Hippocampal MR Volumetric Studies in Paediatric Patients with Epilepsy and Normal Controls

The aim of this study was to determine and compare the hippocampal volume in children with epilepsy and in children in a control group and to compare the mean of right and left hippocampal volume in control subjects. This study was carried out at University Sains Malaysia (USM) from January 2008 to June 2009. This is a cross sectional study of 40 children with epilepsy and 40 children in a control volunteer group. Serial MRI of brain and temporal lobe were performed using a Signa Horizon LX 1.0 Tesla system. Oblique coronal sections perpendicular to the axis of temporal lobe were done with 4 mm slice thickness and 1 mm gap. T1, T2, FLAIR and SPGR series were done. The whole hippocampal volume was measured. Volumetry was done manually by using Osirix workstation (v 3.5.1-64 bit). All slices were measured three times and the average volume was taken. Data were analyzed by paired t test and independent t test for univariate data. The mean hippocampal volume in the control group was 2.81 cm(3) (SD=0.38) and 2.65 cm(3) (SD=0.41) for right and left hippocampus respectively. The mean hippocampal volume in epilepsy patients was 2.47 cm(3) (SD=0.52) and 2.39 cm(3) (SD=0.44) for right and left respectively. The hippocampal volume in epileptic children was significantly smaller than normal control children in average volume (p=0.001) and both right (p=0.002) and left (p=0.007) individually. In the control group, the right hippocampus volume was much greater than the left (p<0.001). The data of this study provide a useful reference for the study of hippocampal volume in the Malay paediatric population. It is useful in doubtful cases to determine which side is affected and also serves as part of the study to establish the whole age-related hippocampal growth.