Magnetic resonance imaging of arachnoid diverticula associated with cauda equina syndrome in ankylosing spondylitis.

Cauda equina syndrome is an uncommon complication of ankylosing spondylitis (AS), but results in significant morbidity in those patients affected. We report 2 patients who developed classical cauda equina syndrome, which was well visualized by magnetic resonance imaging. This technique allows accurate noninvasive diagnosis of this complication of AS.