By in Osteopathy

What Should We Know About Pain?

Pain is so hard to define because it’s a subjective sensation.

The current definition of pain is “An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage” [source: International Association for the Study of Pain].

“A sensory and emotional experience associated with actual or potential tissue damage”, but what does that mean?

I’ll break down each element for you to create a complete picture of pain perception, otherwise known as nociception (from the Latin word for “hurt”).

A  sensation from any part of the body that activates nerve endings to convey a signal to the brain as a warning that some type of physical or chemical stimulus is causing, or may cause damage.

Sensory perceptions in the skin such as light touch or pressure and temperature, are conveyed via nerve endings that communicate the signal very fast (approximately 70-120 meters per second).

Nociceptors (the pain receptors) can only convey the signal at around  2 meters per second, which means if a man of average height stubs his big toe it will take almost a full second to reach the brain.

The signal for actual physical damage is conveyed via the nociceptor to the spinal cord which is passed via a second neuron in the spinal cord to the thalamus. The thalamus is the relay station between the body and the brain. At this point, the thalamus tells the brain that there is danger ( it does not communicate Pain) in the relevant part of the body.

Emotional Pain

At this point, the brain takes over, and completely out of your conscious control, will start to make decisions relating to the nature of the stimulus. It will go to various other parts of the brain for advice and ask questions in order to make a decision within thousandths of a second on whether to make you feel pain and to what degree you feel it.

Questions such as:

Have we felt this before?  What are the circumstances? could this potentially affect life or work? has anyone told me any stories of similar experiences?  have I observed a friend or family member suffering because of this?

The amount of pain we feel is dependent purely on the amount of threat perceived by the brain after this conversation. This has now become known as a “neurotag” in certain scientific and research circles, to convey the individual nature of the pain we feel ( a “tag” is the mark used by graffiti artists to identify themselves, in the same way, traditional artists signs their work).

Problems occur when the brain misrepresents or misinterprets the neurotag.

Optical illusions work because the brain is tricked into interpreting an image incorrectly.  The same thing can happen with pain i.e. some stimuli that should not cause pain do and other stimuli that you would expect to cause pain do not. There are many stories of soldiers with horrific wounds sustained in battle, that do not feel pain until they are away from battle. There are also lots of people who are living with constant pain and have had every test under the sun without finding a physical cause of their pain.

This is a short animation that is regularly shown to patients in specialist pain clinics.

Actual Damage

It is perfectly normal and appropriate to feel pain with a physical injury. If we didn’t then we could potentially cause more physical damage. But we know that as the injury heals the pain reduces and eventually disappears completely.

Potential damage

Pain can be excruciating, even with very little stimulus. If the neurotag has been sensitised by previous experience then the pain perceived from a relatively innocuous disturbance can be excruciating. This process is not in our conscious control, remember it is the brain that controls the amount of pain we feel, it is not relative to the amount of stimulus.

The Pain Gate Theory

Messrs Melzak and Wall developed this theory in the 1960s and it is still considered relevant today. The pain gate theory claims that sensory information (such as rubbing the skin over the painful area) that travels in the fast conducting neurons in the skin, blocks the signal from the slow conducting nociceptors carrying the noxious stimulus at the level it enters the spinal cord, i.e. before it gets to the thalamus and the brain. Basically, the source of potential pain has been prevented from reaching the brain by a secondary stimulus and therefore pain perception has reduced or is relieved completely.

The pain gate can be used therapeutically to relieve symptoms. Below is a synopsis of various types of therapy that can help reduce pain.

Manual therapies, such as Osteopathy and Sports Therapy manipulate muscles and joints and can relieve pressure on nerves.

Massage therapy stimulates blood flow, relieves muscle spasms and increases sensory nerve output, which can relieve pain through the gate control theory.

Hot applications increase blood flow, and cold applications reduce inflammation, both of which can ease the pain.

Stimulation of the skin with small electrodes (Electrotherapy) can close the pain gate.

Acupuncture may stimulate nerve cells and release endorphins. The increased stimulation might also close the gate to pain.

Mental control techniques rely on the ability of the mind and emotions to control and alleviate pain through descending neural pathways. They include relaxation techniques, hypnosis, biofeedback and distraction techniques.

Pain-management plans involve the patient and their family members as well as health professionals and complementary therapies, As with any medical treatment, the source of pain, pain tolerance, and the potential benefits and risks must be considered before any treatment is given.

Pain Assessment

There is no absolute measurement for the degree of pain felt by one individual, relative to another.

Pain is subjective, meaning that as an Osteopath, I can only use the patient’s own perception of the amount of pain as a guide to relief or aggravation. I use a numerical rating scale and ask patients to rate their pain intensity on a scale from zero (no pain at all) to 10 (worst pain imaginable).

Louise
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