Symptom/Sign: Pain
Classifications and external resources

ICD-10	R52
ICD-9	338
DiseasesDB	9503
MedlinePlus	002164
MeSH	D010146

Pain, in the sense of physical pain,^[1] is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm. A symptom' (from Greek σύμπτωμα, "accident misfortune that which befalls" from συμπίπτω, "I befall" from A Sign is an indication of some fact or quality and a medical sign is an objective indication of some medical fact or quality that is detected by a Physician The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The International Statistical Classification of Diseases and Related Health Problems 10th Revision ( ICD -10) is a coding of diseases and signs symptoms abnormal findings The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. The Diseases Database is a free Website that provides information about the relationships between medical conditions Symptoms, and Medications. MedlinePlus, with the MedlinePlus Medical Encyclopedia, is a website network containing Health information from the world's largest medical Library Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Individuals get acquainted to pain through various daily hurts and aches, and occasionally through more serious injuries or illnesses. For scientific and clinical purposes, pain is defined by the International Association for the Study of Pain (IASP) as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage". The International Association for the Study of Pain (IASP is an international professional organization promoting research education and policies for the knowledge and management of ^[2][3]

Pain is highly subjective to the individual experiencing it. A definition that is widely used in nursing was first given as early as 1968 by Margo McCaffery: "'Pain is whatever the experiencing person says it is, existing whenever he says it does". Margo McCaffery is a Nurse and pioneer of the field of Pain medicine. ^[4][5]

Pain of any type is the most frequent reason for physician consultation in the United States, prompting half of all Americans to seek medical care annually. ^[6] It is a major symptom in many medical conditions, significantly interfering with a person's quality of life and general functioning. Diagnosis is based on characterizing pain in various ways, according to duration, intensity, type (dull, burning or stabbing), source, or location in body. Usually pain stops without treatment or responds to simple measures such as resting or taking an analgesic, and it is then called ‘acute’ pain. In Medicine, an acute disease is a disease with either or both of a rapid onset a short course (as opposed to a chronic course But it may also become intractable and develop into a condition called chronic pain, in which pain is no longer considered a symptom but an illness by itself. Chronic pain is defined as Pain that persists longer than the temporal course of natural healing associated with a particular type of injury or disease process The study of pain has in recent years attracted many different fields such as pharmacology, neurobiology, nursing sciences, dentistry, physiotherapy, and psychology. Pain medicine is a separate subspecialty^[7] figuring under some medical specialties like anesthesiology, physiatry, neurology, psychiatry. Pain management (also called pain medicine is the medical discipline concerned with the relief of Pain.

Pain is part of the body's defense system, triggering a reflex reaction to retract from a painful stimulus, and helps adjust behaviour to increase avoidance of that particular harmful situation in the future. Given its significance, physical pain is also linked to various cultural, religious, philosophical, or social issues.

Etymology : "Pain (n. ) 1297, "punishment," especially for a crime; also (c. 1300) "condition one feels when hurt, opposite of pleasure," from O. Fr. peine, from L. poena "punishment, penalty" (in L. L. also "torment, hardship, suffering"), from Gk. poine "punishment," from PIE *kwei- "to pay, atone, compensate" (. . . ). " Online Etymology Dictionary

Contents 1 Clarification on the use of certain pain-related terms 2 Mechanism 3 Evolutionary and behavioral role 4 Diagnosis 4.1 Verbal characterization 4.2 Intensity 4.3 Localization 5 Management 5.1 Anesthesia 5.2 Analgesia 5.3 Complementary and alternative medicine 6 Special cases 6.1 Phantom pain 6.2 Pain asymbolia 6.3 Insensitivity to pain 6.4 Psychogenic pain 6.5 Pain as pleasure 7 Society and culture 8 In other species 9 Notes and references 10 External links

