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We’ve all felt pain at some time or other, but what is its function and how can we minimise it in our daily lives?
Pain is defined by the International Association for the Study of Pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage”.
Our perception of pain is influenced by a range of factors including our emotional and psychological state, memories of past pains, upbringing, age, attitude to life and cultural beliefs. A child’s first visit to the dentist, for example, may seem more painful because the environment is unfamiliar, while a professional boxer is able to withstand the pain associated with repeated blows.
Acute and chronic pain
Acute pain is defined as “pain of recent onset and probable limited duration”. It usually has an obvious identifiable relationship to injury or disease and it generally accompanies illness, injury or surgery and diminishes as the injury heals. It may be mild and last for a moment, such as pain from a sting, or it can be severe and last for weeks or months (pain from a burn, a pulled muscle or a broken bone).
Chronic pain was originally defined as pain that has lasted six months or longer but it is now regarded more as a disease of pain or, in other words, a problem with the pain pathway itself. It is sometimes difficult to sort out whether continuing pain is a result of ongoing problems with the affected part per se (such as chronic infection) or whether it is an imbalance of the pain pathways themselves.
This in no way diminishes the reality of the pain. The one consistent fact of chronic pain is that, as a disease, it cannot be understood in the same terms as acute pain, and the failure to make this distinction (particularly in those who suffer chronic pain) can give rise to suffering and feelings of depression, social isolation and helplessness.
There is, in fact, increasing evidence that inadequately treating acute pain can be one of the factors leading to chronic pain.
The science of pain
How we feel pain is a complicated phenomenon but a great deal is now known about what happens, for example, from the moment we stub our toe to the instant we utter ‘ouch!’ The physiological process whereby pain nerves (nociceptors) are activated by tissue injury or inflammation in a particular part of the body sending impulses to the brain is called nociception.
The pathway starts when a nociceptor responds to a broad range of chemical or physical (heat, cold, pressure) stimuli. Initially the pressure applied to the toe creates the sensation of pain, but later inflammation and/or infection is associated with the local release of chemical substances such as histamine and prostanoids that also stimulate the pain nerve. In response to these stimuli the pain receptor sends its electrical signals along its nerve pathway to the brain via the spinal cord.
A ‘gate control’ theory, developed in 1965 by psychologists Patrick Wall and Ronald Melzack, suggests a neurological gate at the entrance to the brain and in the spinal cord that regulates pain signals. By barring some sensations, the gatekeeper (our central nervous system comprising the brain and spinal cord) filters out some types of pain while admitting others. This, according to Dr Scott Fishman in his book The War On Pain, explains why the brain is “not bombarded by a cacophony of sensations, emotions and thoughts.”
It also explains why, when we rub an injured area or ‘kiss away’ a child’s pain, this helps soothe it: the gate mechanisms allow the rubbing sensation and the nurturing feel of the kiss to override the sharp uncomfortable sensation and there’s less pain!
Surgical pain
The number of drugs and techniques used to manage the pain associated with surgical operations has increased in recent years. It has been realised that complications such as a post-operative heart attack related to the stress of the operation, or a chest infection resulting from an inability to breathe deeply or cough can be prevented by better pain
relief.
Anaesthetists who generally manage the pain aspects of surgery plan a programme for each patient that is designed to minimise post-operative discomfort and permit quicker return of normal function. Frequently, local anaesthesia drugs are used to block pain pathways. Pain killers are now generally given early (sometimes even before the surgery) in order to prevent pain down the track
Common pain medications
A large variety of pain killer (analgesic) medications are available and some are more suited to certain conditions than others. Unfortunately all pain killers can have side effects. Analgesics need to be taken at a dose level that is effective. Toxic effects from taking doses in excess of that recommended or prescribed can have serious consequences.
Paracetamol
Paracetamol is perhaps the most commonly used simple analgesic. Its action blocks pain messages to the brain, relieving pain and fever. Paracetamol does not reduce inflammation and is usually well-tolerated by the stomach.
Non-steroidal anti-inflammatory drugs (NSAIDs)
NSAIDs reduce fever and slow the production of prostaglandins: chemicals that cause pain and inflammation. However, if taken regularly, NSAIDs may cause indigestion and irritate the stomach. Some asthmatics may find that these medications worsen their asthma. Aspirin and ibuprofen are the best-known NSAIDs.
Codeine
A strong pain reliever for moderate to severe pain. Usually mixed with paracetamol, ibuprofen or aspirin, codeine is a weak narcotic that dulls pain messages to the brain by binding to cerebral pain receptors. As well as being addictive, codeine’s side effects include constipation, nausea and drowsiness.
Pain Relief Gels and Creams
While tablets affect the whole body, pain relief gels and creams offer fast localised pain relief with fewer side effects. Some gels contain ibuprofen to reduce pain and inflammation while others contain chemicals that create either hot or cold sensation to distract your attention from the pain.
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