Delayed evoked potentials in patients with ankylosing spondylitis.

Visual, brainstem auditory and somatosensory evoked potentials were studied in 30 patients with ankylosing spondylitis (AS). Twenty-four patients were male and 6 were female. The mean age was 44 years and the mean duration of AS was 16 years (range 1-34 years). Evoked potential abnormalities affecting the visual pathways were recorded in 18 (60%) patients. Somatosensory evoked potentials were abnormal in 19 (63%) patients, and 9 patients had impaired function on brainstem auditory evoked potentials. The pathophysiology of these abnormalities is unknown. We recommend that caution be exercised in interpreting delayed evoked potentials if multiple sclerosis is suspected in a patient with AS.