Lumbar bone erosion with anterior dural ectasia in ankylosing spondylitis: a case report.

Bony erosion and dural ectasia rarely occur in the posterior part of the vertebral body in ankylosing spondylitis (AS). Because of the compression of nerve tissue that adheres to the inflamed dura mater, a range of neurologic symptoms may develop. Few studies have investigated therapies for this condition, and surgical intervention might alleviate the neurologic dysfunction. Here, we report an uncommon case of lumbar spinal cord herniation secondary to anterior dural ectasia in a patient with AS. The patient had a 31-year history of AS and presented with progressive numbness and weakness of his left leg that had lasted for nearly 1 month. Magnetic resonance imaging (MRI) revealed a dural defect in the posterior aspect of the L1 and L2 vertebral bodies, with displacement of the nerve tissue adjacent to the lytic lesion. The patient declined surgery and was prescribed oral meloxicam. The neurological symptoms of the left leg remained stable during 2 years of follow-up. The dural enhancement on MRI resolved, although the erosion-like lesion in the vertebral bodies persisted. This unusual case supports the central role of inflammation in anterior dural ectasia of patients with AS. Anti-inflammatory treatment may be an alternative therapy for patients who decline surgery.