Ventricular enlargement in pediatric TBI is a common observation in clinical practice, yet volumetric studies of ventricle volume are sparse. In this study, MRIs and neuropsychological testing were performed on children who had sustained a traumatic brain injury (n=38) and control children (n=34) between the ages of six and eighteen years. Children with traumatic brain injury (mean GCS=9.0) were evaluated at two time points (time one: mean=55 days post injury, n=38; time two: mean=324 days post injury, n=21). Results revealed that ventricular enlargement and deficits in cognitive function were present in the TBI group during both the semi-acute (\u3c6 months post injury) and chronic (\u3e6 months post injury) phases of injury (as compared to typically developing controls). Furthermore, ventricular enlargement and cognitive function during the semi-acute phase of injury were correlated with initial injury severity (as measured by the Glasgow Coma Scale). Additionally, lateral ventricle volume and third ventricle volume were correlated with the executive composite during the semi-acute phase of injury. During the chronic phase of injury, only third ventricle volume (not lateral ventricle volume) was significantly correlated with the executive and memory composites. Examination of the longitudinal data revealed that third ventricle volume significantly decreased between times one and two, while cognitive function significantly improved. Finally, results of regression analyses revealed that third ventricle enlargement at time one was the best predictor of cognitive function at time two. Our results reiterate the importance of longitudinal designs in pediatric TBI and indicate the utility of third ventricle volume in the semi-acute phase of injury as a predictor of neuropsychological function
