Hippocampal and thalamic atrophy in temporal lobe epilepsy (TLE): A VBM study

Rationale:We recently described that MRI-detected mesial temporal sclerosis (MTS) is often encountered in patients with TLE (1). We used voxel based morphometry (VBM) based on high resolution T1-weighted MRI to compare grey matter volume (GM) between patients with TLE with MTS (pTLE) and patients without MTS (nTLE) (2,3).We aimed to confirm the visual detection ofMTSin our population and to identifyGM abnormalities temporal or extratemporal abnormalities differ between the two groups Methods: Brain MRI and optimized VBM of GM with modulation was performed in 33 unrelated patients with pTLE (19 women; mean age 36.3 + 15.2 years), 61 patients with nTLE (32 women; mean age 36.7 + 16.0 years) and 37 healthy controls (25 women, mean age 37.3 + 10.6 years). MRI diagnosis of MTS was based on the atrophy of the hippocampal formation and/or mesial temporal hyperintensity on FLAIR or T2 images, or both. Results: All patients had been seizure free for week before the scanning. As showed in figure 1, pTLE patients showed grey matter volume reduction of the bilateral thalamus and left hippocampus when compared to controls (p < 0.001 corrected for multiple comparisons), simple regression analysis did not reveal any significant co-variation. In nTLE there was only a trend towards bilateral thalamic GM loss, nevertheless high significant correlations have been found between GM volume and age, age at onset and disease duration variables (Figure 1). Conclusions: This finding suggests that in pTLE patients secondary brainGMreductions exist in regions outside the presumed epileptogenic focus suggesting a phatophisiological role of the thalamus in partial epilepsy.