The occipital-vertebral anastomosis as a collateral pathway: hemodynamic patterns--case report.

The authors describe the case of a 67-year-old man with acquired obstruction of the common carotid artery and a large, direct occipital-vertebral artery anastomosis bridging the vertebral and carotid artery systems. They discuss the hemodynamics within this type of anastomosis in the context of cerebrovascular occlusive disease and outline their classification of the hemodynamic patterns that have been observed. Surgical procedures for occlusive disease in the presence of such anastomoses are also addressed.