As Sympathetic block Artificial interruptions of certain nerve branches of the autonomic sympathetic nervous system in certain body regions are called.
The mostly irreversible interruptions or severing of the sympathetic nerves are achieved by mechanical endoscopic interventions or by the local introduction of chemical substances into a vein that runs near the nerve to be sclerosed. The interventions are carried out to treat chronic pain and to contain a pathologically increased secretion of sweat (hyperhidrosis).
What is the sympathetic block?
The autonomic nervous system, also known as the autonomous nervous system, unconsciously controls a large number of body functions, only a few of which can be consciously influenced, such as breathing. The vegetative nervous system includes the sympathetic and parasympathetic nervous systems, which mostly act antagonistically to one another.
As a third component, the enteric nervous system (ENS), the intestinal or intestinal nervous system, is included in the autonomic nervous system. The activated sympathetic nervous system puts the body under stress and controls body functions in such a way that brief muscular and energetic maximum performance can be achieved for escape or attack. The parasympathetic nervous system usually acts as an opponent of the sympathetic nervous system and stands for relaxation, growth and internal stabilization. The sympathetic system not only controls body functions, but also sensations that are consciously perceived, such as pain and many others.
Contrary to what the term suggests, sympathetic blockades are usually not of natural origin, but are brought about willfully by an operative intervention. Sympathetic blockades are carried out on certain branches of the sympathetic nervous system in order to literally switch off obvious malfunctions, the symptoms of which cannot be treated otherwise. A sympathetic block can be achieved either mechanically by endoscopic intervention or by an intravenous agent to the site where the sympathetic nerve branch is in close proximity. Most procedures are reversible unless the nerve has been completely severed.
Function, effect & goals
The most important areas of application for the implementation of a sympathetic blockade are primary hyperhidrosis, excessive and uncontrollable sweating in limited body regions and certain chronic pain conditions.
Sweat formation on the body is controlled sympathetically and is normally used to regulate body temperature. With increased perspiration on almost the entire body surface, the cooling effect of the evaporative cold is used and is an effective means of cooling the body down during vigorous physical activity and / or high outside temperatures. The secretion of sweat in certain regions of the body such as in the armpits, on the forehead and in the intimate area, however, also serves for communication, the notification of existing emotions such as fear, aggression anger or also about the sexual status. The odorous substances contained in sweat in these cases are largely unconsciously absorbed and processed directly in the brain stem.
In this respect it seems logical that sweat secretions in the armpits or on the forehead can be the result of an increased stress level and need not be coupled with the sweat secretion all over the body for cooling purposes. In some people there is a pathologically increased and for those affected very uncomfortable sweat formation in the armpits and sometimes in other parts of the body. The increased perspiration is often coupled with a flushing of the face. If conservative therapies and combating symptoms with deodorants or powders are unsuccessful, the only effective therapy left is usually a blockage of the sympathetic nerves that cause excessive sweating in the body regions in question.
In most cases, it is sympathetic nerves in the chest area, if the head and hands are affected, and the armpits are also affected. Sympathetic nerves in the lumbar area need to be blocked when the feet and genital area are affected. Mostly minimally invasive surgical procedures are used to block the sympathetic nerves. The blocking itself can be done by charring, severing or by properly clamping it off using a titanium clip. Clamping with a titanium clip is usually reversible. The second area of application of the sympathetic blockade is the treatment of chronic pain, of which it must be ensured by differential diagnosis that they are caused by sympathetic nerves.
Often it is neuropathic pain as a "leftover" of a serious previous illness such as herpes zoster (shingles). A sympathetic blockade is only used as a therapy when conservative therapies do not lead to lasting pain relief. Blocking of the sympathetic nerve with chemical agents is usually chosen as the procedure. The active substances are injected into a vein near the section of nerve in question. During the procedure, the vein is tied off in front of and behind the injection site for about 20 minutes so that the active substance is not transported by the vein before it starts to work on the sympathetic nervous system.
Risks, side effects & dangers
The minimally intensive surgical procedures, which aim to block certain nerve sections, are very well developed and the usual risks, which also apply to other minimally invasive interventions, are not higher even with sympathetic blocks. However, the interventions require great care because there is a fundamental risk of injuring other nerves or vessels, with sometimes serious consequences in individual cases.
For example, if the sympathetic nervous system is blocked in the chest area (transthoracic sympathectomy) and the stellate ganglion is injured, a one-sided disorder of facial expression with drooping eyelids can occur (Horner syndrome). There is also a low risk of vocal cord paralysis. Compensatory sweating occurs as an undesirable side effect with every sympathetic block for the treatment of hyperhidrosis, because the nerve block does not eliminate the cause of the excessive sweating. In principle, surgical techniques that enable the nerve block to be removed are to be preferred.
When the sympathetic nervous system is chemically blocked by local anesthetics, there is, on the one hand, the usual risk of injuring the vein or arterial vessels and a low risk of infection. After the vein blockage has been lifted, the anesthetic can lead to allergic reactions if there is an intolerance.
