STROKE RISK AFTER ABRUPT INTERNAL CAROTID-ARTERY SACRIFICE - ACCURACYOF PREOPERATIVE ASSESSMENT WITH BALLOON TEST OCCLUSION AND STABLE XENON-ENHANCED CT

PURPOSE: To evaluate stable xenon-enhanced CT cerebral blood flow with balloon test occlusion as a predictor of stroke risk in internal caro tid artery sacrifice. METHODS: Abrupt internal carotid artery occlusio n was performed by surgical or endovascular means below the origin of the ophthalmic artery in 31 normotensive patients who were assessed pr eoperatively by a 15-minute clinical balloon test occlusion followed b y an internal carotid artery-occluded xenon CT cerebral blood flow stu dy. RESULTS: One patient, who passed the clinical test occlusion but e xhibited regions of cerebral blood flow less than 30 mL/100 g per minu te on the occlusion xenon CT cerebral blood flow study went on to have a fatal stroke corresponding exactly to the region of reduced blood f low. Thirty patients passed both components of the preoperative stroke -risk assessment. Neuroimaging demonstrated possible flow-related infa rctions, which subsequently developed in three patients. Two patients were asymptomatic, and one patient was left with a mild residual hemip aresis. CONCLUSIONS: Our protocol provided a statistically significant reduction in subsequent infarction rate and infarction-related death rate when compared with a control group of normotensive abrupt interna l carotid artery occlusion patients who did not undergo any preoperati ve stroke-risk assessment (reported in the literature). The estimated false-negative rate for our preoperative assessment protocol ranged fr om 3.3% to 10% depending on the assessment of the cause of the three p otentially flow-related infarctions. Although life-threatening major v ascular territory infarctions have been avoided, our protocol is less sensitive to changes predicting smaller, often minimally symptomatic, vascular border lone infarctions and does not predict postoperative th romboembolic strokes.