Cauda equina syndrome in ankylosing spondylitis: a case report and review of the literature.

The cauda equina syndrome (CES) is an infrequently recognised and poorly understood complication of ankylosing spondylitis (AS). We report a case of CES with enlarged caudal sac and multiple posterior arachnoid diverticula eroding the laminae and spinous processes of the lumbosacral vertebrae in a patient with long-standing AS. The diagnosis was established using computerised tomography (CT) and magnetic resonance imaging (MRI).