Clarification on the use of certain pain-related terms

• The word pain used without a modifier usually refers to physical pain, but it may also refer to pain in the broad sense, i. e. suffering. Suffering, or pain, is an individual's basic Affective experience of unpleasantness and aversion associated with harm or threat of harm The latter includes physical pain and mental pain, or any unpleasant feeling, sensation, and emotion. It may be described as a private feeling of unpleasantness and aversion associated with harm or threat of harm in an individual. Care should be taken to make the appropriate distinction when required between the two meanings. For instance, philosophy of pain is essentially about physical pain, while a philosophical outlook on pain is rather about pain in the broad sense. Pain is often referred to in philosophical discussions concerning Qualia and the fundamental nature of human experience Or, as another quite different instance, nausea or itch are not 'physical pains', but they are unpleasant sensory or bodily experience, and a person 'suffering' from severe or prolonged nausea or itch may be said 'in pain'. Nausea ( Latin: Nausea, Greek:, " Sea-sickness " also called wamble) is the sensation of unease and discomfort Itch ( Latin: pruritus) is an unpleasant Sensation that evokes the desire or Reflex to scratch

• Nociception, the unconscious activity induced by a harmful stimulus in sense receptors, peripheral nerves, spinal column and brain, should not be confused with physical pain, which is a conscious experience. Nociception (synonym nociperception is defined as "the neural processes of encoding and processing Noxious stimuli. ^[8]

• Qualifiers, such as mental, emotional, psychological, and spiritual, are often used for referring to more specific types of pain or suffering. In particular, 'mental pain' may be used in relationship with 'physical pain' for distinguishing between two wide categories of pain. A first caveat concerning such a distinction is that it uses 'physical pain' in a sense that normally includes not only the 'typical sensory experience' of 'physical pain' but also other unpleasant bodily experience such as itch or nausea. A second caveat is that the terms physical or mental should not be taken too literally: physical pain, as a matter of fact, happens through conscious minds and involves emotional aspects, while mental pain happens through physical brains and, being an emotion, it involves important bodily physiological aspects.

• The term unpleasant or unpleasantness commonly means painful or painfulness in a broad sense. It is also used in (physical) pain science for referring to the affective dimension of pain, usually in contrast with the sensory dimension. For instance: “Pain-unpleasantness is often, though not always, closely linked to both the intensity and unique qualities of the painful sensation. ”^[9] Pain science acknowledges, in a puzzling challenge to IASP definition, that pain may be experienced as a sensation devoid of any unpleasantness: see below pain asymbolia. ^[10]

• Suffering is sometimes used in the specific narrow sense of physical pain, but more often it refers to mental pain, or more often yet to pain in the broad sense. Suffering, or pain, is an individual's basic Affective experience of unpleasantness and aversion associated with harm or threat of harm Suffering is described as an individual's basic affective experience of unpleasantness and aversion associated with harm or threat of harm. Affect, like the adjective affective, refers to the experience of feeling or Emotion.

The terms pain and suffering are often used together in different senses which can become confusing, for example:

• being used as synonyms;
• being used in contradistinction to one another: e. g. "pain is inevitable, suffering is optional", or "pain is physical, suffering is mental";
• being used to define each other: e. g. "pain is physical suffering", or "suffering is severe physical or mental pain".

To avoid confusion: this article is about physical pain in the narrow sense of a typical sensory experience associated with actual or potential tissue damage. This excludes pain in the broad sense of any unpleasant experience, which is covered in detail by the article Suffering. Suffering, or pain, is an individual's basic Affective experience of unpleasantness and aversion associated with harm or threat of harm

Mechanism

Stimulation of a nociceptor, due to a chemical, thermal, or mechanical event that has the potential to damage body tissue, may cause nociceptive pain. A nociceptor is a Sensory receptor that sends signals that cause the perception of Pain in response to a potentially damaging stimulus Nociception (synonym nociperception is defined as "the neural processes of encoding and processing Noxious stimuli.

Damage to the nervous system itself, due to disease or trauma, may cause neuropathic (or neurogenic) pain. Neuropathy is a medical term usually short for Peripheral neuropathy. The nervous system is a Network of specialized cells that communicate information about an animal's surroundings and itself ^[11] Neuropathic pain may refer to peripheral neuropathic pain, which is caused by damage to nerves, or to central pain, which is caused by damage to the brain, brainstem, or spinal cord. A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons.

Nociceptive pain and neuropathic pain are the two main kinds of pain when the primary mechanism of production is considered. A third kind may be mentioned: see below the rare case of psychogenic pain.

