What is carpal tunnel syndrome?

In carpal tunnel syndrome (KTS, also carpal tunnel syndrome, CTS), a certain nerve in the wrist area, the so-called median nerve, is narrowed

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Carpal tunnel syndrome - in short

In carpal canal syndrome, a nerve in the area of ​​the wrist, in the so-called carpal tunnel, becomes too narrow. The result is typically pain, tingling and numbness in the area of ​​the thumb to the middle finger. If the nerve is under pressure for a long time, the muscles of the ball of the thumb lose strength and can recede. An electrophysiological examination is necessary to diagnose carapal canal syndrome. In the early stages, a splint for the night and short-term treatment with anti-inflammatory drugs can help. In more advanced stages, an operation is necessary in which the ligament that closes the carpal canal at the top is cut, thus giving the nerve more space.

In the case of carpal tunnel syndrome (KTS, medianus compression syndrome, other spelling: carpal tunnel syndrome, CTS), there is damage to a nerve in the hand area. The nerve in question is called the median nerve.

The carpal canal (circled in red) is in the wrist area. Many tendons and the median nerve run through it

© W & B / Martina Ibelherr

The carpal tunnel - also called the carpal canal - is the space between the carpal bones and the overlying carpal ligament (ligamentum carpi transversum) through which various tendons and the median nerve run. This nerve is responsible for the sensitivity of the thumb, index and partly also middle finger. He is also responsible for controlling certain hand and finger muscles.

The damage to the nerve consequently leads to symptoms such as tingling at night and numbness in the area from the thumb to the middle finger. In the later stages, you may experience pain when grasping or the muscles of the heel of your hand degrade (see "Symptoms" section). Carpal tunnel syndrome is most common in older people, with women three to four times more likely to be affected than men.

Cross-section through the wrist: In carpal tunnel syndrome, the median nerve in the carpal canal becomes too narrow

© W & B / Ulrike Möhle

Causes and Risk Factors

Carpal tunnel syndrome occurs when the carpal canal is too narrow in relation to the space required by the structures it contains. Since the space inside the carpal tunnel is limited, the pressure in the tunnel increases and with it on the nerves and the small vessels that supply it with blood. If these vessels are compressed, they can no longer supply the nerve with enough oxygen and nutrients, which means that its function is impaired and can be damaged in the long term. Corresponding symptoms such as numbness and pain in the thumb to middle finger of the affected hand arise and in an advanced stage it can even happen that the muscles in the area of ​​the ball of the thumb that this nerve controls (see chapter Symptoms).

Carpal tunnel syndrome can be caused, for example:
• Anatomical bottleneck due to its nature, for example in certain variants of a carpal bone, the so-called hamate bone
• Swelling of the tendon sheaths (including due to excessive strain, rheumatic diseases, certain metabolic disorders or during pregnancy)
• Fractures of the radius or carpal bones which, when they heal, lead to a change in the bony structure
• Arthrosis of the wrist with the bony changes it causes
• Other changes in the wrist area occupying space

In rare cases, the mostly chronic carpal tunnel syndrome also occurs in an acute form. It can occur, for example, following fractures and dislocations of the spoke and carpal bones or as a result of bleeding in the area of ​​the wrist.

The symptoms of carpal tunnel syndrome can be provoked: If you bend your wrist very strongly (for example when cycling or at night while sleeping), this reduces blood flow. If there is already a bottleneck, symptoms such as the typical tingling or numbness can arise. Excessive stress can also inflame the tendon sheaths, causing them to thicken and require more space. This can also promote carpal tunnel syndrome.

Is Carpal Tunnel Syndrome Hereditary?

Carpal tunnel syndrome cannot be inherited directly, but in fact, external influences play only a minor role in carpal tunnel syndrome (KTS). Carpal tunnel syndrome is almost always genetic.

Examples of risk factors for carpal tunnel syndrome are:

  • Diabetes
  • rheumatic diseases
  • pregnancy
  • Strong occupational wrist strain with persistently recurring kinking of the hand in the wrist (for example during assembly work). Anyone who engages in such activities should therefore take adequate breaks as a preventive measure.

Normal everyday activities such as writing, using a computer, or exercising do not increase the likelihood of developing carpal tunnel syndrome. The temperature also has no influence.

Angled hand while sleeping: this hinders blood circulation

© Digital Vision / RYF

Symptoms: how does carpal tunnel syndrome show up?

Onset of carpal tunnel syndrome

At the beginning of a carpal tunnel syndrome, the disease manifests itself through symptoms such as painful or tingling fingers, which however disappear again after a short time. Some of these complaints radiate into the arm. For those affected it feels as if they have "fallen asleep" with the thumb to the middle finger. There may also be pain in the thumb to middle finger, possibly even radiating to the arm. Doctors call this "Brachialgia nocturna paresthetica".

