Causes, incidence, and risk factors.
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This article is about physical pain. For pain in the broader sense, see Suffering. For other uses, see Pain (disambiguation).
( ICD-10: R52,
MeSH: D010146 )
Pain is an unpleasant feeling often caused by intense or damaging stimuli, such as stubbing a toe, burning a finger, putting alcohol on a cut, and bumping the "funny bone". The International Association for the Study of Pain's widely used definition states: "Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage."
Pain motivates the individual to withdraw from damaging situations, to protect a damaged body part while it heals, and to avoid similar experiences in the future. Most pain resolves promptly once the painful stimulus is removed and the body has healed, but sometimes pain persists despite removal of the stimulus and apparent healing of the body; and sometimes pain arises in the absence of any detectable stimulus, damage or disease.
Pain is the most common reason for physician consultation in the United States. It is a major symptom in many medical conditions, and can significantly interfere with a person's quality of life and general functioning. Psychological factors such as social support, hypnotic suggestion, excitement, or distraction can significantly modulate pain's intensity or unpleasantness.
In 1994, responding to the need for a more useful system for describing chronic pain, the International Association for the Study of Pain (IASP) classified pain according to specific characteristics: (1) region of the body involved (e.g. abdomen, lower limbs), (2) system whose dysfunction may be causing the pain (e.g., nervous, gastrointestinal), (3) duration and pattern of occurrence, (4) intensity and time since onset, and (5) etiology. This system has been criticized by Clifford J. Woolf and others as inadequate for guiding research and treatment.
According to Woolf, there are three classes of pain : nociceptive pain (see hereunder), inflammatory pain which is associated with tissue damage and the infiltration of immune cells, and pathological pain which is a disease state caused by damage to the nervous system (neuropathic pain, see hereunder) or by its abnormal function (dysfunctional pain, like in fibromyalgia, irritable bowel syndrome, tension type headache, etc.).
Duration: Chronic pain |
Pain is usually transitory, lasting only until the noxious stimulus is removed or the underlying damage or pathology has healed, but some painful conditions, such as rheumatoid arthritis, peripheral neuropathy, cancer and idiopathic pain, may persist for years. Pain that lasts a long time is called chronic, and pain that resolves quickly is called acute. Traditionally, the distinction between acute and chronic pain has relied upon an arbitrary interval of time from onset; the two most commonly used markers being 3 months and 6 months since the onset of pain, though some theorists and researchers have placed the transition from acute to chronic pain at 12 months.
Others apply acute to pain that lasts less than 30 days, chronic to pain of more than six months duration, and subacute to pain that lasts from one to six months. A popular alternative definition of chronic pain, involving no arbitrarily fixed durations is "pain that extends beyond the expected period of healing". Chronic pain may be classified as cancer pain or benign.
Nociceptive pain is caused by stimulation of peripheral nerve fibers that respond only to stimuli approaching or exceeding harmful intensity (nociceptors), and may be classified according to the mode of noxious stimulation. The most common categories being "thermal" (e.g. heat or cold), "mechanical" (e.g. crushing, tearing, shearing, etc.) and "chemical" (e.g. iodine in a cut, chili powder in the eyes).
Nociceptive pain may also be divided into "visceral", "deep somatic" and "superficial somatic" pain. Visceral structures are highly sensitive to stretch, ischemia and inflammation, but relatively insensitive to other stimuli that normally evoke pain in other structures, such as burning and cutting. Visceral pain is diffuse, difficult to locate and often referred to a distant, usually superficial, structure. It may be accompanied by nausea and vomiting and may be described as sickening, deep, squeezing, and dull.
Deep somatic pain is initiated by stimulation of nociceptors in ligaments, tendons, bones, blood vessels, fasciae and muscles, and is dull, aching, poorly localized pain. Examples include sprains and broken bones. Superficial pain is initiated by activation of nociceptors in the skin or other superficial tissue, and is sharp, well-defined and clearly located. Examples of injuries that produce superficial somatic pain include minor wounds and minor (first degree) burns.
Neuropathic pain |
Neuropathic pain is caused by damage or disease affecting any part of the nervous system involved in bodily feelings (the somatosensory system).
Peripheral neuropathic pain is often described as "burning", "tingling", "electrical", "stabbing", or "pins and needles". Bumping the "funny bone" elicits acute peripheral neuropathic pain.
Phantom pain |
Phantom pain is pain felt in a part of the body that has been lost or from which the brain no longer receives signals. It is a type of neuropathic pain. Phantom limb pain is a common experience of amputees.
The prevalence of phantom pain in upper limb amputees is nearly 82%, and in lower limb amputees is 54%. One study found that eight days after amputation, 72 percent of patients had phantom limb pain, and six months later, 65 percent reported it.
