title: Reduced response of cerebral blood flow to hypercapnia: restoration by extracranial-intracranial bypass.
abstract: Cerebral blood flow, estimated by the xenon clearance technique, has been used to study eight patients before and after extracranial-intracranial (EC-IC) bypass surgery. Response of cerebral blood flow to hypercapnia was also measured to estimate cerebral reactivity, an indicator of cerebral vasodilator reserve capacity. Measurements in all patients were repeated 3 months after surgery. Resting cerebral blood flow was not increased by the operation but cerebral reactivity in the ipsilateral hemisphere was significantly increased in all patients (P = 0.002). Reactivity also increased in the contralateral hemisphere in six of the eight patients (P = 0.065). The response of cerebral blood flow to hypercapnia may prove useful in the selection of symptomatic patients with carotid occlusions or inaccessible stenoses for revascularization by EC-IC bypass.
mesh_terms: D000368:Aged; D001157:Arterial Occlusive Diseases / Q000503:physiopathology; D002245:Carbon Dioxide / Q000502:physiology*; D002340:Carotid Artery Diseases / Q000503:physiopathology; D002539:Cerebral Arterial Diseases / Q000503:physiopathology; D002548:Cerebral Revascularization; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow
chemical_list: D002245:Carbon Dioxide