The Chattering Brain – How Chronic Pain Throws our Cortex out of Sync




Neuroscience_Neurology2.jpgA new study from the Northwestern University’s Feinberg School of Medicine has provided important clues to how chronic pain might throw our lives out of gear by affecting many areas of the cerebral cortex. Worse, if left unchecked, it could lead to irreversible damage to the interconnection between the neurons, leading to permanent changes in the way our brain functions.

Using functional MRI (fMRI) scanning, Dante Chialvo, lead author and associate research professor of physiology at the Feinberg School, compared the brain activation patterns of people with chronic low back pain to a group of pain-free volunteers while both groups were visually tracking a moving object on computer screens. The study showed that although the pain sufferers performed the task well, they were using their brain in a very different way compared to the normal control group.

With normal brains, when the subject concentrated on one task, like visual tracking, only a few areas of the brain were activated, while the other areas were ‘silent’ from a neurological point of view. This is a state of equilibrium, known as the resting state of the brain, as the different areas of the brain co-operate to give ‘rest’ to each other, while only a few relevant areas are active.

In contrast in the brains of the group with chronic pain, this co-operative resting state was typically absent, and the neurons kept on firing indefinitely without periods of rest. Dr Chialvo’s work suggests that in chronic pain, this continued firing prevents normal interneuronal connections and damages the brain, causing functional alterations. He hypothesizes that this overactive brain firing in chronic pain sufferers could affect their mood, producing chronic depression and a host of other neurological abnormalities seen with chronic pain. In the future in chronic pain sufferers, simply treating pain might be inadequate, as this study implies. Chronic pain may be much more of a whole-brained phenomenon than we once thought.

Reference

Baliki, M.N., Geha, P.Y., Apkarian, A.V., Chialvo, D.R. (2008). Beyond Feeling: Chronic Pain Hurts the Brain, Disrupting the Default-Mode Network Dynamics. Journal of Neuroscience, 28(6), 1398-1403. DOI: 10.1523/JNEUROSCI.4123-07.2008

  • Wenchypoo

    My husband suffers from chronic pain in his ankle–he fell down a steep stairwell on a ship, and broke his leg in two places trying to stop himself (by sticking his foot through the side rails). As a result, he lost cartilage in his right ankle, and now has permanent damage, permanent pain, and arthritis in a very tiny bone in the center of his foot (not remedied by any standard treatments). He asked the doctor for something to allow him to sleep at night, and got Tramadol–a few years later, he now has sleep apnea and snores like all get-out.

    The doctor says it’s because he gained weight, but since he’s losing weight, I think the Tramadol (an epilepsy drug used to trick the brain into misinterpreting pain) has affected his brain somehow, and his sleep patterns are forever altered. When he started the Tramadol, the first bottle he got carried a warning about breathing problems, but all subsequent bottles carried none–I brought this up to his latest doctor, and he denied the drug has that side effect. Looking it up on the web, I couldn’t find anything either, but I wonder that since he ISN’T an epileptic, and this medication is frequently used off-label for chronic pain, could there be something the docs are missing?

    We go in for a sleep study next month. Maybe that’ll shed some light on this.

  • http://brainblogger.com Sudip Ghosh, MD

    Tramadol can cause sleep apnea only in a handful — one paper estimates it to be 3%.

    Reference

    Webster, L.R., Choi, Y., Desai, H., Webster, L., Grant, B.J. (2007). Sleep-Disordered Breathing and Chronic Opioid Therapy. Pain Medicine DOI: 10.1111/j.1526-4637.2007.00343.x

Sudip Ghosh, MD

Sudip Ghosh, MD, is a surgeon at the University of Manchester, UK and a medical writer.
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