Nociceptive pain may be classified further in three types that have distinct organic origins and felt qualities. ^[12]

1. Superficial somatic pain (or cutaneous pain) is caused by injury to the skin or superficial tissues. "Somatic" redirects here for the musician known as Somatic see Hahn Rowe. The skin is the outer covering of living tissue of an animal (or plant Cutaneous nociceptors terminate just below the skin, and due to the high concentration of nerve endings, produce a sharp, well-defined, localized pain of short duration. Examples of injuries that produce cutaneous pain include minor wounds, and minor (first degree) burns. In Medicine, a wound is a type of Injury in which the Skin is torn cut or punctured (an open wound or where blunt force trauma A burn is a type of Injury that may be caused by Heat, cold, Electricity, Chemicals, Light, Radiation, or
   
   
2. Deep somatic pain originates from ligaments, tendons, bones, blood vessels, fasciae, and muscles. "Somatic" redirects here for the musician known as Somatic see Hahn Rowe. In Anatomy, the term ligament is used to denote three different types of structures Fibrous tissue that connects Bones to other bones A tendon (or sinew) is a tough band of Fibrous connective tissue that usually connects Muscle to Bone and is capable of withstanding tension The blood vessels are part of the Circulatory system and function to transport Blood throughout the body Fascia (făsh'ē-ə pl fas·ci·ae (făsh'ē-ē adj fascial (făsh'ē-əl (from Latin: a band is the Soft tissue component of Muscle (from Latin musculus, diminutive of mus "mouse" is contractile tissue of the body and is derived from the It is detected with somatic nociceptors. The scarcity of pain receptors in these areas produces a dull, aching, poorly-localized pain of longer duration than cutaneous pain; examples include sprains, broken bones, and myofascial pain. A sprain (from the French espraindre - to wring is an Injury which occurs to Ligaments caused by a sudden overtearing (for the Muscle Myofascial Pain Syndrome (or MPS is a term used to describe one of the conditions characterized by chronic pain
   
   
3. Visceral pain originates from body's viscera, or organs. In Anatomy, a viscus (ˈvɪskəs ( Plural: viscera /ˈvɪsərə/ is an internal organ of an animal (including humans in particular an internal Visceral nociceptors are located within body organs and internal cavities. The even greater scarcity of nociceptors in these areas produces pain that is usually more aching or cramping and of a longer duration than somatic pain. Visceral pain may be well-localized, but often it is extremely difficult to localize, and several injuries to visceral tissue exhibit "referred" pain, where the sensation is localized to an area completely unrelated to the site of injury.

Nociception is the unconscious afferent activity produced in the peripheral and central nervous system by stimuli that have the potential to damage tissue. It should not be confused with pain, which is a conscious experience. ^[8] It is initiated by nociceptors that can detect mechanical, thermal or chemical changes above a certain threshold. A nociceptor is a Sensory receptor that sends signals that cause the perception of Pain in response to a potentially damaging stimulus All nociceptors are free nerve endings of fast-conducting myelinated A delta fibers or slow-conducting unmyelinated C fibers, respectively responsible for fast, localized, sharp pain and slow, poorly-localized, dull pain. A delta fibers, or Aδ fibers are a Type of sensory fiber. They are associated with cold and pressure and as Nociceptors they convey fast Pain information Structure and Anatomy Location C fibers are found in the peripheral nerves of the somatic sensory system. Once stimulated, they transmit signals that travel along the spinal cord and within the brain. Nociception, even in the absence of pain, may trigger withdrawal reflexes and a variety of autonomic responses such as pallor, diaphoresis, bradycardia, hypotension, lightheadedness, nausea and fainting. Pallor (also called pastiness or wanness) is a reduced amount of oxy Hemoglobin in Skin or Mucous membrane, a pale color which can Diaphoresis is excessive sweating commonly associated with shock and other Medical emergency conditions Bradycardia, as applied to adult medicine is defined as a resting Heart rate of under 60 beats per minute though it is seldom symptomatic until the rate drops below 50 beat/min In Physiology and Medicine, hypotension refers to an abnormally low Blood pressure. Light-headedness is a common and often unpleasant sensation of Dizziness and/or feeling that one may be about to faint, which may be transient recurrent or occasionally Nausea ( Latin: Nausea, Greek:, " Sea-sickness " also called wamble) is the sensation of unease and discomfort ^[13]

