Chronic Pain

What is chronic pain?

To understand chronic pain, we need to understand what acute pain is. Acute pain is a protective reaction from the body that occurs in response to perceived danger which may or may not be in the presence of tissue damage. When there is tissue damage, tissue healing occurs within the first 6 weeks after the damage has occurred, with further maturation of scar tissue occurring in the second 6 weeks. Any pain that goes beyond these 12weeks/3months is classified as chronic pain.

During this acute phase of healing the nerves lower their action potentials. An action potential is the minimum threshold a stimulus needs to reach in order for a nerve to fire. This is a protective reaction to prevent further damage to the body. Imagine how it feels when you have sun burn. Normally you are not aware of your clothing against your skin as the stimulus is not of a high enough intensity to alert the nerves, but when you have sun burn, you suddenly become aware of everything that touches the burnt area. As your body heals these action potentials slowly rise again, back to their resting levels, thus reducing the hypersensitivity. However, for various reasons this does not occur with chronic pain & the longer the pain is present the lower these thresholds go.

Besides changes to the nerve’s action potential thresholds, additional changes occur in the nervous system and the longer the pain continues the more complicated it becomes. When the nerves in our body have been active for a long time without being able to achieve a resolution to the problem they start to recruit nerves in surrounding areas to assist. A concept referred to as “nosey neighbours”. The more neighbours you have the more alert the nervous system becomes. These nosey neighbours then send information to the brain about the area next to them, and not only the area that they innervate, leading to a smudging of the information in the brain.

Motor & sensory representations on the brain.

Within the brain there are areas dedicated to receiving sensory and motor information called the sensory and motor homunculus respectively. Each area of the body is represented based on how much sensory and motor information it needs to process daily in order to perform its function e.g.: the hand is highly represented as it has millions of nerve endings which allow it the variety of functions it is capable of. It’s why a paper cut on the finger is so painful. When an area of the body becomes smudged at the sensory and/or motor homunculus the brain can no longer accurately interpret the information it is receiving from the body. Smudging is the reason why a painful area often feels swollen even when you can clearly see it’s not. This is not un-similar to what happens to the brain when you look at an optical illusion.

These changes to the nervous system are only one of the reasons why a pain response can be elicited from a task as simple as putting your shoes on, or clothing that is too tight, when you have been struggling with chronic pain. This is often confusing as we expect pain to mean that we have damaged something within our bodies. However, pain is how our body protects itself from perceived dangers that could potentially lead to tissue damage.

So if pain can occur without tissue damage, what else can cause pain?

In a sensitised nervous system something as simple as stress can lead to an increased perception of pain. But how? During a stressful event things like your blood pressure & heart rate increase. These two things are more harmful to your body so you will automatically divert resources to getting them under control. Now if you imagine your body to be a bank account with no overdraft, extra resources for one area means something has to go without. Pain that has been around for longer than 3 months has less threat value so it will go without its required resources for a time period but it will eventually make it known that it also needs resources by increasing the pain output.

Here are some of the other factors that can drive up the perception of pain in a sensitised nervous system leading to the perpetuation of pain:

• Poor Diet
• Poor sleep
• Unaccustomed activity
• Illness
• Uncontrolled chronic conditions (e.g.: diabetes or hypertension)
• Stress

But what does this mean for you if you are struggling with chronic pain?

Well, when you have been experiencing pain for a long time the body makes changes to the nervous system to protect itself. And just as those changes have been made, they can also be corrected & reversed with the right tools and understanding of the driving forces behind the perpetuation of pain. All of the other factors mentioned that contribute to the perpetuation of pain are manageable with the right tools and understanding of their mechanisms to the contribution of pain.

While this all seems scary & can make you feel helpless when you are the one going through it, there is always hope. The brain & the nervous system are amazingly plastic, meaning that they can rewire themselves, and revert back to normal levels, within the right environment. A thorough assessment of your unique combination of contributing factors can lead to a management strategy and tool kit that can help you to live with your pain instead of it living for you.