視神経脊髄炎スペクトラム障害加療中にCOVID-19を発症した1例

A case of COVID-19 during treatment for neuromyelitis optica spectrum disorders

要約　目的：抗アクアポリン（AQP）4抗体陽性の視神経脊髄炎スペクトラム障害（NMOSD）に対するステロイドパルス療法および血漿交換療法施行中に新型コロナウイルス感染症（COVID-19）を発症した1例を経験したので報告する。

症例：患者は65歳，女性。8年前より抗AQP4抗体陽性の左眼発症のNMOSDと診断され，過去に3度のステロイドパルス療法を施行されていた。今回，右視力低下を自覚し，福岡大学筑紫病院眼科を再診した。著明な右視力低下（光覚なし）と抗AQP4抗体価40U/ml以上の上昇を認め，集学的な治療が必要と判断し，ステロイドパルス療法および血漿交換療法を開始した。ステロイドパルス療法2コース，血漿交換療法5コースを施行した時点で，スクリーニング目的のPCR検査にてCOVID-19陽性が判明した。

経過：同日より個室への隔離を開始し，血漿交換療法を終了し，ステロイドパルス療法はプレドニゾロン内服漸減療法へ移行した。COVID-19陽性判明時は無症状であったが，陽性判明から4日後より発熱・咳嗽の症状が出現し，7日後から胸部単純X線写真で右肺上下葉の陰影が出現し血中酸素濃度の低下を認めたため，同日より酸素・ファビピラビルの投与を開始した。治療開始後13日で両肺野の陰影は改善し，14日間でファビピラビル投与を終了し，その後肺炎の再燃はなかった。抗AQP4抗体価は減少し，第76病日には矯正視力は右1.2，左0.2と改善した。プレドニゾロン10mg/日維持療法を行い，以降現在まで再発はない。

結論：NMOSDおよびCOVID-19に対し早期より集学的治療を行い，良好な経過を得た。今後も感染症を併発する症例の発生が予測され，早期発見・治療が重要と考えた。

Abstract　Purpose：We report a case of COVID-19 developed during steroid pulse and plasma exchange therapy for anti-AQP4 antibody-positive NMOSD.

Case：A 65-year-old woman diagnosed with anti-AQP4 antibody-positive NMOSD for 8 years had been treated with steroid pulse three times in the past. She realized that she had poor eyesight this time, and she returned to our department. Marked decrease in visual acuity without light sensation and an increase in antibody titer of 40 U/ml or more were observed, and it was diagnosed as NMOSD. Steroid pulse and plasma exchange therapy were started. When 2 courses of steroid pulse and 5 courses of plasma exchange therapy were performed, the PCR test for screening was positive for COVID-19.

Clinical course：From the same day, isolation to a private room was started, plasma exchange therapy was terminated, and steroid pulse was switched to oral tapering therapy. Although she was asymptomatic when the positive result was found, symptoms of fever and cough gradually appeared over 4 days. Since shadows of the right upper and lower lobes appeared on X-ray at day 7, and blood oxygen decreased, we began administration of favipiravir. The shadows of both lungs improved on day 13, and favipiravir administration was terminated day 14. The anti-AQP4 antibody titer decreased, the corrected visual acuity improved to 1.2 in the right and 0.2 in the left on day 76. No recurrence was noted under prednisolone 10mg maintenance therapy.

Conclusion：NMOSD and COVID-19 were discovered at an early stage, and a good course was obtained with steroid, plasma exchange, and anti-virus therapy. Further careful observation is important for early detection and treatment against infectious disease.