Predicting Intolerance to Common Carotid Artery Ligation by Carotid Angiography

Abstract

C ERVICAL carotid artery occlusion in its various forms (staged ligation, internal carotid artery ligation, common carotid artery ligation, and gradual clamping) continues to be a valuable procedure. Unfortunately, it carries a 30% morbidity from cerebral ischemia, 9 which would be difficult to justify were it not for the explosive and potentially fatal nature of the basic lesion. Neurosurgeons have recognized the need to predict which patients will or will not tolerate carotid ligation. However, attempts to correlate the fall in carotid pressure or decrease in blood flow at the time of ligation with individual tolerance have been discouraging and statistically insignificant. 2,13,15 Apparently, there is little change in either factor until the vessel lumen has been decreased about 90%. Intolerance studies utilizing preoperative angiograms similarly have been inconclusive and often confusing. Generalizations have been made after analyzing patients whose various intracranial lesions have been treated by different modifications of carotid ligation, thus involving factors not strictly comparable. 9 Finally, isolated angiographic features, such as hypoplastic arteries in the circle of Willis, have been studied instead of regarding the circle of Willis as a whole. Our study attempts to resolve some of these problems by considering two separate groups of patients, namely, those with anterior communicating artery aneurysms (ACA) and those with internal carotid-posterior communicating artery junction aneurysms (PCA). In each group, common carotid artery ligation was used.