EEG Microstate in Obstructive Sleep Apnea Patients

Obstructive sleep apnea (OSA) is a common sleep respiratory disease. Previous studies have found that the wakefulness electroencephalogram (EEG) of OSA patients has changed, such as increased EEG power. However, whether the microstate reflecting the transient state of the brain is abnormal is unclear during sleep apnea or hypopnea. We investigated the microstates of sleep EEG in 30 OSA patients and in 10 healthy control volunteers. Then correlation analysis was carried out between microstate parameters and EEG markers of sleep disturbance, such as power spectrum, sample entropy and detrended fluctuation analysis (DFA). We observed that there was an additional fifth microstate E during apnea or hypopnea in N1 and N3 stages in OSA patients. And the microstate E was correlated with the power spectrum of delta, theta and alpha bands, not correlated with sample entropy, but correlated with DFA in N1-OA/OH stage. Moreover, Global Explained Variance, Mean Duration, Time Coverage and Segment Density of microstate E were positively correlated with DFA. We can interpret that the abnormal transition of brain active areas of OSA patients in N1-OA/OH stages leads to an extra microstate E, which might be related to the change of alpha activity in the cortex. And the generation of microstate E is not correlated with the decrease of EEG complexity, but correlated with the stronger self-similar regularity of EEG signals in OSA patients. These findings indicate that the microstate has the potential as a biomarker of EEG and has potential application value in OSA diagnosis.