We have witnessed a remarkable development during the past 10 years in the development of extra-intracranial anastomosis to revascularize the brain. Initially, the intention was to create ameans of performing embolectomy in small corticaI arteries after cardiac surgery. Gradually a plan was conceived to form an extra-intracranial bypass(10) to treat inaccessible lesions of the carotid and vertebral arteries as weIl as tumors and giant aneurysms that involved these arteries. The basic techniques and principles of microvascular sur gery, which had been refined over 30 years on peripheral ar...