Effects of dry needling of active trigger points in the scalene muscles in individuals with mechanical neck pain: a randomized clinical trial

Objective: The aim of this study was to compare the effects of dry needling (DN) versus pressure release over scalene muscle trigger points (TrPs) on pain, related disability, and inspiratory vital capacity in individuals with neck pain. Methods: In this randomized, single-blind trial, 30 patients with mechanical neck pain and active TrPs in the scalene musculature were randomly allocated to trigger point dry needling (TrP-DN; n = 15) or pressure release (n = 15) groups. The DN group received a single session of DN of active TrPs in the anterior scalene muscles, and the pressure release group received a single session of TrP pressure release over the same muscle lasting 30 s. The primary outcome was pain intensity as assessed by a numerical pain rate scale (NPRS, 0-10). Secondary outcomes included disability (neck disability index, NDI) and inspiratory vital capacity. Outcomes were assessed at baseline and 1 day (immediately post), 1 week, and 1 month after the treatment session. Data were expressed as mean score difference (Delta) and standardized mean difference (SMD). Results: Patients receiving DN exhibited a greater decrease in pain intensity than those receiving TrP pressure release at 1 month (Delta 1.2 (95% CI-1.8, -0.6), p = 0.01), but not immediately (1 day) or 1 week after. Patients in the DN group exhibited a greater increase in inspiratory vital capacity at all follow-up time points (Delta 281 mm (95% CI 130, 432) immediately after, Delta 358 mm (95% CI 227, 489) 1 week after, and Delta 310 mm (95% CI 180, 440) 1 month after treatment) than those in the pressure release group (p = 0.006). Between-group effect sizes were large at all follow-up time points (1.1 > SMD > 1.3) in favor of DN. Conclusion: This trial suggests that a single session of DN over active TrPs in the scalene muscles could be effective at reducing pain and increasing inspiratory vital capacity in individuals with mechanical neck pain. Future studies are needed to further confirm these results.