エタンブトール視神経症の1例

A case suspected of ethambutol optic neuritis

要約　目的：非結核性好酸菌症に対するエタンブトール投与後に発症した視神経炎の1症例の報告。症例：71歳女性が内科から紹介され受診した。17年前に関節リウマチでステロイド剤と免疫抑制薬を内服し，8年前に非結核性肺好酸菌症と診断され，抗菌薬の内服を開始し，白内障手術を受けた。所見：矯正視力は右0.6，左1.2で，右眼に黄斑変性があった。初診と同時にエタンブトールを含む治療を開始し，その2か月後に両下肢にしびれ感が生じた。初診から7か月後に「両眼が暗い」と訴え，矯正視力が右0.09，左手動弁に低下し，中心暗点があり，球後視神経炎が疑われた。初診から18か月後の現在，視力は右0.15，左0.04を維持している。結論：本症例はエタンブトール内服が原因として関与した可能性が大きい。

Abstract.　Purpose：To report a case of bilateral optic neuropathy following peroral treatment with ethambutol. Case：A 71-year-old female was referred from an internist. She had been diagnosed with rheumatoid arthritis followed by treatment with corticosteroid and immunosuppressive agents. She started receiving antibiotics for nontuberculous pneumonitis since 8 years before. Findings：Her corrected visual acuity was 0.6 right and 1.2 left. The right eye showed macular degeneration. She immediately started receiving systemic treatment including ethambutol. She developed numbness in the lower extremities 2 months later. She noted impaired vision 7 months after start of ethambutol with visual acuity of 0.09 right and hand motion left. Both eyes showed central scotoma suggestive of retrobulbar optic neuropathy. Visual acuity improved to 0.15 right and 0.04 left 18 months after her initial visit. Conclusion：There is a high possibility that systemic ethambutol was involved in the causation of optic neuropathy in the present case.