Fetal Type Posterior Cerebral Artery in the Tribal and Nontribal Populations of Assam

Background: Fetal type posterior cerebral artery (FTP) is a variant of the circle of Willis in which the distal posterior cerebral artery is perfused by a branch of internal carotid artery. Objectives: Estimation of different types of posterior cerebral artery configurations in the tribal, nontribal and total populations of Assam. Subjects and Methods: The circle of Willis of 109 human brains belonging to both tribal and nontribal populations of Assam were dissected and observed under the dissecting microscope. External diameters of both sided precommunicating and postcommunicating segments of posterior cerebral arteries close to their origins and that of the posterior communicating artery at the midpoint were measured using Vernier calipers. The circle of Willis was classified as having adult configuration, transitional configuration, and fetal or embryonic configuration using the specific criteria. Results and Observations: Right transitional configuration was observed in 10.53% tribals, 6.67% nontribals, and 7.34% of total population. Left transitional configuration was observed in 5.56% nontribals and 4.59% of otal population. Right fetal configuration was observed in 10.53% tribals, 21.11% nontribals, and 19.27% of total population. Left fetal configuration was observed in 10.53% tribals, 15.56% nontribals, and 14.68% of total population. Bilateral fetal configuration was observed in 3.3% nontribals and 2.75% of total population. Conclusion: A study of this nature is potentially useful to vascular surgeons, neurosurgeons performing surgeries in the tribal and nontribal populations of Assam.