Vertebrobasilar variants and their basic clinical implications

Cerebrovascular diseases are the leading illness affecting the modern world with a high mortality rate. The posterior circulation of the brain consists of vertebrobasilar system, shows a high incidence of anomalies in the form of hypoplasia, fenestrations and asymmetry of the vessels, which precipitate the development of vertebrobasilar insufficiency and posterior circulation stroke. A detailed knowledge of the vertebrobasilar variants is essential in the diagnosis, treatment as well as in educating the patients suffered from posterior circulation stroke. The present study is aimed to analyze the size, asymmetry and anomalies of the vertebrobasilar system and their implications in posterior circulation infarcts. Fifty adult brains were studied during routine dissection of the cadavers. The base of the brain with intact vertebral, basilar and posterior cerebral arteries were dissected, preserved in 10% formalin and analyzed for the variations in the size, length and asymmetry in the configuration. The dimensions of the vessels were measured using graduated calipers. Anomalies of the basilar artery were found in 14% of the brains, in the form of hypoplasia, fenestration and terminal expansion at its bifurcation. The vertebral arteries showed asymmetry with right vertebral were hypoplastic in majority of the brains. The variations of the vertebrobasilar system increase the risk of vertebrobasilar insufficiency and posterior circulation stroke. Anomalies of the vertebrobasilar arteries were also found to be associated with aneurysms. The right vertebral artery has been frequently hypoplastic and there was no consistent correlation between the left vertebral dominance and right handedness of the person. Hypoplastic vessels were frequently associated with vertebrobasilar territory ischemic stroke.