Ultrasound and trigger point injections have both been used in the treatment of myofascial pain, as have a variety of other therapies. Examples include transcutaneous electrical nerve stimulation (TENS), so-called "dry needling," and massage therapy. Ultrasound is thought to promote pain relief as the result of several factors. It may neutralize pain mediators due to increased circulation in the painful area, or it may cause other changes that result in decreased inflammation.
Trigger point injections have typically used a local anesthetic. However, some investigators think that injecting the needle itself causes pain relief. Injecting the needle may disrupt the trigger point mechanism, block the nerve fibers, and neutralize nerve-sensitizing substances due to either the injected fluid or local bleeding. On the other hand, the drug that is injected may interrupt the trigger point.
This study involved 102 patients who had trigger points on one side of the upper trapezius. The individuals' pain had lasted from six months to seven years. The subjects were grouped randomly to receive ultrasound with neck-stretching exercises, trigger point injections with neck-stretching exercises, or neck-stretching exercises only. The average age of the 38 men and 64 women was 31 years. Pain intensity was assessed by patients describing their pain on a scale of 0 to 10. The investigators also measured the time at which a patient reported discomfort when pressure was applied to the painful area (the pain threshold, or PT).
Compared with controls, both treatment groups had a statistically significant reduction in pain intensity, and an increase in both PT and range of motion at two-week and three-month follow-up assessments after treatment. Controls showed no improvement; there were no differences between the ultrasound and the trigger point injection groups.
Depression and anxiety were both relatively high among all subjects, with 22.9% of patients having high depression scores and 89.3% having high anxiety scores. Although these scores were not correlated to either pain intensity or PT, they were correlated to the duration of pain prior to treatment.
- Myofascial pain is a chronic condition that affects the connective tissue covering muscles.
- Ultrasound is just as effective a treatment as trigger point injections and should be offered as an alternative since it is a less invasive procedure.
- Psychological and social factors may play a role in chronic myofascial pain, so patients should be assessed and treated for any contributing factors.