[Ankylosing spondylarthritis and partial cauda equina syndrome. Apropos of 4 cases and review of the literature].

Four new cases of ankylosing spondylitis complicated by a cauda equina syndrome are reported. Similarly to the previous descriptions, the patients present with long-standing and severe spondylitis at the time when neurological symptoms, mainly radicular pain, develop. Computed tomography of the lumbar spine demonstrates in all cases typical laminar erosions and posterior arachnoid diverticula. Up to now, magnetic resonance imaging has rarely been performed in this particular pathology, though it is helpful in determining the anatomical relations and the nature of the lesions. Based on the previous publications, our study aims at describing the clinical and pathogenic aspects of the disease and defining the most useful diagnostic investigations and treatment choices. Therapeutic possibilities are often limited because of a late diagnosis. Better knowledge of this rare complication could lead to earlier recognition and more efficient therapy.