Research of the autonomic nervous system

To evaluate vegetative functions in many cases, a careful analysis of the patient's complaints and anamnestic information about the function of the genitourinary and rectum, the presence of excessive sweating, mandatory urination, urinary incontinence and erectile dysfunction (in men) is sufficient in many cases. A more detailed study of the autonomic nervous system is advisable to conduct in patients presenting the appropriate complaints, as well as for a number of polyneuropathies.

Blood pressure, heart rate

• Orthostatic test is designed to assess the involvement of the sympathetic nervous system in the vegetative support of activity. Measure blood pressure and heart rate (heart rate) in the patient's lying position, then standing. Repeat the measurement of blood pressure and heart rate 3 minutes after taking the vertical position. Under normal autonomic support, the heart rate (at 30 per minute) and systolic blood pressure (by 20 mm Hg) increase immediately when going to the vertical position, and the diastolic blood pressure changes little. During standing, the heart rate may increase by 40 per minute, and systolic blood pressure may decrease by 15 mmHg. Below the original level or it remains unchanged; the diastolic blood pressure does not change or slightly increases compared to the baseline level. Insufficient vegetative maintenance is diagnosed if the systolic blood pressure drops by 10 mm Hg in the orthostatic sample. And more immediately after going to the vertical position or by 15 mm Hg. And more when standing. In this case, it should be assumed that the function of the sympathetic nervous system is inadequate and the probability of orthostatic arterial hypotension. Excessive vegetative maintenance is diagnosed if the systolic blood pressure rises immediately after going over to the vertical position by more than 20 mm Hg; or if the heart rate increases by more than 30 per minute; or if there is only an isolated rise in diastolic blood pressure.

• The sample with the compression of the hand in the fist is also used to evaluate the vegetative support of the activity. The patient compresses the brush for 3 minutes with a force equal to 30% of the maximum possible (determined by the dynamometer). Normally, the diastolic blood pressure rises by 15 mm Hg. And more. With vegetative insufficiency such an increase does not occur.
• Using a deep breathing test, the parasympathetic nervous system is evaluated. The patient is asked to breathe deeply and rarely (6 breaths per minute). Deep rare breathing in a healthy person slows the pulse by at least 15 per minute. Deceleration less than 10 per minute, indicates a decrease in the activity of the vagus nerve system.
• A test with pressure on eyeballs (Dagnini-Ashner) allows to evaluate the reactivity of the parasympathetic nervous system. Pads of his fingers pressed on the eyeballs of the patient lying on his back, until he had a slight pain. Continue exposure for 6-10 seconds. Normally, by the end of the test, the patient's pulse becomes less often at 6-12 per minute. A more pronounced deceleration (vagal reaction) indicates an increased autonomic reactivity, less pronounced - of decreased vegetative reactivity. The lack of reaction or the paradoxical increase in the pulse (perverse vegetative reactivity) indicates a predominance of the tone of the sympathetic nervous system.

[1], [2], [3]

Sweating

To assess sweating, touch the skin. In doubtful cases, you can resort to an iodine starch trial. The patient's skin is lubricated with a solution of iodine in a mixture of ethyl alcohol and castor oil (iodine - 1.5, castor oil - 10, ethyl alcohol - 90). A few minutes after drying, the skin is evenly sprinkled with starch powder. Then, sweating (1 acetylsalicylic acid orally and a glass of hot tea) are artificially induced in the patient. In places where sweat is secreted, the starch reacts with iodine and intense dark violet staining occurs. Zones where sweating is absent remain uncolored.

Urination

If the patient makes complaints relating to urination, first of all palpate his stomach. This will allow in some cases to detect a stretched overflowing bladder. The nature of impaired urination is refined usually based on the results of instrumental urodynamic examination (cystomanometry, uroflowmetry ).

Lesion of the frontal lobe, especially bilateral, leads to a decrease in descending inhibitory effects on the spinal center of urination, which is manifested by mandatory urination and urinary incontinence (central unblocked bladder). The sensitivity of the bladder and the feeling of its filling are preserved, the function of the sphincters of the bladder is not disturbed, since its spinal innervation is intact. The central unblocked bladder is typical for the elderly, and also occurs with diffuse lesions of the brain. Cognitive disorders contribute to impaired urination.