Brain areas that are particularly studied in relation with pain include the somatosensory cortex which mostly accounts for the sensory discriminative dimension of pain, and the limbic system, of which the thalamus and the anterior cingulate cortex are said to be especially involved in the affective dimension. The lateral postcentral gyrus is a prominent structure in the Parietal lobe of the human Brain and an important landmark The limbic system, or Paleomammalian brain is a term for a set of brain structures including the Hippocampus and Amygdala and anterior thalamic nuclei and a limbic The thalamus (from Greek θάλαμος = room chamber, IPA= /ˈθæləməs/ is a pair and symmetric part of the brain The Anterior cingulate cortex (ACC is the frontal part of the Cingulate cortex, which resembles a "collar" form around the Corpus callosum, the fibrous

The gate control theory of pain describes how the perception of pain is not a direct result of activation of nociceptors, but instead is modulated by interaction between different neurons, both pain-transmitting and non-pain-transmitting. The gate control theory of pain, put forward by Ronald Melzack (a Canadian psychologist and Patrick David Wall (a British physician in 1962 and again in 1965 In other words, the theory asserts that activation, at the spine level or even by higher cognitive brain processes, of nerves or neurons that do not transmit pain signals can interfere with signals from pain fibers and inhibit or modulate an individual's experience of pain.

Pain may be experienced differently depending on genotype; as an example individuals with red hair may be more susceptible to pain caused by heat,^[14] but redheads with a non-functional melanocortin 1 receptor (MC1R) gene are less sensitive to pain from electric shock. The genotype is the genetic constitution of a cell an organism or an individual (i The melanocortin 1 receptor (also known as melanocyte-stimulating hormone receptor or Mc1r) is one of the key Proteins in regulating hair and skin color ^[15] Gene Nav1.7 has been identified as a major factor in the development of the pain-perception systems within the body. The Nav17 Sodium ion channel protein is encoded by gene.Recent studies have associated a defect in SCN9A with Congenital insensitivity to pain. A rare genetic mutation in this area causes non-functional development of certain sodium channels in the nervous system, which prevents the brain from receiving messages of physical damage, resulting in congenital insensitivity to pain. Sodium channels are Integral membrane proteins that form Ion channels, conducting sodium ions ( Na+) through a cell's Plasma membrane Congenital insensitivity to pain (CIPA also known as congenital analgia, is a rare condition where a person cannot feel (and has never felt physical Pain. ^[16] The same gene also appears to mediate a form of pain hyper-sensitivity, while other mutations may be the root of paroxysmal extreme pain disorder. Paroxysmal extreme pain disorder ( PEPD) originally named familial rectal pain syndrome, is a rare disorder whose most notable features are pain in the mandibular ^[16][17]

Evolutionary and behavioral role

Pain is part of the body's defense system, triggering mental and physical behavior to end the painful experience. It promotes learning so that repetition of the painful situation will be less likely.

Despite its unpleasantness, pain is an important part of the existence of humans and other animals; in fact, it is vital to healthy survival (see below Insensitivity to pain). Pain encourages an organism to disengage from the noxious stimulus associated with the pain. Preliminary pain can serve to indicate that an injury is imminent, such as the ache from a soon-to-be-broken bone. Pain may also promote the healing process, since most organisms will protect an injured region in order to avoid further pain.

Interestingly, the brain itself is devoid of nociceptive tissue, and hence cannot experience pain. Thus, a headache is not due to stimulation of pain fibers in the brain itself. A headache ( cephalalgia in medical terminology is a condition of pain in the Head; sometimes Neck or upper back pain may also be interpreted Rather, the membrane surrounding the brain and spinal cord, called the dura mater, is innervated with pain receptors, and stimulation of these dural nociceptors is thought to be involved to some extent in producing headache pain. The dura mater (from the Latin "hard mother" or pachymeninx, is the tough and inflexible outermost of the three layers of the Meninges surrounding the The vasoconstriction of pain-innervated blood vessels in the head is another common cause. Some evolutionary biologists have speculated that this lack of nociceptive tissue in the brain might be because any injury of sufficient magnitude to cause pain in the brain has a sufficiently high probability of being fatal that development of nociceptive tissue therein would have little to no survival benefit. eVolution is the third Album by eLDee, it was due to be released in 2008

Chronic pain, in which the pain becomes pathological rather than beneficial, may be an exception to the idea that pain is helpful to survival, although some specialists believe that psychogenic chronic pain exists as a protective distraction to keep dangerous repressed emotions such as anger or rage unconscious. ^[18] It is not clear what the survival benefit of some extreme forms of pain (e. g. toothache) might be; and the intensity of some forms of pain (for example as a result of injury to fingernails or toenails) seem to be out of all proportion to any survival benefits. A toothache, also known as odontalgia or less frequently as odontalgy, is an aching Pain in or around a Tooth. A nail is a horn -like structure at the end of an animal's Finger or Toe. A nail is a horn -like structure at the end of an animal's Finger or Toe.

