[A case of a basilar bifurcation aneurysm associated with common carotid artery occlusion].

A case of a basilar bifurcation aneurysm associated with common carotid artery occlusion is reported. A 40-year-old woman was admitted to our hospital with severe headache and nausea. On admission, no neurological abnormality was observed. CT scan showed thin subarachnoid hemorrhage in the basal cistern. Left vertebral angiograms revealed a basilar bifurcation aneurysm located in the high position. Also, the left internal and external carotid arteries were supplied through the anastomotic muscle branches of the left occipital and vertebral artery. The trunk of the left common carotid artery was not visualised from its origin on the aortogram. CT scan at the level of C6 showed thinning of the left common carotid artery and contrast enhancement study indicated occlusion. Neck clipping of the aneurysm was successfully performed by right trans-sylvian approach. Right zygomatic arch was removed to obtain a wider operative field for avoiding further retraction of the brain tissue. The postoperative course was uneventful except transient disorientation for two weeks. It has been well known that internal carotid artery occlusion may be associated with cerebral aneurysm in some cases. However, it seemed to be a rather rare case that the common carotid artery occlusion due to arteriosclerosis was associated with cerebral aneurysm. Hemodynamic factor was positively suggested for aneurysmal formation in this case.