Disturbance of thermoregulation: causes, symptoms, diagnosis, treatment

Thermoregulation disorders are manifested by hyperthermia, hypothermia, oznobopodobnym hyperkinesis, the syndrome of "fever".

[1], [2], [3], [4], [5]

Pathogenesis of thermoregulatory disorders

Regulation of body temperature in warm-blooded animals, i.e., maintenance of thermomoeostasis irrespective of the temperature of the environment, is an achievement of evolutionary development. Body temperature reflects the intensity of bioenergetic processes and is the resultant processes of heat production and heat transfer. There are two main phases of thermoregulation - chemical and physical. Chemical thermoregulation is carried out at the expense of local and general metabolism, which contributes to the increase of heat formation. Physical - provides heat transfer processes through thermal conduct (convention) and heat radiation (radiation), as well as by evaporation of water from the surface of the skin and mucous membranes. The main role is played by sweating and vasomotor mechanisms. There are central and peripheral temperature sensitive systems. Peripheral thermoregulation includes the nerve receptors of the skin, subcutaneous adipose tissue and internal organs. The skin is a heat exchange body and a body temperature regulator. An essential role is assigned to hemodynamics. It is one of the mechanisms of maintaining the body's optimal temperature for metabolism. Information on temperature changes is transmitted through afferent systems in the central nervous system. Numerous studies, beginning with the works of Claude strongernard, performed in the eighties of the XIX century, confirmed the special role of the hypothalamus in the processes of thermoregulation.

In the hypothalamus, the medial preoptic area of the anterior hypothalamus (MPO) is distinguished, which is assigned the role of a "heat center" or center of heat transfer, and the posterior hypothalamus is the "cold center" or center of heat production, which includes the ventro- and dorsomedial nuclei of the hypothalamus. The thermosensitive neurons of MPO and the posterior hypothalamus are sensitive to both central and peripheral temperature changes. The thermosensitive centers of the brain include the mesencephalic activating system, the hypocampus, the amygdala nucleus, and the cerebral cortex. In the spinal cord there are specific heat-sensitive elements.

There are several theories explaining the maintenance of body temperature. The most common theory is the "fixing point". By "setting point" is meant that temperature level at which the activity of thermoregulatory mechanisms is minimal, tends to zero and is optimal under given conditions. Perturbative influences that change the temperature regime of the organism lead to the activation of processes or heat production, or heat transfer, which returns the temperature to the initial "setting point". In studies on thermoregulation, the participation of sympathetic and parasympathetic systems is reflected.

Effects of pharmacological drugs on autonomic functions, including thermoregulation, are devoted to numerous works. It is established that alpha and beta-adrenoblockers lead to a decrease in body temperature due to an increase in cutaneous blood flow, which changes the activity of peripheral thermoreceptors. General and local anesthetics, barbiturates, tranquilizers, neuroleptics, ganglion blockers, acetylcholine and other substances also affect the change in body temperature. There is information about their effect on tissue metabolism, the tone of the skin vessels, sweating, the myoneural synapse (curare-like remedies), muscle tone (cold trembling), but not thermoreceptors.

The value of stem adreno-and serotonergic systems for thermoregulation and the temperature dependence on the balance of norepinephrine and serotonin in the hypothalamus are shown. Much attention is paid to the ratio of the concentration of sodium and calcium ions in the extracellular fluid. Thus, the temperature homeostasis is the result of the integrative activity of physiological systems that provide metabolic processes that are under the coordinating influence of the nervous system.

Noninfectious fever was considered a manifestation of vegetative neurosis, autonomic dystonia, vasomotor neurosis; anomalous temperature response of "vegetatively-stigmatized" subjects under the influence of usual factors or psychogenic fever in people with certain constitutional features of the nervous system.

The main causes of prolonged subfebrile condition, "unclear" temperature rises are physiological, psychogenic, neuroendocrine disorders, false causes. Physiological disorders of thermoregulation include fever (up to subfebrile digits) of a constitutional (correct) nature, as a result of physical and sports overloads, in some cases in the second half of the menstrual cycle, rarely during the first 3-4 months. Pregnancy, which is associated with the activity of the yellow body. The false temperature depends on the failure of the thermometer or simulation. The rise in temperature (up to 40-42 ° C) is often described in hysterical fits. The temperature curve is characterized by a very rapid rise and a critical drop to a normal, subfebrile or hypo-febrile level. Subfebrile in neuroses is found in a third of patients. Psychogenic temperature increase is observed mainly in childhood and adolescence against the background of vegetative endocrine disorders of the pubertal period. In these cases, the provoking, starting factor can be emotions, physical overstrain, stressful situations. Favorable background is allergization, endocrine dysregulation, etc. Perhaps conditional-reflex increase in temperature, when the situation itself, for example, temperature measurement, serves as a conditioned stimulus.

The disorders of thermoregulation are described by many in the hypothalamic syndrome and are even regarded as its obligatory sign. In 10-30% of all patients with a long subfebrile condition there are neuroendocrine-exchange manifestations of the hypothalamic syndrome.

