Extra-hippocampal grey matter density abnormalities in paediatric mesial temporal sclerosis.

The aim of this study was to identify grey matter density abnormalities in children with temporal lobe epilepsy and mesial temporal sclerosis. Magnetic resonance T1 weighted 3D datasets were obtained in children with temporal lobe epilepsy (20 left and 10 right sided, mean age 11.9 years, range 6.6-17.5) and compared to scans obtained from age-matched controls (n = 22, mean age 12.8 years, range 7.1-17.5) using voxel-based morphometry. This method detected reduced grey matter ipsilateral to the seizure focus not only in the hippocampus, but also in the lateral temporal lobe and in extra-temporal regions including the thalamus, posterior cingulate cortex and cerebellum. Bilateral differences were present in the frontal and parietal opercular cortices and lateral temporal regions. These grey matter density reductions broadly reflect the pattern of hippocampal connections and may be caused by the disruption of cortical development by the recurrent seizures, as well as by loss of functional input from the sclerotic hippocampus.