Linear and non-linear EEG analyses before and after psychosis in patients with epilepsy

Abstract

To investigate the linearity and nonlinearity of EEGs before and after psychosis in patients with epilepsy, continuous EEGs before and after psychosis of five patients who developed epileptic psychosis were examined. The continuous EEGs of eight patients without psychosis were used as controls. EEGs were analyzed by Fourier transform for the frequency bands of delta, theta, alpha, and beta as linear indices and by Sample entropy (SampEn) as a nonlinear index. Significant changes were seen in SampEn before vs after psychosis at bilateral frontal and frontal-anterior temporal regions. Significant differences in SampEn between the before psychosis group and the control group were found at the right frontal and frontal-anterior temporal regions. In patients with epilepsy, SampEn may not only decrease in the right frontal and frontal-anterior temporal regions before psychosis, but it may also increase in the frontal and frontal-temporal regions during psychosis. EEG complexity may be useful to investigate the pathophysiological association between epilepsy and psychosis.