With all we know about the brain, you’d think we’d have the full picture when it comes to memories. Yet research is still revealing more about things like Post-traumatic stress disorder (PTSD), complex PTSD and other disorders. A paper recently appearing in the Asia Pacific Chiropractic Journal has thrown a new consideration into the fray though: could mind, trauma and muscle inhibition be linked ? And if so, what role would chiropractic care play in rehabilitation?
The healthcare industry has come a long way when it comes to our ability to find and repair damage, and yet our understanding of musculoskeletal dysfunction remains an area for growth. For example, many of us have learned the acronym “RICE” or “Rest, Ice, Compression and Elevation” as a first response to injury, and yet years after the man who coined the term reported aspects of the technique may actually delay the recovery of injured tissue [2,3,4].
Despite this recognition, advances in better treatment options have stagnated. Musculoskeletal disorders remain one of the most frequent causes of disability. However, while research has yielded a good understanding of the mechanisms underlying the onset of muscle weakness, we don’t have a great idea of the mechanisms underlying its persistence (even following ‘successful’ treatment).
Muscle weakness, diagnostically referred to as muscle inhibition, has been stated as a contributing factor to a diverse range of conditions such as whiplash, tennis elbow, runner’s knee and much more. It has also been mentioned in relation to many ‘unexplained’ pain syndromes. Muscle inhibition is a fascinating phenomenon. It is a protective factor in a way, as it stops aberrant movement of the muscle or tissue in the immediate wake of an injury. However, in the long term, it can result in persistent weakness of individual skeletal muscles.
But there’s potentially more to it than that.
This is where the new paper authored by Weissfeld in the Asia Pacific Chiropractic Journal proves interesting . “The hypothesis we are putting forth is that chronic weakness of individually tested muscles, more technically known as ‘muscle inhibition’, is sustained by maladaptive memories, making it similar to some descriptions of post-traumatic stress disorder (PTSD).”
One known initiator of inhibition is the arthrogenic inhibitory reflex in the brain (leading to arthrogenic muscle inhibition or AMI) which shuts down alpha motor neurons to certain muscles in response to trauma (1,2). It is thought to be a protective mechanism against the injurious muscle stretching. Neurologists have identified a similar phenomenon in ‘functional weakness’ which refers to weakness which is inconsistent with any recognisable neurological disease. One school of thought is that this may be part of ‘conversion syndromes’ where emotional upset manifests as physical symptoms.
Generally, muscle inhibition is thought to be irreversible as no treatment has been found to effectively ‘cure’ the condition. AMI is said to be resistant to rehabilitation and generally unresponsive to even intense or aggressive intervention.
In the recent paper, Weissfeld remarked that, “…‘Strengthening the inhibited muscle with an exercise program often reinforces the abnormal motor behavior, and makes it more difficult for the patient to recover normal function.’ Even when outward function is restored, it may come at the cost of locking patients into a lifetime of dysfunctional movement .”
What then do we do to improve it?
Some studies have found that Applied Kinesiology (AK) had the potential to reverse inhibition in a lasting way. The AK protocol (pioneered by George Goodheart) involves treating a set of specific reflex points located around the body that relate to unique muscles. These reflex points are thought to relate to the circulation of blood, lymph, and meridian energy to muscles, and points of interconnection between muscles and surrounding tissues and organs. The treatment includes neurological activation of the muscle by spinal manipulation to restore normal functionality. This may include:
The obvious link to chiropractic is in the spinal manipulation area. However, we also know that chiropractic care has been linked to changes in the brain. At this point, there has been no research specific to chiropractic treatment of muscle inhibition and thus we cannot make any claims yet. But it is an area that is laden with possibility.
It has often been said that chiropractic is about adaptability – that the nervous system that runs optimally is able to adapt more easily to the life and circumstances it exists in and around. So, what if we look at muscle inhibition as a maladaptation issue? This is the essential premise of the Weissfeld paper.
“Adaptation can be defined as a set of behavioural strategies developed during or following stress or trauma that serve one of two purposes. The first purpose is to avoid pain or other bad outcomes, and the second is to compensate for functional deficits.”
A more recent variation of the AK protocol was developed by a practitioner named Alan Beardall. It incorporated more muscle tests and reflex treatments. The treatments used are often simple (such as a single spinal or extremity adjustment, or 15 seconds massaging a muscle) but the results can be immediate and notable. The treatments may appear to be quite physiologically and anatomically unrelated to the muscles being addressed. Removal of inhibition can be seen in many muscles at once. There seems to be little relationship between the severity of symptoms, chronicity of problem, and treatments required. For example, a simple treatment might have the same success for an acute and mild issue as for a chronic and severe case.
It was a novel finding, one that seemed to demand more research. But perhaps the answer could lie somewhere in the intersection of memory, unlearning, and adaptation.
Memory and Unlearning
It is a little-known fact that memory is actually quite malleable. When you recall a memory, it becomes unstable and able to be adapted, updated, or even erased. For a memory to endure it needs to be re-stabilised when it is recalled. We call this ‘reconsolidation.’
If you present contradictory information to the recalled memory, you can basically stop it from being reconsolidated. This impacts the longevity and accuracy of the memory. This goes for all types of memory essentially (motor, emotional). In recent years we have begun to see therapeutic uses for this (which of course have to be ethical, as tampering with memory can have catastrophic results). One such application is Eye Movement Desensitization and Reprocessing (EMDR): a technique used to block reconsolidation and treat PTSD. The rapid side-to-side eye movement is performed while thinking about an emotionally charged memory. The effect is an almost immediate decrease in intensity of psychological pain associated with memories. The bilateral stimulation is thought to facilitate the erasure (adds a motor activity as a sensory stimulation)
So then: how can we apply this to muscle inhibition? In the Weissfeld paper, Applied Kinesiology practitioners used a technique called the sub-maximal break (SMB) test to assess muscle strength (they would isolate a muscle and tell the participant to resist increasing force). The force resisted was ramped up until a stable robust resistance/strength is seen or the muscle gives way.
The practitioners involved in the Weissfeld study treated 8 patients and a total of 136 inhibited muscles. Participants had to have a medical history including no neurological or musculoskeletal disorders in order to be included. They had a follow up check at least seven days after treatment and a maximum of 42 days post treatment.
The results of the study were impressive. 91% of muscles reactivated following treatment with 88% remaining strong 15 days later.
So, what does this mean? Why would a modified AK protocol that includes an adjustment and a short application of massaging a muscle or applying an acupuncture point yield such profound results? It is this point, it is an answer only more research can answer, but it is exciting. Perhaps, as Weissfeld suggests, muscle inhibition is muscle PTSD: mPTSD if you like.
While we are going to have to sit on the edge of our seats and wait for more research to be done, but it does beg the question: how deeply is memory involved in other injuries, restrictions or disorders? Well done, Robert Weissfeld on this exciting hypothesis paper.