The effect of cryotherapy on post dry needling soreness

Abstract

Dry needling is the most effective way of treating Myofascial Pain Syndrome and appears to be as effective as an injection of an anaesthetic into myofascial trigger points. However the side effect common to both dry needling and the injection of an anaesthetic, is the development of post-needling soreness. Post-needling soreness results from bleeding at the area of needle insertion. The immediate application of cold to a needled area may decrease the severity of the cellular damage by restricting local bleeding. Cryotherapy can also decrease both nerve excitability and histamine release, which may result in decreased pain experienced by patients. The purpose of this study was to determine the effectiveness of cryotherapy on post dry needling soreness. Therefore a randomised, 2 group parallel controlled clinical trial was proposed to test this hypothesis. Sixty asymptomatic volunteer participants between 18 and 50 were randomly divided into two equal groups - group A (combination group) received dry needling in conjunction with a cold gel pack, and group B received dry needling only. Algometer readings, a Numerical Pain Rating Scale (NRS 101) and a 24 Hour Pain Diary were used as assessment tools. SPSS version 15 was used for data analysis (SPSS Inc. Chicago, Ill, USA). Baseline demographics and outcome measurements (NRS 101, Algometer readings and 24 Hour Pain Diaries) were compared between the two groups using Pearson’s chi square tests or Independent Samples t-tests as appropriate For the evaluation of the treatment effect for the NRS 101 and Algometer outcomes, repeated measures ANOVA procedure was used. Twenty four hour Pain Diaries by group interactions were reported for comparison of the treatment effect in the two treatment groups. The number of participants reporting pain at various time points post treatment were compared cross-sectionally by group with Pearson’s chi square tests. A Mann-Whitney U test was used to compare time points post treatment at which the worst pain was experienced between groups. The change in the presence of pain over time was recorded as either no change, an increase (from no pain to pain) or a decrease (from pain to no pain). This wascompared between treatment groups using the Pearson’s chi square test. Intragroup correlations between changes in outcome variables were achieved with Pearson’s correlation. P values of <0.05 were considered as statistically significant. The results of the study showed no evidence of a beneficial effect of cryotherapy on objective or subjective findings. Thus it can be concluded that cryotherapy as used in this study had no significant effect on reducing post dry needling soreness.