Sources of Pain
The definition of pain given by the International Association for the Study of Pain is:
An unpleasant sensory or emotional experience associated with actual or potential damage, or described by the patient in terms of such damage.
We can see from this definition that pain is not equal to damage; it may occur even before the damage has occurred or with no damage at all. Pain definitely becomes an emotional experience, especially when it interferes with ones’ daily life. It is very hard to objectively quantify pain. Moreover, the emotional aspect of pain can have a huge impact not only on the perception of pain but also on its perpetuation. Even if the pain has a structural cause, the presence of an associated anxiety, depression or fear avoidance behaviour will perpetuate the pain.
Acute pain has a clear purpose. If you put your hand in a fire, or cut your hand with a knife, you definitely want to know as soon as possible that it is in your best interest to take your hand away from the danger. These pain signals are transmitted in special type A beta pain fibres which transmit these pain signals really fast, leading to a reflex, even before you feel the pain. When pain lingers on for a few days, it is supposed to tell your body that there is something acutely going on and your body needs to rest in order that it can repair any damage or cure inflammation that has resulted.
Chronic pain is defined as pain that lingers on for more than 6 months. Chronic pain in itself has been classified as a disease in its own rights and incurs huge financial worldwide costs, affecting up to 20% of the population.
For information on chronic pain, please refer to the section on chronic pain.
There are various types of pain, mainly divided into somatic pain, (coming from the muscles, ligaments, tendons, joints and bones), visceral pain, from the internal organs, and neuropathic pain, from the nerves. However, pain from some sources may have components of the pain coming from more than one group. Pain from the back, for example, may have both somatic and neuropathic components. The following discussion deals with pain from the most dominant sources of pain.