Lidocaine Injections Quelled Pain Sensitivity for Fibromyalgia Patients

Lidocaine injected into peripheral tissues reduced fibromyalgia (FM) patients’ pain sensitivity, researchers at the University of Florida (UF) revealed.

Many FM sufferers complain of chronic pain throughout their bodies, but treating it is difficult since the evidence of an injury isn’t present where the pain is exhibited, Michael Robinson, PhD, director of the UF Center for Pain Research and Behavioral Health and co-contributor to the research, said. Furthermore, he added, an effective treatment could also improve FM patients’ hyperalgesia, which is the nervous system’s hypersensitive response to actual and anticipatory pain.

“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,” Roland Staud, MD, the study’s co-contributor and a professor of medicine at the UF College of Medicine, said in a statement.

For their double-blind study, published in the European Journal of Pain, investigators administered 100 or 200 mg of lidocaine or saline injections into 62 female FM patients’ buttocks and shoulders. The participants were then subjected to mechanical and heat pain stimuli for a 30-minute period.

For subjects treated with lidocaine, mechanical hyperalgesia in their shoulders and buttocks decreased significantly (p = 0.004) in comparison to their saline-treated counterparts. The investigators also found a drop in heat hyperalgesia in lidocaine patient’s arms (p = 0.04). The researchers observed a 38% decline in FM pain upon injecting patients’ muscles with either lidocaine or saline.

However, a participant's expectation of relief accounted for 19.9% of the variance in clinical pain upon injection.

Since Staud claimed effective treatment for chronic pain is “multidisciplinary and multimodal” in nature, with “peripheral and social and behavioral components” in affected patients, he believed their findings bring researchers closer to fully understanding and treating these conditions.

“Over-the-counter medications and prescriptions, such as opiates, aren’t really effective for controlling chronic pain conditions,” Staud said. “We are able to explain the pain of chronic patients better and manage it better. We are making progress but it will take time.”