The emergence of temperature disorders, in particular hyperthermia, as shown by clinical and electrophysiological research, indicates a certain inferiority of hypothalamic mechanisms. Long-existing neurotic syndrome (this is typical for the syndrome of vegetative dystonia), in turn, contributes to deepening and fixing the anomaly of temperature reactions.

The diagnosis of thermoregulatory disorders is hitherto difficult and requires a phased approach. It should begin with an epidemiological analysis, a complete analysis of the disease, a physical examination, standard laboratory tests and, in some cases, using special methods to exclude a pathological condition leading to an increase in body temperature. In this case, first of all, infectious diseases, tumor, immunological, systemic connective tissue diseases, demyelinating processes, intoxications, etc. Should be excluded.

Hyperthermia

Hyperthermia can be permanent, paroxysmal and permanently paroxysmal.

Hyperthermia of a permanent nature is represented by a protracted sub- or febrile condition. Under a protracted subfebrile condition, or an increase in the temperature of non-infectious genesis, it means a fluctuation in the range 37-38 ° C (ie, above the individual norm) for more than 2-3 weeks. Periods of elevated temperature can last for several years. In a history of such patients, often before the onset of temperature disorders, a high fever is noted in infections and long temperature "tails" - after them. Most patients and without treatment can normalize the temperature in the summer or during the rest, regardless of the season. The temperature rises in children and adolescents when attending classes in educational institutions, before the control questionnaire and control work. At students the subfebrile condition appears or renews from 9-10th day of study.

A relatively satisfactory tolerability of prolonged and high temperature is characteristic, with the preservation of motor and intellectual activity. Some patients complain of weakness, weakness, headache. The temperature does not change in the circadian rhythm compared to its increase in healthy subjects against the background of the infection. It can be monotonous during the day or inverted (higher in the first half of the day). With an amidopyrine sample, there is no decrease in temperature; Excludes pathological conditions that can cause a rise in body temperature (infection, tumor, immunological, collagen and other processes).

Currently, such temperature disorders are considered as manifestations of cerebral vegetative disorders and enter the picture of the syndrome of vegetative dystonia, which is treated as a psycho-vegetative syndrome. It is known that the syndrome of autonomic dysfunction can develop against the background of clinical signs of constitutionally acquired hypothalamic dysfunction and without it. In this case, there is no difference in the incidence of hyperthermia. However, with hyperthermia, which appeared against the background of the hypothalamic syndrome, monotonous subfebrile condition is more common, which is combined with neuro-exchange-endocrine disorders, vegetative disorders of both permanent and paroxysmal (vegetative crises). In the syndrome of vegetative dystonia, accompanied by a disorder of thermoregulation without clinical signs of hypothalamic dysfunction, hyperthermia is characterized by febrile numbers that can have a long persistent character.

Paroxysmal hyperthermia are temperature crises. The crisis manifests itself by a sudden increase in temperature to 39-41 ° C, accompanied by chill-like hyperkinesis, a feeling of internal tension, headache, facial flushing and other vegetative symptoms. The temperature lasts for several hours and falls down lytically. After its decrease, there remain weakness and weakness, which take place after a while. Hyperthermal crises can occur both against the background of normal body temperature, and against a background of long-holding subfebrile condition (permanent-paroxysmal hyperthermic disorders). Paroxysmal sharp rise in temperature can occur in isolation.

An objective examination of patients showed that the signs of a dysraphic status and allergic reactions in the anamnesis are significantly more frequent in hyperthermia than in the syndrome of autonomic dysfunction without hyperthermia.

Patients with a violation of thermoregulation found features in the manifestations of psycho-vegetative syndrome, consisting in the predominance of depressive-hypochondriacal traits in combination with intraversion and lower indicators of anxiety level in comparison with these indicators in patients without thermoregulatory disorders. In the first EEG study there are signs of an increase in the activity of the thalamo-cortical system, which is expressed in a higher percentage of the a-index and the current synchronization index.

The study of the state of the vegetative nervous system indicates an increase in the activity of the sympathetic system, which is manifested by spasm of the vessels of the skin and subcutaneous tissue according to plethysmography and skin thermotopography (the phenomenon of thermoamputation on the limbs), the results of intradermal adrenaline test, RGR, etc.

Despite the success of medicine in the treatment of febrile infectious diseases, the number of patients with prolonged persistent subfebrile condition of unknown origin does not decrease, but increases. Among children aged 7 to 17 years, a long subfebrile condition is observed in 14.5%, in the adult population - in 4-9% of the examined.

Hyperthermia is associated with a violation of the central nervous system, which can be based on both psychogenic and organic processes. In the case of organic CNS lesions, hyperthermia occurs with craniopharyngiomas, tumors, hemorrhage in the hypothalamus, craniocerebral trauma, axial polyencephalopathy of Gaye-Wernicke, neurosurgical interventions, intoxications, as a rare complication of general anesthesia, hyperthermic disorders in the face of severely current mental illness. When taking medications - antibiotics, especially penicillin series, antihypertensive drugs, diphenine, neuroleptics, etc.

