Variations and anomalies of the posterior communicating artery in Northwest Indian brains.

Abstract Background The PCoA is a major branch of the supraclinoid internal carotid artery. Thorough knowledge of the anatomy and awareness of the variations and anomalies are of clinical importance. Methods The PCoA was studied in 200 male and 80 female adults and in 20 male and 25 female children. These were medicolegal cases that died of an accident or poisoning after staying in a hospital for a few days. In addition to autopsy specimens, PCoA was also examined in 45 fetuses obtained from the department of obstetrics and gynecology of this institute. Results In fetal brains, at 61 to 70 mm CR stage, the average diameter of PCoA was more than that of the proximal part of the PCA; at 91 to 100 mm CR stage, the diameters of both vessels were equal and remained so until 130 mm CR stage; thereafter, the diameter of the proximal part of PCA became larger than PCoA. Incidence of tortuosity was more on the left than on the right side in children, and the reverse was the case in adults. Tortuosity was not found in fetal brains. The incidence of hypoplasticity and absence of PCoA in children and adults in both sexes were noted. The embryonic type (where the diameter of PCoA is more than the diameter of proximal part of PCA) was observed in 3 children and 20 adults. The incidence of aneurysms involving PCoA was 0.92% in adults. They were not seen in fetuses, newborns, and children. Conclusions Because of hemodynamic factors in fetuses of more than 130 mm CR stage, the diameter of PCA becomes larger than that of the PCoA. An aneurysm was seen in only 1 male adult (0.5%), other anomalies present were absence, hypoplasticity, and duplication of PCoA. Present observations were different from the findings of 2 groups of the Indian workers ( J Neurosurg 1984;60:572-576; J Anat Soc India 1970;19:71-79). Case history of the patients with anomalies of PCoA did not show any mental aberration.