COVID-19罹患を契機に発症したMOG抗体陽性視神経炎の1例

A case of myelin oligodendrocyte glycoprotein antibody-positive optic neuritis related to coronavirus disease 2019

要約　目的：COVID-19はSARS-CoV-2による感染症であり，罹患を契機としたさまざまな神経免疫疾患の発症報告がある。筆者らはCOVID-19罹患を契機に発症した抗ミエリンオリゴデンドロサイト糖蛋白質（MOG）抗体陽性視神経炎を報告する。

症例：43歳，男性。COVID-19陽性確認前日より左視野の違和感と，両眼球運動時痛を自覚した。感染隔離期間中の陽性確認後4日目の検査により，視力は右 光覚消失，左 光覚弁，眼底では両視神経乳頭浮腫があった。視野検査にて両中心暗点を認めた。頭部造影MRIでは，両視神経の高信号域，視交叉付近まで及ぶ視神経周囲の異常濃染を認め，両視神経炎と診断された。隔離解除初日の陽性確認後8日目から，メチルプレドニゾロン1,000mg/日を5日間のパルス療法を1クール施行し，血漿交換療法を7回行った。血清・髄液検査の結果からMOG抗体陽性視神経炎と診断した。陽性確認後45日目に矯正視力は右0.5，左0.7と回復し，乳頭浮腫，視野障害も改善した。治療開始後1年経過し，眼症状（視力障害，視野障害，眼球運動時痛）のみで再発はなく，矯正視力は左右とも1.2と安定している。

結語：COVID-19罹患を契機に発症したMOG抗体陽性視神経炎に対してステロイドパルス治療，血漿交換療法が著効し，以後再発なく経過良好であった。

Abstract　Purpose：Coronavirus disease 2019（COVID-19）is an infectious disease caused by severe acute respiratory syndrome coronavirus 2, and various neuroimmune diseases have been reported to develop following infection. We report an anti-myelin oligodendrocyte glycoprotein（MOG）antibody-positive optic neuritis that developed after COVID-19 infection.

Case：A 43-year-old man had experienced discomfort in the left visual field and pains in ocular movement a day before COVID-19 positive result was confirmed. On the fourth day of infection during isolation, he lost visual acuity in the right eye, light perception in the left eye, and papillary edema of both optic nerves was found in the fundus of the eyes. Visual field examination revealed bilateral central scotoma. Contrast-enhanced magnetic resonance imaging showed high-signal areas in both optic nerves and abnormal peripapillary staining extending to the optic chiasm, and bilateral optic neuritis was diagnosed. From the eighth day of illness, which was the first day after the patient was released from isolation, a course of pulse therapy with methylprednisolone 1000 mg/day for 5 days was administered, and plasma exchange therapy was administered seven times. Anti-MOG antibody-positive optic neuritis was diagnosed based on the results of serum and cerebrospinal fluid examination. On the 45th day of illness, the best corrected visual acuity was 0.5 and 0.7 on the right and left eyes, respectively, and papillary edema and visual field defects had also improved. One year after the start of treatment, there was no recurrence and had only ocular symptoms（visual disturbance, visual field disturbance, pains in ocular movement）, and the best corrected visual acuity was stable at 1.2 and 1.2 on the right and left eyes, respectively.

Conclusion：A patient with anti-MOG antibody-positive optic neuritis which developed after contracting COVID-19 responded well to steroid pulse and plasma exchange therapies, with no recurrence to date.