Acute damage to the spinal cord above the level of sacral segments (vertebral-spinal trauma) causes a spinal shock, in which inhibition of detrusor function is observed and, accordingly, bladder overflow. Perhaps "incontinence from overflow". Then, as spasticity develops in the legs, the detrusor also becomes "spastic" (hyperactive) due to the fact that brake suprasegmental control is lost and disinhibition of the preserved sacral segments and their local reflex arcs occurs. A suprasacral bubble is formed, or an automatic reflex bubble that can not be controlled arbitrarily, functions automatically (in response to reflex filling, detrusor reduction occurs) and is manifested by imperative urinary incontinence. The feeling of filling the bladder and its sensitivity during urination are reduced or lost, as the ascending sensory pathways in the spinal cord are interrupted.

The defeat of parasympathetic neurons of the sacral segments (S ₂ -S ₃ ) or their axons (trauma, radiculomyelichemia, meningomyelocele) leads to the development of atony of the bladder, while the sensitivity of the bladder can be preserved (infrasacral bladder, motor paralytic bladder). There is a delay in urination, the bladder is filled with urine. In this case, "incontinence from overfilling" or paradoxical incontinence (ischuria paradoxa) is possible: there are signs of both urinary retention (the bladder is constantly full and not emptying itself) and incontinence (urine constantly flows by drop due to the mechanical overstretch of the external sphincter ). Continuous presence in the bladder of a significant amount of residual urine is accompanied by a high risk of urinary tract infection.

Damage to the peripheral nerves innervating the bladder or the posterior spinal roots results in its deafferentation. He loses sensitivity and becomes atonic (peripheral extramedullary bladder, sensory paralytic bladder). This form of the bladder is characteristic for diabetic autonomic polyneuropathy, dorsal dryness. The feeling of filling the bubble is lost and the bubble emptying reflex disappears, as a result it overflows. There is incontinence from overflow. The constant presence of residual urine in the bladder is associated with a high risk of infection.

"Autonomous" bladder is completely deprived of any innervation (secondary damage to intramural vesicle ganglia with prolonged stretching of the walls of the bladder). In this case, the intramural reflex is turned off, which closes at the level of the wall of the bladder and is the basis for the excitation of more complex reflexes. Sensory information about the bladder is absent in such cases, and the efferent impulses by the wall of the bladder are not perceived, which is manifested by the atony of the bladder and the retention of urine.

Meningeal syndrome

Meningeal symptoms appear with inflammation of the meninges ( meningitis ), when they are irritated with bleeding ( subarachnoid hemorrhage ), less often with exogenous or endogenous intoxication and increased intracranial pressure (with brain tumors). The most informative meningeal signs include stiff neck, Kernig's symptom, and symptoms of Brudzinsky. All meningeal symptoms are examined in the position of the patient lying on the back.

• To determine the rigidity of the occipital muscles, the doctor puts the patient's neck on his arm and waits until the neck muscles relax. Then gently bends the patient's neck, bringing his chin to his chest. Normally, with passive neck bending, the chin touches the chest, with the stimulation of the meninges there is a tension in the muscles of the neck and the chin does not reach the chest. It should be remembered that the limitation of the volume of movements in the cervical spine can be due to arthrosis of the articular joints of the cervical vertebrae (spondyloarthrosis). Nevertheless, with spondyloarthrosis, the neck flexion is not so severely affected and at the same time, the lateral rotation of the neck is severely limited, which is not typical for the syndrome of stimulation of the meninges. Severe rigidity of the neck muscles is also possible with Parkinson's disease, but if you continue to press gently on the occiput, the neck can be bent in full, although the patient may experience slight discomfort while doing so.
• Kernig Symptom : flex the patient's leg at right angles to the hip and knee joints, and then straighten it in the knee joint. With stimulation of the meninges, the tension of the flexor muscles of the lower leg is felt, which makes it impossible to straighten the leg.
• Symptoms of Brudzinsky : when trying to passively incline the patient's head to the breast, flexion occurs in the hip and knee joints (the upper symptom of Brudzinsky); a similar movement of the lower extremities is also caused by pressure on the region of the pubic symphysis (the mean symptom of Brudzinsky); a similar flexural movement in the contralateral lower limb occurs when the Kernig sample is performed (the lower Brudzinsky symptom).