Why do some people develop chronic pain?

THAT'S THE WHY:WHY DO some people, but not others, go on to develop chronic, persistent pain after an episode of back pain?

It’s a question that can baffle, but a new brain imaging study has thrown up some interesting findings.

The study, published online in Nature Neuroscience, involved almost 40 patients who had initially presented with subacute back pain.

The researchers at Northwestern University in Chicago looked at brain characteristics at time points over the course of a year.

Pain persisted in about half of the patients, and in those people the researchers saw differences in the brain compared with those who recovered and to healthy controls.

“This study suggests that in some people, an episode of back pain ‘is linked with activation of particular regions of the brain’, in this case ‘corticolimbic’ areas that might ultimately enhance and amplify pain signalling and perception in a way that contributes to the persistence of pain long after the initial injury has healed,” says Keith Smart, a clinical specialist physiotherapist at St Vincent’s University Hospital with a special interest in chronic pain. He was not involved in the study.

“It contributes to a growing body of scientific evidence indicating that chronic and persistent pain states likely reflect a degree of disordered neural functioning within the brain,” according to Smart.

The challenge facing researchers of chronic pain now is to try to find out why these brain changes happen in some people but not others, and whether they can be prevented or reversed, he says.

“If we can do this, we may be able to lessen the chances of chronic pain from developing, or when it does, we may be able to treat it better.”