Reduction of frontal neocortical grey matter associated with affective aggression in patients with temporal lobe epilepsy: an objective voxel by voxel analysis of automatically segmented MRI

Background-Interictal episodes of aggression are often reported in patients with epilepsy. Some have characteristics of what has been referred to as e pisodic dyscontrol or intermittent explosive disorder (IED). Although struc tural brain abnormalities are thought to play a part in the pathophysiology of aggression, there are few in vivo studies of structural cerebral change s in patients with epilepsy and aggression. Using quantitative MRI, subtle structural brain abnormalities can be investigated in subgroups of patients with both epilepsy and episodes of affective aggression. Methods-After automated segmentation of cerebral grey matter from T1 weight ed MRI, the objective technique of statistical parametric mapping (SPM) was applied to the analysis of 35 control subjects, 24 patients with temporal lobe epilepsy (TLE) with a history of repeated, interictal episodes of aggr ession, and 24 patients with TLE without episodes of aggression. Both TLE p atient groups were compared with each other and with the control subjects o n a voxel by voxel basis for increases and decreases of grey matter. Results-The patients with TLE with aggressive episodes had a decrease of gr ey matter, most markedly in the left frontal lobe, compared with the contro l group and with patients with TLE without aggressive episodes. Conclusion-These findings suggest that a reduction of frontal neocortical g rey matter might underly the pathophysiology of aggression in TLE. These vo xel by voxel comparisons can guide further in vivo studies into aggression.