Cauda equina lesions in ankylosing spondylitis.

Three patients with the combination of long-standing ankylosing spondylitis (AS) and cauda equina syndrome are described and compared with 17 from the literature. The nerve root lesion has been of gradual onset and has since the time of diagnosis either been stationary or progressed slowly. Radicular pain in the feet and legs, and genito-urinary complaints have been the dominant and most disabling symptoms. Typical myelographic findings were expansion of the dural sac and arachnoidal diverticula. There is a highly probable relationship between AS and the neurological syndrome. The pathogenesis is probably related to early arachnoiditis with subsequent loss of meningeal elasticity. Earlier recognition of the root lesion may result in a more effective treatment.