Feel the Pain: Part 4: Pain Modulation
In previous posts, we reviewed the tissue producing the pain, the character of the pain, and how pain impulses travel from the periphery up to the brain. We should have called this post: Stop the Pain, since we will be talking about how what you do helps modulate the pain.
We recall that pain results from adequate activation of the nociceptive afferent system, the pain carrying sensory pathways. Most modulation occurs due to inhibition that attenuates activation. Think of it like a dimmer switch for a light.
- your hand is the stimulus (or your foot if you are really talented, like Dr Allen)
- the dimmer is the receptor (in the case of pain it is a bare nerve ending)
- the wiring are the pathways from the periphery to the brain (path from the dimmer switch to fuse box)
- and the fuse box represents the brain
- the light going on represents pain
- and the dimmer represents pain modulation (lots of pain or less pain)
Are you with me so far? Are you smelling what we are stepping in?
How can we stop from turning the light on ? We can never touch the switch. This represents good biomechanics; if we have good biomechanics, we are less likely to cause tissue damage and less likely to elicit pain because the receptor (the dimmer switch) was not stimulated, hence no turning on of the light.
What else? … There is a possibility that we can turn the light on only a little. This is means we activate the receptor (the dimmer) only a little. This is what happens in the spinal cord. All primary afferents (sensory nerves from mechanoreceptors, muscle spindles and golgi tendon organs) activate an inhibitory interneuron in the spinal cord (see diagrams above) which presynaptically inhibits the the 2nd neuron in the pain pathway (the pain neuron comes into the cord, synapses in the dorsal horn with a 2nd neuron which travels up the cord to the reticular formation and parietal lobe of the brain, to let us experience pain).
Think about it. Good mechanics, massage, manipulation, and exercise all involve stimulating primary afferents (sensory nerves). They all inhibit the 2nd order neuron in the pain pathway. They all affect the “adequate” part of the equation, making it more or less adequate, thus different degrees of pain are possible.
Remember, that which travels up the spinal cord to the brain is the sum total of ALL MODALITIES acting on the 2nd order pain neuron. MORE ACTIVATION = LESS PAIN.
Wow, is there more? You bet! What if the wiring goes to a junction box to join other wires? This is what happens in both the spinal cord and thalamus; MORE MODULATION (Incidentally, ALL AFFERENT STIMULI EXCEPT SMELL pass through the thalamus). You mean vision and hearing can affect the perception of pain? Yes, remember it is an emotional response. Is it better to go to the dentist with the nice relaxing music, private rooms, soft colors and clean smells or is it better to have your dental work done in a prison camp? There are visual, auditory and emotional components to pain.
The brain itself can modulate the perception of pain (think of people who are wounded in battle and never feel the pain) both at the level of the brain, AND by sending stimuli back down the cord to modulate it at the thalamus and spinal cord. Remember endorphins, your bodies own little heroin factory?
Wow, LOTS of things we do can modulate pain!
It makes shaking your hand after you whack it with a hammer (or your head after making it through this blog post) kind of make sense: that being, activating more peripheral receptors to modulate the pain. It is also what elicits a possible different emotional response when comparing being kicked high between the legs by your best friend while standing in a fresh spring meadow with birds chirping gleefully or by your worst enemy in a dark rainy alley during a thunderstorm (don’t believe us ? Give us a call, we are pleased to give free personal demonstrations). The environment, the mental settings, the smell, the sounds, your emotional standpoint, your overall pro-inflammatory health …… they all play into your pain and how it is interpreted, modulated and responded.
The Gait Guys. Modulating the learning process to make it easier for all to understand.
Ivo and Shawn…….. part-time, semi-pro punters. Give us a call on your way to divorce court or your next custody suit ….. our loving kicks will help modulate your true pain.
