Behçet's disease and the nervous system.

Behçet's disease is a multisystem inflammatory disorder with unknown aetiology. It is a disease of young adults with a more severe course in males subjects. Its prevalence is high in the Mediterranean basin and Japan and has been linked with human leucocyte antigen B5 (HLA-B5) in those countries. According to the diagnostic criteria formed by the International Study Group, recurrent oral ulceration is a prerequisite, with two more typical symptoms or signs. Neurological involvement is one of the most devastating manifestations of Behçet's disease. The involvement is either caused by primary neural parenchymal lesions (neuro-Behçet) or secondary to major vascular involvement (vasculo Behçet). The course is relapsing-remitting, secondary progressive or primary progressive. The most commonly involved area is the brain stem, with additional symptoms or signs, hemispherical involvement with mental changes being the most common. Intracranial hypertension, usually owing to dural sinus thrombosis, has a special place in Behçet's disease. The most common clinical findings are pyramidal signs. Sensory symptoms or signs are much less frequent, and hemianopia and higher cortical function disturbances as well as pure cerebellar syndrome are rare features. Cerebrospinal fluid usually has a high protein content and/or pleocytosis. Notably, in the acute period most patients have lesions shown by magnetic resonance imaging (MRI) extending from the brain-stem to diencephalic structures. Differential diagnosis from multiple sclerosis can be difficult in patients with hemispheric white matter MRI hyperintensities. Immunosuppressives are used in treatment.