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Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
White matter abnormalities differentiate severe from benign temporal lobe epilepsy
Angelo Labate1,2, Andrea Cherubini2, Giovanni Tripepi3
1Institute of Neurology, University Magna Graecia, Catanzaro, Italy.
Objective:
Temporal and extratemporal white matter abnormalities have been identified frequently in patients with refractory mesial temporal lobe epilepsy (rMTLE). However, the identification of potential water diffusion abnormalities in patients with drug-responsive, benign MTLE (bMTLE) is still missing. The aim of this study was to identify markers of refractoriness in MTLE.
Methods:
The study group included 48 patients with bMTLE (mean age 42.8 + 13.5 years), 38 with rMTLE (mean age 41.7 + 14.1 years) and 54 healthy volunteers. Diffusion tensor imaging (DTI) was performed to measure mean diffusivity (MD) and fractional anisotropy (FA) in a regions-of-interest analysis comprising hippocampi and temporal lobe gray and white matter regions. The presence of hippocampal sclerosis (Hs) was assessed using automated magnetic resonance imaging (MRI) evaluation. For statistics we used chi-square test; two-tailed, two-sample t-test; and stratified linear regression.
Results:
The significant demographic differences between the two patient groups were sex (p = 0.003), duration of epilepsy (p = 0.003) and complex febrile convulsions (p = 0.0001). In rMTLE, temporal white matter MD was higher and FA lower, as compared to bMTLE. The analysis of diagnostic accuracy (area under the receiver operator characteristic [ROC] curve [AUC]) showed that FA had an AUC for discriminating patients affected from those unaffected by refractory MTLE of 74.0% (p < 0.001), a value that was higher than that of temporal MD (64.0%), hippocampus volume (65.0%), and Hs (66.0%).
Significance:
We performed DTI measurements in MTLE and found a significant reduction of FA along the white matter of the temporal lobes in rMTLE, suggesting it as a valuable measure of refractoriness in MTLE.
Insights
Diffusion tensor imaging reveals reduced fractional anisotropy (FA) in the temporal white matter of patients with refractory mesial temporal lobe epilepsy (rMTLE). This finding suggests FA is a valuable marker for identifying epilepsy refractoriness.
Area of Science:
- Neuroimaging
- Epilepsy research
- White matter integrity
Background:
- Mesial temporal lobe epilepsy (MTLE) can be refractory to treatment.
- White matter abnormalities are common in refractory MTLE (rMTLE).
- Diffusion abnormalities in drug-responsive MTLE (bMTLE) are not well understood.
Purpose of the Study:
- To identify markers of refractoriness in MTLE.
- To investigate diffusion abnormalities in drug-responsive MTLE (bMTLE) compared to refractory MTLE (rMTLE).
Main Methods:
- Diffusion tensor imaging (DTI) was used to measure mean diffusivity (MD) and fractional anisotropy (FA).
- Regions of interest included hippocampi and temporal lobe gray and white matter.
- Automated MRI evaluated hippocampal sclerosis (Hs); statistical analyses included t-tests and regression.
Main Results:
- Refractory MTLE (rMTLE) showed higher temporal white matter MD and lower FA compared to benign MTLE (bMTLE).
- Fractional anisotropy (FA) demonstrated high diagnostic accuracy (74.0% AUC) in distinguishing refractory MTLE.
- FA outperformed temporal MD, hippocampus volume, and hippocampal sclerosis (Hs) in discriminating refractory cases.
Conclusions:
- Diffusion tensor imaging (DTI) measurements revealed significantly reduced FA in the temporal white matter of rMTLE patients.
- Reduced FA in temporal white matter is a potential imaging biomarker for MTLE refractoriness.
- This finding aids in differentiating refractory epilepsy cases.
