Anomalies, Aneurysm and Histology of the Middle Cerebral Artery in Nigerian Africans.

The histology of the middle cerebral artery (MCA) in Nigerian Africans has not been previously studied. One hundred MCAs obtained at autopsy from fifty adult Nigerians were studied. The vessels were processed and stained with Ehrlich's haematoxylin and eosin, elastic Van Gieson and Masson's trichrome stains. Early branches were given off before the perforators in two middle cerebral arteries, and there was one accessory MCA, making an incidence of anomalies of 3%. No aneurysm was observed in any of the cases. The internal elastic laminas were well developed but the external elastic laminas of the vessels were poorly developed. Close to the bifurcations the tunica media tapered gradually and at the bifurcations, the tunica media was completely deficient being replaced by the tunica adventitia (Forbus raphe). The tunica adventitia was thicker at the bifurcations (0.21mm) compared to other sites of the vessel. The average thickness of the MCA tunica media at its origin was 0.12mm while that of the tunica adventitia was 0.10mm. These results are similar to what has been described in the literature for Caucasians. It buttresses the assertion that anatomical anomalies of the MCA are rare. The seemingly low frequency of MCA aneurysms in Nigerian Africans is not due to its anomalies or histology. [ABSTRACT FROM AUTHOR]