一過性垂直注視麻痺を呈した右視床中脳梗塞の1例

A Case of Transient Vertical Gaze Palsy Following Right Thalamic and Midbrain Infarction

　我々は右視床中脳梗塞で発症1時間後に垂直（上下）注視麻痺のみを認め，翌日に上方注視麻痺となり，第4病日には眼球運動障害が改善した71歳，男性例を報告した。責任病巣はMRIでは右中脳に限局していた。しかし，垂直注視麻痺の出現は初期の短期間における—過性であったこと，かつその間意識水準の低下が認められたことより，MRI上に現れない超急性期の軽度の浮腫などによる両側性の機能障害の存在が示唆された。また，発症後4日間の経過で垂直注視麻痺が改善している事実から片側病変による垂直注視麻痺は持続期問が非常に短いため，あるいは頭部CTスキャンでは病巣が不明瞭なために今までは見逃されていた可能性が考えられた。

The authers report a 71-year-old male who suffered from vertical gaze palsy due to infarction localized on MRI in the right midbrain. Vertical gaze palsy was observed 1 hour after the onset of his stroke. Upgaze palsy was noted the following day. Four days later, the disturbances of ocular move-ment disappeared. T2 weighted MR imaging showed a high signal intensity lesion, which was localized in the right side of the thalamomesence-phalic portion. However, since the vertical gaze palsy appeared only transiently for a short time inthe initial stage and since the level of consciousness decreased during that time, it was suggested that there was a bilateral functional disorder caused by mild edema, etc., in the hyperacute stage, which was not demonstrated on MRI. This disorder had been overlooked either because the duration of the verti-cal gaze palsy due to the unilateral lesion was very short, i. e. improvement was seen 4 days after onset, or the lesion was not clearly delineated in a CT scan of the head. It appeared possible that this sign might not be very rare if careful observations are performed in the hyperacute stage of midbrain infarction.