The effect of low intensity laser therapy on post needling soreness in trigger point 2 of the upper trapezius muscle

Abstract

Introduction: Myofascial pain syndrome is a condition of collective sensory, motor and autonomic symptoms caused by myofascial trigger points, which are hyper-irritable foci in a muscle and palpated as a taut, tender, ropey band. There are many types of treatment for myofascial pain syndrome; dry needling is one of the most effective forms. Dry needling involves the insertion of a needle into the myofascial trigger points in order to break up the contractile elements and any somatic components that may contribute to trigger point hyperactivity, and to stimulate sensitive nerve ending in the area. Although therapeutic, an unpleasant side effect of dry needling is the post-needling soreness. Various modalities have been utilised to decrease post-needling soreness, such as ice, heat and action potential simulation, to mention a few, however no study has been conducted to date that documents low intensity laser therapy and its effect on post-needling soreness. This study therefore aimed to evaluate the effect of low intensity laser therapy on post-needling soreness in trigger point 2 of the upper trapezius muscle.

Methodology: This study was designed as a randomised, controlled pre-test and post-test experimental trial. Forty participants were randomly allocated into two equal groups of 20 participants each. Group 1 received the needling and laser therapy; Group 2 received needling and placebo laser. Algometer and Numerical Pain Rating Scale 11 (NRS 11) readings were taken immediately before the dry needling procedure; after the laser or placebo laser therapy; and again, at the follow-up visit 24 hours later. Subjects used a 24- hour pain diary which was completed at three-hour intervals, to record any post-needling soreness. The NRS 11 scale was used immediately before the needling and again at the follow-up visit 24 hours later. Results: Statistical analysis was done using SPSS version 24.0 to conduct inferential and deductive statistics. A significance of p=0.05 was set. Baseline demographics and outcome measurements were compared between the two groups using t-tests or ANOVA where appropriate. An inter-group analysis revealed that objectively and subjectively all groups experienced some degree of post-needling soreness, which deceased significantly over time. This decrease of pain was not significantly related to the treatment group, and there is no evidence of the differential time effect with the treatment. An inter-group analysis yielded no statistically significant results regarding the effectiveness of the treatments received by the patients. This could be because of the small sample size or because low intensity laser therapy is not a useful intervention.

Conclusion: The results from this study revealed that both treatment groups responded equally in the alleviation of pain. It can thus be concluded that low intensity laser therapy had no significant beneficial effects on post-needling soreness.