Incidence and Predictive Factors of Cerebral Hyperperfusion After Extracranial-Intracranial Bypass for Occlusive Cerebrovascular Diseases

Abstract

Abstract BACKGROUND: Although many studies of postoperative cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy have been reported, there are few reports related to extracranial-intracranial (EC-IC) bypass for atherosclerotic occlusive cerebrovascular diseases. OBJECTIVE: To examine the incidence of cerebral hyperperfusion and CHS after EC-IC bypass and to investigate predictive factors. METHODS: Fifty consecutive patients undergoing EC-IC bypass for atherosclerotic occlusive cerebrovascular diseases were studied. Immediately after bypass surgery, resting regional cerebral blood flow was determined under continuous sedation, and postoperative hyperperfusion was evaluated according to the definitions as follows: > 50% increase in regional cerebral blood flow compared with the contralateral side (method 1) and > 100% increase in corrected regional cerebral blood flow compared with preoperative values (method 2). Logistic regression analysis was conducted to determine the effect of multiple variables on postoperative hyperperfusion. RESULTS: Transient symptoms of CHS were observed in 3 patients. Cerebral hyperperfusion was detected in 12 patients (24%) as defined by method 1 and in 9 patients (18%) by method 2. Postoperative hyperperfusion occurred significantly more frequently in patients with the steal phenomenon (regional cerebral vasoreactivity ≤ 0%; P = .001 by method 1 and P = .001 by method 2) and correlated with impaired preoperative regional cerebral vasoreactivity (P < .001). Logistic regression analysis revealed that the steal phenomenon was a significant risk factor for hyperperfusion as defined by both methods 1 (P = .009) and 2 (P = .03). CONCLUSION: The incidence of cerebral blood flow-assessed postoperative hyperperfusion after EC-IC bypass for atherosclerotic occlusive cerebrovascular diseases was not rare. Post EC-IC bypass CHS could be reduced by continuous, strict blood pressure control under sedation.