Pain has a function; it is to warn us that there is actual tissue damage or the possibility of tissue damage and that action is required.  Usually the intensity of the pain is related to the actual damage.   Therefore, pain is usually an important mechanism for our protection and survival.  However, sometimes pain goes wrong and becomes a diseased process in itself resulting from structural and functional changes in the nervous system that maintain the pain, even if there is no longer any damage to the tissue or no possibility of damage.  Chronic pain has been defined as  “a persistence of the memory of pain and/or the inability to extinguish the memory of pain evoked by an initial inciting injury” (Apkarian et al., 2009).


Our brains continuously scan the environment and interpret pain signals.  No two brains are alike and perception also differs between persons.  Depending on a number of factors, including beliefs about pain, past experiences, and memories, pain messages may become amplified.  Sensitization refers to neurological changes that occur as a result of chronic pain where the pain receptors and different parts of the nervous system that process pain become more sensitive to incoming stimulation.  Therefore pain signals may become amplified.  As pain captures our attention we tend to focus upon it, and as we discussed in the section on neuroplasticity, what we pay attention to helps drive neuroplastic changes.  Chronic pain will increase our sensitivity to pain and not only in the area of the injury but throughout the body resulting in hypersensitivity and hyperalgesia.  What is normally non-painful stimulation such as touch may become painful, what is referred to as allodynia.

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A useful image is that of your home alarm.  The alarm is wired so that it will be activated when someone tries to break in the house through a door or window, or because of activation of a motion detector.  What would happen if your alarm was able to change its sensitivity automatically, so that after an attempt to break in, it became more sensitive (arguably more efficient).  Now every time someone walks by your home, the house alarm perceives this as a threat, and the alarm sounds.  There is no real danger, only a perception of danger in this case.  This is what happens with chronic pain.  Unfortunately, once the gain on pain has been increased in your body, a maladaptive form of neuroplasticity, it is difficult to scale down.  Treatment in such a case needs to be multidimensional, addressing the cognitive, neurological and physical aspects of the pain.



The treatment of acute pain is usually now more aggressive to stop this process from initially happening.