What is this thing called pain?

Someone wise once said that everything that happens to you throughout your life represents ten percent of your experience. The remaining ninety percent is how you respond to those events. So, if you are injured or suffer from a disease and the result is pain, you could give in and be an invalid or you could respond positively. Just talking about pain in terms of the central nervous system misses the point. You cannot separate pain from the emotions. Some may react to pain with despair and depression. Others may fight to make their lives better despite the pain. All this requires an answer to the question, "What is this thing called pain?" The first part of the answer distinguishes between acute and chronic. When you are injured, have some type of inflammation or a disease, the pain is said to be acute if the cause has been diagnosed and treatment will produce a cure, i.e. the pain is not going to last long. Chronic pain becomes a disease in its own right, i.e. it comes to have a existence independent of the cause. The psychological response to knowing the pain is going to persist often makes it seem worse and can make it resistant to treatment.
Chronic pain can be caused directly by an injury or disease, or it may be a side effect or complication following surgery, caused by drug interactions, etc. Always liking to produce lists, doctors have classified pain into the following categories:
Nociceptive where you feel a sensation in a specific location. This may be somatic and so felt in the joints, bones, muscles and ligaments, or visceral which is felt in the internal organs such as the heart, lungs, liver and kidneys. The latter can be more difficult to localize because the pain simply comes from inside the body.
Non-nociceptive may be neuropathic, i.e. pain generated by the nervous system and not tied to a specific location in the body. When the nervous system is damaged, the messages become more difficult to interpret and the brain is often confused by random effects. The result is unpredictable feelings of tingling, numbness, pins and needles and other unpleasant symptoms. Alternatively, there may be sympathetic pain where the skin and tissue around an injury become unusually sensitive and restrict movement.
No matter which variety of pain you may have, there are a range of analgesics or painkillers available to relieve any suffering. The less powerful drugs are the nonsteroidal anti-inflammatory drugs (NSAIDs) which reduce swelling and inflammation in the joints and elsewhere. The more powerful deal with moderate to severe pain with tramadol being the most commonly prescribed because it is less likely to cause dependence than the opiates. Tramadol works by changing the way in which the neurotransmitters carry messages in the nervous system. Because of this, it is equally effective no matter what the cause of the pain, i.e. localized or arising from the nervous system itself. The messages are not carried to the brain or not clearly interpreted as being pain messages. Thus, you can have a reasonably good quality of life even though the source of the pain remains active in your body.