Postoperative arachnoidal diverticula of the lumbar spine.

Arachnoidal diverticula are a rare complication of spinal surgery and occur most often at lumbar level, especially after discectomy. We report a case of lumbar arachnoidal diverticulum that arose two years after an L4-L5 discectomy and presented clinically with low back pain and sciatic pain and neurological deficits. We analyze the etiopathogenesis, clinical and radiological features and treatment.