Sources and types of pain
We have discussed the differences between acute and chronic pain. Acute pain - what you could almost describe as "useful pain", has a protective influence. Lack of pain sensation, for instance in leprosy, may lead to repeated trauma to the hands and feet that the sufferer does not realise is happening: it is this that leads to the damaged limbs, not the leprosy itself.
The mechanisms underlying pain are discussed in more detail in the "how does the body feel pain" section of our site, and individual pain types are listed under the "different pains" section.
Pain receptors, called nociceptors, send signals to your brain via your spinal column telling you of the danger so you can take measures to protect yourself or prevent further injury. nociceptors are present in almost all the tissues in our body. This type of pain, called nociceptive pain, is the one we most commonly experience, with trauma, muscle or bone injuries, surgery, or pressure from an infection or condition like cancer. Nociceptive pain can be experienced as sharp, dull or aching, in a large or small area, and generally goes away as the damage to your body heals.
Nociceptive pain can last for months or years when damaged tissues cannot heal, and chronic inflammation may be involved. Arthritis, some kinds of neck and back pain, osteoporosis pain, some kinds of cancer pain, and many other types of chronic pain are nociceptive. These processes often involve changes of inflammation leading to sensitisation of the pain nerves, called "peripheral sensitisation", which makes pain nerves more "jumpy" and reactive and can even make pain nerves that are normally silent become active.
Another type of pain is caused by injured nerves, or other changes in the nervous system, and is called neuropathic pain.
Sometimes the disturbed nervous system sends pain signals to the brain even when there is no other ongoing tissue damage. Neuropathic pain is often experienced as tingling, aching, or burning and can last for months or years. One example of this type of pain is phantom limb pain, when a person who has had an arm or leg removed still experiences pain as if it were coming from the missing limb. Other types of neuropathic pain include trigeminal neuralgia, peripheral neuropathy, postherpetic neuralgia, and complex regional pain syndrome (CRPS). Individual neuropathic pains are discussed in more detail here.
We cannot always identify a physical abnormality that is causing chronic pain. Pain is a complex phenomenon of interacting "vicious cycles" and these act together, and interact, to cause pain. Other pain sources can develop as a result, particularly myofascial pain, and central sensitisation can make existing pain more severe. The longer that a pain continues for, the more likely it is that changes will occur in the central nervous system (brain and spinal cord) to make it become chronic – whatever the cause was in the first place. This means that it may be important to deal with pain early, if possible.
All types of pain are subjective and can be measured and reported only by the person experiencing it. All types of pain are real and can be treated. Many factors influence the experience of pain, including the mechanisms in the body that are sustaining the pain, the meaning of the pain, and psychological factors, such as individual coping styles and emotional support.
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Pain Service Website, Gloucestershire Hospitals NHS Foundation Trust
Webmaster Dr J G de Courcy, Consultant in Pain Medicine and Anaesthesia
Page updated 15/02/2016