Two of the most interesting new treatments for chronic pain are graded motor imagery and mirror therapy. A related experimental treatment is called “tactile discrimination.”
Chronic pain creates changes in your brain. We think that these brain changes cause other functions to become impaired as well, for example, right-side and left-side discrimination. Right-side and left-side discrimination is simply knowing your left side from your right side. If you have chronic pain in your right hand, your brain will have a harder time identifying right hands. Re-train the brain to again be able to discriminate right versus left, and pain can decrease.
We are finding out that chronic pain also creates an impairment in “tactile discrimination,” which is simply your brain figuring out what is touching your body, without you looking with your eyes. Here’s an example: While you look the other way, I can touch your arm with, let’s say, the point of a pencil or an eraser. Your brain should be able to figure out which is which – the pencil point is pointy and the eraser would feel softer. However, in chronic pain, this ability becomes impaired in the area you have pain. For example, patients with back pain have a harder time figuring out if they’re being touched by that pointy pencil or the soft eraser on their back.
Research is looking to see if re-training patients to again discriminate touch can help decrease their pain. In other words, does this type of re-training work the same as re-training to figure out right and left.
One of my favorite researchers, Lorimer Moseley, recently published a small trial looking at this question. 13 patients with complex regional pain syndrome (CRPS) of one limb had tactile discrimination for 2 weeks. The control group were simply touched, without being asked to figure out what the touch was. Thus this tested if just touch or actual discriminating what the touch is results in any change in pain.
The results: There was no change in pain or being able to discriminate after simply being touched. But, pain and touch discrimination were better after practicing touch discrimination. And the improvements still continued at a 3-month follow-up.
This is very exciting work! I have been using this type of treatment with some of my patients, and look forward to more studies coming out. Several national pain associations are trying to spread the word about these treatments and train clinicians in using them. Knowledge is power!
The original article is Tactile discrimination, but not tactile stimulation alone, reduces chronic limb pain, Pain 2008, Vol 137, Pages 600-608.