Variations of Circle of Willis in Indian Population

Variations of Circle of Willis

Abstract

Background: Circle of Willis(CoW) provides the crucial anastomotic vascular supply to brain, Variations of Circle of Willis are associated with high incidence of Cerebrovascular accidents. Scant data exists in Indian context on the CoW variations prevalent. Aims: To find the frequency of variations of  CoW in Indian population and review literature on stroke epidemiology. Settings and Design: Prospective observational study in a tertiary care hospital. Subjects and Methods: A study was undertaken between January  2017 and February  2018. Apparently healthy individuals underwent 3 dimensional Time of Flight MR angiography (3D TOF MRA) imaging of circle of Willis.  Anatomy of circle of Willis was evaluated on the  Image  volume dataset and MIP reformations. Percentage of variations of CoW was calculated and compared with the existing data. Review of literature on epidemiology and pathophysiology of stroke in India was done. Statistical analysis used: Percentage of variations of CoW calculated. Results: The study included 197 volunteers with a mean age of 33 years and 5 months, who underwent 3D TOF MRA. Complete and balanced CoW was seen in 37.1% of them. Posterior circulation variations were found in 58.3%  and anterior circulation variations in 20.3%. Hypoplastic/aplastic Posterior communicating arteries were the commonest segmental variations.  No immediate or direct correlation was found between results obtained and epidemiology of stroke in India. Conclusion: Variations are the rule in CoW and are more often seen in  posterior circulation. Increased prevalence rates of particular variations are likely to be associated with certain patterns of cerebrovascular disease.