One of the most unique things about human beings is our nervous system and how it sets us apart from the rest of the animal kingdom. At its basest form, the nervous system is designed to promote survival. This is why we have pain. Pain is an interpretation by the brain that there is some sort of threat to survival, usually resulting in a response to mitigate that threat. In most cases these responses are normal and necessary; however, what about the times when the system gets it wrong?
Sometimes due to postural, biomechanical, or neuromuscular dysfunction, the mobility of our peripheral nerves can be compromised. Nerves are primarily made up of collagen fibers that have no specific alignment, which is quite different from the greater elasticity and more parallel fiber alignment of muscles and tendons. For this reason, nerves do not tend to stretch well and, in fact, tend to get quite irritated when they are exposed to too much tension. This irritation can lead to an increase in sympathetic nervous system activity resulting in further alteration of the neuromuscular system.
As nerves get stretched and therefore damaged to a small degree, the threshold necessary to produce an impulse decreases resulting in increased sensitivity. As sensitivity increases, the actual number of nerve impulses going to the brain increases. The brain must then interpret this influx of impulses, and we tend to see a decrease in the ability of the brain to determine whether or not the impulse is noxious. All too often in cases of prolonged dysfunction, the brain automatically assumes the worst-case scenario, and even the lightest of touch or change in position can result in a tremendous pain response.
David Butler is a researcher and clinician doing most of his work in Australia and the United Kingdom. He has developed several techniques and approaches designed to improve the mobility of the nervous system thereby reducing the irritation and sensitivity and allowing the brain to have a better opportunity to discriminate amongst different types of stimuli.
Lorimer Mosely is also a researcher from Australia investigating neurodynamics and what he refers to as the neuromatrix nature of pain. The neuromatrix refers to the interplay of the peripheral nerves and the central nervous system (brain) and where dysfunctions can occur. Mosely has done extensive research on chronic pain, and he has discovered that simple education of patients regarding physiology of the nervous system can have a greater effect even than exercise. At Paradigm we are emphatic that education is a major component of patients’ recoveries.
Another one of Mosely’s concepts is called the neurotag. The neurotag refers to how we individually process different stimuli, environments, and situations. It is very important to note that a neurotag is specific only to a particular individual and is very dependent of past experiences. Take for instance someone who has been in a motor vehicle collision. That person very likely has some reservations about driving, especially in particular parts of town or in particular conditions (e.g. snow or rain). When that person is behind the wheel, visible changes can be noticed in how he positions himself and an increase in tonic neuromuscularactivity occurs. This increase in tonic activity results in alteration of movement pattern, which can very likely perpetuate their symptoms. Another example of a neurotag involves someone who fell off a ladder at work. If we were able to do a functional MRI of her brain and simply showed her a picture of the ladder in her workplace, it is very likely that the areas of the brain classically associated with pain and fear are activated.
Psychology can play an important role in our pain perceptions and neurotags, as well. Carl Jung was one of the first modern philosophers to propose the concept of archetype and how it relates to the human psyche. We can sense the presence of the archetype in the attitudes and behaviors of our patients and how they perceive injury and recovery. Although we don’t like to admit it, there are people who have had bad experiences with exercise and perceive it to be harmful rather than ultimately helpful, and although we practice physical therapy, we do have to address some of the psychological resistance to movement and training.
There is good news, though. If we can educate patients about the phenomena of the mobility of the nervous system and the neurotag and allow them to explore new ways of non-threatening movement, studies have shown that they can re-establish their perceptions, responses, and neuromuscular control allowing for improved tolerance to activities with better management of symptoms.