Diagnosis

To establish an understanding of an individual's pain, health-care practitioners will typically try to establish certain characteristics of the pain:

• Quality
• Intensity
• Localization
• Radiation
• Frequency and Duration
• Onset and Offset
• Exacerbating Factors
• Ameliorating Factors

By using the gestalt of these characteristics, the source or cause of the pain can often be established. A complete diagnosis of pain will require also to look at the patient's general condition, symptoms, and history of illness or surgery. The physician may order blood tests, X-rays, scans, EMG, etc. Pain clinics may investigate the person's psychosocial history and situation.

Pain assessment also uses the concepts of pain threshold, the least experience of pain which a subject can recognize, and pain tolerance, the greatest level of pain which a subject is prepared to tolerate. The term pain threshold refers to the maximum intensity or duration of a sensory stimulus at which the body shuts down Pain tolerance is the amount of pain that a person can withstand before breaking down emotionally and/or physically Among the most frequent technical terms for referring to abnormal perturbations in pain experience, there are:

• allodynia, pain due to a stimulus which does not normally provoke pain,
• hyperalgesia, an increased response to a stimulus which is normally painful,
• hypoalgesia, diminished pain in response to a normally painful stimulus. Allodynia, meaning "other pain" is a Painful response to a usually non-painful stimulus and can be either static or mechanical Hyperalgesia is an increased sensitivity to Pain, which may be caused by damage to Nociceptors or Peripheral nerves. Hypoalgesia or hypalgesia denotes a decreased sensitivity to painful stimuli ^[19]

Verbal characterization

The quality of the pain remains a key characteristic, and is often the first question a practitioner will ask. Typical descriptions of pain quality include sharp, stabbing, tearing, squeezing, cramping, burning, lancinating (electric-shock like), or heaviness. It may be experienced as throbbing, dull, nauseating, shooting or a combination of these. Indeed, individuals who are clearly in extreme distress such as from a myocardial infarction may not describe the sensation as pain, but instead as an extreme heaviness on the chest. Myocardial infarction ( MI or AMI for acute myocardial infarction) also known as a heart attack, occurs when the blood supply Another individual with pain in the same region and with the same intensity may describe the pain as tearing which would lead the practitioner to consider aortic dissection. Inflammatory pain is commonly associated with some degree of itch sensation, leading to a chronic urge to rub or otherwise stimulate the affected area. Itch ( Latin: pruritus) is an unpleasant Sensation that evokes the desire or Reflex to scratch The difference between these diagnoses and many others rests on the quality of the pain. The McGill Pain Questionnaire is an instrument often used for verbal assessment of pain. The McGill Pain Questionnaire, also known as McGill pain index is a scale of rating Pain developed at McGill University by Melzack and Torgerson in

Intensity

Pain may range in intensity from slight through severe to agonizing and can appear as constant or intermittent. The threshold of pain varies widely between individuals. Sensory threshold is a theoretical concept used in Psychophysics. Many attempts have been made to create a pain scale that can be used to quantify pain, for instance on a numeric scale that ranges from 1 to 10 points. Pain is the Fifth Vital Sign. Pain scales measure Patient 's Pain, using different methods The purpose of these scales is to monitor an individual's pain over time, allowing care-givers to see how a patient responds to therapy for example. Accurate quantification can also allow researchers to compare results between groups of patients.

