Abstracts

Rationale:
The most commonly described pathology in temporal lobe epilepsy (TLE) is hippocampal atrophy. However, there is evidence for more widespread damage in the mesial temporal lobe and the limbic network involving the amygdala, the entorhinal cortex, the fornix and the thalamus. In patients with TLE with hippocampal sclerosis (HS), analysis of diffusion tensor imaging (DTI) data provides some indirect radiologic evidence of microstructural changes. We investigated whether the volume changes in mesial TLE could be correlate with water diffusion abnormalities by means of voxel-based DTI analysis.
Method:
Subjects and Evaluation The study population included 30 patients (17 women and 13 men; mean age, 35.6 ± 9.9 years, range 15–50 years) with mTLE (left TLE/right TLE, 18:12) who were undergoing video-EEG monitoring. The identification of the epileptogenic focus was based on seizure semiology and prolonged ictal and interictal vEEG in all patients. These patients had evidence of unilateral hippocampal sclerosis (TLE-HS) based on the qualitative MRI assessment of hippocampal atrophy on T1-weighted images and a high signal on T2-weighted or FLAIR images. All patients had been seizure free for ≥24 h before the MRI. The age at onset of epilepsy is 16.9 ± 11.2 years and the duration of epilepsy is 18.2 ± 10.9 years. Image Acquisition and Data Analysis Axial T2-weighted and coronal FLAIR images were also acquired. Diffusion-weighted echoplanar images were acquired with a standard head coil for signal reception. Thirty-four slices were obtained using the following parameters: After normalization, images composed of isovoxels (2 X 2 X 2 mm) were acquired. The acquisition was ungated. Diffusion weighting was performed along 25 optimized noncollinear directions, with one excitation resulting in 884 images acquired in less than 6 min. A single b value of 1,000 s/mm2 was applied. In addition, a reference image with no diffusion weighting was also obtained (b0 image). Raw diffusion-weighted data were corrected for geometric distortion secondary to eddy currents using a registration technique based upon the geometric model of distortions. Maps of fractional anisotropy (FA) and mean diffusivity (MD) were calculated using homemade software based on MATLAB (The MathWorks, Natick, MA, U.S.A.). For voxel-based analysis, data were analyzed using SPM running on MATLAB. Results1. No Brain area showed abnormal diffsion properties correlation with regional volume reduction in right TLE patients 2. No significant region correlated between diffusion property change and the regional volume change of entorhinal cortex and fornix in left and right TLE patients. 3. Brain area showed reduced FA value correlation with decreased amygdala, hippocampal and thamamic volume in left mTLE. These area were left cingulate gyrus
Conclusion:
Our results demonstrate that water diffusion abnormalities of left cingulate gyrus is correlated with the left amygdala, hippocampal, and thalamic atrophy in the left mTLE. The present data show that volume loss in left mTLE is associated with a widespread limbic systems atrophy. These findings are helpful to better understand the functional deficit and reorganization often found in temporal lobe epilepsy and will also provide a basis to assess neural plasticity in the limbic system for those patients who will undergo curative temporal lobe surgery.
Funding:
:No related funding