According to the The International Association for the Study of Pain pain is "an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage."
Medically speaking, pain is classified into three different types: somatic, neuropathic, and visceral.
Somatic pain is the result of activity by pain receptors in the deep tissues of the body, or on the surface. An example of deep tissue pain would be that of cancer that has spread to the bone. The site of pain cannot be pinpointed, and has a dull, achy feeling. An example of surface pain is pain at a surgical incision site. People describe this pain as being sharp, and possibly have a burning sensation.
Neuropathic pain is the most severe of the three types of pain.It is often described as a burning or tingling sensation. It is caused by injury to the nervous system. The injury can include a tumor putting pressure on the spinal cord or nerves. Chemotherapy or radiation can also cause chemical damage to the nervous system resulting in pain.
Viscera are internal organs contained in a cavity of the body, like the chest, abdomen and pelvis. So, visceral pain is pain felt in one of these areas caused the activity of pain receptors in these areas. In cancer, the activation of pain receptors can be caused by a tumor putting pressure on one or more of the organs, the stretching of the viscera, or general invasion of cancer. This type of pain is described as having a throbbing, pressured sensation.
Once the type of pain has been established, then it is categorized into either acute pain or chronic pain.
Acute PainAcute pain refers to pain that is short lived and the cause can be easily identified such as an activity causing such pain. Acute pain can come and go and may increase over time.
Chronic PainChronic Pain lasts longer than three months. Physicians often have a tough time treating chronic pain as it is often hard to describe.