A Guide To Better Understanding Pain

Reading Time ~ 10 minutes.

During my education as a chiropractor, I came across the work of Lorimor Mosely on several occasions. He is a neuroscientist from Australia that studies pain. His book, Explain Pain, does a fantastic job at exploring the complex science behind what pain is and how to best understand it. I have summarized the concepts below with the permission of the publisher.

What is pain?

Pain is an experience or an output that is felt when a person is in danger. It is a decision that only the brain can make once it has processed all relevant information.  You can break a bone, sever a nerve or tear a muscle but you won’t experience pain if your brain does not think you are in danger. The primary purpose behind why pain exists is to motivate you to take action against threat, ultimately keeping you out of harms way.

The authors make reference to several cases in which people are in catastrophic events and experience no pain.

• The athlete who fractures a limb while in the final seconds of a game and continues playing without pain.

•  Surfers who have had their legs bitten off by a shark and only reported feeling a bump at the time.

Pain is Context Dependant

Consider two individuals, one a pianist and one a professional dancer. If both sustain the same finger injury, which individual’s finger do you think will hurt more? Finger damage poses a greater threat to the pianist compared to the dancer and thus pain will likely be more prominent. In this way, context gives meaning to the pain response.

The authors make reference to “Ignition Cues” which are environmental sensory cues that serve to kick start the pain experience. An example of this is pain being influenced by those around us. Males have been shown to have greater pain thresholds if the person administering the test is a female. Another example would be an employee experiencing more pain when a boss is present at work.

The Physiology of Pain

Sensors are spread out throughout your entire body. These sensors are specific to certain types of stimulation (mechanical, temperature, chemical).  When activated, these sensors carry information to the spinal cord about what is going on in the tissue. Nociceptors are specialized sensors which respond to a variety of different stimuli. Regardless of the stimuli, the message is always the same. “DANGER.” The information travels to the spinal cord and is relayed to the peripheral nervous system’s minibrain, the dorsal root ganglion. This is the first area where information is evaluated and/or modified. The information is then relayed to the brain, at which time a very complex process begins. The brain evaluates the information by looking at memory, emotional context, consequences and reasoning. It very quickly consults with the premotor/motor cortex, cingulate cortex, prefrontal cortex, amygdala, sensory cortex and several other areas before making a decision. If the brain concludes that the threat is real, then it will output a pain signal. Several systems are involved in the expression of pain such as the endocrine, motor, autonomic and immune systems.

What is important to note here is that humans do not have pain pathways, pain receptors or pain centers in the brain.

“Nociception is neither sufficient nor necessary for pain.”

Recent brain imaging studies have shown that activity patterns of individuals experiencing pain varies from person to person. There are no specific pain centers but rather areas of the brain which are considered ‘ignition nodes’. These are the same areas of the brain that are used for sensation, movement, emotions and memory. Pain hijacks these areas to express itself.

Central Sensitization & Chronic/Persistent Pain

Sensors are designed to pass information to the brain as efficiently as possible. Sensors only live for a couple of days and adapt frequently, change thresholds, stay open longer and even increase in number. The system is always adapting to keep you out of harm.

more danger = more sensors = more sensitivity = more pain

The authors make reference to pain neurotags, which the brain is able to activate in response to a familiar stimulus. For example, you may have a painful experience in a specific context, so the brain stores the information in the brain as a neurotag which can be activated if the same stimulation is perceived by the brain in the future. The brain becomes more efficient at producing pain the more the neurotag is activated.

Some factors that increase sensitivity of receptors contributing to persistent pain are:

• Autonomic Nervous System (sympathetic vs parasympathetic)

• HPA Axis/Endocrine System (excess cortisol/adrenaline)

• Immune System (high levels of pro-inflammatories)

Increased stress levels, being labeled with a diagnosis, your beliefs about your pain, activity levels and previous episodes all influence your pain experience.

The authors make reference to “Thought Viruses” which are beliefs that are powerful enough to maintain a pain state.

“I’m in pain so there must be something harmful happening to my body.”
“I’m not doing anything until the pain goes away.”
“The CT machine couldn’t find it so it must be bad.”

Modern Management of Chronic/Persistent Pain 

The ultimate goal is to get individuals moving without activating pain neurotags. The human body is designed to move. Appropriate movement that is planned and graded will help reduce central sensitization and decrease pain.

The first step in helping someone with chronic/persistent pain is understanding the relationship between his or her pain and activity level. Education, knowledge and understanding provide the foundation for therapeutic movement. These 3 elements also reduce the threat associated with pain. No patient should be performing painful movement if they don’t understand why they are hurting.

“Educated movement is brain nourishing, because it establishes and re-establishes fine functional sensory and motor representations in the brain, using pathways laid low by fear and ignorance.”

Education and Understanding

Therapists should start by educating the patient and debunking myths about pain. For example:

• “No pain, no gain” attitude – some pain during rehab may be appropriate, however, you need to understand the necessary balance.

• “Let pain be your guide” – WRONG. If chronic pain patients followed this sentiment, they would do nothing to improve their wellbeing. They must take control of their pain.

Things to keep in mind:

• Pain physiology can and must be explained to all patients regardless of their academic backgrounds.

• Knowledge of pain physiology reduces the threat value of pain – reduced threat means reduced activation of protective systems.

• Combine pain physiology education with movement approaches to improve physical capacity and reduce pain.

• We need to allow for deep learning to take place. Information must be retained, understood and applied – we need to know WHY things hurt and integrate knowledge into our attitudes and beliefs.

Smart Thinking (“Your hurts won’t harm you.”)

If you are hurting, or hurting more than normal, that does not mean your tissues are being injured more so. Recurrent pain is often protective in nature and does not mean your tissues are experiencing additional damage.

At this stage, it is important for the patient to understand what is triggering their pain and what factors are contributing to it.

Pacing and Graded Exposure

Movement is essential for the health of all body systems and processes. Movement needs to be a graded process because pain can be debilitating if pushed too far. The authors recommend the following steps:

1. Decide what the patient wants or needs to do more of (swimming, cycling, walking the dog etc.).

2. Find your baseline. Find the sweet spot at which you can perform the activity without triggering a flare up.

The Virtual Body

A virtual representation of each body part exists in the brain, known as the virtual body. When experiencing chronic pain, an individual may begin protecting that area of the body by guarding or limiting activity. The result of this type of behaviour is a ‘smudged’ representation of that specific part of the virtual body in the brain which is distorted and less defined. The goal of rehabilitation is to reintroduce movement, either visually or physically, to stimulate the virtual body in the brain to begin dissociating the act of movement from the pain neurotag. It is important to understand that with some patients, even the smallest movement can be aggravating. In this scenario, begin with visual tasks (ex. imagine raising your arm up without actually performing the movement).

Take Home Points:

• Pain is an output of the brain and does not relate to the degree of tissue injury (more pain does NOT equal more harm).

• It is important to discuss the difference between hurt vs. harm with your patients (it may hurt, but it may NOT be harmful).

• It is important to educate patients regarding why they feel pain and why it persists even though the tissues have healed.

• Avoid giving patients diagnostic labels like fibromyalgia or chronic fatigue syndrome. This may cause further fear avoidance, stress and dependence on the medical system. Listen to your patients and understand their individual experience.

(This summary was posted with permission from the authors and publisher).