Abstract
A 43-year-old man was admitted to hospital for treatment of hypertension and diabetes mellitus. Antihypertensive agents including valsartan, trichlormethiazide and cilnidipine were started and blood pressure decreased from 224/126 mmHg to 109/80 mmHg. He then developed dysarthria and unsteady gait and was transferred to our department. Neurological examination revealed bilateral gaze nystagmus, bilateral hearing disturbance and tinnitus, lip numbness, ataxic speech, and ataxia in all four limbs. Brain diffusion-weighted images displayed hyperintensities in bilateral middle cerebellar peduncles and the paramedian portion of the upper pons, suggesting acute brain infarction. Cerebral angiography disclosed occlusion of both vertebral arteries and showed that the basilar artery was perfused through the posterior communicating artery. This data suggested that infarctions developed hemodynamically because of rapid and excessive reduction of systemic blood pressure under bilateral vertebral artery occlusion. The middle cerebellar peduncle and the paramedian portion of the upper pons are located in the watershed area of the vertebrobasilar circulation. Infarctions in these regions can be caused by hemodynamic mechanisms in the presence of bilateral vertebral artery disease.
