89歳高齢発症の単純ヘルペス脳炎―アシクロビル投与で寛解したが，2カ月後再発し死亡した1例

A Case of Elderly-onset Herpes Simplex Encephalitis in an 89-year-old Woman, Who Recovered with Acyclovir Therapy, Showed Relapse 2 Months Later, and Died

はじめに

　単純ヘルペス脳炎（herpes simplex encephalitis：HSE）高齢発症例の報告が増加傾向にある。筆者らは脳梗塞後左半身麻痺，寝たきり状態の89歳女性で，調べ得た範囲において国内最高齢のHSE例を経験した。アシクロビル（acyclovir：ACV）点滴でいったん寛解したが，治療終了2カ月後に再発し，再発時もACVを投与したが改善なく死亡した。その経過について報告し，若干の考察を加える。

Abstract

　The number of case reports on elderly-onset herpes simplex encephalitis (HSE) has been increasing. We encountered the case of an 89-year-old woman with HSE, who was probably one of the oldest-onset patients in Japan. She was a bed patient with underlying diseases of old cerebral infarction and cholangitis. These conditions might be risk factors for the onset of HSE. Concerning HSE among the elderly, it is important to pay attention to underlying diseases that weaken their immunity. Although we delayed in diagnosing her case and started treatment 1 month after convulsions appeared, she completely recovered with intravenous acyclovir (ACV) therapy. However, relapse occurred 2 months after the therapy ended. We treated her again with intravenous ACV but she died without improvement. ACV, which was initially effective, was ineffective at relapse. Cases of ACV-resistant herpes simplex virus (HSV) infection have been reported in immunodeficient patients. The immune system of elderly patients is sometimes too weak to suppress the mutation of the virus. In this case, the HSV may have become resistant to ACV. Therefore, the possibility of ACV resistance should be considerd in HSE relapse in the elderly population.

(Received: March 6, 2012, Accepted: March 23, 2012)