Infundibular dilatation of the posterior communicating artery in a defined population.

Unusual widening of the posterior communicating artery (PCoA) at its beginning from the cerebral portion of the internal carotid artery (ICA) was described as its infundibular dilatation (ID). A possibility of ID rupture or progression to aneurysm was the reason for an investigation of its frequency and morphologic features in specimens of the Serbian population. Cerebral arteries on the brain base of 267 adult cadavers of both genders and varying age and causes of death were dissected. The images of the PCoA in 190 fetuses were also reviewed. ID of the PCoA was defined as a funnel shaped beginning of different width from ICA, wherein PCoA continues from ID apex to the posterior cerebral artery. There were no cases of ID in fetuses. ID and aneurysms of the PCoA were found in 6/267 or 2.2% and 3/267 or 1.12% of adults, respectively. Unilaterally, they existed on the left side and, frequently, in male cases aging 70 years and older, that had died without cerebral cause. Bilaterally, ID was found in 2/6 cases. There was only one case of ID and aneurysm of the PCoA, but from the ID. We are of the opinion that ID of the PCoA only develops postnatally and probably is due to the influence of hemodynamic factors or hypertension.