Persistent Pain, the Neuromatrix, and Pain Perception

Pain demands an answer. Treating persistent pain is a challenge for everyone; providers and patients. Pain neuroscience has changed drastically since I was in physical therapy school. This update comes from the International Spine and Pain Institute headed by the lead author Adriaan Louw, PT, PhD. If you are interested in reading more about persistent pain, I suggest reading the article in its entirety.

This article brings together several comorbidities that pelvic physical therapists often encounter; fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, and chronic Lyme disease. The authors argue that all of these syndromes have many common symptoms and might be dependent on the provider that the individual goes to as to which diagnosis the individual receives. Often, once an individual has a diagnosis, he or she (more often she) then identifies with this label. The authors reason that once medical pathologies have been ruled out, then a more holistic, biopsychosocial approach may create better outcomes.

Pain neuroscience education is a way to explain pain to patients, often with analogies, with a focus on neurobiology and neurophysiology as it relates to that individuals pain experience. To be able to educate our patients, we as providers, must be able to understand neuromatrix, output, and threat. Moseley states “[p]ain is a multiple system output activated by an individual’s specific pain neuromatrix. The neuromatrix is activated whenever the brain perceives a threat”. If that sounds like gibberish, consider watching this TEDx talk by Lorimer Moseley on YouTube (the snake bite story is a favorite of mine):

What is a neuromatrix? Essentially, it is a pain map in the brain; a network of neurons spread throughout the brain, none of which deal specifically with pain processing. The way I visualize it is to think about what goes on when you think of your grandmother. There isn’t a grandmother center in the brain, but there are sights and smells (sensory), feelings (emotional awareness), and memories that all come up when you think about her. When we are overwhelmed with pain, those regions become taxed and the individual may have difficulty concentrating, sleeping, and/or may lose his/her temper more easily. Just as each person’s grandmother is different so is a person’s pain and the neuromatrix is affected by past experiences and beliefs.

Pain is an output. It is a response to a threat. When a person is exposed to a threatening situation, biological systems like the sympathetic nervous system, endocrine system, immune system, gastrointestinal system, and motor response system are activated. When a stress response occurs, these systems are either heightened or suppressed to help cope, thanks to the chemicals epinephrine and cortisol.

What is a threat? Threats can take a variety of forms; accidents, falls, diseases, surgeries, emotional trauma, etc. Tissues are influenced by how the individual thinks and feels, in addition to social and environmental factors. The authors propose that when individuals live with chronic pain, their body reacts as though they are under a constant threat. With this constant threat the system reacts and continues to react, and the nervous system is not allowed to return to baseline levels. This can create a patient presentation with immunodeficiency, GI sensitivity, poor motor control, and more. This sounds like most patients who walk into my clinic. The authors suggest that one system may be affected more and that can influence what the patient is diagnosed with even though the underlying biology is the same for many conditions. There are theories for why that happens; genetics, biological memory, or it could be the lens of the provider that the patient sees. There is a table in the article that shows symptoms, diagnosis, and current best evidence treatment for the conditions of fybromyalgia, chronic fatique syndrome, irritable bowel syndrome, and chronic Lyme disease which is worth a look. The treatments all work to calm the central nervous system.

The authors go on to question the relationship between thyroid function and these conditions as changes in cortisol and the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is fascinating, and confusing. Luckily, the Pelvic Floor Series Capstone course does a great job breaking it down.

Now that this hypothetical patient is in our treatment room what do we do? The authors suggest seeing these conditions for what they are: chronic pain conditions. They recommend that physical therapists see past the label that a patient may have picked up with a previous diagnosis, and keep the following in mind when treating these patients:

• They are hurting
• They are tired
• They may have lost hope
• They may be disillusioned by the medical community
• They need help

These people need the following from their medical providers:

• Compassion
• Dignity
• Respect

With empathy and understanding therapists can use skills in education, exercise and movement with the intent to improve system function (immune, neural, and endocrine), rather than fixing isolated mechanical deficits.

Louw, Adriaan PT, PhD; Schmidt, Stephen PT ; Zimney, Kory PT, DPT ; Puentedura, Emilio J. PT, DPT, PhD Treat the Patient, Not the Label: A Pain Neuroscience Update.[Editorial] Journal of Women's Health Physical Therapy. 43(2):89-97, April/June 2019.