[The significance of hypoplasia of the circle of Willis in patients with Binswanger-type cerebrovascular disease].

We evaluated the correlation between hypoplasia of the circle of Willis detected by MR angiography and ischemia of the white matter in patients with Binswanger-type cerebrovascular disease. We defined P1 hypoplasia as the condition in which the posterior cerebral artery at P1 protein was narrower than the posterior communicating artery, and A1 hypoplasia as that in which the ratio of the one anterior cerebral artery to the other at A1 portion was 1:2 or less. Of 68 patients with this disease. 33 (48.5%) had P1 hypoplasia and 23 (30.9%) had A1 hypoplasia. These incidences were significantly higher than those of patients with lacunar infarction (138 cases), where P1 and A1 hypoplasia were 29.0% and 18.1% respectively. P1 hypoplasia tended to be found more frequently in patients with lacunar infarction having advanced periventricular hyperintensity than in those having mild one. The large intracranial vessels, as seen by MR angiography, were less stenotic, and the serum concentration of apolipoprotein A-I was higher and B/A-I was lower in hypoplasia cases suffering from Binswanger-type cerebrovascular disease than in non-hypoplasia cases. In summary, hypoplasia of the circle of Willis was considered to precipitate the onset or progression of this disease without any relationship to arteriosclerosis.