The determination and comparison of the vascular configurations of the posterior cerebral and posterior communicating arteries by two different techniques.

Abstract Although configurations of the posterior cerebral artery (PCA) and posterior communicating artery (PComA) have been extensively studied, reported rates of adult (AC), fetal (FC) and transitional configurations (TC) vary widely due to techniques used. A histological technique was applied to measure the circumference of the arteries and this was compared with caliper measurements taken from the same arteries. Ninetyfive brains were examined. The external diameters of all precommunicating, postcommunicating PCAs and PComAs were measured under operating microscope with a micrometer caliper. After measurements, all arteries were prepared for histology, sections were stained with Verhoff's elastic technique and the circumferences were measured using the light microscope. In the caliper group, AC was found in 77.2%, FC was found in 17.3% and TC was found in 5.5% of the right hemispheres, while on the left AC was found in 81.7%, FC in 18.3% and no TC was found. In the histology group, AC was found in 78.3% and FC was found in 21.7% of the right, while on the left AC was found in 81.7% and FC was found in 18.3% of cases. No TC was found in any hemisphere. There was no statistical significance between the two groups. Results of the present study reveal several important findings. When the PComA was absent in one hemisphere, the PComA was FC on the contralateral hemisphere. Transitional configuration was found in a very small number of cases in the caliper group compared to previous studies, and no TC was found in the histology group.