Localization

Pains are usually called according to their subjective localization in a specific area or region of the body: headache, toothache, shoulder pain, abdominal pain, back pain, joint pain, myalgia, etc. Localization is not always accurate in defining the problematic area, although it will often help narrow the diagnostic possibilities. Some pain sensations may be diffuse (radiating) or referred. Radiation of pain occurs in neuralgia when stimulus of a nerve at one site is perceived as pain in the sensory distribution of that nerve. Neuralgia is a painful disorder of the Nerves. Under the general heading of neuralgia are Trigeminal neuralgia (TN Atypical trigeminal neuralgia (ATN Sciatica, for instance, involves pain running down the back of the buttock, leg and bottom of foot that results from compression of a nerve root in the lumbar spine. Sciatica is a set of symptoms including Pain that may be caused by general compression and/or irritation of one of five nerve roots that give rise to the Sciatic nerve Referred pain usually happens when sensory fibres from the viscera enter the same segment of the spinal cord as somatic nerves i. Referred pain is a term used to describe the phenomenon of pain perceived at a site adjacent to or at a distance from the site of an injury's origin e. those from superficial tissues. The sensory nerve from the viscera stimulates the nearby somatic nerve so that the pain localization in the brain is confused. A well-known example is when heart damage is perceived as pain the left shoulder or arm. ^[20]

Management

Main article: Pain management

Medical management of pain has given rise to a distinction between acute pain and chronic pain. Pain management (also called pain medicine is the medical discipline concerned with the relief of Pain. Chronic pain is defined as Pain that persists longer than the temporal course of natural healing associated with a particular type of injury or disease process Acute pain is 'normal' pain, it is felt when hurting a toe, breaking a bone, having a toothache, or walking after an extensive surgical operation. Chronic pain is a 'pain illness', it is felt day after day, month after month, and seems impossible to heal.

In general, physicians are more comfortable treating acute pain, which usually is caused by soft tissue damage, infection and/or inflammation among other causes. It is usually treated simultaneously with pharmaceuticals, commonly analgesics, or appropriate techniques for removing the cause and for controlling the pain sensation. A drug, broadly speaking is any chemical substance that when absorbed into the body The failure to treat acute pain properly may lead to chronic pain in some cases. ^[21]

General physicians have only elementary training in chronic pain management. Chronic pain is defined as Pain that persists longer than the temporal course of natural healing associated with a particular type of injury or disease process Often, patients suffering from it are referred to various medical specialists. Though usually caused by an injury, an operation, or an obvious illness, chronic pain may as well have no apparent cause, or may be caused by a developing illness or imbalance. This disorder can trigger multiple psychological problems that confound both patient and health care providers, leading to various differential diagnoses and to patient's feelings of helplessness and hopelessness. Multidisciplinary pain clinics are growing in number since a few decades.

Anesthesia

Anesthesia is the condition of having the feeling of pain and other sensations blocked by drugs that induces a lack of awareness. Anesthesia, or anaesthesia (see spelling differences; from Greek grc αν- an-, "without" and grc αἲσθησις It may be a total or a minimal lack of awareness throughout the body (i. e. general anesthesia), or a lack of awareness in a part of the body (i. e. regional or local anesthesia).

Analgesia

Analgesia is an alteration of the sense of pain without loss of consciousness. The body possesses an endogenous analgesia system, which can be supplemented with painkillers or analgesic drugs to regulate nociception and pain. The word endogenous means "arising from within" the opposite of Exogenous. Nociception (synonym nociperception is defined as "the neural processes of encoding and processing Noxious stimuli. Analgesia may occur in the central nervous system or in peripheral nerves and nociceptors. The perception of pain can also be modified by the body according to the gate control theory of pain. The gate control theory of pain, put forward by Ronald Melzack (a Canadian psychologist and Patrick David Wall (a British physician in 1962 and again in 1965

The endogenous central analgesia system is mediated by 3 major components : the periaquaductal grey matter, the nucleus raphe magnus and the nociception inhibitory neurons within the dorsal horns of the spinal cord, which act to inhibit nociception-transmitting neurons also located in the spinal dorsal horn. Periaqueductal gray (PAG also called the "central gray" is the Midbrain Grey matter that is located around the Cerebral aqueduct within the The nucleus raphe magnus, located directly rostral to the Raphe obscurus, is afferently stimulated from axons in the Spinal cord and Cerebellum. The posterior horn ( posterior cornu, dorsal horn, spinal dorsal horn) of the Spinal cord is the dorsal (more towards the back grey matter of The peripheral regulation consists of several different types of opioid receptors that are activated in response to the binding of the body's endorphins. Opioid receptors are a group of G-protein coupled receptors with Opioids as Ligands The Endogenous Opioids are Dynorphins Endorphins are Endogenous Opioid Polypeptide compounds They are produced by the Pituitary gland and the Hypothalamus in Vertebrates These receptors, which exist in a variety of areas in the body, inhibit firing of neurons that would otherwise be stimulated to do so by nociceptors.

