[Hemodynamics in the anterior part of the circle of Willis in patients with the anterior communicating artery aneurysm--a study by cerebral angiography (author's transl)].

In order to study the cerebral angiographic findings of the hypoplasia of the A1 of the anterior cerebral artery, and the abnormal blood circulation in the anterior part of the circle of Willis, 485 patients who had had at least bilateral carotid angiography and complete data were selected, out of 1,000 patients with cerebral aneurysms to whom intracranial direct surgery had been done from June 1961 to September 1975. Patients with multiple cerebral aneurysms were excluded in this study. Seventy six patients were selected as controls. 1. Cerebral angiography revealed that hypoplasia of the A1 of the anterior cerebral artery is much more frequent in patients with aneurysms of the anterior communicating artery than in those with aneurysms of other intracranial arteries. It was observed in 145 of the 213 patients with aneurysms of the anterior communicating artery (68.1%). As for the hypoplasia of the A1, the angiographic findings corresponded to the surgical findings in 86.9% of all the patients. The incidence of hypoplasia of the left and right A1 portions was higher in patients with aneurysms of the anterior communicating artery than in those with aneurysms of other intracranial arteries. The incidence was about 3 times higher on the right side than on the left side. 2. It was considered that the abnormal blood circulation was observed in the anterior part of the circle of Willis in 155 patients, including 145 with angiographic findings of hypoplasia of a unilateral A1 and 10 with anomalies of the anterior communicating artery or A1 of anterior cerebral artery other than hypoplasia, out of 213 patients with aneurysms of the anterior communicating artery (72.8%). 3. The above findings are considered important for a diagnosis of an aneurysm of the anterior communicating artery and for a surgical approach.