How common is brain atrophy in patients with medial temporal lobe epilepsy?
OBJECTIVE
It is unclear whether extrahippocampal brain damage in patients with medial temporal lobe epilepsy (MTLE) is a homogeneous phenomenon, as most data relates to the average volume reduction in groups of patients. This study aimed to evaluate where and how much atrophy is to be expected in an individual patient with MTLE.


METHODS
High-resolution T(1) magnetic resonance imaging (MRI) was obtained from 23 consecutive patients with unilateral MTLE and from a matched control group. Parametric tests of voxel-based gray matter volume evaluated mean regional atrophy in MTLE compared with controls. Gray matter images were then submitted to a voxel by voxel calculation of the fitted receiver operating characteristic (ROC) curve area, plotting the sensitivity versus 1-specificity for a binary classifier (MTLE vs. controls). The area under the curve (AUC) was calculated for each voxel and a resulting three-dimensional map of gray matter voxel-wise AUCs was obtained.


RESULTS
On average, patients with MTLE showed atrophy in the ipsilateral hippocampus and on a limbic network. Elevated AUC was demonstrated in the ipsilateral hippocampus and medial temporal lobe, the ipsilateral thalamus and occipitotemporal cortex, the ipsilateral cerebellum, the cingulate, the contralateral insula, and the occipitoparietal and dorsolateral prefrontal cortex.


CONCLUSIONS
This study suggests that the medial temporal lobe, occipitotemporal areas, the cerebellum, the cingulate cortex, the ipsilateral insula, and thalamus are more likely to be atrophied in randomly selected patients with MTLE. Structures such as the orbitofrontal cortex, the contralateral medial temporal areas and insula, the putamen, and the caudate may be atrophied, but not as consistently.
Bonilha
Leonardo
L
Division of Neurology, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA. bonilha@musc.edu
Elm
Jordan J
JJ
Edwards
Jonathan C
JC
Morgan
Paul S
PS
Hicks
Christian
C
Lozar
Carl
C
Rumboldt
Zoran
Z
Roberts
Donna R
DR
Rorden
Chris
C
Eckert
Mark A
MA
D000328:Adult; D001284:Atrophy / Q000473:pathology; D001921:Brain / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013702:Temporal Lobe / Q000473:pathology; D013788:Thalamus / Q000473:pathology