Chronic Pain can Rewire the Brain’s Circuitry

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About Complex Region Pain Syndrome

Complex region pain syndrome (CRPS) is a particularly devastating disease for a very peculiar region: people with this syndrome experience chronic pain for no apparent reason.

CRPS develops very rarely in people who have sustained a significant injury to a foot or hand. For most people who sustain such an injury, the pain will dissipate when the injury has fully healed. For a very small number of people – around five percent – the pain will linger long after the injury has healed. In some cases the pain can linger for the remainder of the person’s life.

In a case where a person sustains a hand injury, for example, the pain might radiate from the injury site throughout the entire arm, or even over the whole body. People with CRPS may experience unusual symptoms such as a change in skin color – to blue or red – or a change in skin temperature (the skin becomes warmer, then progressively cooler, as the condition changes from acute to chronic). Around 200,000 people are afflicted with CRPS in the United States.

CRPS Rewires the Brain

A recent study completed by researchers at Northwestern University’s Feinberg School of Medicine has revealed new information about how CRPS affects the brain.

In a prior study, the team discovered that chronic pain can cause the brain’s so-called ‘gray matter’ – the region which contains neurons – to atrophy. Now, they have determined that in people with CRPS, the brain’s ‘white matter’ also changes.

The white matter is where neuronal connections are made. And in people with CRPS, this region of the brain is a mess, with rewired connections made in areas of the brain corresponding to pain perception, skin temperature, and emotion.

Previously, many physicians have simply doubted that CRPS is a real condition. But now, it seems, the existence of a real chronic pain syndrome with real physical symptoms has been proven. This is, in fact, the first evidence that there is a biological change underlying the symptoms that people with CRPS experience.

However, the researchers point out that a cause-and-effect relationship hasn’t been established: they don’t know whether CRPS causes these changes in the brain’s white matter, or whether people with CRPS are susceptible to the condition because they have pre-existing brain abnormalities. Either way, these findings may prove highly useful, as for the first time, it may be possible to locate targets for pharmaceutical treatments for the condition.

References

Paul Y. Geha, Marwan N. Baliki, R. Norman Harden, William R. Bauer,Todd B. Parrish and A. Vania Apkarian. The Brain in Chronic CRPS Pain: Abnormal Gray-White Matter Interactions in Emotional and Autonomic Regions. Neuron, Volume 60, Issue 4, 570-581, 26 November 2008.