Patients with fibromyalgia resistant to more routine therapies have a new pain relief treatment available, according to a study presented at the ANESTHESIOLOGY™ 2013 annual meeting. Intravenous (IV) lidocaine infusion provided significant pain relief to fibromyalgia patients, although the pain relief was much less for African-Americans and smokers.

Fibromyalgia is one of the most common chronic pain conditions. The disorder affects an estimated 10 million people in the United States and an estimated three to six percent of the world population. Women account for 80 to 90 percent of those with the condition. Fibromyalgia is a central nervous system disorder characterized by widespread pain throughout the body as well as a heightened, painful response to pressure. Additional symptoms include fatigue, sleep disorders and joint stiffness.

"Fibromyalgia is a truly debilitating disease that can have a severe impact on quality of life," said Billy K. Huh, M.D., Ph.D., professor and medical director of the Department of Pain Medicine at The University of Texas MD Anderson Cancer Center, Houston, and adjunct professor of the Department of Anesthesiology at Duke University Medical Center, Durham, N.C.

The study was a retrospective review of 55 fibromyalgia patients whose pain did not respond to more conservative treatments. Statistics were collected for sex, race, body weight, pain duration, pain relief duration after lidocaine infusion, and scores on the brief pain inventory scale, visual analog scale and pain interference scale before and after the infusion.

The study found an almost 10 percent average decrease in the brief pain inventory scale score, which dropped from 83.18 before the infusion to 73.68 after the infusion. The average pain interference score dropped from 7.73 to 6.88. The brief pain inventory score was much lower for non-smokers than for smokers; non-smokers' average score was 72.63, while smokers' average score was 89.98.

Dr. Huh hypothesized that because smokers frequently have vascular damage that impairs blood circulation, the lidocaine may not reach the painful area because of poor blood flow. He also suggested that the benefit of lidocaine may be reduced because smokers have significant amounts of toxic chemicals in their blood.

The difference in pain interference scores for white patients and African-American patients was .028. For this test, a score less than .05 is considered statistically significant. Dr. Huh could not be certain about the reason for the difference, but noted, "Many drugs are more effective or less effective for certain ethnic groups. For example, some blood pressure medications are more effective for certain races. I think this finding is quite possibly related to genetic makeup."