[A case of transient vertical gaze palsy following right thalamic and midbrain infarction]

The authors 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 movement disappeared. T2 weighted MR imaging showed a high signal intensity lesion, which was localized in the right side of the thalamo-mesencephalic portion. However, since the vertical gaze palsy appeared only transiently for a short time in the 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 vertical 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.