Acute or subacute pain are useful sensations. They inform us about potential or actual damage to the body’s tissues. Specific sensory nerve cells with pain receptor endings (nociceptors) in the tissues react to strong stimuli such as pressure, heat, cold or chemicals. Stimulated nociceptors send a message to the spinal cord, which is then forwarded to the brain, where it is interpreted and a response is coordinated.
What is different in chronic pain?
Research has shown that if pain persists for longer periods, changes occur in the body at all levels of pain processing.
At the site of the injury, peripheral nerves become easily excitable, which means that even a minor stimulus may cause them to ‘fire off’. In some cases, a gentle brush against the skin can be enough to trigger the pain pathway. Not only the damaged nerves become more sensitive, but the neighbouring nerves will become affected as well, which leads to further amplification of the pain message. Some nerves may even start ‘firing off’ spontaneously.
Changes in the Spinal Cord
In the dorsal horn of the spinal cord, where the peripheral nerves enter, similar changes occur. This leads to increased sensitivity of this part of the spinal cord. Over time alterations can also occur in neighbouring spinal cord areas. Furthermore cells, which create ‘intercellular memory’, may get involved. All this leads to an amplified response to the peripheral stimulus.
Changes in the Brain
The brain normally has the ability to decrease the level of pain we experience through releasing ‘natural opioid hormones’. In chronic pain conditions, changes may also occur in the midbrain, which leads to an increase of nociceptive messages and ultimately to heightened pain perception.
‘Chronic pain messages’ also stimulate parts of the brain, which are involved in experiencing emotions, such as fear or anxiety. It is therefore not surprising that conditions such as sleep disorders and depression are often linked in with chronic pain.
Since you are here, you might be interested in reading some interesting articles and watch some videos about pain written by experts in the field.
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