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Jamaica Scientific Research Institute

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Pain is a feeling that is brought about by the nervous system.

"Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage" - The International Association for the Study of Pain.

Image Credit: National Institutes of Health

Pain may be described as sharp or dull; sporadic or constant; local or generalized. Pain may be a symptom of an underlying disease or disorder, but is a disorder in its own right.

Pain can be divided into two main categories, namely acute and chronic.

  • Acute pain comes on quickly and can be quite severe, but it only lasts for a relatively short time. It is the normal sensation triggered in the nervous system to alert you to possible tissue or bodily injury.
  • Chronic pain lasts for weeks, months or even years.Chronic pain can be mild or excruciating, episodic or continuous, merely inconvenient or totally incapacitating. Sometimes chronic pain is due to an initial mishap such as a sprained back, serious infection or the presence of other chronic disorders such as Cancer or Arthritis. Sometimes the cause is unknown.

Chronic pain may be classified as nociceptive, neuropathic, psychogenic, a mix of any of these three or it may be classified as unknown.

Nociceptive Pain

Occurs when pain-sensitive nerve endings called nociceptors are activated or stimulated. 

A majority of nociceptors in the human body are located in the skin and joints, with some also being present in muscle tissues and in the walls of internal organs. 

Nociceptors are specialized to detect different types of painful stimuli and are divided as such— "thermal"(heat or cold), "mechanical" (crushing, tearing, etc.) and"chemical" (such as iodine or alcohol in a cut).


Image Credit: National institutes of Health

Neuropathic Pain

Usually accompanies tissue injury and associated damage to nerve fibers. 

It may involve the central nervous system (the brain and spinal cord); the peripheral nervous system (the nerve trunks leading away from the spine to the limbs, plus the12 pairs of cranial nerves on the lower surface of the brain); or both.

Neuropathic pain is usually associated with an identifiable disorder such as stroke, diabetes, or spinal cord injury, and is frequently described as having a"hot" or burning sensation.

Image Credit: Themanualtherapist

Psychogenic Pain

Arises from
and is increased or prolonged by mental, emotional, or behavioral factors.

The pain has no organic or tangible explanation. Common psychogenic pain syndromes include chronic headaches, low back pain, atypical facial pain or pelvic pain of unknown origin.

It is important to recognize that some pain syndromes may involve more than one type of pain. For example, a cancer patient may suffer from neuropathic pain as a side effect of cancer treatment as well as from nociceptive pain associated with pressure from the tumor itself on nociceptors in a blood vessel or hollow organ.


Acute pain may follow from a trauma to the body such as surgery, accident, disease or other conditions.

Chronic pain may be caused by a myriad of factors ranging from a bad mattress to stomach ulcers. While it may begin with something tangible such as an injury or illness, the pain may transit to a psychological dimension once the physical problem heals.

Risk factors promoting Chronic Pain
  • Alcoholism 
  • Amputation
  • Back, leg, and hip problems 
  • A torn or slipped disc will cause nerve inflammation
  • Spine surgery
  • Chemotherapy
  • Diabetes 
  • Facial nerve problems
  • HIV infection or AIDS 
  • Multiple sclerosis 
  • Nerve infections such as shingles

The feeling of physical pain can vary greatly – from mild to severe.

Acute pain is felt immediately following injury,and is usually described with intense words such as sharp, stinging, biting or stabbing.

Neuropathic pain is usually described as shooting and burning pain, tingling and numbness, dull and throbbing.

Psychogenic pain is usually characterized by headaches, muscle pains, back pain, and stomach pains.

For further reading and research into the causes, nature and risk factors of Chronic Pain, you may visit the links below, among others.

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