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. 2009 Jun;46(2):353-9.
doi: 10.1016/j.neuroimage.2009.02.020. Epub 2009 Feb 26.

Widespread neocortical abnormalities in temporal lobe epilepsy with and without mesial sclerosis

S G Mueller  1 , K D Laxer, J Barakos, I Cheong, P Garcia, M W Weiner
Affiliations

Widespread neocortical abnormalities in temporal lobe epilepsy with and without mesial sclerosis

S G Mueller et al. Neuroimage. 2009 Jun.

Abstract

Purpose: Extrafocal structural abnormalities have been consistently described in temporal lobe epilepsy (TLE) with mesial temporal lobe sclerosis (TLE-MTS). In TLE without MTS (TLE-no) extrafocal abnormalities are more subtle and often require region of interest analyses for their detection. Cortical thickness measurements might be better suited to detect such subtle abnormalities than conventional whole brain volumetric techniques which are often negative in TLE-no. The aim of this study was to seek and characterize patterns of cortical thinning in TLE-MTS and TLE-no.

Methods: T1 weighted whole brain images were acquired on a 4 T magnet in 66 subjects (35 controls, 15 TLE-MTS, 16 TLE-no). Cortical thickness measurements were obtained using the FreeSurfer software routine. Group comparisons and correlation analyses were done using the statistical routine of FreeSurfer (FDR, p=0.05).

Results: TLE-MTS and TLE-no showed both widespread temporal and extratemporal cortical thinning. In TLE-MTS, the inferior medial and posterior temporal regions were most prominently affected while lateral temporal and opercular regions were more affected in TLE-no. The correlation analysis showed a significant correlation between the ipsilateral hippocampal volume and regions of thinning in TLE-MTS and between inferior temporal cortical thickness and thinning in extratemporal cortical regions in TLE-no.

Conclusion: The pattern of thinning in TLE-no was different from the pattern in TLE-MTS. This finding suggests that different epileptogenic networks could be involved in TLE-MTS and TLE and further supports the hypothesis that TLE-MTS and TLE-no might represent two distinct TLE syndromes.

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Figures

Figure 1
Figure 1
Regional labeling of neocortical structures as provided by Freesurfer (Desikan et. al, 2006). Medial and lateral view of A. Normal brain. B. Inflated brain. The region labeled as inferior temporal gyrus which was used for the correlation analyses is indicated by *.
Figure 2
Figure 2
A. Regions with significant neocortical thinning in TLE-MTS compared to age matched controls. Please see text for details. B. Regions with significant neocortical thinning in TLE-no compared to age matched controls. C. Regions with significant thinning in TLE-MTS compared to TLE-no (blue) and significant thinning in TLE-no compared to TLE-MTS (red).
Figure 3
Figure 3
a. Regions with significant positive correlations between ipsilateral hippocampal volume and ipsilateral cortical thickness in TLE-MTS and controls. b, Regions with significant positive correlations between ipsilateral mean inferior temporal gyral thickness and cortical thickness beyond the temporal lobe. Regions with the most significant correlations show a good concordance with regions with maximal cortical thinning in the direct comparisons TLE-MTS with controls (Figure 2a) and TLE-no with controls (Figure 2 b).
See this image and copyright information in PMC

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