Some amputees experience continuous pain that varies in intensity or quality; others experience several bouts a day, or it may occur only once every week or two. It is often described as shooting, crushing, burning or cramping. If the pain is continuous for a long period, parts of the intact body may become sensitized, so that touching them evokes pain in the phantom limb, or phantom limb pain may accompany urination or defecation.
Local anesthetic injections into the nerves or sensitive areas of the stump may relieve pain for days, weeks or, sometimes permanently, despite the drug wearing off in a matter of hours; and small injections of hypertonic saline into the soft tissue between vertebrae produces local pain that radiates into the phantom limb for ten minutes or so and may be followed by hours, weeks or even longer of partial or total relief from phantom pain.
Vigorous vibration or electrical stimulation of the stump, or current from electrodes surgically implanted onto the spinal cord all produce relief in some patients.
Work by Vilayanur S. Ramachandran using mirror box therapy allows for illusions of movement and touch in a phantom limb which in turn cause a reduction in pain.
Paraplegia, the loss of sensation and voluntary motor control after serious spinal cord damage, may be accompanied by girdle pain at the level of the spinal cord damage, visceral pain evoked by a filling bladder or bowel, or, in five to ten per cent of paraplegics, phantom body pain in areas of complete sensory loss.
This phantom body pain is initially described as burning or tingling but may evolve into severe crushing or pinching pain, fire running down the legs, or a knife twisting in the flesh. Onset may be immediate or may not occur until years after the disabling injury. Surgical treatment rarely provides lasting relief.
Psychogenic pain |
Psychogenic pain, also called psychalgia or somatoform pain, is pain caused, increased, or prolonged by mental, emotional, or behavioral factors. Headache, back pain, and stomach pain are sometimes diagnosed as psychogenic. Sufferers are often stigmatized, because both medical professionals and the general public tend to think that pain from a psychological source is not "real". However, specialists consider that it is no less actual or hurtful than pain from any other source.
People with long term pain frequently display psychological disturbance, with elevated scores on the Minnesota Multiphasic Personality Inventory scales of hysteria, depression and hypochondriasis (the "neurotic triad"). Some investigators have argued that it is this neuroticism that causes acute pain to turn chronic, but clinical evidence points the other way, to chronic pain causing neuroticism. When long term pain is relieved by therapeutic intervention, scores on the neurotic triad and anxiety fall, often to normal levels. Self-esteem, often low in chronic pain patients, also shows improvement once pain has resolved.
"The term 'psychogenic' assumes that medical diagnosis is so perfect that all organic causes of pain can be detected; regrettably, we are far from such infallibility... All too often, the diagnosis of neurosis as the cause of pain hides our ignorance of many aspects of pain medicine."
— Ronald Melzack, 1996.
Breakthrough pain |
Breakthrough pain is pain that comes on suddenly for short periods of time and is not alleviated by the patients' normal pain management. It is common in cancer patients who often have a background level of pain controlled by medications, but whose pain periodically "breaks through" the medication.
The characteristics of breakthrough cancer pain vary from person to person and according to the cause.
Incident pain |
Incident pain is pain that arises as a result of activity,
such as movement of an arthritic joint, stretching a wound, etc.
Pain asymbolia and insensitivity:
Pain asymbolia and Congenital insensitivity to pain |
The ability to experience pain is essential for protection from injury, and recognition of the presence of injury. Episodic analgesia may occur under special circumstances, such as in the excitement of sport or war: a soldier on the battlefield may feel no pain for many hours from a traumatic amputation or other severe injury.
Although unpleasantness is an essential part of the IASP definition of pain, it is possible to induce a state described as intense pain devoid of unpleasantness in some patients, with morphine injection or psychosurgery. Such patients report that they have pain but are not bothered by it; they recognize the sensation of pain but suffer little, or not at all. Indifference to pain can also rarely be present from birth; these people have normal nerves on medical investigations, and find pain unpleasant, but do not avoid repetition of the pain stimulus.
Insensitivity to pain may also result from abnormalities in the nervous system. This is usually the result of acquired damage to the nerves, such as spinal cord injury, diabetes mellitus (diabetic neuropathy), or leprosy in countries where this is prevalent. These individuals are at risk of tissue damage due to undiscovered injury. People with diabetes-related nerve damage, for instance, sustain poorly healing foot ulcers as a result of decreased sensation.
A much smaller number of people are insensitive to pain due to an inborn abnormality of the nervous system, known as "congenital insensitivity to pain". Children with this condition incur carelessly repeated damage to their tongue, eyes, joints, skin, and muscles. Some die before adulthood, and others have a reduced life expectancy.
Most people with congenital insensitivity to pain have one of five hereditary sensory and autonomic neuropathies (which includes familial dysautonomia and congenital insensitivity to pain with anhidrosis). These conditions feature decreased sensitivity to pain together with other neurological abnormalties, particularly of the autonomic nervous system. A very rare syndrome with isolated congenital insensitivity to pain has been linked with mutations in the SCN9A gene, which codes for a sodium channel (Nav1.7) necessary in conducting pain nerve stimuli.
