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Causes and pathogenesis of autonomic disorders in the extremities
Last reviewed: 04.07.2025
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Causes and pathogenesis of neurovascular syndromes. The vertebrogenic factor plays a leading role in the origin of neurovascular disorders, and its role is ambiguous: the mechanisms of these disorders can be compression (direct compression of the nerve and vascular formations by a hernia, osteophytes, hypertrophied ligaments, pathologically altered muscles) and reflex. Reflex mechanisms concern both the tension of some muscles and pathological vascular reactions. Irritation of perivascular sympathetic formations is also important. The pathogenetic role of motor-visceral reflexes cannot be ruled out.
The spastic state of the vessels is maintained by pathological impulses (pain, 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 from one stage to another: myogenic, when vascular spasm causes disruption of muscle nutrition, and its prolonged contraction contributes to disruption of blood circulation in it, and neurogenic, when the contracted muscle can compress the vegetative1 nerve fibers, which in turn worsens muscle nutrition. In the formation of neurovascular disorders, a certain role is undoubtedly played by disruption of the adaptive-trophic influence of the sympathetic nervous system.
General issues of pathogenesis of vegetative disorders in the extremities
Clinical symptoms of vegetative disorders in the limbs have some characteristic features depending on the topical organization of the syndrome. Vegetative disorders in spinal cord pathology are associated with damage to segmental vegetative formations and conductors located in the spinal cord. In addition to frequent pain phenomena, vascular disorders are detected, manifested in the initial stage of the disease by vascular paresis, and then by spasm, which often leads to asymmetry in blood pressure, skin color, skin temperature, sweating, pilomotor reflexes, dermographism. Trophic disorders are detected (hyperkeratosis, edema, bedsores, trophic ulcers, changes in hair growth, pigmentation disorders). An example of this type of disorder is syringomyelia, for which vegetative disorders are an obligatory symptom.
In case of damage to the spinal cord roots, vegetative disorders are vivid, accompanied by vasodilation, increased skin temperature, loss of sweat functions, changes in pilomotor reactions, and skin electrical conductivity. The vegetative component in radicular syndrome is often sympathetic in nature. Irritation of the preganglionic fibers that go with the cervical roots of the spinal cord causes simultaneously mydriasis, exophthalmos, narrowing of the skin and gland vessels with a decrease in the viscosity of their secretion. Cutting these sympathetic branches causes the opposite effect: miosis, anophthalmos, narrowing of the eye slit (Horner's syndrome), and dilation of the vessels of the head and neck.
Vegetative disorders are often paroxysmal and manifest lateralized. Irritation of the thoracic roots leads to vasoconstriction, decreased sweating, piloerection, activation of the chest organs. Parasympathetic vagal innervation has the opposite effect on the chest organs and activates the abdominal organs. Lumbosacral radicular lesions are always accompanied by 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 state of large vascular trunks, small arteries, capillaries, and disturbances in the intensity of hair growth.
Damage to the nerve plexuses is accompanied by pronounced sympathalgia on the affected side, as well as neurovascular disorders. Symptoms of loss and irritation are also distinguished, but a combination of these symptoms is more common.
When peripheral nerves are damaged, vegetative disorders also occur, but they are more pronounced in nerves rich in vegetative fibers - the sciatic and median. Causalgia is known when these nerves are damaged, occurring with severe pain syndrome, hyperpathy, trophic and vegetative disorders. Vascular disorders are found mainly in the distal parts of the limbs. The pain is of a distinct vegetative nature, accompanied by senestopathies.
In the case of pathology of suprasegmental vegetative formations, polymorphic clinical syndromes of vegetative disorders in the extremities are observed. Their characteristic features are symmetry, paroxysmal nature, dependence on the functional states of the brain, and some biorhythmological dependence.
Psychovegetative syndrome, which is an obligatory component of neuroses, migraines, and Raynaud's disease, is characterized clinically by distal hyperhidrosis, changes in the color of the skin of the extremities, increased sensitivity of these areas to changes in ambient temperature, and, in thermography, amputation-type disturbances of thermotopography in the extremities.
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