What is Pain

What is Pain

Pain is an ‘unpleasant sensory and emotional experience associated with actual or potential tissue damage” (IASP-The International Association for the study of pain).  All pain is purely subjective and can only be truly appreciated by the person experiencing it.  Pain can vary greatly both in its intensity, frequency and duration. How long this pain lasts for is often categorised into acute and chronic pain.


Acute pain can be intense but is short-lived, being less than 12 weeks in duration. Acute pain is common in tissue damage, such as a back injury or ankle sprain. People can remain active and soon return to normal life, including work. Eventually, the injury or condition heals and the pain dissipates.  Timely treatment is often essential to prevent the transition to chronic pain.


Chronic pain lasts for more than three months where tissue damage is not the main issue.  The brain keeps producing pain even though the body is out of danger and tissue damage has been restored.  This is complex pain and can potentially take years to diagnose or may exist without a clear reason at all.  Some manifestations of chronic pain may be associated with osteoarthritis, rheumatoid arthritis or neuropathic pain.  Its impact on one’s ability to perform normal activities, sustain emotional well-being and relationships can be devastating. 

1 in 5 people in Australia have chronic pain and although it mostly impacts on the 50 plus age group, it can happen to anyone, including the youth.

 

Pain is often classified by the kind of damage it causes.  The two main categories of pain is caused by nociceptive pain and neuropathic pain.

Nociceptive Pain is pain arising from tissue damage.  Receptors are stimulated when they sense changes in temperature (hot/cold), vibration, stretch, and chemicals released from damaged cells. It’s the pain most people are familiar with, everything from burns and bee stings to strain injury and inflammatory arthritis. The pain comes from outside the nervous system, such as injury to tissues (skin, muscles, joints, tendons) and the nervous system reacts to it.
Examples include:

Somatic Pain originates from pain receptors located on the surface of the body or in the musculoskeletal tissues.  The pain tends to be sharp and localised.  Moving the affected area leads to more pain.  The pain receptors are sensitive to temperature, vibration, and stretch (in the muscles) and inflammation. 
Visceral Pain is more difficult to localise than somatic pain. The pain is initiated by pain receptors located in the internal organs within a cavity of the body, producing a type of pain that is often described as a dull ache. Cramps, sprains and broken bones are examples of visceral pain.  The pain receptors sense inflammation, stretch and ischemia (oxygen starvation). 

Neuropathic or Nerve Pain is a type of non-nociceptive pain and occurs when there is actual nerve damage. Nerves connect the spinal cord to allow the brain to communicate with muscles, skin and internal organs.  Damage to nerves can interfere with the way those signals are transmitted. This type of pain is typically described as a burning, tingling, electrical or sharp, shooting pain. A trapped nerve, a slipped disk, a bump on the ‘funny bone’ will trigger neuropathic pain. Nerve infections, such as shingles, can also cause neuropathic pain.  Nerves don’t heal as well as tissue and is more likely to lead to chronic pain.