Analgesic efficacy of ultrasound identified trigger point injection in myofascial pain syndrome: A pilot study in Indian patients

Abstract

Background: Myofascial pain syndrome (MPS) is described as sensory symptoms, sometimes with motor and autonomic symptoms caused by myofascial trigger points (TPs). Injection at TPs is most likely to benefit patients with such disorder. The identification of TPs is usually clinical. However, in sites where there are major vital structures, ultrasound guidance and real-time visualization may help in decreasing complications. Methodology: Twenty patients who presented to pain clinic with classic symptoms of MPS in the neck and shoulder area with clinically detectable TPs were selected. The points were imaged with ultrasound to find correlation with clinical positions. They were injected with a mixture of local anesthetic and steroid on TPs with real-time ultrasound guidance and needle visualization. Pretreatment visual analog scale (VAS) scores and posttreatment (immediate and after 1 month) were noted. The mean reduction in VAS scores was analyzed with paired Student′s t-test. Any side effect was observed and managed. Results: Clinically detectable TPs coincided with an echogenic point on the undersurface of the trapezius. There was a significant reduction in pain scores at both times. The needle sign was positive in all the cases. There were no major complications. Conclusion: The clinically identified TPs in trapezius muscle coincided well with ultrasound imaged echogenic structure in the muscle in all the cases. Ultrasound-assisted injections also produced the needle sign in all the cases. The achieved analgesia both immediately after the injection and a month later was satisfactory in the majority of cases. The echogenic mass corresponding to the TP is found to be on the undersurface of the muscle rather than inside the mass of the muscle.

Keywords

• Myofascial pain
• trigger point
• ultrasound