両側性中脳傍正中部梗塞による垂直one-and-a-half症候群の1例

Vertical one-and-a-half syndrome in a case of bilateral meso-diencephalic infarctions

48歳男性が3か月前に複視を契機として両側の視床梗塞と診断された。複視が軽快せず当科を受診した。矯正視力は右1.5，左1.2であった。第一眼位で左上斜視があり，両眼とも水平方向には運動制限がなかった。垂直運動で，左眼は上転したが右眼は上転不良であり，両眼とも下方注視麻痺があった。磁気共鳴画像検査（MRI）で両側の視床梗塞と，両側の縦束吻側間室核（rostral interstitial nucleus of medial longitudinal fascicles：riMLF）を含む中脳傍正中部梗塞があった。Skew deviationと眼球運動から，両側のriMLFの障害に加えて，左riMLFからカハル間質核と後交連を経由して対側のカハル間室核とriMLFに向かう経路が障害されたために，右眼のみの上転障害とone-and-a-half症候群が起こったと考えられた。

A 48-year-old male developed diplopia and was diagnosed with bilateral thalamo-mesencephalic infarction 3 months before. He visited us for persistent diplopia. His corrected visual acuity was 1.5 right and 1.2 left. Monocular elevation paresis was present in the right eye. Both eyes showed downward gaze palsy. The findings were compatible with vertical one-and-a-half syndrome. Magnetic resonance imaging（MRI）showed bilateral thalamic infarction and bilateral infarction involving the rostral interstitial nucleus of medial longitudinal fascicles. Additional involvement of fibers through left interstitial nucleus of Cajal appeared to have resulted in vertical one-and-a-half syndrome in this patient.