Chronic Pain and the Brain

The brains of chronic pain patients fail to maintain the state of “activity equilibrium” seen in healthy patients. New research has demonstrated that a key emotional control center in the frontal lobe remains active constantly in chronic pain, while in pain-free patients it shuts down in order for other areas of the brain to function adequately.

Researchers compared functional magnetic resonance imaging (fMRI) brain scans of chronic pain patients to healthy controls. The healthy patients showed decreased function of a specific area in the frontal cortex while performing simple tasks. The chronic pain patients, however, performed the task equally well but with constant activity in this frontal lobe emotional center.

It is normal for the brain to shut off one area while another is being used. This allows nutrients and oxygen to be efficiently delivered to the part of the brain whose activity is most important, and allows neurons to rest from their normal excitatory state. When areas of the brain become constitutively active, as seen in the brains of chronic pain patients in this study, the abnormal activity may produce a variety of unwanted effects. Overactive cells may “steal” energy that would otherwise supply different parts of the brain; they may also alter their connections with other neurons or may “burn out” and die from over-excitation.

Chronic pain patients frequently suffer from a variety of concomitant health problems, including depression, anxiety and insomnia. This research may help us to understand the underlying factors that allow chronic pain to produce these symptoms. It may be that hyperactivity of this emotional center in the frontal cortex results in altered emotional response to a variety of normal life occurrences.

Understanding the effects of chronic pain on brain function will hopefully aid in the treatment of the emotional and psychological symptoms that many patients experience, and may provide insight into the underlying mechanisms of the pain and its consequences.