Case report: CT and MRI of the cauda equina syndrome in ankylosing spondylitis.

The clinical and radiological findings in a patient with long-standing ankylosing spondylitis who developed the clinical features of a cauda equina syndrome are presented. CT and MRI revealed characteristic expansion of the lumbar spinal canal with scalloping of the laminae and spinous processes related to the presence of dorsal dural diverticulae. MRI permitted confident exclusion of other intradural pathology without recourse to invasive investigations.