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A Pictorial Review of Cystic Intradural and Extradural Masses in the Lumbar Spine 2014

Category General Spine Austin Bourgeois, MD, BS Matthew Layman, MD, BS Yong Bradley, MD Purpose Magnetic Resonance Imaging (MRI) plays a prominent role in the imaging of low back pain, providing high yield in identifying space-occupying lesions attributable to focal neurological deficit. Extradural cysts are such lesions that are prevalent and readily identified by MRI. Their potential etiologies of include: synovial cysts, cysts of the ligamentum flavum, epidural extension of interspinous bursitis, arachnoid cysts, perineural cyst, dermoid cysts, and discal cysts. We report a pictoral review of these common and uncommon cystic lesions in the lumbar spine. Of particular interest, we present a case of three synchronous discal cysts, providing insight into the evolutionary process of their development. A focused literature review and discussion of current diagnostic criteria, pathogenesis, and treatment of these lesions will be incorporated into the discussion. Materials & Methods Following IRB approval, a retrospective chart review was performed to obtain illustrative cases of the following processes: synovial cysts, cysts of the ligamentum flavum, epidural extension of Baastrup’s disease, cystic schwannoma, arachnoid cyst, perineural cyst, dermoid cysts, and discal cysts. Results Accurate characterization of cystic lesions in the lumbar spine derives from localization as intradural or extradural. Localization adjacent to the ligamentum flavum, facets, interspinous ligaments, or intervertebral cysts can provide added specificity. CT guided biopsy/aspiration and surgical excision may warranted if these lesions are clinically symptomatic or of malignant suspicion. Discal cysts are among the most rare of these entities, having less than 100 reported cases. They are usually solitary in nature, most prevalent in young males, and do not always associate with concomitant same-level disc pathology. Conclusion Discal cysts are a rare cause of low back pain and radiculopathy in young patients. They should be considered in the differential diagnosis of a patient with a cystic extradural mass. MRI and CT myelogram provide acceptable diagnostic accuracy in evaluation cystic lesions in the lumbar spine, can help evaluate nerve compression, and may help to guide therapy. References 1. Chiba K, Toyama Y, Matsumoto M, Maruiwa H, Watanabe M, Nishizawa T. “Intraspinal cyst communicating with the intervertebral disc in the lumbar spine: discal cyst.” Spine. 2001 Oct 1;26(19):2112-8. 2. Hyung-Jun K, Dae-Yong K, et al. “Lumbar discal cyst causing bilateral radiculopathy.” Surg Neurol Int. 2011 Feb 23;2:21. 3. Khalatbari MR, Moharamzad Y. “Discal Cyst in Pediatric Patients: Case Report and Review of the Literature.” Neuropediatrics. 2012 Aug 31. 4. Koga H, Yone K, Yamamoto T, Komiya S. “Percutaneous CT-guided puncture and steroid injection for the treatment of lumbar discal cyst: a case report.” Spine 2003 Jun 1;28(11):E212-6.