Deep Versus Superficial Dry Needling for Neck Pain: A Systematic Review of Randomised Clinical Trials

This systematic review investigated the comparative efficacy of deep versus superficial dry needling for the treatment of neck pain associated with myofascial trigger points (MTrPs) in the upper trapezius muscle. Myofascial trigger points are areas of localized muscle tension that can cause referred pain and functional limitation, affecting approximately 30-85% of the population at some point in life. Dry needling is a physical therapy technique that uses thin needles to treat these points, applied either deeply (reaching the trigger point directly) or superficially (only in the skin and subcutaneous tissue). The researchers conducted a comprehensive search across seven scientific databases, identifying 8 randomized controlled trials that directly compared these two techniques in 525 participants.

The methodological quality of the studies varied, with only 2 studies showing a low risk of bias, 4 with some methodological concerns, and 2 with a high risk of bias. The deep technique used 25-50 mm long needles with a diameter of 0.2-0.25 mm, inserted directly into the trigger points for 1.5-15 minutes, while the superficial technique used similar needles inserted only 5-15 mm into the skin, without reaching the deep muscle. The results demonstrated that both techniques were effective in reducing pain in the short term. On the visual analog scale (0-10), deep needling reduced pain by 2.2-3.98 points, while the superficial technique provided a reduction of 1.8-2.36 points.

Regarding cervical function, measured by the Neck Disability Index (NDI), the deep technique improved by 5.2-8.0 points, while the superficial improved by 2.0-7.2 points. Although some studies showed numerical advantages for the deep technique, most found no clinically significant differences between the approaches. Limitations include heterogeneity in treatment protocols across studies, variability in application techniques, different follow-up durations, and uneven methodological quality. In addition, most studies evaluated only one treatment session, limiting the understanding of medium- and long-term effects.

The mechanisms of action differ between the techniques: deep needling acts directly on the trigger point, reducing abnormal electrical activity and improving local blood flow, while superficial needling stimulates superficial nerve fibers, activating central pain modulation mechanisms. Both mechanisms appear to contribute to the symptomatic relief observed. The clinical implications, in the international context of the study where the technique is applied, suggest that practitioners can choose between the techniques based on patient preference, tolerance to the procedure, and professional experience, since both demonstrated similar efficacy for short-term relief of cervical pain associated with myofascial trigger points.