Rubbing or shaking the hand usually makes the symptoms go away quickly. Since many people have bent their wrists while sleeping, which restricts blood flow, the symptoms occur more frequently at night. After activities such as cycling or talking on the phone, problems also occur more frequently for the same reason.

Advanced median compression syndrome

If a carpal tunnel syndrome is more advanced, the abnormal sensations in the hands are no longer temporary but permanent. In addition, those affected have the feeling of receiving an electric shock when grasping movements, which can be very painful.

Late stage

If the median nerve is already severely affected by the consequences of a carpal tunnel syndrome, it can hardly or not at all fulfill its function. In such a case, the thumb to parts of the middle finger are numb and the hands are no longer able to perform fine motor activities. In the later stages, the ball of the thumb on the side of the affected hand recedes (muscle atrophy, ball of the thumb atrophy). This results in poor splay or flexion of the thumb and thus a loss of strength during gripping movements.

Phalen test: If the symptoms typical of carpal tunnel syndrome can be triggered, this is another indication

© W & B / B.Seidl


The patient's medical history usually quickly leads the suspicion to carpal tunnel syndrome. In order to confirm this assumption and to make the diagnosis, the doctor will carry out further examinations.

Examination of the hand

First he will look closely at both hands. He will use various tests to check whether the mobility of the hand and fingers is intact and whether there are any sensory disorders. He will also try to see whether the symptoms can be provoked by certain movements and measures. For example, he may tap the carpal canal to determine whether the person's median nerve is sensitive to it, or he may bend the wrist sharply for a certain period of time to see whether there is numbness or discomfort in the thumb area afterwards.

Electrophysiological studies

So-called electrophysiological examinations are then necessary to confirm the diagnosis and to obtain a picture of the extent of the nerve damage. Above all, the nerve conduction velocity is measured, i.e. the time that the median nerve needs to pass on a stimulus. This examination can be used to determine how severely the nerve has already been damaged, as the nerve conduction speed decreases accordingly.

Further investigations

Further examinations may also be necessary. Arthrosis of the wrist can be diagnosed with an X-ray examination, an ultrasound examination is suitable, among other things, to visualize the tendon sheaths, and magnetic resonance imaging (MRI) can be useful if, for example, a tumor is suspected. Electromyography (EMG), i.e. a measurement of the electrical activity in the muscles on the ball of the thumb supplied by the median nerve, may also be considered.

Operation: The doctor splits the ligament of connective tissue over the carpal canal

© W & B / Szczesny

Therapy: what helps with carpal tunnel syndrome?

Treatment is always necessary if the symptoms occur frequently or persistently.

Splints and Cortioson Treatment

If the carpal tunnel syndrome is milder, the doctor can prescribe a wrist splint for the night or administer anti-inflammatory cortisone in tablet form or as an injection into the carpal tunnel. Cortisone therapy should only be given for a short period of time.

It has not been scientifically proven whether certain exercises can help.


Then, if numbness and failures of muscle function persist, do not improve with the above-mentioned treatment measures or put a lot of strain on the person concerned, an operation is an option.The surgeon splits the ligament structure (ligamentum carpi transversum), which borders the carpal tunnel at the top - similar to a roof. This gives the tendons and nerves contained in the carpal canal more space, and the pressure on the structures is reduced.

The surgical treatment of a carpal tunnel syndrome can be carried out either by an open or by an endoscopic operation (in the "keyhole method"). Both procedures can often take place on an outpatient basis, so that no overnight stay in hospital is necessary. In most cases the result is good. Many complaints, such as pain and numbness at night, improve almost immediately. In the case of pronounced nerve damage, however, it can take about half a year for the symptoms to largely disappear. Very rarely is the nerve so damaged that symptoms remain despite the operation. A muscle breakdown that existed for more than a year before the operation can no longer be reversed even after the operation.

Our expert: PD Dr. med. Oliver Kastrup

© W & B / private

Consulting expert

Dr. med. Oliver Kastrup is a specialist in neurology and psychiatry. He received his doctorate in 1993 from the University of Essen, where he was previously employed as an assistant doctor. He then worked as a research assistant from 1993 to 1998 and then from 1998 to 2006 senior physician at the Neurological Clinic and Polyclinic of the University of Essen. From 2006 to 2016 he was the senior physician there. In 2013 he completed his habilitation at the University of Duisburg-Essen. Since April 2016, PD Oliver Kastrup has been the head physician at the Clinic for Neurology and Neurophysiology at the Philippus Foundation of the Catholic Clinic in Essen.

Important NOTE:
This article contains general information only and should not be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor. Unfortunately, our experts cannot answer individual questions.

Further sources:

Assmus H, Antoniadis G, Bischoff C: Carpal tunnel, cubital tunnel and rare nerve compression syndromes. Online: https://www.aerzteblatt.de/archiv/166988/Karpaltunnel-Kubitaltunnel-und-seltene-Nervenkompressionssyndrome (accessed on February 1, 2019)

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