Brain Response to Pain Control in People With Chronic Pain

Different pain reducing drugs work in different ways to reduce pain. Many drugs, including morphine and codeine, reduce pain by binding to opiate receptors in the brain. Another chemical, naloxone, can block the effect of these drugs. In this study, we are looking at brain responses to a pain-relieving cream and whether naloxone blocks the effect of the cream. We will compare the results of people with chronic pain (fibromyalgia) to those of people without chronic pain. Design: The study compares MRI response to painful stimulation between people with fibromyalgia and healthy volunteers under two conditions: 1) naloxone, 2) placebo. Outcome measures: Pain ratings and pain-related MRI responses are compared between people with fibromyalgia and healthy volunteers