Tuesday, 29 January 2013

Psychology of pain

Last week, I had the opportunity to talk to the Retired Business and Professional Men's Club about low back pain.  Over 100 members showed up, and they all asked a number of great questions.  In the end, much of what we discussed revolved around how to address chronic pain.  With this article, I am going to take a quick look at some of what we discussed.

Chronic pain is not just in the tissues, it's in the brain
What is the difference between acute and chronic pain?

With acute injuries, it is usually pretty clear why pain exists.  An injury takes place, tissues are damaged, inflammation pools into these areas, and things start to hurt.  With chronic cases, the reason why people feel pain is much more complex.  Often tissues are healed after 6 months, yet pain still persists for some reason.  A common example of that is the chronically painful Achilles tendon, which I blogged about here.

Recently, I wrote an article for the New Hamburg Independent discussing factors associated with back pain. Interestingly, psychosocial and lifestyle factors  (i.e. depression, obesity, anxiety, job dissatisfaction) were more strongly correlated to back pain than test results, such as findings on radiographs.

So why is this?  The answer, at least in part, comes down to the fact that pain is something that exists only if there is a brain there to perceive it.  If you tear a muscle, you could remove that muscle from the body, pass a current through it, and its contraction strength would be decreased compared to the healthy version of the same muscle.

However, as soon as you disconnect that muscle from the body, that muscle is no longer painful.  Pain is not an intrinsic characteristic of tissues like force of contraction is.  Pain is something that only exists if there is a brain to process the signal.

Psychology of pain

While a painful experience requires a brain, that is not to say chronic pain is all in your head.  However, it does explain why two people with very similar levels of tissue damage can have vastly different pain experiences depending on an array of factors impacting their psychology.

A great 2005 article summarized a number of different factors that contribute to how we perceive pain.  First, they explain that pain is actually processed in the limbic system, the emotional part of our brain.  When cancer patients underwent a frontal lobotomy (part of their brain was removed), these patients were still aware of the pain, but they no longer cared or considered it painful.  The same pain signal was reaching the brain, the brain  just was no longer equipped to tell the person that they are in pain.  Thus, pain no longer existed.

On a more practical note, they do a beautiful job of summarizing modifiable factors that have been shown to have an impact on the pain we perceive   Examples include how focused you are on the pain, how you learn to react to pain, the context you feel the pain in, how anxious or scared you are, and how you expect to react to the pain.  All of these are examples of things you can change to alter how much pain you feel without changing how much tissue damage is present.

An interesting example of this is how distracting patients may be an effective means to control pain.  For instance, burn patients experience excruciating levels of pain during their treatments and physical therapy.  Even with the use of opioid painkillers, the process can be unbearable.  Yet, when these same individuals are distracted using a virtual reality game, the pain they feel is significantly reduced.  There is no change in the tissue, no change in the pain signal reaching the brain; it only changes to how the brain processes that signal.

Another example discussed within the article takes a look at learned pain.  Two groups of people had their pain threshold tested.  One group observed models who were trained to react calmly and to have a stoic demeanor in response to the stimulus.  The other group of subjects observed models exhibiting poor tolerance to pain.  With no other difference between the subjects other than what they observed, those who watched the models with good pain tolerance required almost 3.5 times the stimulus until they reached their pain threshold.

What is the practical application?

At the end of the day, chronic pain is an extremely complicated issue.  It is of course important to address the specific tissues that are causing your pain, but it is also very important to look at these broad factors as pieces to the puzzle to solving your chronic pain.  Chronic pain is, by no means, all in your head.  However, altering what is going on in your head will undoubtedly have a positive impact on the pain you feel, and as a result, your quality of life.

Here is a cool video explaining chronic pain.

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