studied. Cross-filling of the cerebral arteries during the compression of the carotid artery on the side of the aneurysm was studied by angiography after an injection of contrast medium into the opposite carotid artery. Operative procedure: Under general anaesthesia, the bifurcation of the carotid artery in the neck was exposed and superficial temporal artery to middle cerebral artery anastomosis was performed through the ipsilateral frontotemporal craniotomy. One or two thermal diffusion flow probes (Plate-type, outside diameter 13 mm,