An optimized voxel-based morphometric study of gray matter changes in patients with left-sided and right-sided mesial temporal lobe epilepsy and hippocampal sclerosis (MTLE/HS).
OBJECTIVE
To determine whether changes in gray matter volume (GMV) differ according to the affected side in mesial temporal lobe epilepsy/hippocampal sclerosis (MTLE/HS) syndrome, and moreover to test the hypothesis of more pronounced structural changes in right-sided MTLE/HS. This hypothesis (especially that the contralateral thalamus is more affected in right-sided MTLE/HS) arose from the results of our recent study, wherein more expressed structural and functional changes were observed in a small sample of patients with right-sided MTLE/HS (Brázdil et al., 2009).


METHODS
Twenty patients with left-sided and 20 with right-sided MTLE/HS and 40 sex- and age-matched healthy controls were included in the study. Voxel-based morphometry (VBM) with a modulation step was applied to magnetic resonance imaging (MRI) brain images. Statistical parametric maps were used to compare structural changes between patients and controls separately for the left- and right-sided MTLE/HS subgroups. We also compared the local GMV of the brain structures (insula and thalamus) between the subgroups of patients.


RESULTS
In the subgroup with right-sided MTLE/HS, a reduction of GMV was detected in the mesiotemporal structures and the ipsilateral thalamus (as in left-sided MTLE/HS), but also notably in the ipsilateral insula and contralateral thalamus. A statistical analysis revealed a significantly more extensive reduction of GMV in the ipsilateral/contralateral insula and the contralateral thalamus in the subgroup with right-sided compared to left-sided MTLE/HS.


CONCLUSIONS
We found asymmetrical morphologic changes in patients with left- and right-sided MTLE/HS syndrome (more pronounced in right-sided MTLE/HS). These differences could be theoretically explained by different neuronal networks and pathophysiologic changes in temporolimbic structures.
Pail
Martin
M
Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University Brno, Brno, Czech Republic. m.pail@seznam.cz
Brázdil
Milan
M
Marecek
Radek
R
Mikl
Michal
M
D000328:Adult; D000679:Amygdala / Q000473:pathology; D001284:Atrophy; D001931:Brain Mapping / Q000379:methods; D001933:Brain Stem / Q000473:pathology; D004292:Dominance, Cerebral / Q000502:physiology*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009929:Organ Size / Q000502:physiology; D020534:Parahippocampal Gyrus / Q000473:pathology; D012016:Reference Values; D012598:Sclerosis; D013702:Temporal Lobe / Q000473:pathology*; D013788:Thalamus / Q000473:pathology; D055815:Young Adult