[A nationwide survey of patients with Bickerstaff brainstem encephalitis: diversity of underlying mechanism].

Bickerstaff brainstem encephalitis (BBE) is characterized by acutely progressive bilateral ophthalmoparesis and ataxia with impaired consciousness or pyramidal signs, or both; all of which are followed by a monophasic course with good recovery. Alike Guillain-Barré syndrome (GBS), BBE is proposed to have an autoimmune mechanism triggered by antecedent infection. The nationwide epidemiologic survey for BBE, which the author had performed in Japan, suggests that BBE consists of typical and atypical cases. Typical BBE has similar neurological and serological features to Fisher syndrome and shows good recovery, whereas atypical BBE is characterized by delayed recovery, negative anti-GQ1b antibodies, and abnormal cerebrospinal fluid and brain MRI findings with other possible pathogeneses.