急性内斜視を呈した無菌性髄膜炎の1例

A case of aseptic meningitis with acute esotropia as the chief complaint

要約　目的：急性内斜視を呈した髄膜炎の1例を経験したので報告する。

症例：14歳，女児。頭痛と嘔気にて近医脳神経外科を受診した。頭部MRIでは異常所見はなく経過観察となっていた。10日後に左眼複視が出現し，急性内斜視にて東海大学医学部付属病院眼科を紹介され受診した。初診時視力は右（0.8），左（1.2）で，左眼に内斜視と外転制限を認めた。限界フリッカ値は正常であったが両眼視神経乳頭腫脹とマリオット盲点の拡大を認め，MRI検査で視神経周囲に軽度の浮腫性変化を認めた。一方，髄液検査では髄液圧の上昇，リンパ球優位の細胞数増多，蛋白上昇を伴う髄膜炎を認めたが，細菌は検出されなかった。視神経乳頭腫脹と髄膜刺激徴候を認めたことから視神経脊髄炎の可能性も考えられたため，ステロイドパルス療法を施行，症状の継続のため計3クールおよび内服による漸減療法を行った。治療後髄液所見は正常化し，視力も両眼（1.2）と改善した。左眼外転障害および両眼視神経乳頭腫脹ともに改善がみられた。抗アクアポリン4抗体，抗ミエリンオリゴデンドロサイト糖蛋白抗体ともに陰性で，脊椎MRI検査でも異常所見がなかったこと，初診時の採血にてサイトメガロウイルス抗体が陽性であったことより，本症例は視神経脊髄炎の可能性が低く，無菌性髄膜炎に起因するものと考えた。

結論：急性内斜視および視神経乳頭腫脹を呈した，無菌性髄膜炎と考えられる症例を経験した。眼位異常を呈し髄膜刺激症状を伴う症例では，MRIなどの画像検査のほかに髄液検査も診断に有用である。

Abstract　Purpose：We report a case of meningitis wherein the patient's chief complaint was acute esotropia.

Case：A 14-year-old girl presented to a local neurosurgery clinic with a headache and nausea. Brain MRI scan showed no cerebral abnormalities, and the patient was kept under observation. Ten days later, she developed diplopia and was referred to our department due to acute-onset esotropia. The best-corrected visual acuity was 0.8 in the right eye and 1.2 in the left eye；esotropia and abduction disorder of the left eye were observed. Although the critical flicker frequency was normal, papilledema was observed in both eyes. Goldmann visual field examination revealed enlargement of the left Mariotte's blind spot, and MRI showed mild edematous changes around the optic nerves. Meanwhile, cerebrospinal fluid（CSF）examination revealed meningitis with elevated CSF pressure, increased lymphocyte-predominant cell counts and elevated protein levels, but no bacteria were detected. Since papilledema and signs of meningeal irritation suggested the possibility of neuromyelitis optica, the patient received pulse therapy with subsequent oral prednisolone therapy.

　After treatment, CSF abnormalities subsided and visual acuity improved to 1.2 in both eyes. Both left eye abduction disorder and bilateral papilledema were improved. Since the patient was negative for anti-aquaporin 4 and anti-MOG antibodies, no abnormal findings were observed on spinal MRI. Further, the presence of cytomegalovirus（CMV）antibodies was revealed in the blood test. We considered that patient's symptoms might be due to aseptic meningitis caused by CMV.

Conclusion：We reported a case of aseptic meningitis presenting with acute esotropia and papilledema. For cases with abnormal ocular movement and symptoms of meningeal irritation, CSF examination is an important diagnostic tool.