EEG spectral power analysis in idiopathic generalised epilepsy

Abstract

Background and aims: A single inter-ictal electroencephalogram (EEG) has a sensitivity of around 50% for epilepsy and relies on the detection of abnormal discharges, which are not objectively defined. Examining objective differences in the background rhythm of the EEG, using methods such as Spectral Power Analysis, is of potential value to improve the diagnostic capability of EEG. Furthermore, there is currently no biomarker of drug resistance in epilepsy, which affects 20-30% of patients. Despite this, there is limited research exploring objective EEG measures in drug-resistant epilepsy. Aim is to To compare EEG spectral power in Idiopathic Generalised Epilepsy (IGE) to controls. To compare EEG spectral power in controlled IGE to drug-resistant IGE. Method(s): Participants: 16 drug resistant IGE,16 controlled IGE, 16 age and sex matched controls. Data acquisition & EEG analysis: A 3-minute, 63 channel, eyes-closed, resting state EEG was recorded. Data was preprocessed using EEGLAB software. Using SPM, time frequency analysis was carried out on 1-second epochs using a Morlet transform with 5 wavelet cycles. Data was time-averaged and converted to an image representing spectral power. Statistical analysis: ANOVA testing was conducted on 1D spectra images at 6-70Hz frequency. This was controlled for all frequencies tested using FWE <0.05. Result(s): EEG power was significantly higher in IGE compared to controls at 6Hz-8Hz and 18-32Hz. There was no difference between controlled and drug resistant IGE. (Figure presented) Conclusion(s): People with IGE have greater background EEG power than controls. This finding could be further built upon as a method to improve the diagnostic capability of EEG.