[A case of posterior communicating artery aneurysm associated with vascular anomaly of circle of Willis].

The patient, 68 year-old, male, was admitted to our clinic with episode of the second attack of subarachnoid hemorrhage in October, 1979. The cerebral angiogram demonstrated an aneurysm arising from the junction of posterior communicating artery and aberrant origin of the anterior choroidal artery. Additionally, bilateral posterior cerebral arteries were filled only through the anterior circulation via the posterior communicating artery. The patient was successfully operated with clipping of the aneurysm through the pterional approach. The aneurysm arising from the posterior communicating artery itself is exceedingly rare. Incidence, symptom and operative approach were discussed with the review of the literature.