Collateral Circulation of the Brain -With Special Reference to Atherosclerosis of the Major Cervical and Cerebral Arteries-

Collateral circulation is of most concern in the pathologic process of the brain, particularly in the occlusive disease of the cervical and cerebral arteries. The collateral circulation to the brain exists in three main areas (Kaplan)1): (1) through extracranial arterial connections; (2) through developmental extracranial to intracranial persisting arteries; and (3) through intracranial cerebral arterial anastomoses. The author directed efforts toward an analysis of collateral circulation to the brain of the aged subjects with some degree of atherosclerosis in the cervical as well as in the cerebral arteries. The present study consists of three parts: (1) a study on atherosclerosis of the major cervical and cerebral arteries; (2) a demonstration of the collateral circulation between the internal carotid, external carotid, and vertebral arteries; as to the intracranial anastomoses, emphasis was laid on the variations of the basal cerebral arteries, including the circle of Willis; and (3) a clinical consideration of cases with severe stenosis of the cervical arteries, with regard to cerebral vascular insufficiency due to a drop of the systemic blood pressure.