無症候性のBasedow病を合併した自己抗体陰性の眼筋型重症筋無力症の1例

A case of seronegative ocular myasthenia gravis with asymptomatic Graves' disease

要約　目的：無症候性のBasedow病を合併した自己抗体陰性の眼筋型重症筋無力症の症例の報告。症例：45歳男性が両眼複視と左眼瞼下垂を主訴に受診した。所見：両眼とも矯正視力は1.2で左眼の眼瞼下垂と内転，下転障害を認めた。抗アセチルコリン受容体抗体は陰性で，その後，右眼瞼下垂と左眼球運動障害の変動がみられるようになった。テンシロンテストで陽性を示し，全身症状がみられなかったため，眼筋型重症筋無力症と診断した。繰り返し行った血液検査と甲状腺超音波検査で無症候のBasedow病の合併が判明した。結論：重症筋無力症では経過中にBasedow病などの自己免疫疾患を合併することがあり，繰り返し検査を行い早期発見に努める必要がある。

Abstract.　Purpose：To report a case of seronegative ocular myasthenia gravis（MG）with asymptomatic Graves'disease. Cases：A 45-year-old male was referred for binocular diplopia and left blepharoptosis. Findings：Corrected visual acuity was 1.2 both. The left eye showed limited inferior and lateral movement. Antiacetylcholine receptor antibodies were undetectable. Subsequently, right blepharoptosis occurred, and fluctuation in impaired ocular movement of the left eye was observed. Tensilon test was positive. There were no other symptoms related to MG, and he was diagnosed with ocular MG. Later, serological examination and thyroid ultrasonography disclosed asymptomatic Graves' disease. Conclusions：MG is sometimes combined with other autoimmune disorders like Graves' disease. Repetitive examinations for these diseases are needed for early detection.