Pain in terms of medicine

From the point of view of medicine, pain is:

• reaction  on this sensation, which is characterized by a certain emotional coloring, reflex changes of functions internal organs, motor unconditioned reflexes, as well as volitional efforts aimed at getting rid of the pain factor.
• an unpleasant sensory and emotional experience associated with actual or perceived tissue damage, and at the same time an organism's response, mobilizing various functional systems to protect it from the effects of a pathogenic factor.

Prolonged pain is accompanied by changes in physiological parameters (blood pressure, pulse, dilated pupils, changes in the concentration of hormones).

International definition

Nociception is a neurophysiological concept denoting the perception, conduct, and central processing of signals about harmful processes or influences. That is it physiological mechanism  transmission of pain, and it does not affect the description of its emotional component. The fact that the conduction of pain signals in the nociceptive system is not equivalent to the perceived pain is important.

Types of physical pain

Acute pain

Acute pain is defined as a brief pain manifestation with an easily identifiable cause. Acute pain is a warning to the body of the current risk of organic damage or disease. Often persistent and acute pain  accompanied by aching pain. Acute pain is usually concentrated in a certain area before it somehow spreads wider. This type of pain is usually well treated.

Chronic pain

Chronic pain was originally defined as pain that lasts about 6 months or more. It is now defined as pain that persists for longer than the corresponding length of time during which it should usually end. Often it is more difficult to cure than acute pain. Special attention is required when referring to any pain that has become chronic. In exceptional cases, neurosurgeons can perform complex surgery to remove parts of a patient’s brain to cope with chronic pain. Such an intervention can relieve the patient from the subjective sensation of pain, but since the signals from the painful focus will still be transmitted through the neurons, the body will continue to respond to them.

Skin pain

Skin pain occurs when skin or subcutaneous tissue is damaged. Skin nociceptors terminate just below the skin, and due to the high concentration of nerve endings, they provide a highly accurate, localized sensation of pain of short duration.

Somatic pain

Somatic pain occurs in the ligaments, tendons, joints, bones, blood vessels and even in the nerves themselves. It is determined by somatic nociceptors. Due to the lack of pain receptors in these areas, they produce dull, poorly localized, longer pain than skin pain. This includes, for example, sprained joints and broken bones.

Internal pain

Internal pain arises from the internal organs of the body. Internal nociceptors are located in organs and internal cavities. An even greater lack of pain receptors in these parts of the body leads to more painful and prolonged, compared with somatic pain. Internal pain is particularly difficult to localize, and some internal organic damage is “attributed” to pain, when the sensation of pain is attributed to a part of the body that is not related to the part of the injury itself. Cardiac ischemia (insufficient blood content in the heart muscle) is perhaps the most famous example of pain attributed; the sensation can be located as a separate feeling of pain just above chest, in the left shoulder, arm or even in the palm. The attributed pain can be explained by the discovery that pain receptors in the internal organs also excite spinal neurons, which are excited by skin lesions. After the brain begins to associate the stimulation of these spinal neurons with the stimulation of somatic tissues in the skin or muscles, the pain signals from the internal organs begin to be interpreted by the brain as originating from the skin.

Phantom pain

Phantom pain in the limbs is a sensation of pain that occurs in a lost limb or in a limb that is not felt by ordinary sensations. This phenomenon is almost always associated with cases of amputations and paralysis.

Neuropathic pain

Neuropathic pain (“neuralgia”) can occur as a result of damage or disease of the nerve tissue itself (for example, toothache). This can interfere with the ability of sensory nerves to transmit the correct information to the thalamus (a division of the diencephalon), and hence the brain does not correctly interpret pain stimuli, even if there are no obvious physiological causes of pain.

Psychogenic pain

Psychogenic pain is diagnosed in the absence of an organic disease or when the latter cannot explain the nature and severity pain syndrome. Psychogenic pain is always chronic in nature and occurs against the background of mental disorders: depression, anxiety, hypochondria, hysteria, phobias. In a significant proportion of patients, psychosocial factors play an important role (job dissatisfaction, the desire to gain moral or material benefit). Especially close links exist between chronic pain and depression.

