Chronic pain has no sympathy.
It has no discrimination either.
It doesn't care about your age, gender or race.
As long as there is ongoing cause or contributing factors, chronic pain continues to thrive.
If you have not read the first part of understanding pain, please read it.
For part two, I will expand on the process of sensory input assimilation and central nervous system centralization as part of the neurological adaptations from chronic pain.
Our brain relies on sensory inputs to function.
The brain is constantly seeking information from the skins, eyes, organs, muscles, tendons, ligaments and joints.
The brain then takes the sensory inputs and adjusts everything accordingly including body physiology, chemistry, muscles, joints and behaviors.
If it's too hot, the sensory input from the skin advises the brain to cool you down by sweating.
If you put your back out or have a kink in your neck, feedback information from the spinal joint and muscles alerts the brain of an injury.
The brain will then respond with pain, inflammation and muscle spasm.
Think of it this way.
The brain is like a computer.
If you press Enter, you'll get a line return.
If you press the mute button on the keyboard, the computer turns the speaker off.
Like the brain, the computer depends on whatever input you type on the keyboard to display the result.
Since the brain and nervous system rely on sensory inputs to produce or adjust any results, each neurological input is different with distinctive result.
Back to the computer, the Enter key is different from the mute button.
Their function is also different.
However, with chronic pain, the brain is confused.
It cannot clearly identify which input is which.
With chronic pain, many sensory inputs look similar to the brain.
The computer cannot tell the difference between the Enter key or mute button.
For simplicity, I refer to this as sensory assimilation.
But in neurophysiology, this process is called central nervous system centralization.
If you are wondering what does central nervous system centralization have to do with chronic pain, please give yourself a reward.
May I suggest a cold, crisp, beach-wood aged lager beer.
Hmm...
beer.
Oh yeah, where were we? In central nervous system centralization, the pain threshold tolerance is reduced.
The lowered threshold allows other sensory stimuli to behave as pain stimuli.
Think of pain threshold as a hill.
Normally, only performance cars with V6 and stronger engines are powerful enough to go up the hill.
However, in chronic pain, the threshold is lowered.
The hill is not as steep as before.
Even a Toyota Echo can go up the hill now.
If you are wondering what's so significant about pain threshold lowering? Reward yourself with another beer.
The significance is that the brain will continue to notice pain in the absence of actual pain stimulus.
There is no relief unless the threshold is returned to normal and the central nervous system centralization is reset.
This is a very common phenomenon in people living with chronic pain.
Normally, you should not feel any pain from touching.
Touch is not a pain provoking input to the brain.
Regardless of how hard or deep you are being touched or pressed during palpation, there should be no pain.
The brain can adjust to different levels of pressure and touch.
However, in chronic pain, various non-provoking pain stimuli including touch and pressure can cause pain.
This is referred to as allodynia in neurophysiology.
Can you sympathize with people living chronic pain, myofascial pain syndrome and fibromyalgia? Even the simplicity of sleeping and wearing heavy clothing can cause pain.
In any injury, there is some level of inflammation.
With inflammation, the body produces neurochemical pain mediators such as Substance P, Bradykinin and Prostaglandin.
These pain mediators are always present in chronic pain.
They will not go away as long as the inflammation is there.
Unfortunately, prolonged exposure to Substance P, Bradykinin and Prostaglandin sensitizes other nearby sensory inputs to pain.
These nasty pain mediators are also responsible in lowering the pain threshold.
If you're wondering what's so significant about neurochemical sensitization? Go get yourself another beer.
The significance is that Substance P, Bradykinin and Prostaglandin can promote inflammation from non-provoking pain stimuli.
Although I've condensed and simplified a lot of the information, I hope I haven't lost you along the way.
In the final part, I will discuss how chronic pain causes neuroplasticity and induces changes in the brain.
You will also learn how sensory inputs from the muscles, tendons, ligaments and joints can regulate and modulate chronic pain.
We will discuss some common scenarios that you may encounter which can lead to chronic pain.
And more importantly, you will learn how to overcome it.
So, don't miss the action packed, beer drinking, exciting conclusion to understanding pain.