Desensitization.  Honestly, not a very fun approach to an orthopedic manual physical therapist!  I do sort of gripe to myself when I know I need to do this. Results usually are not quick (which we all like!) and the underlying “problem” is quite complicated and not well understood.  

We typically use desensitization to specific areas of the body, particularly the distal limbs, in order to create a more normal response from a sympathetic nervous system principle to different grades of touch.  This helps in decreasing the hypersensitivity, or more specifically allodynia, of pain when a light pressure/touch or brushing of the skin occurs.  I know many of you know more about the molecular and cellular level of allodynia, but I am going to explain a more pragmatic approach to clinical practice.

A Case Example:

I recently had an older lady who had her radial artery harvested for coronary artery revascularization.  Not to get into awful detail, she came to me many months later basically for strengthening of the wrist/hand and desensitization.  As a fairly common side effect of this procedure, the patient presented with distal/lateral radial antebrachium and dorsal thenar parasthesias from an insult to the superficial radial nerve.  It was bad enough that the patient could not sleep, could not wear sleeves/gloves and literally jumped if lightly touched, aka allodynia.  Very disrupting to quality of life as you can expect and was even going to go get the nerve ‘burned’ until she asked surgeon to come to therapy.

Desensitization obviously came to mind but even the most soft material, such as silk, was a painful stimulus. I wanted more as I was not satisfied.  I tend to treat by the approach of,

“if you can satisfy yourself, you can satisfy your patients”

I opted to perform a more reflex inhibition approach through muscle energy techniques to the antagonist aspect of her thumb.  Meaning, I performed thumb MCP and thumb IP flexion low level contractions with a hold (see below).

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Thumb IP Flexion MET (note no hand contact on dorsal thenar eminence)
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Thumb Flexion/Adduction MET (note no hand contact on dorsal thenar eminence)

and BAM!  Immediate results with no pain during light touch to the same region.  I was then able to prescribe this as a self-care approach at home (using her other hand) and then a more effective desensitization routine.  She was satisfied and I was satisfied.  I can’t remember how many visits it took, but I can assure you she recovered much quicker this way.

I have since used this technique on patients s/p ulnar nerve transposition (using other muscle groups of course) with again good results.  I encourage you to try!  Let me know what you think, especially those out there who are more well-versed and trained in neurodynamics.  

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6 comments

  1. Interesting results Harrison. From a neurodynamic perspective, not sure why this helped as well as it did. Could have freed up an AIGs somewhere along the distal neural container, or could have decreased CNS sensitivity to movement/touch by decreasing perceived threat around the area. Either way, simple technique, great results! Good job! What was her normal response to AROM/function prior?

    1. Wow you’re quick E! Ha. Yeh it was much better results than I expected. It was one of those look around and make sure she isn’t pulling my leg. Of course I acted like I have done it hundreds of times before and get great results 🙂

      I am really getting more into the neural education and I don’t have an answer for it. I do agree with the perceived threat aspect and it may be more on the psychological than actual changes on molecular level. Until then, every healthcare provider that worked with her probably “hurt” her by touching it and then giving her data that she did not want to hear (such as more surgery, this may not improve, etc).
      Hv

  2. Harrison,

    From a pain neuroscience standpoint, I think the manual treatment you provided fits into a piece (done by Cory Blickenstaff, PT over on SomaSimple.com – http://www.somasimple.com/forums/showthread.php?t=2823) that explains Manual Therapy in a different unified perspective and why this treatment was effective.

    Cory writes in this thread three primary components of all manual therapy: inside-out neuromodulation, placebo and outside-in neuromodulation. Each is defined as follows: Inside-out neuromodulation – Those treatments which satisfy the needed action sequence, which is the ideomotor expression of the appropriate motor response, which is synonymous with eliminating threat will be successful. Consisting of non-threatening environment, novel stimuli, graded exposure. Placebo – Those tretments which are consistent with the expected relieving therapy will be successful. There is a placeboand/or nocebo component in any therapy, due to patient expectations of treatment effect. Outside-in neuromodulation – Extreroceptively, done with touch to reduce nociception and sympathetic tone, through novel stimulus that is non-threatening and/or fullfills expectations will tend to be more successful. Introceptively, an action that is allowed to be generated internally toward a “goal state” that is consistent with pain resolution will tend to be more successful.

    Looking at this your treatment hit on these. Insideout, it was a non-threatenting environment (you didn’t hurt her like others did), novel stimuli (something new that her brain did not have to run the pain neurotag with) and graded exposure (I’m guessing the amount of force that you applied was a gradual progression). Placebo, she asked to come to therapy, so I’m guessing her expectation was positive of therapy. And from reading your blog Harrison, I would expect you created a non-threatening environment for her in many ways. Outside-in, the touch was non-threatening and provided some sensory motor awareness to the area while not trigging the pain neurotag for the cortical mapping area to help “redraw” some of the smudged area in the brain back by giving it a healthy improved representation of the area.

    Nice work.

    1. Kory,
      Thanks for the very detailed response. I agree with all your comments. I will read into Cory’s post. Definitely very interesting results. I appreciate your time and thoughtful comments!
      Harrison

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