Cauda equina syndrome with multiple lumbar diverticula complicating long-standing ankylosing spondylitis.

A patient with cauda equina syndrome complicating long-standing inactive ankylosing spondylitis is described. The first neurological symptoms started 15 years after the onset of ankylosing spondylitis. Over a follow-up period of 12 years the cauda equina syndrome showed a slowly progressive but disabling course leading to sensory disturbances in the lumbar and sacral dermatomes, weakness and wasting of the muscles innervated by these nerve roots, sphincter disturbances, and impotence. Magnetic resonance imaging, computed tomography, and lumbar myelography showed enlargement of the dural sac with multiple lubar diverticula eroding the lumbosacral vertebrae. The pathophysiology of the cauda equina syndrome in ankylosing spondylitis is unclear. Surgical treatment seems justified only in patients with a short history of neurological symptoms.