Pathological pain

Pathological pain  - altered perception of pain impulses as a result of violations in the cortical and subcortical parts of the central nervous system.

Violations can occur at any level of the nociceptive system, as well as if the connection between nociceptive ascending structures and the antinociceptive system is broken.

Heartache

Mental pain is a specific mental experience that is not associated with organic or functional disorders. Often accompanied by depression, mental disorder. More often long and associated with the loss of a loved one.

Physiological role

Despite its trouble, pain is one of the main components of the body's defense system. This is the most important signal of tissue damage and the development of the pathological process, a permanent regulator of homeostatic reactions, including their higher behavioral forms. However, this does not mean that pain has only protective properties. Under certain conditions, having played its informational role, the pain itself becomes part of the pathological process, often more dangerous than the damage that caused it.

According to one hypothesis, pain is not a specific physical sensation, and there are no special receptors that perceive only pain irritation. The appearance of a feeling of pain can be caused by irritation of any type of receptor, if the strength of the stimulation is large enough.

According to another point of view, there are special pain receptors characterized by a high threshold of perception. They are excited only by stimuli of damaging intensity. All pain receptors have no specialized endings. They are present in the form of free nerve endings. There are mechanical, thermal and chemical pain receptors. They are located in the skin and in the inner surfaces, such as the periosteum or the articular surfaces. Deeply located internal surfaces are weakly associated with pain receptors, and therefore the sensations of chronic, aching pain are transmitted only if organic damage has occurred directly in this area of ​​the body.

It is believed that pain receptors do not adapt to external stimuli. However, in some cases, the activation of the painful fibers becomes too strong, as if the painful stimuli continue to recur, which leads to a condition called hypersensitivity (hyperalgesia). In fact, there are people with a different threshold of pain sensitivity. And this may depend on the emotional and subjective characteristics of the human psyche.

The nociceptive nerves contain primary fibers of small diameter, having sensory endings in various organs and tissues. Their sensory endings resemble small branchy bushes.

The two main classes of nociceptors, Aδ-, and C-fiber, respectively, pass through quick and slow pain sensations. Class Aδ-myelinated fibers (covered with a thin myelin coating) conducts signals at a speed of 5 to 30 m / s and serves to transmit signals of fast pain. This type of pain is felt in one tenth of a second since the onset of pain stimulus. Slow pain, the signals of which pass through slower, unmyelinated (“bare”) C-fibers, at a speed of 0.5 to 2 m / s, is aching, throbbing, burning pain. Chemical pain (whether it is poisoning through food, air, water, accumulation of alcohol, drugs, drugs or radiation contamination, etc.) is an example of slow pain.

Other points of view

The study of pain in recent years has spread in various areas from pharmacology to psychology and neuropsychiatry. It was impossible to even imagine that the fruit flies would be used as an object for pharmacological studies of pain. Some psychiatrists are also trying to use pain to find a neurological “substitute” for human awareness, since pain has many subjective psychological moments other than pure physiology.

Interestingly, the brain itself is devoid of nociceptive tissues, and therefore cannot feel pain. Thus, a headache can not occur in the brain itself. Some suggest that the membrane surrounding the brain and the spinal cord, which is called the dura mater, is supplied with nerves with pain receptors, and these dural (dura mater) nociceptors are stimulated, and they can probably be involved in “production” headache.

Alternative medicine

Surveys conducted by the National Center for Complementary and Alternative Medicine of the United States (NCCAM) showed that pain is a common reason why people turn to complementary and alternative medicine. Cam). Among adult Americans who used KAM in 2002, 16.8% wanted to cure back pain, 6.6% - neck pain, 4.9% - arthritis, 4.9% - joint pain, 3.1% - headache, and 2.4% tried cope with intermittent pain.

