Midline Ligamentum Flavum Cyst of Lumbar Spine.

Background: Ligamentum flavum cysts are thought to develop due to facet joint hypermobility; however, the etiology of these lesions is not completely elucidated. These cysts may lead to compressive pathologies of the spine requiring surgical intervention.

Methods: We report the case of a 63-year-old male with chronic back pain and progressive neurogenic claudication for 6 months. He was found to have a ligamentum flavum cyst situated along the dorsal midline of the lumbar spinal canal contributing to spinal stenosis. The patient underwent a decompressive L4 laminectomy and en bloc excision of the ligamentum flavum cyst with complete resolution of his symptoms postoperatively.

Conclusions: We suggest that chronic mechanical stress leads to degeneration of the ligamentum flavum and contributes directly to cyst formation.