Brain abnormality can predict chronic pain


2013-09-21 11:54

If you have a certain abnormality in your brain structure, you are more likely to develop chronic pain following an injury to your lower back, according to a study published in the journal Pain.

Researchers from the Northwestern University Feinberg School of Medicine say they were able to identify a "specific irregularity" or "marker" in the axons of the brain, and that their findings may initiate changes in how physicians treat patients who are suffering from pain.

What the researchers found are pathways that connect brain cells, allowing them to communicate. Some of the axons surround the nucleus accumbens and medial prefrontal cortex – two areas of the brain that are responsible for processing emotion and pain.

It was this "marker" that researchers say allowed them to predict a patient’s persistent back pain with up to 85% accuracy.

In previous studies, the researchers showed that the emotional processing that goes on in these two areas helps identify which patients will suffer persistent back pain.

However, they also say that this latest study uncovered a "pre-existing culprit" for these emotional responses to injury, and that brain irregularities can trigger vulnerability to pain.

The study involved 46 patients with a lower back injury that occurred within the last month, but had not suffered any back pain in the year before the injury.

Each of the patients underwent an MRI scan, and only those reporting a minimum of 5 out of 10 on a pain scale were allowed to continue in the study, which followed them for a year.

These remaining patients then underwent additional MRI scans, one at the baseline of the study, and another at the end.

After the 1-year follow-up period, approximately one-half of the patients reported having less back pain, whether they took anything to treat the pain or not.

But the patients suffering persistent back pain showed the same structural abnormality "markers" in their white matter, both at the time of the injury and one year later.

"The abnormality makes them vulnerable and predisposes them to enhanced emotional learning that then amplifies the pain and makes it more emotionally significant,” explained A. Vania Apkarian, professor of psychology at Northwestern University Feinburg School of Medicine and senior author of the study.

“We've found the pain is triggered by these irregularities in the brain. We've shown abnormalities in brain structure connections may be enough to push someone to develop chronic pain once they have an injury," Prof. Apkarian added.

Nearly 100 million Americans suffer from chronic pain, which is one of the most expensive health conditions to treat, costing up to $635 billion a year, according to the researchers.

Additional research could help to reduce the burden of chronic pain in the U.S.

"Pain is becoming an enormous burden on the public. The US government recently outlined steps to reduce the future burden of pain through broad-ranging efforts, including enhanced research," says Linda Porter, pain and policy advisor at the National Institute of Neurological Disorders and Stroke (NINDS) and leader of the National Institutes of Health (NIH) Pain Consortium, which funded the study.

"This study is a good example of the kind of innovative research we hope will reduce chronic pain, which affects a huge portion of the population."

SOURCE: Brain white matter structural properties predict transition to chronic pain, doi:10.1016/j.pain.2013.06.044, published in the journal Pain, 17 September 2013.

Image by Patricia Deal. Used under CC License