頸部に律動的不随意運動を呈した脳幹脳炎の1例

Rhythmic Involuntary Movement of the Neck in a Patient with Brainstem Encephalitis

　症例は36歳女性。上気道感染に引き続き左側顔面神経麻痺，全方向性への眼球運動障害，小脳失調の出現を認め，同時に頸部に律動的ミオクローヌスを呈した。髄液検査，血液検査に異常なく，頭部や頸部のMRIも正常であった。臨床的に脳幹脳炎と診断したが，脳幹脳炎において口蓋ミオクローヌスとは異なる頸部の律動的ミオクローヌスを認めた報告はなく，注目に値する症状と思われた。不随意運動出現の背景には免疫学的機序が関与している可能性も考えられた。

A 36-year-old Japanese woman was admitted to our hospital, because of facial palsy, ophthalmoplegia, cerebellar ataxia, and rhythmic myoclonus of the neck. About a few weeks before admission, she devel-oped symptoms of common cold and general fatigue. Her laboratory data were unremarkable, and her CSFwas normal. Serum levels of antibodies to gangliosides were within normal limits. Her MRIs of the brain and neck were normal. Both somatosensory evoked corti-cal potential study and auditory evoked brainstem re-sponse study were normal.