Cerebral revascularization by EC-IC bypass--present status.

The Extra-Intracranial (EC-IC) arterial Bypass = EIAB has been proposed by Yasargil and Donaghy in 1967 to bypass an occlusive process in the arteries supplying the brain that is not accessible surgically in another way. Following a rise in the number of procedures performed annually worldwide, a sharp decline followed after the International EC-IC Bypass Study had shown that the addition of EIAB did not improve the long-term results in the study population compared to best medical therapy by aspirin alone. On the basis of a better understanding of the origin of cerebral ischemic events, more precise indications have been developed targeting to improve hemodynamic insufficiency, by surgically adding an extracranial arterial supply. Furthermore, technical improvements of the procedure allow more deliberate indication for EIAB, e.g. using high-flow bypass while performing an "occlusion-free" anastomosis. Also, variations of the technique of encephalo-myo-synangiosis for Moya-Moya disease patients allow additional blood supply to the brain hemispheres.