Ligamentum flavum cyst
Back pain with numbness in left leg since 4 years
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Small altered signal intensity extradural lesion is noted at L4 vertebral body level along left-posterior aspect moderately displacing cauda equine roots and thecal sac to right side.
It appears hypointense on T1WI and hyperintense on T2WI images and shows suppression on FS study.
Severe ligamentum flavum hypertrophy (6.5mm) as well as with mild spinal canal compromise is noted at this level.
Grade I anterolisthesis of L4 over L5 vertebrae.
Ligamentum flavum cysts are rare lesions, most commonly occurring in the lower lumbar region than cervical region 1. The exact cause is not known, however, they generally tend to occur secondary to degenerative changes. These cysts may cause neuralgic sign due to spinal canal stenosis or lumbar root compression. Pathologically these cysts occur due to fibrocollagenous tissue degeneration and hypermobility of the spinal segment 2. After surgical removal, excellent postoperative results are reported.
- on myelography, it is seen as intraspinal extradural mass 3
- on CT, it appears as a subtle cyst seen adjacent to the ligamentum flavum
- MRI is choice of investigation. It appears as epidural cystic lesion which is of variable intensity on T1WI 4 and hyperintense on T2WI; it may show peripheral enhancement
Differential diagnosis are synovial cysts. These cysts tend to originate from synovial joint and appear as protrusion of synovial membrane into spinal canal.
- 1. Seo DH, Park HR, Oh JS et-al. Ligamentum flavum cyst of lumbar spine: a case report and literature review. Korean J Spine. 2014;11 (1): 18-21. doi:10.14245/kjs.2014.11.1.18 - Free text at pubmed - Pubmed citation
- 2. Gazzeri R, Galarza M, Gorgoglione L et-al. Cervical cyst of the ligamentum flavum and C7-T1 subluxation: case report. Eur Spine J. 2005;14 (8): 807-9. doi:10.1007/s00586-005-0913-7 - Free text at pubmed - Pubmed citation
- 3. Yamamoto A, Nishiura I, Handa H et-al. Ganglion cyst in the ligamentum flavum of the cervical spine causing myelopathy: report of two cases. Surg Neurol. 2002;56 (6): 390-5. Pubmed citation
- 4. Mahallati H, Wallace CJ, Hunter KM et-al. MR imaging of a hemorrhagic and granulomatous cyst of the ligamentum flavum with pathologic correlation. AJNR Am J Neuroradiol. 1999;20 (6): 1166-8. Pubmed citation