肝細胞癌患者に発症した，水痘-帯状疱疹ウイルスとサイトメガロウイルスの関連が示唆された脳幹脳炎および多発性脳神経障害の1症例

A Case of Brainstem Encephalitis following Multiple Cranial Neuropathy in a Hepatocellular Carcinoma Patient―Association with Cytomegalovirus and Varicella-Zoster Virus Infection

はじめに

　サイトメガロウイルス（cytomegalovirus: CMV）は，悪性腫瘍や後天性免疫不全症候群（acquired immune deficiency syndrome: AIDS），臓器移植症例など，免疫能の低下した症例で脳炎を発症することがある^1－4）。また，水痘-帯状疱疹ウイルス（varicella-zoster virus: VZV）も同様に脳炎や髄膜炎，脳神経障害を発症することがあるが，帯状疱疹と同側の顔面神経麻痺，聴力障害をきたした場合はRamsay Hunt症候群と診断される^5－8）。われわれは，左顔面麻痺とふらつきで脳幹脳炎と多発性脳神経障害を発症し，CMVとVZVの関連が示唆された肝細胞癌患者の72歳，男性例を経験した。

　本例では，aciclovir（ACV）とprednisolone（PSL）を投与して病態は改善した。血清CMV-IgM抗体は陽性であったが，髄液CMV-IgG・IgM抗体，髄液CMV-PCRが陰性であり，中枢神経系におけるCMVの存在を直接には証明できなかった。また，髄液VZV-IgG抗体価の上昇からVZVの関連も示唆され，文献的考察を加えて報告する。

Abstract

　A 72-year-old male with liver cirrhosis and hepatocellular carcinoma experienced general fatigue.　Four days later he was admitted to our hospital because of dizziness, dysbasia and left facial palsy (day 1).　On day 6, a neurological examination revealed left trigeminal neuralgia, left medial longitudinal fasciculus (MLF) syndrome, skew deviation, hypacusia, tongue deviation and left limb ataxia.　Magnetic resonance imaging of the brain including diffusion-weighted imaging showed previous lacunar infarctions at the left thalamus and pons.　The immunological investigation for viral infection in his serum samples showed high titers of IgM antibody against cytomegalovirus (CMV).　Cerebrospinal fluid (CSF) investigation revealed mononuclear pleocytosis, elevated protein levels and high titers of IgG antibody against the varicella-zoster virus (VZV).　Anti-CMV antibody measurement and CMV-DNA detection by the polymerase chain reaction in CSF revealed that the central nervous system (CNS) was not infected by CMV.　We diagnosed this case as brainstem encephalitis following multiple cranial neuropathy associated with CMV and VZV infections.　The neurological symptoms gradually improved with aciclovir and prednisolone therapy.　The titers of antibody for CMV in his serum samples normalized 4 months later after onset.

　Although there was no evidence of CMV infection in the CNS was obtained, parainfection or autoimmune mediated responses followed by viral infections might have led to brainstem encephalitis with multiple cranial nerve involvements in our patient.