Comparison of 3 Needle Sizes for Trigger Point Injection in Myofascial Pain Syndrome of Upper- and Middle-Trapezius Muscle: A Randomized Controlled Trial

Abstract 

Yoon S-H, Rah UW, Sheen SS, Cho KH. Comparison of 3 needle sizes for trigger point injection in myofascial pain syndrome of upper- and middle-trapezius muscle: a randomized controlled trial.

Objectives

To investigate (1) the relation between needle diameter and treatment efficacy of myofascial pain syndrome and (2) the relation between needle diameter and pain intensity during injection.

Design

Randomized controlled trial.

Setting

University-affiliated tertiary-care hospital.

Participants

Volunteers (N=77) with myofascial pain syndrome affecting upper- and middle-trapezius muscles with at least 3 months' duration of pain.

Intervention

Participants were randomly assigned to receive trigger point injections on 1 side of the trapezius with a 21-, 23-, or 25-gauge needle. After a 1-time injection, participants were followed up for 14 days. Participants and the assessor were blinded for group assignment.

Main Outcome Measures

Treatment efficacy was measured with the visual analog scale (VAS; at pretreatment, and posttreatment on days 1, 4, 7, 14) for neck and upper-back pain, the Neck Disability Index (NDI; at pretreatment, and posttreatment on days 7, 14), and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36, at pretreatment and posttreatment on days 7, 14) for health-related quality of life. Pain intensity during injection was evaluated immediately after injection with VAS.

Results

VAS scores for posttreatment on days 4, 7, and 14 decreased significantly compared with pretreatment scores in all groups; NDI scores on days 7 and 14 decreased significantly compared with pretreatment scores in all groups; SF-36 scores on days 7 and 14 decreased significantly compared with pretreatment scores in the 21- and 23-gauge needle groups; and SF-36 score on day 14 showed significant difference between the 21- and 25-gauge needle groups. For pain intensity during injection, VAS scores indicated no significant difference between the 3 groups.

Conclusions

No difference between the needle types was observed in terms of VAS or NDI, or in terms of pain intensity felt by patients during injection. In terms of SF-36 scores, injections with 21- or 23-gauge needles were found to be more effective. However, a well-controlled investigation is needed to explore the effect of needle thickness on health-related quality of life.

Key Words: Injections, Myofascial pain syndromes, Neck pain, Quality of life, Rehabilitation

List of Abbreviations: ANOVA, analysis of variance, LTR, local twitch response, NDI, Neck Disability Index, SF-36, Medical Outcomes Study 36-Item Short-Form Health Survey, VAS, visual analog scale