Evaluation of chin EMG activity at sleep onset and termination in obstructive sleep apnea syndrome

Chin EMG is traditionally used for polysomnographic assessment of sleep stages. The aim of this study was to evaluate whether chin EMG shows significant differences between normal and OSA groups in wakefulness and sleep. Chin EMG was collected as part of the polysomnographic data for eighteen normal and twenty severe OSA subjects. For each subject, four time windows at sleep onset and termination were selected and four parameters were computed: the mean power, the maximum power, the maximum-power frequency, and the median frequency. The mean power was significantly higher in the OSA group (7.5 plusmn 3.9) than the normal group (2.0 plusmn 2.4) in the S2 window (p < 0.00002). It was also significantly higher in the OSA (19.8 plusmn 10.5) group than the normal group (8.8 plusmn 6.3) in the W2 window (p < 0.005). Evaluation of Chin EMG power might be a quick and cheap method for OSA screening.