You may have noticed that my blogging frequency has been a little slower than the usual, and I would like to apologize for that. I am in the midst of creating my first course that I am presenting to my coworkers. It has been a very exciting yet time-consuming process. It makes me excited and more motivated to someday start teaching more on the reg.
Ever since I started blogging people started asking me questions. These range from many topics regarding physical therapy, career advice, and the like. Some of the more frequent ones include:
- What courses should I look at?
- Any advice for a new grad?
- Seriously, Bane. What’s the deal?
But the one I get asked more often then not is as follows:
“Zac, how do you integrate PRI into a pain science model?”
A great question indeed, especially to those who are relatively unfamiliar with PRI. With all the HG, GH, AF, FA, and FU’s, it’s easy to get lost in the anatomical explanations.
Hell, the company even has the word (gasp) “posture” in the title. Surely they cannot think that posture and pain are correlated.
I think there is a lot of misinformation regarding PRI’s methodology and framework. What needs to be understood is that PRI is a systematic, biopsychosocial approach that predominately (though not exclusively) deals with the autonomic nervous system. The ANS is very much linked into pain states, though not a causative factor.
But of course, that may not be enough. Perhaps we can dig a little deeper into what may be going on. My hope with this blog is to make a guide to integrating two very effective paradigms which I feel are not mutually exclusive.
PRI Patterns and Nociception
David Butler discusses many nociceptive processes, including mechanically-induced pain, inflammation, and ischemia.
I feel that the PRI patterns, albeit normal, could contribute to nociceptive processes. Mechanical pain makes the most sense. We could think of this process as typical anatomy/biomechanics. If one is in a right-lateralized and extended position, certain areas are going to be more prone to mechanical deformation than others.
Inflammatory processes could be caused by acute injuries secondary to position. The easiest example I could give would be an ankle sprain. If someone is in a right lateralized pattern (a la Left AIC), the right ankle/foot complex would be more supinated, thus being more at risk to sustain an ankle sprain. So in these cases, a right lateralized pattern could be one of many risk factors for leading to an injury.
Ischemic nociception is where things get interesting. There are two ischemic features that Butler mentions in “The Sensitive Nervous System” that stood out to me:
- Symptoms after prolonged or unusual postures.
- Rapid ease of symptoms after a change of posture.
If I am right lateralized and unable to leave right stance, this position could become ischemic after a prolonged period. Less movement, less axoplamsic activity, less blood flow.
Moreover, symptoms would be much more challenging to relieve. If I am unable to adduct and internally rotate my hip maximally, then I effectively limit what movement planes I am capable of utilizing. This concept is what Bill Hartman calls movement variability. When a position becomes nociceptive, movement must occur to reduce danger signals and restore axoplasmic and blood flow. I am looking for freedom. But triplanar activity is unachievable, movement freedom becomes a limited resource.
I simply lose the ability to change posture, which limits my ability to relieve ischemia.
PRI Patterns and Peripheral Neuropathic Pain
When I am in right or left stance, the nervous system slides and glides to accommodate position. Suppose I am in right stance. Right stance would require my right hip to be more extended, adducted, and internally rotated. My left hip would be flexed, abducted, and externally rotated.
When my hips are positioned as above, the sciatic nerve would be more taut on the right and slacked on the left. Now if I never leave right stance (aka left AIC), then I could potentially be more at risk for tension impairments on the right.
Another example would involve spinal position. Research demonstrates that humans have a naturally right oriented spine (here & here) which is precisely what PRI advocates. This orientation may bias more compression on the right nerve root than the left. If we have someone who presents with a dominant PEC i.e. spinal hyperextension, we could potentially see increased compression bilaterally.
PRI, What a Great Defense
Now of course, we know very well that nociception and peripheral neuropathic issues are neither necessary nor sufficient for a pain experience. So how does PRI relate to pain?
Simple, the PRI patterns are the perfect protective postures for us to assume when we are threatened.
We drive these patterns via our autonomic nervous system. If you read Stephen Porges work, he discusses the concept of neuroception. Neuroception is how our nervous system’s evaluates risk. We take all sensory information in regarding our environment and determine if we should fight, flight, freeze, or relax and socialize.
When we neurocept (is that a word??) something as a threat, we will become more sympathetically driven and likely use our most efficient processes to respond to the threat. We use what we know.
We bias ourselves to the right because motor planning occurs in the left hemisphere regardless of hand-dominance. If I stand on my right leg, I simply am better able to make my next move than if I were to stand on my left.
We will increase activity of our anti-gravity muscles, our extensors. To defend against a threat, it probably makes sense to stay upright. This function has governors present in the reticular formation. The pontine reticulospinal tract controls extensor tone, and the medullary reticulospinal tract inhibits this tone. One of these is spontaneously active and the other is not. Guess which one? Extension is the norm to keep upright. Thus, extensor tone is the brain’s reflex-driven path of least resistance. Perhaps if I am under threat long enough, I become a PEC?
Breathing will become faster and shallower. Take a look at the diaphragm. Which side is larger?
The right hemidiaphragm is larger and more powerful than the left. If I am already biased to the right and have a stronger muscle on the right, breathing becomes a less conscious process.
My point of listing these plausible changes in response to theat is to demonstrate that we are fairly similar creatures. Bill again, helped me realize this on a post he made at Somasimple.
If a lion were to walk in the room, what physiological changes would we undergo? Our heart rate would increase, pupils would dilate, HRV decreases, we sweat, etc. Are these responses not the same for all humans? These physiological changes are a common human pattern. Could it be possible there is a common threat response in postural and muscular activity as well? This pattern of positioning and neurological bias is what I feel PRI has put together more completely than anyone else.
Granted, we can still account for individual differences, but realize these changes are likely minor variations off the normal response.
When under threat, your heart rate increases 20 beats per minute, mine increases 10.
When under threat, your sweat accumulates on your brow, mine on my palms.
When under threat, your left anterior hip capsule becomes lax via compensatory external rotation, mine stays intact after compensatory external rotation.
Similar responses occur through varying degrees.
Treating Pain Through PRI Approaches
I think PRI can influence the pain experience by altering autonomics via the vagus nerve. Paced breathing can positively influence pain states, and PRI breathing-style is very much paced.
The positions utilized are the farthest removed from the typical protective response when we perceive threat. If right stance with increased extension is what we do when we are threatened, then I am going to get you into left stance and flex you until the cows come home.
PRI essentially is graded exposure into left stance and parasympathetic paradise.
That doesn’t mean that PRI is going to eliminate the entire pain experience in all cases. There are some people who have injuries that are producing nociception, and may take time to heal. There are some people who have enough neural sensitivity requiring a hands-on or neurodynamic approach. There are some people who have centrally-maintained pain experience that requires graded exposure, pacing, and homuncular refreshments. The autonomic protective response is one piece of the puzzle, and altering that piece is the only way one can know if it is contributing to one’s complaint.
Therapeutic Neuroscience Education…PRI Style
So usually when I educate patients I just run through the above as quickly as possible…
Okay that’s not 100% true.
I actually use the concept of a home security system to explain how PRI patterns are a part of the pain experience. Go ahead, watch the video, I’ll wait.
So as you can see, I do not go into nitty gritty detail of PRI methodology. It is mostly not necessary and could potentially increase threat perception. But framing the system as done above can help the patient understand why we may work at areas far away from the pain experience. We are treating what area of the system continues driving the protective response. We are treating the person.
PRI is a very powerful system that does not have to go against current pain research, not that it ever did. But the above may be a potential framework and justification as to how PRI affects the pain experience. It is the framework that I operate on, and will continue operating on until I am shown otherwise.
I hope that I am.