未治療2型糖尿病に発症した両眼性抗アクアポリン4抗体陽性視神経炎にサトラリズマブを導入した1例

A case of bilateral anti-aquaporin-4 antibody-positive optic neuritis developing in untreated type 2 diabetes treated with satralizumab

要約　目的：未治療2型糖尿病（DM）に発症した両眼性抗アクアポリン4（AQP4）抗体陽性視神経炎に対して，抗IL-6受容体抗体薬（サトラリズマブ）を導入した症例を報告する。

症例：43歳男性が急激な左視力低下を主訴に受診した。右視力（1.5），左視力光覚なし，頭部MRIで左視神経の高信号に加え，血清抗AQP4抗体陽性から左抗AQP4抗体陽性視神経炎と診断した。脳脊髄病変はみられなかった。2型DMが見つかり，内科併診のうえ，ステロイドパルスおよび血漿浄化療法を行い，左視力（0.09）となったが，通院を自己中断した。初診から約36か月後，右抗AQP4抗体陽性視神経炎を発症し，右視力（0.06）となり，血漿浄化療法により右（1.5）まで回復した。プレドニゾロン内服に併用してサトラリズマブを導入した。導入後13か月経過し，視力は右（1.5），左（0.1）を維持し，再発を認めていない。

結論：通院アドヒアランスの低下が懸念される抗AQP4抗体陽性視神経炎症例に対する再発予防に対し，自己皮下注射可能なサトラリズマブは考慮されるべき薬剤と考えられた。その投与時期については，さらなる検討が必要である。

Abstract　Purpose：We report a case of bilateral anti-aquaporin-4 antibody positive optic neuritis（AQP4-ON）with untreated type 2 diabetes mellitus（DM）, treated with anti-IL-6 receptor antibody（satralizumab）.

Case：A 43-year-old male presented with a sudden and severe vision loss in the left eye（LE）. Best correced visual acuity（BCVA）showed 1.5 in the right eye（RE）and no light perception in the LE. A high signal intensity in the optic nerve in the LE was observed on brain MRI, and based on the positive serum anti-AQP4 antibody, AQP4-ON in the LE was diagnosed. However, no cerebrospinal lesion was observed. Untreated type 2 DM was identified, and after consultation with internal medicine, steroid pulse therapy and plasmapheresis were performed, resulting in an improvement to 0.09 in BCVA of the LE. However, he discontinued outpatient visits on his own. Approximately 36 months after the initial diagnosis, he developed AQP4-ON in the RE, resulting in his BCVA of 0.06. BCVA improved to 1.5 in the RE after plasmapheresis. Thereafter, satralizumab was administered in conjunction with oral prednisolone. Thirteen months have passed since the administration, BCVA remains at 1.5 and 0.1 in the RE and LE, and no recurrences have been reported in both eyes.

Conclusion：Self-administrable satralizumab should be considered as a medication for preventing recurrences in AQP4-ON cases where reduced outpatient visit adherence is a concern. Further evaluation is needed regarding the timing of its administration.