Causes and pathogenesis of autonomic disorders in the limbs
Last reviewed: 23.04.2024
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Causes and pathogenesis of neurovascular syndromes. In the origin of neurovascular disorders, the vertebrogenic factor plays a leading role, and its role is ambiguous: the mechanisms of these disorders can be compression (direct compression of the nerve and vascular structures of hernia, osteophytes, hypertrophied ligaments, pathologically altered muscles) and reflex. Reflex mechanisms concern both the strain of some muscles and the pathological vascular responses. Irritation of perivascular sympathetic formations is also important. It is impossible to exclude the pathogenetic role of motor-visceral reflexes.
The spastic state of the vessels is maintained by pathological impulse (painful, proprioceptive) from the tissues of the affected spine and spinal ganglia.
The development of compression neurovascular syndromes goes through two stages - functional and organic. There are two mechanisms of transition of one stage to another: myogenic, when vasospasm causes disruption of muscle nutrition, and its prolonged contraction contributes to impaired blood circulation in it, and neurogenic, when a contracted muscle can squeeze the vegetative fibers of nerves, which in turn worsens muscle nutrition. In the formation of neurovascular disorders, undoubtedly, a certain role is played by a violation of the adaptive-trophic influence of the sympathetic nervous system.
General questions of the pathogenesis of autonomic disorders in the limbs
The clinical symptoms of autonomic disorders in the limbs have some characteristic features depending on the topical organization of the syndrome. Vegetative disorders in the pathology of the spinal cord are associated with damage to segmented vegetative formations and conductors in the spinal cord. In addition to frequent painful phenomena, there are vascular disorders that manifest themselves in the initial stage of the disease with vascular paresis, and then spasm, which often leads to asymmetry in blood pressure, coloration of skin, skin temperature, sweating, pilomotor reflexes, dermographism. Trophic disorders (hyperkeratosis, edema, pressure sores, trophic ulcers, changes in hair growth, pigmentation disorders) are found. An example of this type of disorder may serve as syringomyelia, for which vegetative disorders are an obligate sign.
When the roots of the spinal cord are damaged, vegetative disorders are vivid, accompanied by vasodilation, increased skin temperature, loss of sweat functions, changes in pylor motive reactions, electrical conductivity of the skin. The vegetative component with the root syndrome is often sympathetic. Irritation of preganglionic fibers coming from the cervical roots of the spinal cord causes simultaneously mydriasis, exophthalmos, narrowing of the vessels of the skin and glands with a decrease in the viscosity of their secretions. Transection of these sympathetic branches causes the opposite effect: miosis, anophthalmus, narrowing of the eye gap (Horner's syndrome), widening of the vessels of the head and neck area.
Vegetative disorders are often paroxysmal, manifest laterally. Irritation of the roots of the thoracic region leads to a narrowing of the vessels, a decrease in sweating, piloerectomy, activation of the organs of the thorax. Parasympathetic vaginal innervation has the opposite effect on the organs of the chest and activates the organs of the abdominal cavity. Radicular lumbosacral lesions are always accompanied by a pain syndrome with vascular disorders on the side of the radicular syndrome, which is manifested by changes in skin color, skin temperature, changes in the condition of large vascular trunks, small arteries, capillaries, and violation of hair growth.
The defeat of the nerve plexuses is accompanied by pronounced sympathy on the side of the lesion, as well as neurovascular disorders. There are also symptoms of loss and irritation, but a combination of these symptoms is more common.
When peripheral nerves are affected, vegetative disorders also arise, but they are more pronounced in nerves rich in vegetative fibers, sciatic and median. Known causalgia in the defeat of these nerves, occurring with severe pain syndrome, hyperpathy, trophic and vegetative disorders. Vascular disorders are found mainly in the distal parts of the limbs. Pain has a distinct vegetative character, accompanied by senoropathies.
In the pathology of the supra-segmental vegetative formations polymorphic clinical syndromes of autonomic disorders in the limbs are observed. Their characteristic features - symmetry, paroxysmal, dependence on the functional states of the brain, some biorhythmological dependence.
Psycho-vegetative syndrome, which is an obligatory component of neuroses, migraines, Raynaud's disease, is characterized clinically by the distal hyperhidrosis, by changes in the color of the skin of the extremities, by the increased sensitivity of these areas to changes in ambient temperature, and by thermography by the amputation type of thermotopography violations in the limbs.
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