Loss in brain density is related to pain duration, indicating that 1.3 cubic centimeters of gray matter (the part of the brain that processes information and memory) are lost for every year of chronic pain, said lead researcher A. Vania Apkarian, associate professor of physiology at Northwestern University Feinberg School of Medicine and a researcher at the Northwestern University Institute of Neuroscience.

The study, the first to examine brain changes in chronic pain conditions, was published in the Nov. 23 issue of The Journal of Neuroscience.

At least 25 percent of Americans suffer from back pain; in one fourth of these individuals, back pain is chronic and unremitting. Although chronic pain greatly diminishes quality of life and increases anxiety and depression, it previously had been assumed that the brain reverts to its normal state after chronic pain stops.

Apkarian and co-researchers used structural magnetic resonance imaging brain scan data and two automated analysis techniques to contrast brain images from 26 participants with chronic back pain with those from matched normal subjects.

All participants with chronic back pain had unrelenting pain for more than a year, primarily localized to the lumbosacral region, including buttocks and thighs, with or without pain radiating to the leg.

The participants were divided into neuropathic -- exhibiting pain because of sciatic nerve damage -- and non-neuropathic. Brain scans showing gray matter volume were compared.

In earlier research, Apkarian and colleagues found that back pain sustained for six months or longer is accompanied by abnormal brain chemistry, indicated by chemical changes in the area of the brain known
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Contact: Elizabeth Crown
e-crown@northwestern.edu
312-503-8928
Northwestern University
22-Nov-2004