Effects of High-Intensity Laser on the Upper Trapezius Muscle Activity in Chronic Cervical Myofascial Pain Syndrome

Myofascial Pain Syndrome is the most common musculoskeletal problem that leads to pain, disability, and increased activity of the upper trapezius muscle. The previous studies proposed that the application of lasers could influence pain, function, and muscle activity. Therefore, this study aimed to investigate the effect of high-intensity laser on the upper trapezius muscle activity in Chronic Myofascial Pain Syndrome Patients. In total, 32 patients with chronic Myofascial Pain syndrome were recruited for this double-blind randomized clinical trial. The patients were randomly divided into two groups of High-Intensity Laser and Control group. The High-Intensity Laser group was treated with a High-Power Laser and the Control group received conventional physiotherapy. Overall, muscle activity of the upper trapezius muscle (RMS) was evaluated by surface electromyography device. The pain level was assessed using a Visual Analog Scale and the disability was assessed using Neck Disability Index Questionnaire. Data were analyzed with independent t-tests and paired t-tests (p<0.05).

Intergroup comparison indicated significant progress in pain score, disability index, and upper trapezius muscle activity in both groups (P < 0.05). The results showed more progress in pain score, disability index, and upper trapezius muscle activity in the High-Intensity Laser group than in the control group (p<0.05). The results of this study showed that the application of high-intensity Laser in patients with chronic Myofascial Pain syndrome could effectively reduce pain and improve the disability index. It seems that multimodal intervention can influence signs and symptoms and muscle activity more than conventional physiotherapy alone.