Pain
Introduction
Pain is an unpleasant sensation signaling actual or possible injury.
Pain may be sharp or dull, intermittent or constant, or throbbing or steady. Sometimes pain is very difficult to describe. Pain may be felt at a single site or over a large area. The intensity of pain can vary from minor to intolerable.
People differ remarkably in their ability to tolerate pain. One person cannot tolerate the pain of a small cut or bruise, but another person can tolerate pain caused by a major accident or knife wound with little complaint. The ability to withstand pain varies according to mood, personality, and circumstance. In a moment of excitement during an athletic match, an athlete may not notice a severe bruise but is likely to be very aware of the pain after the match, particularly if the team lost.
The ability to tolerate pain may change with age. As people age, they complain less of pain, perhaps because changes in the body decrease the sensation of pain. On the other hand, older people may simply be more stoic than younger people.
Pain Pathways: Pain due to injury begins at special pain receptors scattered throughout the body. These pain receptors transmit messages or signals as electrical impulses along nerves to the spinal cord and then upward to the brain.Sometimes the signal evokes a reflex response When the signal reaches the spinal cord, a signal is immediately sent back along motor nerves to the original site of the pain, triggering the muscles to contract without involving the brain. For example, when people inadvertently touch something very hot, they immediately pull away. This reflex reaction helps prevent permanent damage. The pain signal is also sent to the brain. Only when the brain processes the signal and interprets it as pain do people become conscious of the pain.
Pain receptors and their nerve pathways differ in different parts of the body. For this reason, pain sensation varies with the type and location of injury. For example, pain receptors in the skin are plentiful and capable of transmitting precise information, including where an injury is located and whether the source was sharp, such as a knife wound, or dull, such as pressure, heat, or cold. In contrast, pain receptors in the intestine are limited and imprecise. The intestine can be pinched, cut, or burned without generating a pain signal. However, stretching and pressure can cause severe intestinal pain, even from something as relatively harmless as a trapped gas bubble. The brain cannot identify the precise source of intestinal pain; the pain is difficult to locate and is likely to be felt over a large area.
Pain felt in one area of the body does not always represent where the problem is, because the pain may be referred there from another area. For example, pain produced by a heart attack may feel as if it is coming from the arm because sensory information from the heart and the arm converge on the same nerve cells in the spinal cord.
Sometimes pain felt in one area of the body does not accurately represent where the problem is, because the pain is referred there from another area. Pain can be referred because signals from several areas of the body often travel through the same nerve pathways going to the spinal cord and brain. For example, pain from a heart attack may be felt in the neck, jaws, arms, or abdomen. Pain from a gallbladder attack may be felt in the back of the shoulder.
Evaluation
Doctors ask about the history and characteristics of pain, so that they can identify its cause and develop a treatment strategy. To evaluate the severity of pain, doctors sometimes use a scale of 0 (none) to 10 (severe) or ask the person to describe the pain as mild, moderate, severe, or excruciating. For children, drawings of faces in a series—from smiling to frowning and crying—can be used to determine the severity of pain. No laboratory test can document the presence or the severity of pain.
Doctors always try to determine whether a bodily injury or disease is causing the pain; they also consider psychologic causes. Many chronic disorders (such as cancer, arthritis, sickle cell anemia, and inflammatory bowel disease) cause pain, as do acute disorders (such as wounds, burns, torn muscles, broken bones, sprained ligaments, appendicitis, kidney stones, and a heart attack). Psychologic disorders (such as depression and anxiety) can worsen pain. Sometimes pain is determined to be caused mostly or completely by psychologic disorders; such pain is called psychogenic pain.
Doctors also consider whether pain is acute or chronic. Acute pain begins suddenly and usually does not last long. When severe, it may cause anxiety, a rapid heartbeat, an increased breathing rate, elevated blood pressure, sweating, and dilated pupils. Chronic pain persists for weeks or months. The term usually describes pain that persists for more than 1 month beyond the usual course of an illness or injury, pain that recurs off and on for months or years, or pain that is associated with a chronic disorder such as cancer. Usually, chronic pain does not affect the heartbeat, breathing rate, blood pressure, or pupils, but it may result in other problems, such as depression, disturbed sleep, decreased energy, loss of appetite, weight loss, and loss of interest in sexual activity.
Many people who are being treated for chronic pain may experience a brief, often severe flare-up of pain. It is called breakthrough pain because it breaks through the regularly scheduled pain treatment. Typically, breakthrough pain begins suddenly, lasts up to 1 hour, and feels much like the person's chronic pain except it is more severe. Breakthrough pain may differ from person to person and is often unpredictable.
