Pain is a perception that signals us that tissue damage has occurred or may be occurring. It is subjective and very complex. Various types of research conducted during the past 50 years has confirmed that there are many mechanisms involved in the pain process.
Pain can be acute or chronic. Acute pain lasts a relatively short time. The time frame may be as brief as a day or two or as long as weeks or months.
Persistent pain may be defined as pain that lasts or persists beyond the healing of an injury. Chronic pain is persistent pain that generally continues for a period of six months or longer.
To develop the best treatment strategies, health care professionals also classify pain into several categories. Common pain categories include "nociceptive," "neuropathic," and "psychogenic."
Types of Pain
Nociceptive Pain is believed to be caused by the ongoing activation of pain receptors in either the surface or deep tissues of the body.
There are two types: somatic pain and visceral pain.
Somatic pain is caused by injury to skin, muscles, bone, joint, and connective tissues. Deep somatic pain is usually described as dull or aching, and localized in one area. Somatic pain from injury to the skin or the tissues just below it often is sharper and may have a burning or pricking quality. /Somatic/ pain often involves inflammation of injured tissue. Although inflammation is a normal response of the body to injury, and is essential for healing, inflammation that does not disappear with time can result in a chronically painful disease. The joint pain caused by rheumatoid arthritis is an example of this type of somatic nociceptive pain.
Visceral Pain refers to pain that originates from ongoing injury to the internal organs or the tissues that support them. When the injured tissue is a "hollow" structure, like the intestine or the gall bladder, the pain often is somewhat localized and cramping. When the injured structure is not a hollow organ, the pain may be pressure-like, deep, and stabbing.
Neuropathic Pain is believed to be caused by changes in the nervous system that contribute to persistent or chronic pain even after an injury heals. In most cases, the injury that starts the pain involves trauma or disease of the peripheral nerves or the central nervous system itself. There are many neuropathic pain syndromes, such as diabetic neuropathy, trigeminal neuralgia, postherpetic neuralgia ("shingles"), post-stroke pain, and complex regional pain syndromes (also called reflex sympathetic dystrophy or "RSD" and causalgia). Some patients who get neuropathy describe it as bizarre, unfamiliar pain, which may be "burning" or "like electricity."
Psychogenic Pain refers to psychological disturbance which often accompanies physical pain. Pain patients may be anxious or depressed, or have trouble coping. Psychological pain may not only be a consequence of the pain, such as depression or anxiety, but may also contribute to the pain itself in the case of an unresolved traumatic grief reaction.
This close relationship between physical and emotional or psychological pain indicates that all patients with chronic pain should be evaluated for these psychological factors, and psychological treatments should be considered an important aspect of pain therapy. It is important to note that patients with pain that appears to be determined primarily by psychological processes are hurting just like those who have pain associated with a clear injury to the body.