Comparison of the efficacy of ultrasound-guided dry needling and extracorporeal shock wave therapy in patients with myofascial pain syndrome

Objective: This study aimed to compare the effectiveness of ultrasound-guided dry needling and extracorporeal shock wave therapy (ESWT) applied to active myofascial trigger points in the upper trapezius muscle of patients with myofascial pain syndrome (MPS), using both clinical and ultrasonographic parameters. Materials and Methods: Patients with chronic neck pain and at least one active trigger point in the upper trapezius muscle were enrolled. Participants were randomly assigned into three groups: ultrasound-guided dry needling + exercise, ESWT + exercise, and exercise alone (control group). All participants performed a standardized home exercise program consisting of trapezius stretching and postural correction exercises. Treatments were administered once weekly for three sessions. Assessments were conducted at baseline (T0), the third week (T3), and the twelfth week (T12). Clinical outcomes included pain intensity using the Visual Analog Scale (VAS), pressure pain threshold (PPT) measured by algometry, cervical lateral flexion range of motion (ROM), Neck Disability Index (NDI), and Short Form-36 (SF-36). Ultrasonographic evaluations comprised trigger point size on B-mode imaging, muscle stiffness by shear-wave elastography (SWE), tissue imaging score (TIS) for echotexture homogeneity, and resistive index (RI) on Doppler ultrasound. Results: Both active treatment groups showed significant reductions in pain intensity (VAS) and increases in pressure pain threshold (PPT) (p<0.001), and these improvements were significantly greater compared to the exercise-only group (p<0.05). NDI scores improved significantly within both active groups, though intergroup differences were not significant (p>0.05). SF-36 scores improved in both physical and mental components, favoring the ESWT and dry needling groups over exercise (p<0.05). Cervical lateral flexion ROM increased in all groups without significant intergroup differences (p>0.05). Early improvements (T3) were more pronounced in the ESWT group, whereas late gains (T12) were more sustained in the dry needling group. Ultrasonographic assessments revealed a decrease in trigger point size, most prominently in the dry needling group (p=0.033, p=0.002), and a reduction in muscle stiffness on SWE, which was more evident in the ESWT group (p=0.002, p=0.001). Although RI and TIS values showed trends toward vascular and structural normalization, intergroup differences were not statistically significant (p>0.05). Conclusion: Both ultrasound-guided dry needling and ESWT were effective in reducing pain, increasing pressure pain threshold, and improving functional capacity in patients with MPS. Ultrasonographic findings supported these clinical outcomes by demonstrating morphological and hemodynamic improvements within the muscle tissue. While ESWT provided faster analgesic and circulatory effects in the early phase, ultrasound-guided dry needling yielded more sustained structural recovery in muscle elasticity at follow-up. These results suggest that both interventions are effective and may exert complementary therapeutic mechanisms, allowing for individualized treatment planning based on patient characteristics. This study highlights the potential of ultrasound-based quantitative imaging parameters as reliable tools for objective monitoring of treatment response in MPS.