PREVALENCE OF ANATOMICAL VARIATIONS OF CIRCLE OF WILLIS IN SOUTH INDIAN POPULATION SUCCUMBING TO ISOLATED TRAUMATIC BRAIN INJURY - A CADAVERIC STUDY

Introduction: The Circle of Willis (COW) is a large arterial anastomotic ring present at the basal cistern of the brain, uniting the internal carotid and the vertebro-basilar system. Sir Thomas Willis was the first to describe the importance of the circle in maintaining collateral flow. It was observed that there is very little mixing of blood between the collateral branches of the circle. These collaterals may however open up during occlusive episodes of the proximal feeding vessels or in case of severe stress such as stroke and traumatic brain injury (TBI) in order to maintain metabolic activity in the brain. This phenomenon is affected to various degrees in the presence of anomalies. The prevalence of anomalies of COW in the general population is up to 75.72% was demonstrated in other studies. Materials and Methodology: This is a cross sectional observational study. 20 consecutive patients above 18 years of age succumbed to isolated TBI who were subjected to medico-legal autopsy in our hospital were included. The anomalies were classified as per the criteria laid down by Stojanovi´c et al. Results: 9 Normal variants (Type A) of COW (45%) was found. The most common type of anomaly was Type C which was noted in 4 cases (20%). Conclusion: Anatomical variations of COW has proven association in the areas of stroke, aneurysm, migraine, carotid endarterectomy and ageing brains. Further studies are needed to determine whether the anomalies of COW really contribute to the mortality in TBI.