Abstracts

Rationale: In refractory temporal lobe epilepsy (rTLE) gray (GM) and white (WM) matter abnormalities are not confined to the hippocampus but also are found in extrahippocampal structures. Less is known about mild TLE (mTLE). In this study, we used optimized voxel-based morphometry (VBM) to identify GM abnormalities beyond the hippocampus in rTLE and in mTLE with evidence of hippocampal sclerosis (HS). Methods: Brain MRI and VBM of GM with modulation was performed in 30 unrelated patients with mTLE (56% women; mean age 35.6 + 15.2 years), 19 patients with rTLE (52% women; mean age 38.4 + 17.4 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 (rTLE and mTLE) did not have any generalised tonic-clonic seizures for at least three weeks before the scanning. Respectively, mTLE patients showed GM volume reduction of the bilateral thalamus and left hippocampus (FWE < 0.05) whereas rTLE in the thalamus bilaterally (FWE < 0.05) when compared with controls. Conversely, no differences of GM concentrations were found between rTLE and mTLE. Conclusions: In either rTLE and mTLE, VBM shows GM reductions not confined to the hippocampus but mainly in the thalamus bilaterally. Moreover, no GM differences were found between the two groups. This supports the hypothesis that mTLE and rTLE might lie along a biological continuum.