Postneedling Soreness and Tenderness After Different Dosages of Dry Needling of an Active Myofascial Trigger Point in Patients With Neck Pain: A Randomized Controlled Trial.

Background: Previous studies in asymptomatic subjects have demonstrated that myofascial trigger point (MTrP) dry needling frequently is associated with postneedling soreness. However, to the authors' knowledge, there is not any study that performs a detailed description of postneedling soreness characteristics in patients with myofascial pain. This information could help clinicians to make evidence-informed decisions considering the benefits and negative effects of different dry needling dosages.

Objective: To (1) compare the prevalence, intensity, and duration of postneedling soreness and tenderness after different dosages of deep dry needling (DDN) and (2) analyze the influence on postneedling soreness of psychological factors and other factors involved in the DDN process DESIGN: 1-week follow-up, double-blind randomized controlled trial.

Setting: University community.

Participants: Patients (n = 120: 34 male; 86 female) aged 18-53 years (median ± interquartile range, 21.0 ± 7.0 years) with active MTrPs in the upper trapezius.

Intervention: All patients received DDN in an active MTrP. They were randomly divided into 4 groups: no local twitch responses (LTRs) elicited (control group), 4 LTRs elicited, 6 LTRs elicited, and DDN until no more LTRs were elicited.

Main Outcome Measures: Postneedling soreness and pressure pain threshold were assessed before treatment, during DDN procedure, and every 24 hours during 1 week.

Results: Postneedling soreness showed a significant effect for time (F = 173.603; P < .001, η = 0.659) and a significant interaction between group and time (F = 3.763; P = .001; η = 0.111). Pressure pain threshold showed a significant effect for time (F = 16.833; P < .001; η = 0.127) and a significant interaction between group and time (F = 2.100; P = .04; η = 0.052). Psychological factors did not show relevant correlations with the intensity of postneedling soreness.

Conclusions: Postneedling soreness is present in most of subjects after DDN of active MTrPs. The groups in which DDN was performed eliciting LTRs exhibited greater post-needling soreness. The number of needle insertions was associated with postneedling soreness but psychological factors did not seem to play a relevant role on its perception.

Clinical Trial Registration Number: NCT02190890 LEVEL OF EVIDENCE: I.