Hyperthermia can occur with a sudden overheating of the body (high ambient temperature), and the body temperature rises to 41 ° C or more. In people with congenital or acquired anhidrosis, with hydration and salt deficiency there are disorders of consciousness, delusions. Central intensive hyperthermia adversely affects the body and disrupts the activity of all systems - cardiovascular, respiratory, metabolic disorders. Body temperature of 43 ° C or higher is incompatible with life. The defeat of the spinal cord at the cervical level, along with the development of tetraplegia, leads to hyperthermia due to a violation of temperature control, which is performed by sympathetic nervous pathways. After the disappearance of hyperthermia below the level of lesions, some disorders of thermoregulation remain.

Hypothermia

Hypothermia is considered to be a body temperature below 35 ° C, as well as hyperthermia, it occurs when the nervous system is disturbed and is often a symptom of a syndrome of autonomic dysfunction. With hypothermia, weakness is noted, decreased ability to work. Vegetative manifestations indicate an increase in the activity of the parasympathetic system (low blood pressure, sweating, persistent red dermographism, sometimes towering, etc.).

With the increase in hypothermia (34 ° C), confusion (precomatous state), hypoxia and other somatic manifestations are noted. Further lowering of temperature leads to death.

It is known that in newborns and old people who are sensitive to temperature changes, hypothermic reactions may occur. Hypothermia can be observed in healthy young people with high heat output (stay in cold water, etc.). Body temperature decreases with organic processes in the central nervous system with hypothalamic damage, which can lead to hypothermia and even poikilothermia. Decrease in body temperature is noted with hypopituitarism, hypothyroidism, parkinsonism (often combined with orthostatic hypotension), as well as with alcohol exhaustion and intoxication.

Hyperthermia can cause and pharmacological drugs that contribute to the development of vasodilation: phenothiazine, barbiturates, benzodiazepines, reserpine, butyrophenones.

Chronic hyperkinesis

Sudden occurrence of chills (cold tremor), accompanied by a sensation of internal tremor, increased pilomotor reaction ("goosebumps"), internal tension; in some cases, combined with an increase in temperature. Oznobopodobny hyperkinesis is often included in the picture of the vegetative crisis. This phenomenon arises as a result of strengthening physiological mechanisms of heat formation and is associated with increased activity of the sympathoadrenal system. The onset of chills is caused by the transfer of efferent stimuli coming from the posterior parts of the hypothalamus through the red nuclei to the motoneurons of the anterior horns of the spinal cord. In this case, an essential role is assigned to adrenaline and thyroxine (activation of ergotropic systems). Chills can be associated with an infection. A fever chill raises the temperature by 3-4 ° C, this is promoted by the pyrogenic substances that are formed, that is, the heat production increases. In addition, it can be a consequence of psychogenic influences (emotional stress), which lead to the ejection of catecholamines and, accordingly, the excitement going along these routes. Investigation of the emotional sphere in such patients reveals the presence of anxiety, anxiety-depressive disorders and symptoms, indicative of the activation of the sympathoadrenal system (pallor of the skin, tachycardia, high blood pressure, etc.).

[6], [7], [8], [9], [10]

Syndrome of "fever"

The syndrome of "fever" is characterized by an almost constant sensation of "cold in the body" or in various parts of the body - back, head. The patient complains that he is freezing, the "goosebumps" are running around the body. In the syndrome of "fever" there are quite gross emotional and personal disturbances (mental disorders), manifested by a senestopatic-hypochondriac syndrome with phobias. Patients do not tolerate and are afraid of drafts, sudden changes in weather, low temperatures. They are forced to constantly warmly dress, even at a relatively high air temperature. In summer they go in winter hats, shawls, as "the head gets cold," they rarely take a bath and wash their hair. Body temperature in this case is normal or subfebrile. The subfebrile condition is long, low, monotonous, often combined with clinical signs of hypothalamic dysfunction - neuro-exchange-endocrine disorders, impairment of drives and motivations. Vegetative symptoms are represented by the lability of blood pressure, pulse, respiratory disorders (hyperventilation syndrome), increased sweating. The study of the autonomic nervous system reveals sympathetic failure on the background of dominance of the activity of the parasympathetic system.

Treatment of thermoregulatory disorders

Disorders of thermoregulation often manifest hyperthermic disorders. Therapy should be conducted taking into account the fact that hyperthermia is a manifestation of the syndrome of autonomic dysfunction. In this regard, the following measures are necessary:

1. Impact on the emotional sphere: the appointment of funds that affect mental disorders, taking into account their nature (tranquilizers, antidepressants, etc.).
2. Appointment of drugs that reduce adrenergic activation, providing both central and peripheral effects (reserpine 0.1 mg 1-2 times a day, beta adrenoblockers at 60-80 mg / day, alpha-adrenoblockers - pyrroxane 0.015 g 1 -3 times a day, phentolamine 25 mg 1-2 times a day, etc.).
3. The use of drugs that enhance heat transfer by expanding the peripheral vessels of the skin: nicotinic acid, no-shpa, etc.
4. General restorative treatment; physical hardening.

In the syndrome of "fever", in addition to the above drugs, it is advisable to appoint neuroleptics.