CT of long-standing ankylosing spondylitis with cauda equina syndrome.

The authors present distinctive computed tomographic (CT) findings in two cases of long-standing ankylosing spondylitis accompanied by the cauda equina syndrome. Multiple, asymmetric erosions of the posterior elements of the lumbar spine on CT were correlated with thecal diverticula demonstrated by myelography. The pathogenesis of these erosions may be related to arachnoiditis in the early phase of the spondylitis.