowledge the help of Dr A. Lammie, Consultant Neuropathologist, University Hospital of Wales, Cardiff, in preparation of the histology images.
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Cited by (30)
Lumbosacral Spine MRI
2021, Atlas of Spinal Imaging: Phenotypes, Measurements and Classification SystemsIntracranial neuroenteric cysts: A concise review including an illustrative patient
2012, Journal of Clinical NeuroscienceCitation Excerpt :The radiographic findings of NC vary significantly with both CT scans and MRI. This has been ascribed to variability of cyst protein content.7,9,77,83,130–133 NC are usually demonstrated as hypodense lesions with no contrast enhancement using CT; however, they can occasionally appear as hyperdense lesions that are compartmentalised with some enhancement of the cyst wall.22,77
Rare cause of spinal cord compression
2011, Feuillets de RadiologieThe spinal canal: From imaging anatomy to diagnosis
2010, Journal de RadiologieImaging spinal cord cystic lesions in adults
2007, Journal de RadiologieRadiology
2007, Interventional Spine E-Book: An Algorithmic Approach
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Reprint requests: A. Evans, MD, Department of Radiology, University Hospital of Wales, Heath Park, Cardiff, Wales, UK CF14 4XN. E-mail: mailto="[email protected].