斜視角が変動する交代性外斜視を伴った両側内側縦束症候群（WEBINO症候群）の1例

A case of bilateral MLF syndrome and alternating exotropia (WEBINO syndrome) with fluctuating angle of strabismus

　38歳女性に複視が突発し，軽快しないので7日後に受診した。矯正視力は両眼1.2で，眼底その他に異常はなかった。右側に著明な，左側に軽微なMLF （内側縦束）症候群があった。斜視角が正位から最大30度と不規則に変動する交代性外斜視があった。輻軽は不可能であった。交代性外斜視を伴うMLF症候群（WEBINO症候群）と診断した。8日後に交代性外斜視は外斜位になり，さらに7日後には外斜位と両眼の内転制限は消失した。比較的若年の女性であり，症状が急速に改善したことから多発性硬化症を疑った。頭部MRI検査では異常所見はなく，WEBINO症候群の原因は特定できなかった。

A 38-year-old female presented with sudden diplopia since 7 days before. Her corrected visual acuity was 1.2 in either eye. There were no abnormal findings by funduscopy or biomicroscopy. Bilateral medial longitudinal fascicule (MLF) syndrome was present which was more manifest in the right side than in the left. Alternating strabismus was present with the angle fluctuating between 0 and 30 degrees. Convergence was impossible. We diagnosed her as bilateral MLF syndrome with alternating strabismus, or WEBINO syndrome. The eye position became exophoria 8 days later. Exophoria and restricted adduction disappeared another 7 days later. We suspected multiple sclerosis because of sex, age and rapid improvement in clinical findings. Cerebral magnetic resonance imaging (MRI) gave inconclusive findings. We could not identify the cause of WEBINO syndrome in this patient.