Effect on functioning |
Experimental subjects challenged by acute pain and patients in chronic pain experience impairments in attention control, working memory, mental flexibility, problem solving, and information processing speed. Acute and chronic pain are also associated with increased depression, anxiety, fear, and anger.
"If I have matters right, the consequences of pain will include direct physical distress, unemployment, financial difficulties, marital disharmony, and difficulties in concentration and attention…"
—Harold Merskey 2000
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An unpleasant sensation occurring in varying degrees of severity as a consequence of injury, disease, or emotional disorder. Suffering or distress. pains The pangs of childbirth.
Pain, especially in its acute form, is usually a reflection of a tissue-damaging or potentially tissue-damaging stimulus. There is a transmission system that conveys this information to the central nervous system. This phenomenon is called nociception. Pain is more complex than other sensory systems such as vision or hearing because it not only involves the transfer of sensory information to the nervous system, but produces suffering which then leads to aversive corrective behavior. In certain disease states, defects in the transmission system can of themselves generate false information to the nervous system, as though tissue damage were occurring in the periphery. An example of this is phantom limb pain, in which the individual often has a crushing type of pain in a foot that has been amputated.
Physical suffering associated with a bodily disorder (such as a disease or injury) and accompanied by mental or emotional distress. Pain, in its simplest form, is a warning mechanism that helps protect an organism by influencing it to withdraw from harmful stimuli (such as a pinprick). In its more complex form, such as in the case of a chronic condition accompanied by depression or anxiety, it can be difficult to isolate and treat. Pain receptors, found in the skin and other tissues, are nerve fibres that react to mechanical, thermal, and chemical stimuli. Pain impulses enter the spinal cord and are transmitted to the brain stem and thalamus. The perception of pain is highly variable among individuals; it is influenced by previous experiences, cultural attitudes (including gender stereotypes), and genetic makeup. Medication, rest, and emotional support are the standard treatments. The most potent pain-relieving drugs are opium and morphine, followed by less-addictive substances and non-narcotic analgesics such as aspirin and ibuprofen.
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Symptoms, Causes, Diagnosis |
Pain is a sensation triggered by the nervous system in response to tissue damage or other damage to the body. Pain can be a dull, achy, stabbing, shooting, burning, or a pins-and-needles sensation. You may feel pain in a specific area of the body, such as your back, or you may feel aches and pains all over, such as when you have the flu (influenza).
Pain can be due to a wide variety of diseases, disorders and conditions that range from a mild injury to a debilitating disease. Pain can be categorized as acute, chronic, referred, cancer, neuropathic, and visceral.
What other symptoms might occur with pain?
Pain may occur with other symptoms depending on the underlying disease, disorder or condition. For instance, if your pain is due to arthritis, you may experience pain in more than one joint. Pain due to a compressed nerve in the lower back can even lead to loss of bladder control.
Pain is often a major symptom of fibromyalgia, which is also characterized by fatigue and sleep problems.... Read more about painsymptoms
What causes pain?
Hundreds of diseases, disorders and conditions can cause pain, such as inflammatory syndromes, malignancy, trauma, and infection. In some cases, pain may be a symptom of a serious or life-threatening condition, such as a heart attack or cancer ...
Read more about paincauses
Bones, Joints and Muscles Overview; Osteoporosis; Osteoarthritis; RA; Back Pain; Glossary of Bones, Joints and Muscles Terms; View All on Bones, Joints and Muscles
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Pain is a feeling triggered in the nervous system. Pain may be sharp or dull. It may come and go, or it may be constant. You may feel pain in one area of your body, such as your back, abdomen or chest or you may feel pain all over, such as when your muscles ache from the flu.
Pain can be helpful in diagnosing a problem. Without pain, you might seriously hurt yourself without knowing it, or you might not realize you have a medical problem that needs treatment. Once you take care of the problem, pain usually goes away. However, sometimes pain goes on for weeks, months or even years. This is called chronic pain. Sometimes chronic pain is due to an ongoing cause, such as cancer or arthritis. Sometimes the cause is unknown.
Fortunately, there are many ways to treat pain. Treatment varies depending on the cause of pain. Pain relievers, acupuncture and sometimes surgery are helpful.
Pain Assessment(Beth Israel Medical Center, Department of Pain Medicine and Palliative Care);
Pain Drawing(American Academy of Physical Medicine and Rehabilitation) - PDF.
JAMA Patient Page: Acute Pain Treatment(American Medical Association) - PDF;
MedlinePlus: Pain Relievers (National Library of Medicine)
Also available in Spanish;
Osteopathic Manipulative Treatment(American Osteopathic Association)
Treatments for Managing Pain(American Society of Anesthesiologists)
Learn more: SOURCE
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