Cauda equina syndrome in ankylosing spondylitis. Anatomical, diagnostic, and therapeutic considerations.

This article describes a case of cauda equina syndrome associated with ankylosing spondylitis, and reviews 28 additional cases in the literature. The neurological symptoms appear late in the evolution of spondylitis, when it is at an inactive stage. The diagnosis is easily confirmed by myelography, with watersoluble contrast and performed in a supine position, and by computerized tomography (CT) scan of the lumbar spine. The typical features are dilated lumbar sac with multiple dorsal diverticula. The pathogenesis of this entity remains the subject of speculation. Arachnoiditis with subsequent adhesions is the most likely explanation. No treatment has proved helpful so far. Surgery is not indicated.