Granisetron vs. lidocaine injection to trigger points in the management of myofascial pain syndrome: a double-blind randomized clinical trial.

Abstract

Granisetron and lidocaine injections have been used for the management of myofascial pain syndrome. This study was aimed to compare the efficacy of granisetron and lidocaine injections to trigger points of upper trapezius in the management of myofascial pain syndrome. We performed a double-blind randomized clinical trial in an outpatient clinic of physical medicine and rehabilitation at a teaching hospital. A total of 40 patients aged≥18 with neck pain due to myofascial pain syndrome were included. They had pain for at least one month with the intensity of at least 30mm on a 100mm visual analog scale. Each participant received a single dose of 1mL lidocaine 2% or 1mg (in 1mL) granisetron. The solutions were injected into a maximum of three trigger points of the upper trapezius. We instructed all patients to remain active while avoiding strenuous activity for three or four days, and to perform stretch exercise and massage of their upper trapezius muscles. We assessed the patients before the interventions, and one month and three months post-injection. The primary outcome was the Neck Disability Index and the secondary outcome was the Neck Pain and Disability Scale. Both interventions were successful in reducing neck pain and disability (all p-values<0.001). However, the neck pain and disability responded more favorably to lidocaine than granisetron (p=0.001 for Neck Disability Index, and p=0.006 for Neck Pain and Disability Scale). No significant side-effect was recognized for both groups. Both lidocaine and granisetron injections to trigger points are effective and safe for the management of the syndrome and the benefits remain at least for three months. However, lidocaine is more effective in reducing pain and disability. The injections are well-tolerated, although a transient pain at the site of injections is a common complaint. One mL of lidocaine 2% is more effective than 1mg (in 1mL) granisetron for injecting into the trigger points of the upper trapezius in myofascial pain syndrome.