単純ヘルペスウイルスによる予後良好な脳幹脳炎の1例

A MILD FORM OF BRAIN STEM ENCEPHALITIS DUE TO HERPES SIMPLEX VIRUS

　抄録　10歳男児で，発熱，咳嗽，頭痛から17日後に歩行および発語障害がみられた。入院時に書字障害，左顔面神経麻痺，視力障害，左方眼振，意識の軽度低下をも伴っていた。脳神経（II,III,VII）症状，小脳症状，錐体路症状を示した。脳波は徐波化，聴性脳幹反応は左側のI-V波間の延長と分離不良を認めたが，脳CTスキャンは異常がなかった。左側優位の脳幹脳炎と診断した。入院後2週間症状の改善がみられないためにステロイドの経口投与を行ったところ，急速に軽快し，後遺症なく退院した。血清および髄液中の単純ヘルペスウイルス（HSV）抗体の推移より，HSV再感染時のものと考えた。予後良好なHSV脳炎の報告は少なく，長期間経過を追い証明した例は重要と思われた。

A 10-year-old boy had gait and speech disturb-ances 17 days after the initial symptoms of a fever, headache and cough. Four days later he was admitted to a hospital with mild disturbances of gait, speech, writing, visual acuity, left facial nerve, nystagmus and consciousness. Impairments of cranial nerves (II, III and VII), pyramidal sign and cerebellar sign were noticed.

EEG showed generalized slow waves. Auditory brain stem response showed prolongation of the interval between I and V waves and poor differ-enciation between them. Brain CT could not find any abnormalities. Brain stem encephalitis was diagnosed.

Clinical signs and symptoms continued for two weeks when steroid therapy was started and it was effective to improve the disease. He was dis-charged from the hospital without sequalae.

Herpes simplex virus (HSV) type 1 was detected from cells in CSF on admission by fluorescence antibody method. HSV antibody titers in sera changed from 1/8 to 1/64 during three months by complement fixation test. Specific IgG and IgA by enzyme linked immunosorbent assay (ELISA) was high in CSF. Specific antibody in CSF/total anti-body in CSF: specific antibody in serum/total antibody in serum for IgG and IgA classes were more than 1.

Reports of mild type of HSV brain stem ence-phalitis seemed to be rare. Our case which was followed for several months carefully would be important to discuss.