Ligamentum Flavum Cyst of the Lumbar Spine Causing Radiculopathy: A Rare Case Report and Review of Literature

Ligamentum flavum cysts (LFCs) are rare but clinically significant lesions in the lumbar spine. These cysts, often found incidentally, can mimic the symptoms of intervertebral disc herniation and cause radiculopathy. This article details a case involving an 80-year-old woman with severe lower back and radicular pain due to an LFC at the right L5/S1 facet joint that was unresponsive to conservative treatment. Magnetic resonance imaging and neurography confirmed that the cyst compressed the right S1 nerve root. Surgical excision via partial hemilaminectomy resulted in complete symptom relief and nerve decompression. Histopathological analysis identified the cyst as degenerative without a synovial lining. This case underscores the importance of considering LFCs in the differential diagnosis of neurogenic leg pain and highlights the efficacy of surgical excision for symptom resolution and preventing recurrence.