Are You a Responsible Pain Modulator
As I have read further and further into the neuroscience literature in search of an explanation for a lot of the effect we see as far as treatment is concerned, a common topic seems to always arise – conditioned pain modulation. Conditioned pain modulation (CPM) is a test of the body’s pain inhibitory capabilities. Often in studies it is tested using a “pain inhibits pain” paradigm. These studies use a noxious stimulus as the conditioning stimulus to induce reduction in pain from another later stimulus. ‘How much does this pinch hurt if I take a sledgehammer to your toe first?’ David Yarnitsky is a world leading researcher on the topic out of Israel. In a study discussing the pain inhibits pain paradigm, he states (1):
The author would like to stress a point often neglected in the context of CPM. The application of this paradigm is done in order to assess the endogenous analgesia capability of the individual being assessed. To that end, a variety of other conditioning stimuli could have been used, including stress, hypnotic suggestion, and such like.
The common use of a painful stimulus as the means of conditioning is due to it being an easy and quick way to induce activity in the descending pain modulatory pathways.
I think this topic is of great relevance to PT as we frequently see painful interventions used with impressive pain relief and short-term change. A few that come to mind are foam rolling the IT band, aggressive instrumented massage, cross-friction massage to painful areas, painful “releases” to muscles, or needling. I don’t know about you but the last time I attempted to roll on my IT band I hated every millisecond of it because it hurt like crazy. Despite this pain I have seen numerous patients come in swearing by it. Science has pointed to the fact that we cannot, using human created force, produce structural deformation of the IT band. Then what the heck are we doing??? Conditioned pain modulation fits here. We can consider the painful stimulus of rolling on the foam roller as the conditioning stimulus that can take any previously painful clinical sign and change it due to this effect. The question we must ask ourselves is whether the pain modulation from the foam roller is worth it. Can we produce this type of effect without having to provide a noxious input to the patient?
Another important thing we need to consider: can we utilize other less or even a non-noxious stimuli to condition this response? It seems the rave these days is to lean on the massive gray area that is neurophysiological effects of our interventions. What if our interventions are driven by this exact pain modulation whether painful or not? Sure different interventions may utilize different modulating pathways (opioid vs canninaboid vs. etc), but what if the common thread is an input that is processed by the central nervous system and produces favorable modulation of output i.e. pain?
The following is a quote from Derek Griffin who has a PhD in pain and is a Specialist MSK Physiotherapist in Ireland that caught my eye on Twitter. Diffuse Noxious Inhibitory Control (DNIC) is a term that has recently been suggested to be changed to CPM.
This quote really brings up questions we need to be willing to ask ourselves. If needling, iastm, or manipulation is just one avenue for such modulation then why and when do we choose it? Should passive ways of eliciting this effect be the hallmark of our care of patients in pain? I continue to hear physical therapists talk about how personal trainers and chiropractors can do exercise so we need to separate ourselves by saddling up onto passive interventions. Shiny tools and techniques often come with theatrics and non-specifics that may be more easy to elicit these effects. These effects, though, are temporary. Should we just choose the easy road of short-term change? Are we going to just hope we made a short-term change that is enough for patient to decide movement is safe on their own?
From my experience, it can be a monumental task to have a patient tap into their own modulation actively when the medical system has created such a sense of damage and frailty. For example, creating a sense of safety for the organism to move their back when the medical system has told them they have the back of an 80 year old or another practitioner has shown them the balloon model of a disc pushing into nerves is tough work. It is not a change that often occurs in the short-term. It often takes a large cognitive shift of the patient and time.
If we truly want to be the change agents in the care of pain, then passive interventions need to be used judiciously and with good clinical reasoning. People in persistent pain will come to you with stories about how they tried everything and while most worked well in the short-term they did not create lasting change. Why do we think our short-term changes are any different? Conditioned pain modulation is a short-lived phenomena and if we are the only ones who can elicit in a patient’s life then are we truly helping? Sure patients will line up for us to modulate their pain but when we see the same patients continue to line up when do we decide that maybe short-term changes are not the answer? Our goal should be a patient who can modulate their pain actively on their own and have an internal locus of control. Good old fashioned movement and cardiovascular exercise may not be as sexy as some of the techniques and tools out there but I would put the literature supporting the use of it up against any other intervention out there.
Listening to a patient’s story and digging into the their attitudes, beliefs, cognition, behaviors, and other psychosocial issues and barriers is a must if we intend to identify what prevents a patient from a sense of safety in movement. It is hard work to move patients into graded exposure and graded activity programs to get them moving. This work though is what gives them the locus of control the biomedical way of treating their pain has taken away from them. Let’s not become another profession who takes this from a patient.