загрузка...
 
Disorders of central autonomic regulation
Повернутись до змісту

Disorders of central autonomic regulation

In disorders of function that involve predominantly the central regulatory centers concerned with the autonomic nervous system, signs and symptoms are generalized rather than focal. Some of them are referable to specific visceral systems; others are more diffuse. Clinical literature as well as experimental data relating to the hypothalamus and to disorders arising from the injury or disease of its parts has increased rapidly, and many characteristic syndromes have been described. There may be disturbances of sleep, abnormalities of temperature regulation, changes in carbohydrate and water metabolism, dysfunction of fat metabolism, or respiratory abnormalities, together with, in many instances, behavioral abnormalities and personality changes. Many of the hypothalamic syndromes that are encountered clinically are residuals of encephalitis or are associated with neoplasms. The hypothalamus is, however, under the influence of the cortex, and it may be difficult to distinguish between cortical and diencephalic manifestations.

Hypothalamic syndromes is accumulated term are those that are associated with the lesion or deficiency of hypothalamus by injury, tumor, encephalitis. Autonomic-vascular-visceral disorders is associated with crisis of paroxysmal character: sympathoadrenal, vago-insular or mixed. Neuro-trophic disorders is associated with trophic disturbances (dryness, neurodermitis, ulcers, bed sores, acute perforates of stomach and esophagus). Neuro-endocrine-metabolic disorders is associated with increasing or decreasing of hypophisis function (Itsenko-Kushing symdrome, acromegaly, early climacterium, impotence, diabetes insipidus, and thyrotoxicosis). Sleeping disorders include insomnia, sleeping inversion, lethargy (narcolepsy) – sudden attack of sleepiness that can happen in any place and position of the patient. Sometimes we can observe thermoregulation disturbances. It may be low grade fever, associated with asymmetry under the arms, in the mouse and rectum. The thermoregulation disturbances may have paroxysmal character.

The signs of sympathoadrenal crisis: skill is pail, dryness of skin, tachycardia, high blood pressure, midriasis and widening of eye-slit, tremor, diarrhea, gooseflesh, frequend urination, hyperglycemia. The signs of vagoinsular crisis: hyperemia, hyperhydrosis, bradycardia, low blood pressure, miosis, salivation, breathlessness, abdominal spastic pain, diarrhea.

Disturbances of Temperature Regulation. Either hypothermia or hyperthermia may result from hypothalamic involvement. Hyperthermia may result from involvement of the tuberal region, and especially of the supraoptic nuclei or the rostral portion of the anterior hypothalamic area. It is associated with sweating, vasodilation, and other mechanisms for heat loss. Hyperthermia is a common symptom of third ventricle tumors, and may follow cerebral trauma or surgery, brain stroke. Hypothermia is associated with mechanisms for heat production including vasoconstriction, increased visceral and somatic activity, and shivering. It may follow involvement of the posterior hypothalamic area and the mammillary bodies, or of the caudal portion of the lateral hypothalamus may follow.

Disturbances of Water Metabolism. The hypothalamus is closely related with the posterior lobe of the hypophysis. Water metabolism is regulated through the posterior lobe, where antidiuretic hormone is produced. Lesions of the supraoptic nuclei or the supraopticohypophyseal tract are followed by diabetes insipidus with polydipsia and polyuria. Diabetes insipidus is a common symptom of tumors in the parasellar region, of encephalitis, and of meningitis, and may develop following intracranial surgery or cerebral trauma. It can also be congenital.

Disturbances of Glucose Metabolism. Hyperglycemia with glycosurea, a syndrome resembling diabetes mellitus, may result from lesions of the tuberal region, whereas hypoglycemia with abnormal sensitivity to insulin may follow lesions of the paraventricular nuclei.

Disturbances of Fat Metabolism. The adiposogenital syndrome was the first hypothalamic syndrome to be described. This disorder usually occurs in boys and is characterized by disturbances of fat metabolism together with sexual underdevelopment. There is obesity of feminine distribution, often with girdles of fat about the pelvis. Other symptoms of manifestations include gynecomastia, underdevelopment of the external genitalia, and retardation of development of the secondary sexual characteristics. The Laurence – Moon - Biedl syndrome is characterized by obesity, hypogenitalism, mental retardation, polydactylism, and pigmentary degeneration of the retina; it is an inherited disorder.

Disturbances of Blood Circulation. Through its regulatory effect upon the autonomic nervous system, the hypothalamus plays an important part in the regulation of circulation, heart rate and rhythm, and blood pressure. Stimulation of the posterior and lateral hypothalamic nuclei causes vasoconstriction, an increased heart rate, and a rise in blood pressure, whereas stimulation of the anterior and midline hypothalamic nuclei and the tuber cinereum produces vasodilation and a reduction in heart rate.

