[Symptomatic lumbar intradural arachnoid cyst: A case report]

Spinal arachnoid cysts are rare benign lesions filled with cerebrospinal fluid and lined by an arachnoid membrane. We report an observation of an intradural arachnoid cyst in the lumbar region causing spinal cord compression.

This is a 37-year-old female patient with no past medical history who consulted for bilateral lumbosciatica, hyperalgia, poorly systematized pain associated with sphincter disorders, such as dysuria and constipation, weakness in the lower limbs, and walking difficulties. The physical examination revealed a positive Sonnelli sign at the lumbar level. The neurological examination revealed bilateral motor deficit at the L4-L5 level with muscle strength estimated at 3/5 and decreased tendon reflexes. The cervical-dorsal-lumbar MRI showed an intradural lumbar cyst at the L1-L2 level. During surgery, a laminectomy of L1 and L2 and a flavectomy were performed, then the cyst was removed in one piece. The postoperative course was uneventful. Histological examination of the surgical specimen showed a fibro-collagenous cyst wall lined by a layer of meningothelial cells consistent with an arachnoid cyst. The clinical course was marked by a gradual recovery from neurological deficits with an ability to walk without support after 5 months.

Intradural arachnoid cysts of the spine are rare benign lesions. In exceptional cases, they may cause spinal cord compression. A definitive diagnosis is based on pathological examination after removal of the cyst walls.