Analysis of the myoelectric characteristics of genioglossus in REM sleep and its improvement by CPAP treatment in OSA patients

Objectives To reveal the characteristics of genioglossus (GG) activation in moderate and severe obstructive sleep apnea (OSA) patients during rapid eye movement (REM) sleep compared with non-rapid eye movement (NREM) sleep and to determine whether continuous positive airway pressure (CPAP) could improve GG activation in OSA patients during sleep. Methods All subjects underwent polysomnography (PSG) with synchronous GG electromyography (GGEMG) recording with intra-oral surface electrodes at baseline on the first night. Only those subjects diagnosed with moderate and severe OSA were included and were manually titrated with CPAP to achieve a therapeutic pressure (Pt) with GGEMG recording on the second night. Results Nine OSA patients and six normal controls were analyzed in this study. The tonic GGEMG was higher in OSA patients during wakefulness ( p = 0.003) and NREM sleep ( p = 0.015), but it was not higher in REM sleep ( p = 0.862). The average phasic activity of OSA patients was significantly higher in all stages, including wakefulness ( p = 0.007), NREM sleep ( p = 0.005), and REM sleep ( p = 0.021). The peak phasic GGEMG was not different in wakefulness compared with normal controls ( p = 0.240), but it was higher in OSA patients in NREM sleep ( p = 0.001) and REM sleep ( p = 0.021), and it was significantly reduced by using CPAP during sleep (NREM sleep: p = 0.027; REM sleep: p = 0.001). Conclusions Our results demonstrate that GG activation during NREM and REM sleep is associated with component differences. The tonic component of GGEMG exhibited less of a compensatory increase compared with the phasic component in REM sleep, suggesting that it may be one of the pathological mechanisms of UA collapsibility in REM sleep. In addition, treatment with CPAP can normalize GGEMG activity and mostly reduced the peak phasic GGEMG during sleep.