Peripheral autonomic failure - Symptoms

Symptoms of peripheral autonomic failure are present in all physiological systems of the body and can occur under the guise of many somatic diseases. Typical clinical syndromes are the following:

1. Orthostatic hypotension.
2. Tachycardia at rest.
3. Hypertension in the supine position.
4. Hypohidrosis.
5. Impotence.
6. Gastroparesis.
7. Constipation.
8. Diarrhea.
9. Urinary incontinence.
10. Decreased vision at dusk.
11. Sleep apnea.

The indicated syndromes are presented in the order that corresponds to the prevailing frequency of occurrence. However, in each specific case of peripheral autonomic failure, the "set" of symptoms may be different and not always complete (11 signs). Thus, for primary forms of peripheral autonomic failure, such manifestations as orthostatic hypotension, tachycardia at rest, hypohidrosis, impotence are more typical. In secondary syndromes of peripheral autonomic failure, sweating disorders dominate in some cases (in alcoholism, polyneuropathy), in others - tachycardia at rest (in diabetes mellitus) or gastrointestinal disorders (amyloidosis, porphyria), etc. It is not surprising that patients with signs of autonomic failure seek help from specialists of various profiles - cardiologists, neurologists, gynecologists, sexologists, geriatricians, etc.

The most dramatic manifestation of peripheral autonomic failure in the cardiovascular system is orthostatic hypotension, which leads to frequent fainting when moving to a vertical position or when standing for a long time. Orthostatic hypotension is a condition that occurs in a variety of diseases (neurogenic syncope, anemia, varicose veins, heart disease, etc.). However, it should be noted that in peripheral autonomic failure, orthostatic hypotension is caused by damage to the lateral horns of the spinal cord and / or efferent sympathetic vasomotor conductors that implement vasoconstrictor effects on peripheral and visceral vessels. Therefore, with orthostatic loads, peripheral vasoconstriction does not occur, which leads to a drop in systemic arterial pressure, and then, accordingly, to acute cerebral anoxia and the development of fainting.

Patients may experience varying severity of clinical manifestations. In mild cases, soon after assuming a vertical position (standing up), the patient begins to notice signs of a pre-syncope state (lipothymia), manifested by a feeling of nausea, dizziness, and a premonition of loss of consciousness. The patient, as a rule, complains of general weakness, darkening in the eyes, noise in the ears and head, unpleasant sensations in the epigastric region, sometimes a feeling of "falling through", "the ground slipping away from under the feet", etc. Paleness of the skin, short-term postural instability are noted. Duration of lipothymia is 3-4 sec. In more severe cases, lipothymia may be followed by fainting. The duration of fainting in peripheral autonomic failure is 8-10 sec, sometimes (in Shy-Drager syndrome) - several tens of seconds. During fainting, diffuse muscular hypotonia, dilated pupils, upward deflection of the eyeballs, threadlike pulse, low blood pressure (60-50/40-30 mm Hg and lower) are observed. If fainting lasts more than 10 seconds, convulsions, hypersalivation, urination may occur, and in extremely rare cases, tongue biting may occur. Severe orthostatic circulatory disorders can lead to death. Fainting states in peripheral autonomic failure differ from other types of fainting by the presence of hypo- and anhidrosis and the absence of a vagal response to slowing down PC. To assess the severity of orthostatic disorders, in addition to taking into account clinical manifestations, it is convenient to use the rate of onset of fainting after assuming a vertical body position. The time interval from the moment the patient moves from a horizontal to a vertical position until fainting develops can be reduced to several minutes or even 1 minute or less. This indicator is always adequately indicated by the patient and quite accurately characterizes the severity of orthostatic circulatory disorders. In dynamics, it also reflects the rate of progression of the disease. In severe cases, fainting can develop even in a sitting position.

Orthostatic hypotension is the main symptom of primary peripheral autonomic failure. Secondarily, it can be observed in diabetes mellitus, alcoholism, Guillain-Barré syndrome, chronic renal failure, amyloidosis, porphyria, bronchial carcinoma, leprosy, and other diseases.

Along with orthostatic hypotension, peripheral autonomic failure often develops a phenomenon known as arterial hypertension in the supine position. As a rule, in these cases, prolonged lying down during the day or during night sleep causes blood pressure to rise to high values (180-220/100-120 mm Hg). These shifts in blood pressure are caused by the so-called post-denervation hypersensitivity of vascular smooth muscle adrenergic receptors, which inevitably develops during chronic denervation processes (Canon's law of post-denervation hypersensitivity). Taking into account the possibility of arterial hypertension in patients with peripheral autonomic failure suffering from orthostatic hypotension is extremely important when prescribing drugs that increase blood pressure. As a rule, drugs with a strong direct vasoconstrictor effect (norepinephrine) are not prescribed.

