Magnetic resonance imaging (MRI) was performed in 25 patients with Beh
cet's disease, of whom 15 had clinical involvement of the central nerv
ous system (CNS). Brain MRI was abnormal in 11/15 with and in 1/10 wit
hout CNS involvement. The most common sites of MR lesions were the cer
ebral white matter and brainstem. Lesions were also seen in the basal
ganglia, cerebellum, optic nerves and spinal cord. The cerebral white
matter lesions were always asymptomatic and usually small, whereas the
brainstem lesions were often symptomatic and sometimes extensive. Fol
low-up MRI in 2 patients presenting with brainstem syndromes and treat
ed with immunosuppression showed resolution of a large lesion in 1 pat
ient in whom there was clinical remission, and the development of mark
ed brainstem atrophy in the other who became severely disabled. The pa
ttern of MRI abnormalities may assist the diagnosis and suggests a rol
e for MRI in monitoring the effect of treatment in patients with neuro
logical Behcet's disease.