Theta dominance in the power spectra of eeg in chronic neurogenic pain

To identify the theta over activity in power spectra of EEG in chronic neurogenic pain patients, spectral analysis of resting EEG of the patients (n=15, 41-64 years, median 48 years, 6 men) in the eye closed state was compared with that of healthy controls (n=15, 39-62 years, median 48 years, 6 men). The study was done with the approval of Institute Ethics Committee and after obtaining written informed consent from the study participants. The average power spectral density of all channels revealed higher spectral power (expressed as μV2/Hz) in the theta band (5-7 Hz frequency range) for the patient group (1.901 ± 1.687) when compared with that of the control group (1.559 ± 0.812). Lower spectral power in the alpha band (8-12 Hz frequency range) was also noted in the patient group (3.401±3.624) when compared to the control group (4.864±4.173). The limitation in sample size may have been the reason for not obtaining statistical significance (p value = 0.485 for theta power comparison and p value = 0.314 for alpha power comparison) for the differences noted between the two groups. Although the data obtained from power spectra of EEG is not confirmatory, increased theta activity and decreased alpha activity may underlie the pathophysiological mechanisms involved in chronic neurogenic pain.