Lidocaine Injection May Help Treat Fibromyalgia
But experts wonder how much of the benefit is due to placebo effect
By Mary Elizabeth Dallas
TUESDAY, Aug. 5, 2014 (HealthDay News) -- The pain of fibromyalgia might be eased with injections of the painkiller lidocaine, a new study suggests.
People with fibromyalgia complain of chronic pain throughout their body as well as an increased sensitivity to pain. Doctors often have trouble treating this pain because it's unclear what causes it, the study authors noted.
In the new study, injecting lidocaine into peripheral tissues -- such as the muscles in the shoulders or buttocks -- effectively reduced pain sensitivity, the researchers found.
"We hypothesized that if pain comes from the peripheral tissues, and we can take this pain away by injecting local anesthetics, then this would be indirect proof of the importance of peripheral tissues for the clinical pain of these individuals," study lead author Dr. Roland Staud, a professor of medicine at the University of Florida College of Medicine, said in a university news release.
"Over-the-counter medications and [narcotic] prescriptions such as opiates aren't really effective for controlling chronic pain conditions," he added. But with the new therapy, "we are able to explain the pain of chronic patients better and manage it better," Staud said. "We are making progress but it will take time."
The study involved 62 women with fibromyalgia. Each woman received four injections: two in certain muscles in their shoulders and two more in their buttocks. Some of the women received lidocaine injections, while a "control group" received saline injections.
Right before the injections were given and 30 minutes afterwards, the women received mild pain stimulations delivered through mechanical means or through heat.
Compared to "dummy" saline injections, the lidocaine significantly eased the women's sensitivity to pain, according to the study published recently in the European Journal of Pain.
The researchers noted, however, that both lidocaine and the placebo resulted in a 38 percent reduction in pain at or near the point of injury.
But chronic pain affects the body differently than a specific injury, like a broken leg, the study authors pointed out. Chronic pain, they explained, actually alters nerve function along the spinal cord.