広範な大脳病変を呈し，脳生検組織を用いたPCR法により確定診断に至った遷延性単純ヘルペス脳炎の61歳女性例

A 61-year-old Female who Suffered from Herpes Simplex Encephalitis with Expanded Cerebral Lesions on MRI and Prolonged Clinical Course : The Diagnostic Usefulness of PCR Using Biopsied Brain Tissue Specimens

はじめに

　単純ヘルペス脳炎（herpes simplex virus encephalitis: HSVE）は通常，急性発症で単相性の経過をとるが，再燃例や遷延例も約1～2割報告されている^1－5）。再燃例や遷延例では多彩な臨床症状を呈し，ウイルス学的検査異常に乏しく，非典型的な画像所見を認める場合も多いため，確定診断に苦慮することも少なくない^1－5）。今回われわれは，脳生検組織を用いたPCR法により確定診断し得たHSVE遷延例を経験したので報告する。

Abstract

　A 61-year-old female developed left hemiparesis after the onset of high fever and a consciousness disturbance.　Fluid attenuated inversion recovery (FLAIR) MR imaging showed high signal intensity lesions in the right temporal lobe, cingulate gyrus, and parietal lobe.　Encephalitis caused by a herpes simplex virus (HSV) infection was suspected and the administration of intravenous aciclovir was thus immediately initiated.　Her consciousness disturbance rapidly became exacerbated; however, the brain lesions progressively expanded to the midbrain and left hemisphere.　The addition of intravenous high-dose corticosteroids to the treatment regimen ameliorated the consciousness disturbance.　Although no HSV DNA was detected by repeated PCR using cerebrospinal fluid (CSF) specimens, real time PCR using a biopsied brain tissue specimens detected HSV type 1 DNA.　A pathological examination showed destruction of the grey matter and a perivascular aggregation of lymphocytes, thus suggesting a diagnosis of necrotizing viral encephalitis.　Immunohistochemical analysis did not reveal the presence of the HSV antigen.　Hence, in the present patient failure of PCR or a serological diagnosis using CSF specimens can be ascribed to the paucity of viral particles in the brain.　We therefore concluded that real-time PCR using biopsied brain tissue specimens is a novel, sensitive method for detecting causative agents in patient with prolonged and undiagnosed encephalitis.

(Received: October 9,2007,Accepted: July 29,2008)