Comparison on Treatment Effects of Pharmaceutic Agents for Trigger Point Injection

ABSTRACT

OBJECTIVE: To compare the effect of pharmaceutic agents which were used in trigger point injection and to establish a relationship between ultrasonographic change in injected muscle and post-injection soreness by a double blinded study. METHOD: Twenty-seven patients who were diagnosed as myofascial pain syndrome with their trigger point in upper trapezius muscle were recruited. They were assigned to four groups by age and sex lidocaine injection (n=8), normal saline injection (n=6), 20%dextrose injection (n=6), and BTX-A injection (n=7). One physiatrist palpated a trigger point at upper trapezius muscle and injected blinded agents with same volume (1 ml). Ultrasonography for injected muscle was done by 2 weeks after injection. Visual analog scale was evaluated up to twenty three weeks. RESULTS: Mean score of visual analog scale was decreased in all groups. Among the four agents, 0.5% lidocaine and BTX-A showed significant decrement in visual analog scale (p<0.05). Ultrasonographic depth of muscle was increased in BTX-A and 20% dextrose injected group at the end of injection (p<0.05). There were no significant different treatment effect in four pharmaceutic agents. CONCLUSION: In all four groups, trigger point injection showed therapeutic effect for myofascial pain syndrome. Among the four agents, 0.5% lidocaine and BTX-A could reduce pain significantly up to twenty three weeks. Mechanical pressure on muscle fiber was thought to be one of the causes of post-injection soreness.