There is an official, agreed upon definition of pain, albeit controversial;
“An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.”
There is certainly a lot of debate on the matter but there is broad agreement that is the best definition around at the moment.
My own definition of what I feel pain is;
“A complicated multifaceted sensation experienced by patients in different ways at different times and fundamentally, it is what the patient says it is.”
Pain which is short lived and to some extent, expected. It tends to follow a known course and trajectory. In my opinion it should settle once the tissue which has been damaged has been repaired.
I will use the words ‘chronic’ and ‘persistent’ interchangeably. This, in my opinion is a much more interesting phenomenon. This field of pain medicine is where my interest lies. Pain is subjective, this much we do know. There is no reliable way to objectively measure pain. There is no blood test, no investigation and no one, effective treatment. Chronic pain is complex and fascinating.
There are a number of causes;
Pain is sensed in the periphery and signals are sent via nerve back to the spinal cord. The signals are sent via the spinothalamic pathway to the brain. The brain processes the signals and sets out to mitigate the pain.
Pain which is caused by nerve damage either from the brain and spinal cord (central) or at the peripheries.
Pain which is caused by tissue damage normally described as sharp or aching.
Well the science is complex. The Pain Pathway by Rene Descartes has been largely debunked but in its simplest form it does have a certain clarity for acute pain. With the advances in neuroscience and the use of functional MRI scans (fMRI), there is a growing consensus that the science behind chronic/persistent pain is broad and complex. Please see Persistent Pain page here for further details.