Itching of the skin is a particularly unpleasant subjective sensation that causes the need to scratch. Physiological itching occurs in response to environmental irritants (friction, insect crawling, temperature changes, etc.) and disappears after elimination of the cause. Pathological itching is caused by changes in the skin or throughout the body and causes a strong need to get rid of itching by combing or any other method. Itching is a common symptom of local (dermatological) or general (systemic) disease. It can be limited (localized) or diffuse (generalized).One of the causes of itching is often noted endocrine diseases and metabolic disorders: hyper- and hypofunction of the thyroid gland, diabetes mellitus and hyperparathyroidism. In thyroid hyperfunction, generalized (inconstant and little-pronounced) itching of the skin is observed in the clinical picture only in 10 % of patients. It is accepted that itching of the skin in thyrotoxicosis syndrome is due to increased activity of kinin in combination with an increase in major metabolism and an increase in body and skin temperature (123).Itching caused by impaired bile secretion is characteristic of many diseases of the liver: primary biliary cirrhosis, sclerosing cholangitis, viral hepatitis caused by cholestasis medications and other causes of obstructive jaundice. It is in these cases that prurigo is usually generalized, but in some typical cases it is more pronounced on the feet and palms. With this pathology, itching is caused by obstruction of the biliary tract, however, and to this day, no close correlation has been found between serum bilirubin and the severity of itching.If it was previously thought that itching in pathology of the peripheral or central nervous system, such as multiple sclerosis, neuropathy, compression or irritation of nerves (e.g., paraesthetic dorsalgia, brachioradial itching) is also a significant symptom, then modern studies prove that in more cases, itching is not characteristic of most pathologies of the nervous system, so after a detailed anamnesis, examination and initial research, the patient should be referred to a related specialist, except in cases of about obvious postherpetic neuropathy, painless paresthesia, or brachioradial itching, which can often be guided in the provision of primary care.Instead, there are some psychological conditions and a number of psychiatric illnesses (obsessive-compulsive disorders, depression, and parasite illusions) that are most commonly diagnosed with the exclusion method. Neurotic squabbles are scattered on the body of the excorii, covered with scales that may occur in any area of the body that the patient may reach, but are often limited by limbs.
Itchy skin is an extremely unpleasant symptom that can provoke insomnia, depression, irritability, loss of appetite. There are several theories of itching. According to one of them, itching is a modified pain caused by a slight irritation of the nerve endings in the skin. According to the second, itching is an independent symptom, in the formation of which nervous, humoral and vascular mechanisms are involved. Other theories consider itching as a reaction of the autonomic nervous system or a hereditary pathological condition. According to recent studies, itchy skin is characterized by the absence of a universal peripheral mediator of itching. The trigger for itching is the action of pruritogen – a mechanical, chemical, thermal or electrical stimulant directly or indirectly through mediators. Free ends of type A delta fibers and type C fibers play a crucial role in itching and pain. If this was previously confirmed only by clinical observations, now there are neurophysiological studies that support the theory that itching and pain fibers are one with different activity thresholds. Today, it is unacceptable that there are separate specific receptors for different sensations. It is now assumed that there are mixed receptors for heat, cold, pain, itching and touch [95]. Systematic use of substances included in the list of drugs and manifested by mental and physical dependence on them – drug addiction, one of the diseases of society. But drug addiction is sometimes forced, according to medical indications, in cases of palliative conditions. Depending on the stage of the person after taking the drug or in the interval between drug use, one of the signs of use may be severe itching of the skin. And after excluding both the main diseases that cause itching and other secondary causes of itching, it can be assumed that a person has idiopathic generalized pruritus (itching) of unknown origin (GPOU). The itching of the elderly, which is quite common in the elderly, as a manifestation of concomitant, often combined, somatic pathology, but may also be due to physiological changes, both on the skin and on the physiological aging of nerve endings.
PAIN is a psychophysiological reaction of an organism that occurs with severe irritation of the sensitive nerve endings embedded in organs and tissues. And also pain is the body’s protective reaction. It is signaling about a discomfort and triggers an appropriate response by the body to eliminate the cause of the pain. Pain is one of the earliest symptoms of some diseases [84]. ITCHING – an unpleasant sensation of irritation, heartburn and tingling in any area of the skin caused by various factors (exposure to chemicals, bacteria, parasites). This feeling is often manifested by the urgent need to rub or scratch some areas of the skin (or mucous membrane) [85]. When considering the pathogenesis of these concepts, a sufficiently large resemblance to the realization of mechanisms of origin, or a certain identity thereof is revealed. The question naturally arises whether itching is an early manifestation of pain, especially in those groups of diseases that are not characterized by pain. Pathology of the hematopoietic system is not accompanied by a symptom such as pain. But for conditions such as iron overload, iron deficiency or polycythemia, itching is a clear symptom. The unknown etiology of chronic itching of the skin is indicative of histological examination of the skin in order to exclude skin lymphoma. One of the least understood mechanisms of itching is itching associated with malignant solid tumors. What pain that itching is a subjective sensation that can have an acute or chronic course, a clear intensity and a very significant impact on quality of life, especially in the case of comorbidity. In addition, the question arises whether itching is an early manifestation of pain, especially in those groups of diseases that are not characterized by pain. How can a doctor manage itching effectively to prevent complications? To these and other questions, we have attempted to systematize the manifestations of itching in pathologies of organs and systems that are not traditionally accompanied by pain.
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