Structural changes of the cerebral gray matter in patients with temporal lobe epilepsy

The formation of an epileptogenic network is considered to be the primary cause of resistance to surgical treatment of temporal lobe epilepsy (TLE). Modern magnetic resonance imaging (MRI) post-processing techniques enable a detailed investigation of the microstructural changes underlying this network. Objective: to assess changes in grey matter volume using voxel-based morphometry in the temporal and extratemporal regions in patients with structural and MRI-negative TLE. Material and methods. The study included 40 patients with TLE and 30 healthy individuals. All patients underwent brain MRI on a 3 T scanner, followed by analysis using voxel-based morphometry (SPM12, CAT12). Results. Prior to correction for multiple comparisons, a reduction in grey matter volume was observed in 16 cortical regions in patients with TLE. Following application of the Benjamini–Hochberg false discovery rate (FDR) procedure, the following findings remained statistically significant: an ipsilateral reduction in the volume of the supramarginal gyrus in TLE with left-sided discharges; a reduction in all hippocampal subregions studied (CA1–CA4 fields, subiculum, alveus, fimbria) in cases of hippocampal sclerosis; and a negative correlation between age and pallidum volume. Additional voxel-based analysis showed that the most significant reduction in grey matter volume was associated with hippocampal sclerosis. Conclusion. The results obtained indicate that structural changes in the brain’s grey matter in TLE vary depending on the subtype of the condition and the lateralization of the pathological focus, and also justify the need for a combined analytical strategy, comprising region-of-interest analysis and voxel-based analysis, with mandatory correction for multiple comparisons to minimize false-positive results.