Comparative angiographic and histological evaluations of intracranial atherosclerosis in hypertensive and normotensive subjects.

Cerebral atherosclerosis without luminal narrowing has been found macroscopically and by angiographic examinations in some patients with cerebral hemorrhage. In order to clarify the histology of non-stenotic atherosclerosis of the cerebral vessels, we examined cleared specimens and serial sections of the main trunks of the cerebral arteries. The middle cerebral artery was selected in 20 cases of cerebral hemorrhage and 7 cases of cerebral infarction. Non-stenotic atherosclerosis was found frequently in cases of cerebral hemorrhage, while most patients with cerebral infarction showed stenotic cerebral atherosclerosis. We counted the numbers of medial smooth muscle cells in 10 autopsied cases of cerebral hemorrhage and 6 of cerebral infraction. The mean numbers of smooth muscle cells per unit area in the patient with cerebral hemorrhage were less than those in cerebral infraction. In cerebral hemorrhage, the main trunks of the cerebral arteries were dilated, probably as a result of the damage to medial muscle cells and higher blood pressure during the course of intimal thickening. It is considered that arterial hypertension spreads to the peripheral, small arteries through the main trunks without luminal narrowing of the cerebral vessels.