One of these alternatives, traditional Chinese medicine, regards pain as an obstruction of the energy "Qi", which resembles resistance in an electrical circuit, or as "blood stagnation", which theoretically looks like dehydration, which worsens the body's metabolism. It has been established that traditional Chinese practice, acupuncture, is more effective for nontraumatic pains than for pain associated with injuries.

In recent decades, there has been a tendency to prevent or treat pain and diseases that create painful sensations, with help proper nutrition. This approach sometimes consists in taking dietary supplements (BAA) and vitamins in large quantities, which is considered from the point of view of medicine as a harmful attempt at self-treatment. In the works of Robert Atkins and Earl Mindela much attention is paid to the relationship between the activity of amino acids and the health of the body. For example, they claim that the essential amino acid DL-phenylalanine contributes to the production of endorphins and has an anesthetic effect that does not cause addiction. But in any case, they urge you to always consult with your doctor.

see also

Notes

Links

• Virtual reality relieves Compulenta phantom pains

Pain I

In the description of patients, the pain in their nature can be acute, dull, cutting, stabbing, burning, oppressive (compressive), aching, pulsating, According to the duration and frequency they can be constant, paroxysmal, associated with the time of day, seasons of the year, exercise , body posture, with certain movements (for example, breathing, walking), eating, acts of defecation or urination, etc., which makes it possible to suspect localization and pathology causing pain. Features of the accompanying pain of emotional reactions, such as the feeling of fear of death, accompanying chest B. with angina, myocardial infarction, pulmonary thromboembolism, have diagnostic value.

A definite diagnostic orientation is given by the distinction between somatoglia, i.e. pains caused by irritation of the somatic nerve fibers, and vegetalgy (sympatalgia), arising from the involvement in the sensitive fibers of the vegetative innervation. Somatalgia (permanent or paroxysmal) are located in the innervation zone of the peripheral nerves or roots and are usually not accompanied by vegetative disturbances or the latter (with very intense pain) have a character (general, increased blood pressure, increased heart rate, etc.).

In vegetalgia, disorders of the vegetative functions are observed as a rule and often have a local character, as expressed by local spasms of peripheral vessels, changes in skin temperature, "goose" skin, impaired sweating, trophic disorders, etc. Sometimes vegetalgia reaches causalgia (causalgia) ,   Often with reflected pains of the type of repercussion (Repercussion) with the appearance of pain in the Zakharyin-Ged zones. Perhaps the appearance of pain in one half of the body (), which is observed, in particular, with the defeat of the thalamus. The high frequency of repercussion with the appearance of pain in areas remote from the affected organ should be borne in mind in the differential diagnosis of diseases of internal organs, blood vessels, bones and joints. for example, in myocardial infarction (myocardial infarction) B. is possible not only in the region of the sternum with irradiation in left hand, but also B. in the thoracic spine, B. in the lower, in the forehead, in right hand, in the abdomen (abdominal form), etc. With all the variety of manifestations of painful repercussion, the total B. characteristic helps to identify features that are typical or atypical for any process in the area of ​​internal organs. for example, dissecting aortic aneurysm in many of B.'s characteristics is similar to myocardial infarction, but B.'s spread along the spine with irradiation to the legs, which is characteristic of dissecting aneurysm, is not typical of myocardial infarction.

The behavior of the patient during painful paroxysms also has diagnostic value. for example, in myocardial infarction, the patient tries to lie still, the patient rushes about with a bout of renal colic, adopts various postures, which is not observed when B. is similarly localized in a patient with lumbar radiculitis.

In diseases of the internal organs of a bladder, it occurs as a result of blood flow disorders (, thrombosis of the mesenteric or renal arteries, atherosclerotic stenosis of the abdominal aorta, etc.); spasm of smooth muscles of internal organs (stomach,); stretching the walls of hollow organs (gallbladder, renal pelvis, ureter); the spread of the inflammatory process in areas supplied with sensitive innervation (to the parietal pleura, peritoneum, etc.). brain substance is not accompanied by B., it occurs when the irritation of the membranes, venous sinuses, intracranial vessels. Pathological processes in a lung are followed by B. only at their distribution on a parietal pleura. Strong B. occur when a spasm of heart vessels. B. in the esophagus, stomach and intestines often occurs when their spastic condition or stretching. Pathological processes in the parenchyma of the liver, spleen, kidneys do not cause pain, unless they are accompanied by acute stretching of the capsule of these organs. Muscle pain occurs with bruises, myositis, convulsions, disorders of the arterial circulation (in the latter cases, B. proceeds as sympathalgia). With the defeat of the periosteum and bone processes B. are extremely painful in nature.