The gate control theory of pain postulates that nociception is "gated" by non-noxious stimuli such as vibration. The gate control theory of pain, put forward by Ronald Melzack (a Canadian psychologist and Patrick David Wall (a British physician in 1962 and again in 1965 Thus, rubbing a bumped knee seems to relieve pain by preventing its transmission to the brain. Pain is also "gated" by signals that descend from the brain to the spinal cord to suppress (and in other cases enhance) incoming nociceptive information.

Complementary and alternative medicine

A survey of American adults found pain was the most common reason that people use complementary and alternative medicine.

Traditional Chinese medicine views pain as a 'blocked' qi, akin to electrical resistance, with treatments such as acupuncture claimed as more effective for nontraumatic pain than traumatic pain. Traditional Chinese medicine (also known as TCM,) includes a range of traditional medical practices originating in China. In traditional Chinese culture, qi (zh [[wikt氣 氣]] Pinyin qì, Wade-Giles ch'i Jyutping Electrical resistance is a ratio of the degree to which an object opposes an Electric current through it measured in Ohms Its reciprocal quantity is History Antiquity In China, the practice of acupuncture can perhaps be traced as far back as Treatment of physical trauma is described here and in First aid. Although the mechanism is not fully understood, acupuncture may stimulate the release of large quantities of endogenous opioids. An opioid is a chemical Substance that has a Morphine -like action in the body ^[22]

Pain treatment may be sought through the use of nutritional supplements such as curcumin, glucosamine, chondroitin, bromelain and omega-3 fatty acids. Curcumin is the principal curcuminoid of the popular Indian curry spice Turmeric, the other two Curcuminoids being desmethoxycurcumin and bis-desmethoxycurcumin Glucosamine (C6H13NO5 is an Amino sugar and a prominent precursor in the Biochemical synthesis of glycosylated proteins Chondroitin sulfate is a sulfated Glycosaminoglycan (GAG composed of a chain of alternating sugars ( N-acetylgalactosamine and Glucuronic acid) Bromelain can refer to one of two Protease Enzymes extracted from the plant family Bromeliaceae, or it can refer to a combination of those enzymes along n −3 fatty acids (popularly referred to as ω−3 fatty acids or omega-3 fatty acids) are a family of unsaturated Fatty acids that

Hypnosis as well as diverse perceptional techniques provoking altered states of consciousness have proven to be of important help in the management of all types of pain. Hypnosis is often thought to be a wakeful state of focused attention and heightened suggestibility with diminished peripheral awareness ^[23]

Some kinds of physical manipulation or exercise are showing interesting results as well. ^[24]

Special cases

Phantom pain

Phantom limb pain is the sensation of pain from a limb that has been lost or from which a person no longer receives physical signals. A phantom limb is the sensation that an amputated or missing limb (even an organ like the appendix is still attached to the body and is moving appropriately It is an experience almost universally reported by amputees and quadriplegics. Amputation is the removal of a body extremity by trauma or Surgery. Quadriplegia, also known as tetraplegia, is a Symptom in which a human experiences Paralysis affecting all four limbs although not necessarily total paralysis Phantom pain is a neuropathic pain.

Pain asymbolia

Pain science acknowledges, in a puzzling challenge to IASP definition,^[3] that pain may be experienced as a sensation devoid of any unpleasantness: this happens in a syndrome called pain asymbolia or pain dissociation, caused by conditions like lobotomy, cingulotomy or morphine analgesia. Pain asymbolia is a condition in which Pain is perceived but does not cause suffering Typically, such patients report that they have pain but are not bothered by it, they recognize the sensation of pain but are mostly or completely immune to suffering from it. ^[10]

Insensitivity to pain

The ability to experience pain is essential for protection from injury, and recognition of the presence of injury. Insensitivity to pain may occur in special circumstances, such as for an athlete in the heat of the action, or for an injured soldier happy to leave the battleground. This phenomenon is now explained by the gate control theory. The gate control theory of pain, put forward by Ronald Melzack (a Canadian psychologist and Patrick David Wall (a British physician in 1962 and again in 1965 However, insensitivity to pain may also be an acquired impairment following conditions such as spinal cord injury, diabetes mellitus, or more rarely Hansen's Disease^[25]. Leprosy (from the Greek lepi (λέπι meaning scales on a fish or Hansen's disease, is a chronic disease caused by the bacterium A few people can also suffer from congenital insensitivity to pain, or congenital analgesia, a rare genetic defect that puts these individuals at constant risk from the consequences of unrecognized injury or illness. Congenital insensitivity to pain (CIPA also known as congenital analgia, is a rare condition where a person cannot feel (and has never felt physical Pain. Children with this condition suffer carelessly repeated damages to their tongue, eyes, bones, skin, muscles. They may attain adulthood, but they have a shortened life expectancy.

