Changes in stiffness at active myofascial trigger points of the upper trapezius after dry needling in patients with chronic neck pain: a randomized controlled trial

Background/objective: Since, to our knowledge, the effects of dry needling (DN) on active myofascial trigger point (MTrP) stiffness have not been analyzed previously with shear wave elastography (SWE), our aim was to compare the effects of a single session of DN and sham DN applied to the most active MTrP located in the upper trapezius muscle on clinical outcomes. Methods: A randomized, double-blinded sham-controlled trial was conducted; 60 patients were randomized into an experimental (DN) or sham (sham DN) group. Baseline data including sociodemographic and clinical characteristics were collected. SWE and pain pressure thresholds (PPTs) at the MTrP and a control point located 3 cm laterally were the main outcomes assessed before and 10 min after the interventions. Results: Patients receiving DN interventions experienced greater increases in the control point PPTs immediately after receiving the intervention compared with sham DN (p < 0.05), but no differences were found for the MTrP (p > 0.05). Post-intervention PPT improvements were found at both locations for both groups (p < 0.01). No significant changes for either MTrP or control locations were found for SWE outcomes in either group (all ps > 0.05). No significant within-group SWE differences were found in the DN or sham DN groups (p > 0.05). Conclusion: A single session of DN or sham DN applied to active MTrPs located in the upper trapezius muscle produced no detectable changes in stiffness at the MTrP or control locations. Real DN induced an immediate analgesic response at both MTrP and control locations, while sham DN induced an immediate MTrP response.