It must be borne in mind that pain in cases of diseases of internal organs may not persist for a long time and will only grow in an avalanche-like manner during the incurable stage of the process (for example, malignant neoplasms). After the cure of a somatic disease, persistent pain is possible due to the consequences of damage to the nerve trunks, their ischemic changes, adhesive process, changes in the functional state of the preganglionic vegetative innervation nodes, as well as psychogenic pain fixation.

The elimination of pain as one of the most painful for the patient manifestations of the disease refers to the priorities that are solved by the doctor in the process of determining therapeutic tactics. The best option is to eliminate the cause of the pain, such as removing a foreign body or squeezing, repressing dislocation, etc. If this is not possible, preference is given to influences on those pathogenesis links with which pain is associated, for example, alkali intake to relieve pain during ulcer duodenal ulcer, nitroglycerin - with angina pectoris, antispasmodics (see. Antispasmodics) and anticholinergics (see Holoblokiruyuschie means) - with hepatic and renal colic, etc. With the ineffectiveness or impossibility of causal and pathogenetic therapy, they resort to symptomatic treatment of pain with the help of analgesics (Analgesics) ,   the effect of which can be enhanced by the simultaneous use of neuroleptic agents (Neuroleptic agents) or tranquilizers (tranquilizers) .   However, with the unspecified nature of the somatic disease, especially with unclear abdominal pains, the use of analgesics is contraindicated due to the possible modification of the clinical picture that makes it difficult to diagnose the disease, in which urgent surgical intervention may be indicated (see Acute abdomen) . With local pains, incl. with some neuralgia, local anesthesia is sometimes advisable. .   For persistent debilitating pains in patients with chronic diseases and low effectiveness of analgesics, symptomatic surgical B. is used - radicotomy, chordotomy, tractotomy and other methods.

  Bibliography:  Waldman A.V. and Ignatov Yu.D. The central mechanisms of pain, L., 1976, bibliogr .; Grinshtein A.M. and Popova N.A. Vegetative syndromes, M., 1971; Erokhina L.G. Facial pain, M., 1973; Kalyuzhny L.V. Physiological mechanisms of regulation of pain sensitivity, M., 1984, bibliogr .; Karpov V.D. nervous diseases, M., 1987; Kassil G.N. The science of pain, M., 1975; Kryzhanovsky G.N. Determinant structures in the pathology of the nervous system, M., 1980; Nordemar R. Back pain,. With Swedish., M., 1988; Shtok V.N. , M., 1987, bibliogr.

Fig. 1. Scheme of occurrence of projected pain. Nerve impulses caused by direct stimulation (indicated by an arrow) reach the corresponding zone of the cerebral cortex along the afferent fibers in the spinotalamic tract, causing a sensation of pain in that part of the body (arm), which is usually caused by irritation of the nerve endings: 1 - a part of the body with pain receptors; 2 - the sensation of pain at the location of the respective receptors of pain; 3 - the brain; 4 - lateral spinothalamic tract; 5 - spinal cord; 6 - afferent nerve fiber.

Fig. 2. Diagram of the occurrence of reflected pain. Pain from the internal come to the spinal cord, the individual structures of which are synaptically in contact with the nerve cells of the spinothalamic tract, on which the nerve fibers innervating a certain segment of the skin end: 1 - skin; 2 - the trunk of the sympathetic nervous system; 3 - rear spine; 4 - lateral spinothalamic tract; 5 - spinal cord; 6 - front spine; 7 - internal organ; 8 - the visceral nerve.