Aneurysm developing on the infundibular widening of the posterior communicating artery

A patient had a subarachnoid hemorrhage in 1969. Four-vessel angiography demonstrated an infundibular widening of the posterior communicating artery alone. In 1978, nine years later, angiography demonstrated that the infundibular widening had enlarged and developed into an aneurysm, though unruptured. Another aneurysm of the anterior communicating artery was also found. Both were confirmed at operation and clipped. Review of the pertinent literature emphasizes that the infundibular widening may be preaneurysmal.