第20巻 2024年8月　第3号

■症例報告

COVID-19感染後に発症した思春期重症筋無力症の1男児例
太田　悠佳¹, 早川　潤¹, 松井　亮介¹, 渡瀬　絵里加¹, 井出　彩香¹, 橋本　康司¹, 宮本　雄策², 酒巻　雅典³, 右田　真^1
1日本医科大学武蔵小杉病院小児科
²聖マリアンナ医科大学小児科
³日本医科大学武蔵小杉病院脳神経内科

A Case of a Boy with Myasthenia Gravis in Adolescence after COVID-19 Infection
Haruka Ota¹, Jun Hayakawa¹, Ryosuke Matsui¹, Erika Watase¹, Sayaka Ide¹, Koji Hashimoto¹, Yusaku Miyamoto², Masanori Sakamaki³ and Makoto Migita^1
1)Department of Pediatrics, Nippon Medical School Musashi Kosugi Hospital
²⁾Department of Pediatrics, St.Marianna University School of Medicine
³⁾Department of Neurology, Nippon Medical School Musashi Kosugi Hospital

Childhood-onset myasthenia gravis (MG), which is more common in children under 5 years of age than in adolescents, is generally characterized by ocular symptoms and an absence of anti-acetylcholine receptor (AChR) and anti-muscle-specific tyrosine kinase (MuSK) antibodies. We treated a 13-year-old boy presenting with a chief complaint of ptosis after COVID-19 infection. Magnetic resonance imaging of the head showed no brain abnormalities, and no anti-AChR or anti-MuSK antibodies were detected. Nor did repetitive nerve stimulation reveal any abnormal decrement. However, a Tensilon test proved positive for MG, leading to a diagnosis of ocular MG. Treatment with a cholinesterase inhibitor brought about no improvement in the patient's symptoms. Prednisolone was administered to treat the diplopia caused by his ocular motility disorder, again with no symptomatic relief. By contrast, steroid pulse therapy was effective in resolving the patient's drooping eyelids and ocular motility issues. No recurrence of symptoms was observed after prednisolone was discontinued. Of note, the exacerbation of the patient's symptoms coincided with the detection of previously undetected AChR antibodies. Routine electromyography and testing for anti-AChR antibodies may prove useful in selecting treatment and predicting outcomes in patients with adolescent MG.

日医大医会誌 2024; 20(3), 216-220

Key words
myasthenia gravis, anti-acetylcholine receptor antibody, COVID-19

Correspondence to
Haruka Ota, Department of Pediatrics, Nippon Medical School Musashi Kosugi Hospital, 1-383 Kosugi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8533, Japan
E-mail：s13-025oh@nms.ac.jp

受付：2024年2月22日　受理：2024年3月28日