What is pain?
Pain is difficult to define because individuals perceive, interpret, describe, and tolerate pain differently. Pain is partly physical sensation and partly how your brain interprets that sensation. Most certainly pain is an unpleasant (but useful) sensation, often the result of harm to the body.
Pain is useful because without it you might not realize that you have been seriously hurt or that you have a medical concern that needs treatment. A couple of examples: You might expect a gunshot wound to cause immense pain that sidelines even the best Warfighter. However, the injured Warfighter on the battlefield may not "feel" pain right away. Another time, a relatively minor injury that doesn’t need much physical treatment might cause intense, constant pain.
When activated (either physically or mentally), nerves in the body produce “pain messages” that first travel to the spinal cord. The spinal cord can activate rapid responses called reflexes that make you automatically remove yourself from harmful situations, such as pulling your hand off a hot stove. The pain messages then travel to your brain, which tells you how to respond to the pain. That is, your brain tells you to put your burned hand under cold water to stop further damage. It also helps you interpret the pain, including how to describe it and how your mood may change because of the pain. However, many things affect the interpretation of “pain messages, including stress, genetics, expectations, and the body’s natural pain blockers, “endorphins.” For more on the pathways of pain, see the University of Texas Medical School's Neuroscience Online website.
There seem to be a lot of different kinds of pain. Why is this?
Pain has many causes and is described in many ways: burning, stabbing, dull, sharp, electric shock, popping, or tingling. Health professionals generally divide pain into groups, with nociceptive, neuropathic, and phantom pain being most significant to Warfighters.
Nociceptive pain is generally from physical injury to the body such as a cut. The pain is caused by damage to nerves surrounding the injury. It is usually localized around the injury and goes away when the injury heals. This type of pain can be mechanical (muscle, joint, or bone injuries; cuts), thermal (frostbite or burns), or chemical (alcohol on a cut or chili powder in the eyes).
Neuropathic pain comes from damaged sensory nerves. Neuropathic pain often is not a result of physical injury, but as damage directly to the nervous system. This type of pain usually causes sensations of burning, electric shock, or tingling. It can come from diseases such as cancer or diabetes, exposure to toxins, pressure from tumors, spinal cord injuries, and other health concerns. Neuropathic pain is more likely to be chronic and less likely to respond to traditional pain medications.
Phantom pain is a special type of neuropathic pain that feels as though it is coming from missing limbs that have been amputated or lost through injury.