[Central nervous system involvement in Behçet's disease].

Central nervous system involvement in Behçet's disease, usually called neuro-Behçet's syndrome (NB), includes acute type and chronic progressive type. Acute NB is characterized by acute meningoencephalitis with focal lesions, presenting high intensity areas in T2-weightened images or FLAIR images on MRI scans. Cyclosporin A frequently causes acute NB. Acute NB responds to steroid therapy, and is usually self-limiting. By contrast, chronic progressive NB is characterized by intractable slowly progressive dementia, ataxia and dysarthria with persistent elevation of cerebrospinal fluid IL-6 activity (more than 20 pg/ml). In our series, most patients (approximately 90%) with chronic progressive NB were HLA-B51 positive, and had history of attacks of acute NB prior to the development of progressive neurological symptoms. Chronic progressive NB is resistant to conventional treatment with steroid, cyclophosphamide, or azathioprine. However, recent studies suggest the efficacy of low dose methotrexate in chronic progressive NB.