Comparison of bupivacaine, etidocaine, and saline for trigger-point therapy.

Injections of local anesthetics, saline, "dry needling," or other stimuli at specific, tender loci (trigger or acupuncture points) are reportedly efficacious in treatment of chronic pain syndromes. In a randomized, double-blind crossover study, subjective responses of 15 patients with myofascial syndrome to trigger-point injections of either bupivacaine 0.5%, etidocaine 1%, or physiologic saline without preservative were compared. Responses in six pain-related categories were determined before treatment and 15 minutes, 24 hours, and 7 days after treatment. Trigger-point injections with bupivacaine and etidocaine were generally preferred over saline in several pain-tested categories. Implications and possible mechanisms are discussed.