Synonym
Nerve compression syndromes This term is used to describe a series of neurological abnormalities in which a peripheral nerve (i.e. not located in the central nervous system, but in the periphery of the body) is constricted in its course. Many nerves have to overcome characteristic constrictions in their course, so that compression is particularly frequent here. A constriction of a nerve often becomes noticeable through neurological symptoms, to which the affected person does not attach too much importance at first, but which sooner or later often lead him to a doctor.
Symptoms
At the beginning they occur frequently: One of the most common nerve congestion syndromes is carpal tunnel syndrome. Here, the median nerve – which, as part of the brachial plexus, is responsible for the nerve supply to the arm – is compressed in the wrist area. Other nerves in the area of the upper extremity can also be constricted at various points, for example the radial nerve in the constriction of the upper arm colloquially known as “park bench paralysis” or the ulnar nerve in the area of the elbow (“funny bone”).
A nerve bottleneck can also occur in the leg. For example, when the cutenous femoral lateral nerve is compressed, as is often caused by wearing too tight pants or belts, or the tibial nerve in tarsal tunnel syndrome, which is caused by constriction of the nerve in the area of the inner ankle. In the following, we present an overview of the most common nerve constriction syndromes.
- Missing sensations like tingling or burning,
- Pain in the affected body part
- Numbness is often an indication of such an event
- Motor deficits in the sense of paralysis of certain muscles can occur. These can then be treated with a visible
- Muscular atrophy (weakness).
Carpal tunnel syndrome
The carpal tunnel syndrome is a nerve constriction syndrome which mainly affects the median nerve (middle arm nerve). Among the various nerve constriction syndromes, it is considered the most common peripheral nerve compression and is now a widespread disease, affecting women about three times more frequently than men. The carpal tunnel is a tunnel-like, anatomical passageway in the hand, which is formed and limited by bony and connective tissue.
Dorsally (to the back of a body part), the carpal tunnel is limited by some carpal bones. On both sides, the bones form a palpable bony elevation. A band, the Retinaculum musculorum flexorum (Lig.
carpi transversum), is stretched over it, which thus limits the carpal tunnel ventrally (i.e. at the top). The narrowest point has a cross-sectional area of 1.6 cm2 and lies approximately 1 cm above the middle of the rear row of bones of the carpal tunnel. One reason for the symptoms of carpal tunnel syndrome is the compression of the median nerve during its course through the carpal tunnel in the area of the carpal.
In addition to the most important structure related to carpal tunnel syndrome, the median nerve, ten tendons of the flexor muscles of the hand also run through the carpal tunnel. If there is an imbalance between the diameter of the carpal tunnel and the volume of the structures passing through it (e.g. in the case of swelling), the median nerve is particularly affected by complications. For this reason, carpal tunnel syndrome is sometimes also referred to as median compression syndrome.
However, the nerve is not only damaged by mechanical pressure but also by a lack of blood supply. EMG (electromyography) shows denervation signs and a reduced nerve conduction velocity. A tightness in the carpal tunnel can be caused and promoted by various factors.
Structural deviations of the limiting structures or a hereditary predisposition for a narrow carpal tunnel can cause carpal tunnel syndrome. Degenerative changes, such as in rheumatoid arthritis, or endocrine metabolic disorders, such as diabetes mellitus or pregnancy, also lead to the corresponding carpal tunnel syndrome symptoms. In the latter case, an increase in connective tissue occurs, resulting in a narrowing of the carpal tunnel.
A frequent cause, which also leads to the narrowing, is tendosynovitis, which is accompanied by swelling and thus corresponds to a space-consuming process.Injuries in the form of dislocations and fractures of the carpal bones can also trigger carpal tunnel syndrome. Finally, the component of mechanical stress should not be forgotten, since everyday movement patterns can provoke carpal tunnel syndrome. This includes the bending hand movement, especially in combination with force application.
There is also an increased risk for dialysis patients and overweight people. Disease patterns such as polyneuropathy, hypothyroidism, acromegaly, gout and amyloidosis are also considered to be favorable factors. The symptoms can vary depending on the severity and cause of carpal tunnel syndrome.
Patients often complain of nocturnal pain and paresthesia, i.e. sensations such as tingling and numbness in the thumb, index and middle fingers, as these areas correspond to the area served by the median nerve that runs through the carpal tunnel. In severe cases, the pain can even radiate into the shoulder. The pain can be aggravated by pressure or stretching of the wrist.
Paresthesia can be controlled with the clinical test “Hoffmann-Tinel sign”, in which the front of the hand is patted. The test is mainly used in the diagnosis of carpal tunnel syndrome in order to observe possible nerve regeneration during the course of the disease. In addition, fine motor skills may be impaired, as from a certain degree, degeneration of the musculature can also occur.
Typical for the carpal tunnel syndrome is the thenar trophy (lat. Thenar: thumb; atrophy: tissue loss of the musculature), in which the thumb ball musculature is less pronounced than before the disease. A complete motor failure can affect the two muscles Mm.
opponens pollicis and Mm. abductor pollicis brevis. In this case, oppositional weakness occurs; a movement in which the thumb is guided towards the little finger.
This movement is essential for grasping, but if the median nerve is compressed, the opposition movement is limited. The classic initial manifestation of the above-mentioned symptoms is pain at night and sensations of discomfort. Only in the later course of the day can the pain occur throughout the day.
In addition, the probability of muscle atrophy increases in the further stage of the disease. Carpal tunnel syndrome is usually treated with surgery. This involves cutting through the retinaculum flexorum, which limits the carpal tunnel to the front (ventral).
This creates more space in that channel for the traversing structures, especially the median nerve, so that the compression symptoms of carpal tunnel syndrome can be relieved. In addition to the surgical therapy, conservative treatment in the sense of protection can be carried out by means of a night splint. The choice of therapy for carpal tunnel syndrome therefore depends on the severity of the carpal tunnel syndrome.
A carpal tunnel syndrome occurring during pregnancy can heal on its own. This nerve constriction syndrome can be divided into anterior and posterior tarsal tunnel syndrome. The classification is based on the affected nerves: the anterior nerve is compressed in the fibular nerve and the posterior nerve is compressed in the tibial nerve.
Both are nerve branches of the sciatic nerve (N. ischiadicus). Especially women who frequently wear high shoes have an increased risk of anterior tarsal tunnel syndrome. A foot misalignment can also promote the development of tarsal tunnel syndrome (such as a flat-foot kink).
In general, space-occupying processes are considered to be the cause of the symptoms, which can arise due to an inflammatory disease (such as rheumatism), a fracture or a sprain of the ankle joint. The symptomatology depends partly on whether the disease is anterior or posterior tarsal tunnel syndrome. In general, pain is characteristic of the inner edge of the foot and the sole of the foot.
During the day, the pain can get worse due to the mechanical strain on the legs and feet. This is accompanied by sensory disturbances in the form of tingling and numbness in corresponding areas. If the compression lasts longer or is too strong, paresis, i.e. paralysis of the short foot muscles, can occur.
As always, two treatment options are available: either conservative or surgical treatment. As a rule, the conservative therapy is first used to try to improve the symptoms.Among other things, insoles are used that can slightly raise the inner edge of the foot and relieve the compression pressure in foot malpositions. Drug therapy with anti-inflammatory and pain-relieving agents is also standard in the conservative treatment of tarsal tunnel syndrome. Surgically, relief can be achieved by splitting the retinaculum musculi flexorum pedis, a band-like structure between the inner heel bone and the inner ankle.
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