Disturbances of Respiration. Abnormalities of the rate, rhythm, and amplitude of respiration, such as hyperpnea, apnea, Cheyne - Stokes respiration, Biot’s breathing, may caused by central, probably hypothalamic, involvement.

Disturbances of Gastrointestinal Function. Lesions of the hypothalamus and its connections can cause accelerated gastrointestinal motility, increased secretion, hypersalivation, and excessive hunger (bulimia or hyperphagia), or they can cause decreased motility and secretion, dry mouth, and decreased appetite. Bulimia is an important symptom of bilateral temporal lobe dysfunction; it may also be present with other cerebral disorders. The Kleine-Levin syndrome consists of periodic attacks of hypersomnia accompanied by bulimia, irritability, behavioral changes, and uninhibited sexuality. It usually occurs in young males.

Disturbances of the Sleep Cycle. The hypothalamus, especially its posterior portions, including the mammillary bodies, is important in the maintenance of normal sleep rhythm, and hypothalamic lesions may cause hypersomnia, inversion of the sleep cycle, or insomnia. The hypersomnia and other abnormalities of sleep may be produced by involvement of the midbrain reticular system, or to interruption of the pathways from the cortex to the hypothalamus.

Disturbances of Sexual Function. Sexual infantilism may occur as an isolated phenomenon or as a part of Frohlich's and other syndromes. It is a manifestation of damage to the nuclei in the middle portion of the tuberal region. Sexual precocity has been described as a characteristic symptom of the pineal syndrome; the hypothalamus, however, is the critical site for lesions causing pubertas praecox, and it is probably due to pressure on or involvement of the ventromedial and lateral tuberal nuclei and mammillary bodies. Both sexual infantilism and sexual precocity may be manifestations of dysfunction of the endocrine glands, especially the pituitary, gonads, and adrenal glands; such changes may be secondary to underlying hypo-thalamic involvement. Increased libido, decreased libido, impotence, amenorrhea, hypermenorrhea, and other manifestations of sexual dysfunction are sometimes partly hypothalamic in origin. The somatic manifestations of the orgasm may be due to hypothalamic stimulation.

Disturbances of the Emotions. The hypothalamus is the center that reinforces and coordinates the neural and humoral mechanisms of emotional expression. When the posterior portion of the hypothalamus is released from control by higher centers of the brain, a complex of primitive pseudoaffective reactions takes place. These physical manifestations suggest that an intense emotional reaction is taking place, but there may be merely a motor expression of rage without a change in affect. Similar manifestations have been produced by stimulation of the posterior and lateral hypothalamic areas and by bilateral removal of the frontal or temporal lobes. Abnormal affective and emotional reactions fear, and aggressive behavior, however, may also be lessened by interruption of the pathways connecting various cortical areas in the frontal and limbic lobes with the thalamus and hypothalamus. The physical concomitants of emotion, namely, tachycardia, tachypnea, elevation of the blood pressure, perspiration, flushing, piloerection, and various disturbances of gastrointestinal function, are in reality manifestations of hypo-thalamic function with secondary visceral effects. In many of the neuroses the symptoms are largely somatic, or vegetative, in nature, and are similar to the physical symptoms encountered in various emotional states. Those referable to the cardiorespiratory system include tachycardia, palpitation, dyspnea, irregular respiration, and pain in the chest. Those referable to the gastrointestinal tract consist of gaseous indigestion, pain, nausea, vomiting, pylorospasm, hyperacidity, spastic constipation, flatulent constipation, and diarrhea. Those referable to the genitourinary system include frequency, dysuria, impotence, lack of libido, amenorrhea, and frigidity. The symptoms of the anxiety neuroses or of normal individuals during periods of stress, namely, tension, palpitation, hyperpnea, nausea, frequency, mydriasis, cold hands and feet, dry mouth, and variable blood pressure, are often the result of hypothalamic stimulation. All are symptoms of autonomic imbalance, and may be of central origin. Many disease syndromes such as hypertension, coronary artery disease, hyperthyroidism, peptic ulcer disease, spastic constipation, ulcerative colitis, migraine, bronchial asthma, and arthritis may have definite psychosomatic correlations.

Disturbances of Endocrine Function. Consequently abnormalities of hypothalamic function may have a close relationship to the various disturbances of endocrine function. The nuclei of the hypothalamus regulate the internal secretions of the thyroid, adrenal, and other glands. The hypothalamus may play a part in the development of either hyperthyroidism or hypothyroidism. Lesions of the hypothalamus may affect the islet cells of the pancreas, causing either diabetes mellitus or hyperinsulinism with hypoglycemia. The effect on the sexual glands may be direct, rather than through the pituitary, and may cause sexual precocity, impotence, amenorrhea, deficient development of primary or secondary sexual characteristics, and sexual infantilism.



загрузка...