pain(redirected from nerve ending pain)
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pain,unpleasant or hurtful sensation resulting from stimulation of nerve endings. The stimulus is carried by nerve fibers to the spinal cord and then to the brain, where the nerve impulse is interpreted as pain. The excessive stimulation of nerve endings during pain is attributed to tissue damage, and in this sense pain has protective value, serving as a danger signal of disease and often facilitating diagnosis. Unlike other sensory experiences, e.g., response to touch or cold, pain may be modified by sedatives and nonsteroidal anti-inflammatory drugs or, if unusually severe, by opioid narcotics. Recently, patient-controlled analgesic techniques have been introduced, in which patients have the option of injecting small quantities of narcotic type analgesics to control their own pain. Microprocessor-controlled injections may be made through intravenous catheters, or through a catheter into the epidural (covering of the spinal cord) area. If such treatments do not suffice and if the cause of the pain cannot be removed or treated, severing a nerve in the pain pathway may bring relief.
Pain is occasionally felt not only at the site of stimulation but in other parts of the body supplied by nerves in the same sensory path; for example, the pain of angina pectoris or coronary thrombosis may extend to the left arm. This phenomenon is known as referred pain. Subjective or hysterical pain originates in the sensory centers of the brain without stimulation of the nerves at the site of the pain.
Progress has been made in the management of chronic pain and in the education of patients and physicians in such techniques as biofeedback, acupuncture, and meditation and the appropriate use of narcotics and other medications. Using advanced medical-imaging technology, researchers have now located multiple pain centers in the cerebral cortex of the brain, offering promise of possible improvements in measuring and managing pain.
See F. T. Vertosick, Jr., Why We Hurt: The Natural History of Pain (2000).
a disagreeable, oppressive, sometimes unbearable sensation arising in animals and man, chiefly in response to exceedingly strong or destructive factors.
In the course of the evolution of the organic world, pain was transformed into a danger signal; it became an important biological means for saving the life of an individual and, consequently, of a species. Pain mobilizes the body’s defenses to eliminate the painful stimuli and restore the normal functioning of organs and physiological systems. According to one concept (the theory of specificity), the sensation of pain occurs when particular structures are stimulated, the so-called pain receptors (free nerve endings), which have their own system of transmitting impulses to the central nervous system. According to another belief (the theory of intensity), strong stimulation of any receptors (touch, heat, cold) may cause pain.
Information about pain is transmitted through the dorsal (sensory) roots to the spinal cord and by way of the spinothalamic tract to the optic thalamus. After this information reaches the cerebral cortex it is perceived by the mind as pain. Other divisions of the brain are also involved in the process, including the reticular formation, limbic system, and hypothalamus. These determine the nature (modality) of pain and the resulting emotional manifestations (facial expressions, crying, and groaning) and autonomic manifestations (changes in blood pressure, heartbeat, respiration, and pupil dilation). The cerebral cortex can translate impulses that do not cause pain into painful impulses and under certain circumstances (emotional excitement and volitional stress) can mitigate and even completely abolish the sensation of pain. Strictly controlled mechanical, electrical, temperature, chemical, and other stimuli are used in laboratory experiments and clinical studies to determine the threshold and intensity of pain.
Pain is one of the earliest symptoms of many disturbances of the life processes. It is therefore a particularly important factor in the diagnosis and treatment of a number of diseases. A distinction is made between true pain, which is felt in the diseased organ (for example, in the heart, liver, and stomach), and referred, or reflex, pain in certain parts of the skin, the so-called Zakhar’in-Head zones (for example, in the left arm or shoulder blade in heart diseases). Stubborn and persistent pain often disturbs the functioning of individual organs, physiological systems, or the entire body and causes pathological phenomena (such as impairment of the central nervous system, gastrointestinal tract, or endocrine glands) which disappear when the pain ceases. The exhaustion of the nerve centers, chiefly the cerebral cortex, that results from prolonged and severe pain may produce shock, collapse, and sometimes even death.
Sensitivity to pain varies from individual to individual. It may be high (hyperalgesia), low (hypalgesia), and in some extremely rare cases absent altogether (analgesia). The perception of pain is quite subjective and dependent on many factors related to individual traits, type of higher nervous activity, impression of one’s own condition, mood, and physical and mental state. Adaptation to pain is much less common than to other kinds of sensations, and in cases where it is not noticed, this is usually due to distraction and the switching of attention.
According to data from modern psychology, the emotional reaction to pain, although determined by inborn nervous and physiological mechanisms, is nevertheless dependent in large measure on developmental conditions and upbringing. The conditioned activity of the brain plays an important role in the perception of pain. A conditioned stimulus may elicit a strong reaction of pain even in the absence of a strong painful stimulus. For example, if the eyes of a patient with causalgia are covered, he will react calmly to light pressure on the affected limb, but such pressure will produce severe pain if his eyes are open. Lesions of the nerve trunks, vascular disorders, metabolic disturbances, and so on may produce various kinds of pain (for example, causalgia, phantom pain, headache, and muscular pain), the genesis of which has to be specifically analyzed in each particular case. Modern medicine has at its disposal a wide array of pharmacological agents to mitigate or relieve pain. Physical agents and surgical methods are used for the same purpose.
The concept of pain is sometimes used in a figurative sense, as when speaking of spiritual pain to describe a special psychic state caused by various external or internal factors and associated with distressing sensations. These sensations are physiologically caused by the action of the higher nerve centers on certain internal organs.
REFERENCESDionesov, S. M. Bol’ i ee vliianie na organizm cheloveka i zhivotnogo, 2nd ed. Moscow, 1963.
Kassil’, G. N. Nauka o boli. Moscow, 1969.
Keele, C. A., and D. Armstrong. Substances Producing Pain and Itch. London, 1964.
Pain. Edited by A. Soulairac, J. Cahn, and J. Charpentier. London-New York, 1968.
G. N. KASSIL’
What does it mean when you dream about pain?
Experiencing pain in one’s dream may be a reflection of real pain that exists somewhere in the dreamer’s body. Alternatively, the dreamer may consider someone or something to be a “pain.” The suppression of painful memories may also be an issue.