ステロイドパルス療法後に追加治療を要した抗MOG抗体陽性小児視神経炎の2症例

Two cases of anti-MOG antibody-positive pediatric optic neuritis that required additional treatment after steroid pulse therapy

要約　目的：ステロイドパルス（IVMP）後に追加治療を要した抗ミエリンオリゴデンドロサイト糖蛋白（MOG）抗体陽性の小児視神経炎2症例を経験したので報告する。

症例：症例1は10歳，男児。虫垂切除術後に視力障害と歩行障害を認め，当院小児科へ入院となった。視力は右（0.06），左光覚弁で，両眼に視神経乳頭腫脹を認めた。MRIで両側視神経，視交叉，小脳，皮質下白質，脊髄に高信号域を認めた。視神経脊髄炎関連疾患（NMOSD）の診断でIVMP 2クール施行したが，両眼視力（0.01）と改善が乏しかった。血漿交換療法，IVMP 3クール目を追加し，発症から約2か月後に両眼視力（1.0）と改善を認めた。血清抗MOG抗体は1,024倍と強陽性であった。症例2は5歳，男児。無菌性髄膜炎の治療後に眼痛と視力低下を認め，当科へ紹介された。視力は右（0.01），左（1.0）であり，右相対的瞳孔求心路障害陽性，右視神経乳頭腫脹を認めた。MRIでは右視神経，両側皮質下白質に高信号域を認め，NMOSDの診断となった。IVMP 3クール施行後，右眼視力（0.2）であった。免疫グロブリン静注療法を追加し，右眼視力（1.0）と改善を認めた。抗MOG抗体は血清で陰性，髄液で16倍と強陽性であった。

結論：小児視神経炎では脱髄性疾患が背景にあることがあり，小児科と連携し全身精査が必要である。抗MOG抗体陽性例ではIVMP後の追加治療や後療法が予後にかかわる可能性があり，抗体検査の実施が重要である。

Abstract　Purpose：To report a case of anti-myelin oligodendrocyte glycoprotein（MOG）antibody-positive pediatric optic neuritis that required additional treatment after intravenous methylprednisolone（IVMP）.

Case：Case 1 was a 10-year-old boy. He was admitted to the Department of Pediatrics at our hospital with visual impairment and gait disturbance after appendectomy. Magnetic resonance imaging（MRI）showed high signal areas in the bilateral optic nerves, optic chiasm, cerebellum, subcortical white matter, and spinal cord. Two courses of IVMP were administered with the diagnosis of neuromyelitis optica spectrum disorders（NMOSD）, but there was little improvement in visual acuity of 0.01 in either eye. Plasma exchange therapy was added, and the patient's visual acuity improved to 1.0 in both eyes. Serum anti-MOG antibody was 1,024-fold positive. Case 2 was a 5-year-old boy. He was referred to our department with ocular pain and decreased vision after treatment for aseptic meningitis. MRI showed high signal areas in the right optic nerve and bilateral subcortical white matter, leading to the diagnosis of NMOSD. After three courses of IVMP, the patient had a visual acuity of 0.2 in the right eye. Intravenous immunoglobulin therapy was added, and the patient's visual acuity improved to 1.0 in the right eye. Anti-MOG antibody was negative in serum and 16-fold positive in the cerebrospinal fluid.

Conclusion：Pediatric optic neuritis may have a background of demyelinating disease, and its systemic examination in cooperation with pediatricians is necessary. In anti-MOG antibody-positive cases, additional treatment after IVMP and post-therapy possibly determine the prognosis, and it is important to perform antibody tests.