重篤な脳浮腫をきたし，軽度低体温療法が奏効した非ヘルペス性急性脳炎の1例

Successful Use of Mild Hypothermia Therapy in an Adult Patient of Non-herpetic Acute Encephalitis with Severe Intracranial Hypertension

要旨　症例は，感冒症状に続いて，意識障害，全身けいれんで発症した非ヘルペス性急性脳炎の41歳の男性。入院時，炎症所見はなく，肝機能，血中アンモニア，血糖は正常で，髄液で軽度の細胞と蛋白の上昇を認めた。ステロイドとアシクロビルを投与し，一時症状が軽快したが，第10病日から脳浮腫が出現し，ステロイドパルス療法などにも反応せず，第18病日に瞳孔不同をきたし，人工呼吸管理となった。同日から，バルビツレート麻酔下に直腸温35℃の軽度低体温療法を7日間施行した。施行3日から，頭部CTで脳浮腫の改善を認め，その後の経過は順調で第46日ほぼ後遺症なく独歩退院した。ウイルス学的検討でインフルエンザ脳症や単純ヘルペス脳炎は否定され，原因は特定できなかったが，本症例のように重篤な脳浮腫を主体とする急性脳炎に，低体温療法は推奨される治療法と考えられた。

A 41-year-old man was admitted to our hospital suffering from generalized convulsion with a high fever and disturbed consciousness one week after exhibiting flu-like symptoms. We made a diagnosis of acute viral encephalitis, based on the clinical features and the evidence of pleocytosis with an increase in protein in the CSF. On admission, MRI was normal and CRP was negative. The levels of transaminase, ammonia, and blood sugar were normal, so that an adult Reye's syndrome could be ruled out. Herpes simplex encephalitis and influenza encephalopathy were also ruled out because of viral examinations, and specific agents could not be determined. Clinical symptoms subsided once after he was treated with dexamethasone, acyclovir, and anti-convulsants, until generalized convulsion accompanied by a high fever again occurred on the 9th day. On the 18th day, the patient showed anisocoria and ataxic respiration due to severe brain edema. Mild hypothermia therapy to rectal temperature 35℃ was induced under mechanical ventilation. Cranial CT taken 3 days after the therapy began to show the improvement of the brain edema. After 7 days of the therapy, his clinical symptoms began to recover dramatically. On the 46th day, he was discharged from hospital without showing almost any neurological symptoms. Mild hypothermia therapy should be considered for adult patients as well as non-adult patients suffering from acute encephalitis with severe intracranial hypertension.