ABSTRACT
A case with a true posterior communicating artery aneurysm is reported, who had been managed by early surgical neck clipping and post-operative intensive cares for numerous complications. The small saccular aneurysm was located at the proximal posterior communicating artery and directed superiorly. A lacunar infarct developed at right anterior thalamus post-operatively, which had resulted probably from the occlusion of a fine posterior communicating arterial perforator. Aneurysms of the posterior communicating artery itself are saccular or fusiform. Great cares should be taken in surgical aneurysmal neck clipping to avoid any injury of the perforators and the oculomotor nerve;trapping of the posterior communicating artery to treat fusiform or wide-necked aneurysms will result in unpredictable outcomes.