EVALUATION OF NORMAL VALUES OF EVANS INDEX IN SOUTH KERALA POPULATION USING COMPUTERIZED TOMOGRAPHY OF BRAIN

Introduction In the adult human brain, there are four connected ventricles - two lateral ventricles within the cerebrum, a midline third ventricle between the right and left thalami, and a midline fourth ventricle lying between the cerebellum posteriorly and the pons and medulla anteriorly1. Evans index is the ratio of the maximum width of the anterior horn of the lateral ventricle to the maximum transverse diameter of the inner table of the skull. A clear understanding of the normal values of Evans index and variations of the ventricular system of brain is useful for clinicians, radiologists and neurosurgeons in their daily clinical practice2. To determine Aims And Objectives the normal values of Evans index using Computerized tomography of brain in South Kerala population. The study was conducted in indi Materials And Methods viduals who attended the Department of Radiodiagnosis in Government Medical College, Thiruvananthapuram. Those patients whose brain CT scans were read as normal by the radiologist were taken up for the study, during the period from January 2019 to June 2020. A total of 200 CT brain of individuals above 10 years of age were taken.100 males and 100 females were included in the study group. Results The mean Evans index in the study was found to be 0.258±0.05 in males, 0.255±0.03 in females and an overall mean of 0.256±0.04 was calculated. Conclusion The present study shows that Evans index was more in individuals who were above 60 years in both males and females. Knowledge of Evans index will help in the diagnosis of idiopathic normal pressure hydrocephalus and in the assessment of outcome of patients with ventriculoperitoneal shunt placement.