Ligamentum Flavum Cyst With Acute Onset Motor Deficit: A Literature Review and Case Series

Background Ligamentum flavum cysts have been rarely described in the literature and are one of the rare causes of neural compression and canal stenosis. Very few cases of their association with neurologic deficits are reported to date, and association with acute onset weakness is even rarer.

Clinical Presentation We report our experience with 3 cases of ligamentum flavum cyst that presented with acute onset weakness and also present a comprehensive literature review on lumbar ligamentum flavum cysts reported to date. All 3 patients had symptoms of severe neurogenic claudication and presented to us with acute onset of motor weakness in lower limbs. Ligamentum flavum cyst was located in the midline in 2 cases and laterally in 1 case. We performed excision of the cyst and decompression with fusion in 2 cases and decompression alone in 1 case. All 3 cases had significant improvement in their neurologic status postoperatively. Histopathological examination confirmed ligamentum flavum cyst in all 3 cases. We performed a PUBMED and EMBASE database search using the MeSH (Medical Subject Headings) terms “ligamentum flavum” and “cysts” for articles published to April 2019. We could identify 7 studies describing 20 cases of lumbar ligamentum flavum cysts with motor weakness in the literature. Only 1 case had been described with an acute onset of weakness.

Conclusions Ligamentum flavum cysts should remain in the differential diagnosis of a patient who has symptoms of lumbar canal stenosis and presents with acute onset of neurological deficits. Such patients have a good improvement with surgery.