Treatment
In some cases, treating the underlying disorder eliminates or minimizes the pain. For example, setting a broken bone in a cast or giving antibiotics for an infected joint helps reduce pain. However, even if the underlying disorder can be treated, pain relievers (analgesics) may still be needed to quickly manage the pain. Doctors choose an analgesic based on the type and duration of pain and on the likely benefits and risks. Most analgesics are effective for nociceptive pain but are less effective for neuropathic pain, which often requires different drugs. For some types of pain, especially chronic pain, nondrug treatments are also important.
Analgesics fall into three categories: opioid (narcotic) analgesics, nonopioid analgesics, and adjuvant analgesics (drugs that are usually given for reasons other than pain but that sometimes relieve pain).
Opioid Analgesics
Opioid analgesics (narcotics), the most powerful analgesics, are the mainstay for treatment of severe acute pain and chronic pain due to cancer and other serious disorders. Opioids are preferred because they are so effective in controlling pain. The use of opioids to treat chronic pain not due to cancer is becoming more acceptable but is still relatively uncommon. Opioids are not appropriate for everyone.
Nonopioid Analgesics
A variety of nonopioid analgesics are available.Several (such as aspirin , ibuprofen , ketoprofen , naproxen Trade , and acetaminophen ) are available in prescription and nonprescription strengths.Prescription-strength formulations contain more active ingredient per dose than OTC formulations. OTC analgesics are reasonably safe to take for short periods of time, but their labels caution against taking them for more than 7 to 10 days to treat pain. A doctor should be consulted if symptoms worsen or do not go away.
Adjuvant Analgesics
Adjuvant analgesics are drugs that are not usually used for pain relief but may relieve pain in certain circumstances and that, when used to relieve pain, are usually used with other analgesics or nondrug pain treatments.
Types Of Pain
- Nociceptive Pain
- Neuropathic Pain
- Psychogenic Pain
Nociceptive pain is caused by an injury to body tissues.
The injury may be a cut, bruise, bone fracture, crush injury, burn, or anything that damages tissues. This type of pain is typically aching, sharp, or throbbing. Most pain is nociceptive pain. Pain receptors for tissue injury (nociceptors) are located mostly in the skin or in the internal organs.
The pain almost universally experienced after surgery is nociceptive pain . The pain may be constant or intermittent, often worsening when a person moves, coughs, laughs, or breathes deeply or when the dressings over the surgical wound are changed.
Most of the pain due to cancer is nociceptive. When a tumor invades bones and organs, it may cause mild discomfort or severe, unrelenting pain. Some cancer treatments, such as surgery and radiation therapy, can also cause nociceptive pain.
Neuropathic Pain
Neuropathic pain is caused by abnormalities in the nerves, spinal cord, or brain. Neuropathic pain may be felt as a burning or tingling sensation or as hypersensitivity to touch or cold.
Psychogenic Pain
Psychogenic pain is entirely or mostly related to a psychologic disorder.
When people have persistent pain with evidence of psychologic disturbances and without evidence of a disorder that could cause the pain, the pain may be described as psychogenic. Pain that is purely psychogenic is rare. More commonly, the pain has a physical cause, but the doctor's assessment indicates that the degree of pain and the disability experienced are out of proportion to what most people with a similar disorder experience. Sometimes this type of pain is described as a chronic pain syndrome. Psychologic factors often contribute to disability and to an exaggeration of pain complaints. Any kind of pain can be complicated by psychologic factors. Even when pain is suspected to be psychogenic, doctors still investigate whether a physical disorder is contributing to the pain.
The fact that the pain is caused or worsened by psychologic factors does not mean that it is not real. Most people who report pain are really experiencing it, even if a physical cause cannot be identified. Pain complicated by psychologic factors still requires treatment, often by a team that includes a psychologist or psychiatrist. As with other kinds of treatment for chronic pain, the treatment for this type of pain varies from person to person, and doctors try to match the treatment with the person's needs. For most people who have chronic psychogenic pain, the goals of treatment are to improve comfort and physical and psychologic function. Doctors may make specific recommendations for gradually increasing physical and social activities. Drugs and nondrug treatments—such as biofeedback, relaxation training, distraction techniques, hypnosis, transcutaneous electrical nerve stimulation (TENS), and physical therapy—may be used. Psychologic counseling is often needed.
Informations obtained from National Institute of Health.