Psychogenic pain

Psychogenic pain, or psychalgia, is pain which to the sufferer is indistinct from actual physical pain, but which is caused by a psychological process. A psychogenic disease is a set of symptoms or complaints whose origin likely lies within the complex interactions of the frontal lobes of the brain and the system in which the complaint It occurs rarely, and generally in persons with a mental disorder. Mental disorder or mental illness is a psychological or behavioral pattern that occurs in an individual and is thought to cause distress or disability that is not expected as Currently, it is considered as physical pain, in conformity with IASP definition of pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage" (emphasis added). ^[3]

Physical pain accompanying or induced by heartache, rejection, depression, or other such mental events, is not usually considered as psychogenic pain.

Pain as pleasure

See algolagnia and sadomasochism. Algolagnia (ælgəˈlægniə (from the Greek άλγος algos, "pain" and λαγνεία lagnia, "lust" is a sexual tendency which is defined Sadism refers to Sexual or non-sexual gratification in the infliction of Pain or humiliation upon or by another person

Society and culture

Physical pain has been diversely understood or defined from antiquity to modern times. ^[26]

Philosophy of pain is a branch of philosophy of mind that deals essentially with physical pain. Pain is often referred to in philosophical discussions concerning Qualia and the fundamental nature of human experience Identity theorists assert that the mental state of pain is completely identical with some physical state caused by various physiological causes. Functionalists consider pain to be defined completely by its causal role and nothing else.

Religious or secular traditions usually define the nature or meaning of physical pain in every society. ^[27] Sometimes, extreme practices are highly regarded: mortification of the flesh, painful rites of passage, walking on hot coals, etc. For the Christian metal band see Mortification (band. For the record label see Mortification Records. A rite of passage is a Ritual that marks a change in a person's social or sexual status

Variations in pain threshold or in pain tolerance occur between individuals because of genetics, but also according to cultural, ethnical, or gender background.

Physical pain is an important political topic in relation with various issues, including resources distribution for pain management, drug control, torture, pain compliance (see also pain beam, pain maker, pain ray). The War on Drugs is a prohibition campaign undertaken by the United States government with the assistance of participating countries intended to reduce the Illegal Torture, according to the United Nations Convention Against Torture, is "any act by which severe pain or suffering, whether physical or mental is intentionally Pain compliance is a law enforcement technique that uses the application of pain to control a person generally to assist with taking that person into custody Pulsed Energy Projectile or PEP is a technology of Non-lethal weaponry currently under development by the U The Active Denial System (ADS is a Non-lethal, Directed-energy weapon developed by the U The Active Denial System (ADS is a Non-lethal, Directed-energy weapon developed by the U Corporal punishment is the deliberate infliction of pain intended to punish a person or change a his/her behavior. Corporal punishment is the deliberate infliction of pain intended to Punish a person or change his/her behavior Historically speaking, most punishments, whether in judicial, domestic, or educational settings, were corporal in basis.

More generally, it is rather as a part of pain in the broad sense, i. e. suffering, that physical pain is dealt with in cultural, religious, philosophical, or social issues. Suffering, or pain, is an individual's basic Affective experience of unpleasantness and aversion associated with harm or threat of harm

In other species

It is not scientifically possible to prove whether an animal, or a human for that matter, experiences pain or not. However, the presence of pain can be inferred through physical and behavioral reactions. ^[28] Specialists currently believe that all vertebrates can feel pain, and that certain invertebrates, like the octopus, might too. As for other animals, plants, or other entities, their ability to feel physical pain is presently a question beyond the scientific reach.

Veterinary medicine uses, for actual or potential animal pain, the same analgesics and anesthetics as used in humans. ^[29]

Notes and references

External links

• Acute Pain Medicine: Scientific Evidence (2nd ed) (2007 updated version)

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