The Characterisitc of Trapezius Surface Myography during Sleep

Trapezius muscle is an important posture muscle to maintain human shoulder-neck stability. Trapezius myalgia (TM) or myofascial pain syndrome is a common problem in general practice. Previous studies indicated TM may be related to mal-posture or biomechanical loading which resulted in micro-trauma or fatigue of muscle and pain. However, the correlation of pain and surface electromyographic (SEMG) findings in TM patients was weak in many previous studies. The authors found that over-activities of trapezius cannot explain the development of pain. A series of studies done byWestgarrd et al. showed that failure to recovery of SEMG activities of trapezius to the baseline level after mental stress or work in chronic TM patients. It can be hypothesized that central sensitization may be involved in pathogenesis of chronic TM from these results. Mork et al. noted the SEMG activities of trapezius during sleep were significantly higher in chronic TM patients. But it is still unclear that the relationship among sleep, muscle activities and pain development. Only one study was conducted to measure the SEMG activities of trapezius during sleep and found a characteristic low frequency (<0.3 Hz) oscillation of SEMG signals of trapezius in healthy subjects. This phenomenon may be related to excitability of motor cortex during sleep. However, it is difficult to conclude the change of trapezius SEMG during sleep in TM patients since there was no available data regarding other physiological parameters during sleep in previous studies. Our study’s goal is to analyze the SEMG characteristics of trapezius muscles and its association with other sleep parameters during sleep in healthy and TM patients. Combining polysomnography (PSG) and SEMG recording of bilateral trapezius muscles during sleep will be conducted. The results of our study will establish the norm data of human trapezius SEMG activities during sleep and provide valuable data to further explore the pathogenesis of chronic TM.