Anatomical Variability in the Origin, Length and Termination of Basilar Artery and its Clinical Implications

Abstract

Introduction: Basilar artery is one of the frequent locations for cerebrovascular lesions like aneurysm, thrombosis and haemorrhage. Hence,an intricate knowledge of its variant anatomy is essential for diagnostic procedures like Computed Tomography (CT) brain and Magnetic Resonance (MR) angiography. An accurate interpretation of the arterial pattern will help in performing surgeries of brain stem precisely. Any misinterpretation of arterial pattern may affect the diagnosis, treatment and prognosis of the disease. Aim: To elucidate the anatomical variability in the origin, length and termination of basilar artery. Materials and Methods: This cross-sectional study was conducted from May 2019 to April 2020, on 100 human cadaveric brain specimens available in the Department of Anatomy at Government Medical College Pudukkottai, Tamil Nadu, India. The morphology of the basilar artery was studied with respect to the level of the origin, length, level and mode of termination of the basilar artery. Results: Among the 100 human cadaveric brain specimens dissected and examined (mean age of 63.4 years), the mean length of basilar arteries was 2.792±0.32 cm. In all 100 specimens, the basilar artery was formed by the union of right and left vertebral arteries. The basilar artery was found to originate at the level of pontomedullary junction in 84%, below the pontomedullary junction in 14% and above the pontomedullary junction in 2% of specimens. The termination of basilar artery was at the level of upper border of pons in 90%, below the upper border of pons in 7% and above in the interpeduncular fossa in 3% of specimens. The mode of termination was 'V’ shaped in 83%, 'T' shaped in 10%, trifurcation in 3%, quadrifurcation in 3% and pentafurcation in 1% of specimens. Fenestration of basilar artery was seen in 1%. Other variations of basilar artery like duplication were not detected. Conclusion: The level and mode of origin and termination of basilar artery are important with regard to surgical procedures in the lower basilar region. Variations in the basilar artery should be identified preoperatively so that neurosurgeons can modify the surgical approaches.