Brain Imaging May Provide First Objective Measure Of Pain
April 11, 2013

Breakthrough Study Looks To The Brain To Objectively Measure Pain

Brett Smith for - Your Universe Online

Physicians are often concerned about pain their patients may be experiencing, but without a way to quantify it, the experience of pain can be somewhat subjective and abstract.

According to a new report in The New England Journal of Medicine, a group of American researchers has set out to determine how much pain a person is experiencing by looking at the brain´s reaction to it.

Using Functional magnetic resonance imaging (fMRI), the scientists were able to determine which individuals were experiencing pain and which were not simply by looking at their brain scans.

"Right now, there's no clinically acceptable way to measure pain and other emotions other than to ask a person how they feel," said co-author Tor Wager, an associate professor of psychology and neuroscience at the University of Colorado at Boulder.

"We found a pattern across multiple systems in the brain that is diagnostic of how much pain people feel in response to painful heat.”

Wagner and his colleagues said that prior to the study, they expected to see a unique pain signature, or neurological pattern, for each individual. Instead, what they found was a signature that was highly similar among different subjects. This provided a baseline which allowed them to calculate how much pain a person was experiencing from a heat stimulus, with between 90 and 100 percent accuracy, without referring to prior brain scans of the individual.

The team began by taking fMRI images of 20 volunteers to identify a signature that changed predictably as the participants felt varying amounts of heat, ranging from warm to scalding hot. After the scanned images were created, the research team used computer data-mining technology to identify a discrete neurologic pattern for experiencing pain. After settling on a pain signature, the team was able to predict pain responses in a different set of subjects.

The team tested subjects to see whether the heat pain signature also appeared in instances of psychological pain. However, when study participants were shown images of their recent former romantic partners, they did not produce the same neurologic response as that observed during physical pain.

The scientists also tested the neurologic effects of an analgesic that was used to dull the heat-induced pain. The results showed a dulling effect in the brain-pain response in subjects who were given either a painkiller or placebo.

The results of the study could have major implications for creating the first ever objective metric for assessing pain. According to Wager and his colleagues, they are already applying the neurologic signature to different types of pain stimuli.

"I think there are many ways to extend this study, and we're looking to test the patterns that we've developed for predicting pain across different conditions," Wager said. "Is the predictive signature different if you experience pressure pain or mechanical pain, or pain on different parts of the body?

"We're also looking towards using these same techniques to develop measures for chronic pain. The pattern we have found is not a measure of chronic pain, but we think it may be an 'ingredient' of chronic pain under some circumstances. Understanding the different contributions of different systems to chronic pain and other forms of suffering is an important step towards understanding and alleviating human suffering."