Clinical Study Of Dual Wavelength Low Level Laser In Treatment Of Trapezius Myofascial Pain Syndrome

Myofascial pain syndrome(MPS)is a common chronic pain syndrome caused by myofascial trigger points(MTrPs)with high incidence and wide range of patients.Physical therapy is often used in clinical treatment for MPS.Low level laser therapy(LLLT),one of the common physical therapies,has been widely recognized,but relationship between the laser wavelength,irradiation mode and the clinical efficacy need further research.In addition,evaluation of clinical curative effect of MPS used subjective methods,such as visual analogue score(VAS),objective evaluation criteria was absent.Objective:Study the clinical curative effect of 635 nm,808 nm laser with two kinds of irradiation mode for myofascial pain syndrome,and evaluate the clinical curative effect from the perspective of muscle mechanical properties.Methods:Study the muscle tension and shear wave elasticity modulus of MTrPs.In the randomized,double blind,controlled clinical trials of dual wavelength laser in treatment of the trapezius muscle MPS,stretching exercise was basic treatments,subjects were divided into 635 group(receive 635nm laser irradiation),808 group(receive 808nm laser irradiation),alternate group(635nm/808nm laser alternate irradiation)and placebo group.Power density is 200 mw/cm2.The low level laser therapy(LLLT)was applied 15 minutes a time,3 times a week for successive 4 weeks.VAS,pressure pain threshold(PPT),Neck disability index(NDI)and range of motion(ROM)of neck were measured at the baseline,the middle,the end of laser session and follow-up,and compare the difference between groups,and muscle tension was used as objective evaluation indicator.Results:The muscle tension and elastic modulus in MTrPs lesions were significantly higher than those in adjacent areas,can be used to identify lesion areas and adjacent areas.The muscle tension,VAS,NDI and PPT were significantly improved at the middle laser sessions,at the end of laser session the degree of improvement was increased,and the ROM of neck increased.At the eighth week follow-up,the muscle tension was no difference compared with the end of the treatment,and there was no definite trend for other indexes.The changes of muscle tension,VAS,and PPT in the laser treatment group were greater than those in the control group,but the difference between the three laser groups was not statistically significant.Conclusion:The muscle tension and elastic modulus can differentiate the the lesion area of MTrPs from the adjacent area,provide quantitative basis for the muscle mechanics in the palpation experience,and can be used as an objective index for the evaluation of clinical efficacy.The LLLT are effective in reducing muscle tension and pain intensity,improving ROM of neck,however,the difference between different laser mode need further large sample trials.