Valproate treatment normalizes EEG functional connectivity in successfully treated idiopathic generalized epilepsy patients

Aim: To investigate the effect of chronic VPA treatment of EEG functional connectivity insuccessfully treated idiopathic generalized epilepsy (IGE) patients.Patients and methods: 19-channel waking, resting-state EEG records of 26 IGE patients wereanalyzed before treatment (IGE) and after the 90th day of treatment (VPA), in seizure-free condition.Three minutes of artifact-free EEG background activity (without epileptiform potentials)was analyzed for each patient in both conditions. A group of 26 age-matched healthy normativecontrol persons (NC) was analyzed in the same way. All the EEG samples were processed toLORETA (Low Resolution Electromagnetic Tomography) to localize multiple distributed sourcesof EEG activity. Current source density time series were generated for 33 regions of interest(ROI)in each hemisphere for four frequency bands. Pearson correlation coefficients (R) were computedbetween all ROIs in each hemisphere, for four bands across the investigated samples. Rvalues corresponded to intrahemispheric, cortico-cortical functional EEG connectivity (EEGfC).Group and condition differences were analyzed by statistical parametric network method.Main results: p < 0.05, corrected for multiple comparisons: (1) The untreated IGE group showedincreased EEGfC in the delta and theta bands, and decreased EEGfC in the alpha band (as comparedto the NC group); (2) VPA treatment normalized EEGfC in the delta, theta and alpha bands;and (3) degree of normalization depended on frequency band and cortical region.Conclusions: VPA treatment normalizes EEGfC in IGE patients