Volume of focal brain lesions and hippocampal formation in relation to memory function after closed head injury in children

Objectives-(1) A study of verbal learning and memory in children who had su stained a closed head injury (CHI) at least 3 months earlier. (2) To relate memory function to focal brain lesion and hippocampal formation volumes us ing morphometric analysis of MRI. Methods-A group of 245 children who had been admitted to hospital for CHI g raded by the Glasgow coma scale (GCS), including 161 patients with severe a nd 84 with mild CHI completed the California verbal learning test (CVLT) an d underwent MRI which was analysed for focal brain lesion volume independen tly of memory test data. Brain MRI with 1.5 mm coronal slices obtained in s ubsets of 25 patients with severe and 25 patients with mild CHI were analys ed for hippocampal formation volume. Interoperator reliability in morphomet ry was satisfactory. Results-Severity of CHI and age at study significantly affected memory perf ormance. Regression analysis showed that bifrontal, left frontal, and right frontal lesion volumes incremented prediction of various learning and memo ry indices after entering the GCS score and age into the model. Extrafronta l lesion volume did not contribute to predicting memory performance. Conclusions-Prefrontal lesions contribute to residual impairment of learnin g and memory after severe CHI in children. Although effects of CHI on hippo campal formation volume might be difficult to demonstrate in non-fatal paed iatric CHI, further investigation using functional brain imaging could pote ntially demonstrate hippocampal dysfunction.