Ankylosing spondylitis and multiple sclerosis: an apparent association?

The prevalence of HLA-B27 in 420 patients with multiple sclerosis (MS) was 43 (10.2%). Five of 20 B27 positive patients who were further assessed clinically and radiologically had ankylosing spondylitis (AS), a prevalence of between 12 and 25%, compared with previously established prevalence rates of B27 in members of the normal population of between 1 and 2% Sixteen patients with AS underwent brainstem auditory (BAEP), visual (VEP) and somatosensory (SSEP) evoked potential studies, with only minor, and predominantly peripheral, abnormalities of SSEP, except for one patient who developed MS during the study. Our data lend some support to an association between AS and MS but refute the possibility of a frequent subclinical MS-like syndrome in AS. They show there is unlikely to be any confusion when performing evoked potential studies in patients with AS.