A multicenter randomized controlled trial of injections of sterile water and saline for chronic myofascial pain syndromes.

A randomised controlled trial was used to test the hypothesis that cutaneous injections of sterile water (SWI) have no benefit over saline (PSI) as a method of pain reduction among patients with myofascial pain syndromes. Six general practitioners located at 6 different clinics of general practice treated 117 patients (91 female, 26 male, aged > or = 25 years) with myofascial pain syndrome for at least 3 months in one or both of the upper quadrants of the body. Patients were randomised to receive either SWI or PSI which was administered sub- and intracutaneously on 1 occasion. The patients received a mean number of 10 injections of 0.5 ml of either substance. The main outcome measure was pain intensity which was measured with visual analogue scales before intervention, 10 min after intervention and 14 days after intervention. We found no statistically or clinically significant difference in pain level reduction between the 2 groups. However, patients who received SWI reported a much more painful treatment experience than those who received PSI. Our study shows that injections of sterile water are substantially more painful but demonstrate no better clinical outcome than similar injections of saline as a method to treat patients with chronic myofascial pain syndrome.