Another clear sign of peripheral autonomic failure is tachycardia at rest (90-100 bpm). Due to the reduced variability of the heart rate, this phenomenon is called "fixed pulse". In a patient with peripheral autonomic failure, various loads (standing up, walking, etc.) are not accompanied by an adequate change in heart rate, with a clear tendency towards tachycardia at rest. It has been proven that tachycardia and reduced variability in this case are caused by parasympathetic insufficiency due to damage to the efferent vagal cardiac branches. Damage to the afferent visceral nerves coming from the heart muscle leads to the fact that myocardial infarction can occur without pain. For example, in patients with diabetes mellitus, every third myocardial infarction occurs without pain. It is precisely painless myocardial infarction that is one of the causes of sudden death in diabetes mellitus.

One of the characteristic manifestations of peripheral autonomic failure is hypo- or anhidrosis. Reduced sweating on the limbs and trunk in peripheral autonomic failure is the result of damage to the efferent sudomotor sympathetic apparatus (lateral horns of the spinal cord, autonomic ganglia of the sympathetic chain, pre- and post-tanglionic sympathetic fibers). The prevalence of sweating disorders (diffuse, distal, asymmetric, etc.) is determined by the mechanisms of the underlying disease. As a rule, patients do not pay attention to reduced sweating, so the doctor must clarify and assess the state of the sweating function. Detection of hypohidrosis along with orthostatic hypotension, tachycardia at rest, gastrointestinal disorders, and urination disorders makes the diagnosis of peripheral autonomic failure more likely.

Peripheral autonomic failure in the gastrointestinal system is caused by damage to both sympathetic and parasympathetic fibers, manifested by impaired gastrointestinal motility and secretion of gastrointestinal hormones. Gastrointestinal symptoms are often nonspecific and inconstant. The symptom complex of gastroparesis includes nausea, vomiting, a feeling of a "full" stomach after eating, anorexia and is caused by damage to the gastric motor branches of the vagus nerve. It should be emphasized that constipation and diarrhea in peripheral autonomic failure are not associated with an alimentary factor, and their severity depends on the degree of impairment of the parasympathetic and sympathetic innervation of the intestine, respectively. These disorders can be observed in the form of attacks from several hours to several days. Between attacks, bowel function is normal. For correct diagnosis, it is necessary to exclude all other causes of gastroparesis, constipation and diarrhea.

Bladder dysfunction in peripheral autonomic failure is caused by the involvement of parasympathetic innervation of the detrusor and sympathetic fibers going to the internal sphincter in the pathological process. Most often, these disorders are manifested by a picture of bladder atony: straining during urination, long breaks between urination acts, urine excretion from an overfilled bladder, a feeling of incomplete emptying, and the addition of secondary urinary infection. The differential diagnosis of doleken includes adenoma and hypertrophy of the prostate gland, other obstructive processes in the genitourinary sphere.

One of the symptoms of peripheral autonomic failure is impotence, caused in such cases by damage to the parasympathetic nerves of the cavernous and spongy bodies. In primary forms, impotence occurs in up to 90% of cases, in diabetes mellitus - in 50% of patients. The most pressing task is to differentiate psychogenic impotence from impotence in peripheral autonomic failure. It is important to pay attention to the features of the onset of impotence (psychogenic forms occur suddenly, organic (peripheral autonomic failure) - gradually) and the presence of erections during night sleep. The preservation of the latter confirms the psychogenic nature of the disorder.

Peripheral autonomic failure may manifest itself in respiratory disorders. These include, for example, short-term pauses in breathing and cardiac activity in diabetes mellitus (the so-called "cardiorespiratory arrests"). They usually occur during general anesthesia and in severe bronchopneumonia. Another common clinical phenomenon in patients with peripheral autonomic failure (Shy-Drager syndrome, diabetes mellitus) are episodes of sleep apnea, which can sometimes take on a dramatic character; less frequently, involuntary attacks of suffocation (stridor, "cluster" breathing) are described. The above-mentioned ventilation disorders become dangerous in the event of a violation of cardiovascular reflexes, and it is assumed that they can be the cause of sudden unexplained death, in particular in diabetes mellitus.

Impaired vision in the twilight with peripheral autonomic failure is associated with impaired innervation of the pupil, which leads to its insufficient dilation in low light conditions and, accordingly, impairs visual perception. Such a disorder should be distinguished from the condition that occurs with vitamin A deficiency. Other symptoms of peripheral autonomic failure or manifestations of hypovitaminosis A may be auxiliary in this case. Usually, pupillary disorders with peripheral autonomic failure do not reach a pronounced degree and are not noticed by patients for a long time.

Thus, it should be emphasized that the clinical manifestations of peripheral autonomic failure are polysystemic and often nonspecific. It is some of the clinical nuances described above that allow us to assume that the patient has peripheral autonomic failure. To clarify the diagnosis, it is necessary to exclude all other possible causes of the existing clinical symptoms, for which additional research methods can be used.

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