Types of pain
Acute pain is roughly defined as short-term pain or pain with an easily identifiable cause. Acute pain is the body's warning of present damage to tissue or disease. It is often fast and sharp followed by aching pain. Acute pain is centralized in one area before becoming somewhat spread out. This type of pain responds well to medications.
Chronic pain is roughly defined as long-term pain. This constant or intermittent pain has often outlived its purpose, as it does not help the body to prevent injury. It is often more difficult to treat with medication. Expert care is generally necessary to treat any pain that has become chronic. When opioid analgesics are used indiscriminately for prolonged periods, tolerance, dependence and even addiction may occur.
The experience of physiological pain can be grouped into four categories according to the source and related nociceptors (pain detecting nerves).
Cutaneous pain is caused by injury to the skin or superficial tissues. Cutaneous nociceptors terminate just below the skin, and due to the high concentration of nerve endings, produce a well-defined, localised pain of short duration. Example injuries that produce cutaneous pain include paper cuts, minor (first degree) burns and lacerations.
Somatic pain originates from ligaments, tendons, bones, blood vessels, and even nerves themselves, and are detected with somatic nociceptors. The scarcity of pain receptors in these areas produces a dull, poorly-localised pain of longer duration than cutaneous pain; examples include sprained ankle and broken bones.
Visceral pain originates from body organs visceral nociceptors are located within body organs and internal cavities. The even greater scarcity of nociceptors in these areas produces a pain usually more aching and of a longer duration than somatic pain. Visceral pain is extremely difficult to localise, and several injuries to visceral tissue exhibit "referred" pain, where the sensation is localised to an area completely unrelated to the site of injury. Myocardial ischaemia (the loss of blood flow to a part of the heart muscle tissue) is possibly the best known example of referred pain; the sensation can occur in the upper chest as a restricted feeling, or as an ache in the left shoulder, arm or even hand.
Phantom limb pain is the sensation of pain from a limb that one no longer has or no longer gets physical signals from - an experience almost universally reported by amputees and quadriplegics.
Finally neuropathic pain ("neuralgia") can occur as a result of injury or disease to the nerve tissue itself. This can disrupt the ability of the sensory nerves to transmit correct information to the thalamus, and hence the brain interprets painful stimuli even though there is no obvious or documented physiologic cause for the pain.
Chronic pain treatment
In modern societies, medical care is highly effective at treating most causes of pain. The inability to provide adequate relief for the remaining group causes dissatisfaction for both professionals and patients. The small group of people that suffer from chronic pain, have, by definition, been poorly served by the biomedical model and often seek alternative therapy to assist their pain control.
Recently, scientific findings show the first evidence that sunlight can affect the perception of pain.
Pain and alternative medicine
A recent survey by NCCAM found pain was the most common reason to use complementary and alternative medicine (CAM) and that 38.7% of adult Americans used CAM for pain in 2002 ([1] p 9). The most common indication was back pain (16.8%), followed by neck pain (6.6%), arthritis (4.9%), joint pain (4.9%), headache (3.1%), and recurring pain (2.4%).
One such alternative, traditional Chinese medicine views pain as a qi "blockage" equivalent to electrical resistance, or as "stagnation of blood" – theorized as dehydration inhibiting metabolism. Traditional Chinese treatments such as acupuncture are relatively more effective for nontraumatic pain than with traumatic pain.
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