What is carpal tunnel syndrome

Carpal tunnel syndrome

What is carpal tunnel syndrome?
Carpal tunnel syndrome (KTS) is an entrapment of the metacarpal nerve (median nerve) in the wrist tunnel (carpal tunnel). This canal for nerves and tendons is formed in a U-shape by the carpal bones with a connective tissue band (retinaculum flexorum) as a roof.

What causes carpal tunnel syndrome?
Many causes are blamed for the disproportion between the tunnel and its contents (nerve and tendons). There are many indications that the tunnel was created too narrow in some people (probably up to 10% of the adult population) from birth and that this narrowness is more common in families. You may know other members of your family (usually the mother) who have symptoms similar to yours.

What are the typical symptoms?
When the "hands go to sleep" this is a very typical sign of carpal tunnel syndrome and allows the correct diagnosis to be made almost immediately. This falling asleep, which usually disappears quickly by shaking, rubbing and moving the hands (also "hanging out of bed"), at least in the initial stages, is also a very typical sign. Falling asleep occurs particularly at night or towards morning and can significantly disrupt night sleep ("the hand is asleep and the patient is not"). During the day it can occur during certain activities such as cycling, driving a car, reading the newspaper, holding the telephone receiver, doing handicrafts. With increasing severity, there are constant tingling sensations of the ring and middle fingers, then also of the index finger and thumb. After all, fingers can and remain numb all the time. This can rarely be the first symptom, especially in the elderly or during pregnancy. The KTS is particularly common among long-term dialysis patients.

Painful, swollen and also "snapping" fingers are often concomitant diseases. It is a pinching of the flexor tendons at the level of the ring ligament. The snapping together with the carpal tunnel syndrome can be eliminated by a small additional operation.

How is the diagnosis confirmed?
To ultimately confirm the diagnosis of carpal tunnel syndrome, an examination of the electrical conductivity of the nerves (NLG) is always required. The examination is generally carried out by neurologists and neurosurgeons and can be carried out largely painlessly without needle electrodes. It is mandatory before any surgical procedure and allows the success of the treatment to be documented later (rarely the lack of success) and diagnostic conclusions to be drawn.

What is the treatment?
This depends on the extent of the symptoms and the duration of the symptoms. In the case of persistent, increasing and painful to excruciating paresthesia as well as permanent sensory disturbance or numbness of the fingers, the small surgical intervention is necessary to remedy the condition. In order to bridge the time until the operation, the wrist can be immobilized on a splint at night. An injection of a cortisone preparation into the wrist tunnel can rarely be appropriate. However, this is reserved for an experienced doctor because of the risk of nerve damage. The value of drug treatment is rather dubious. Spontaneous improvements, especially when the strain on the hand is reduced, are possible. However, one can in no way rely on it. In the vast majority of cases, the symptoms return and progress. Unfortunately, there are still many patients who only go to the operation after severe damage to the nerve has set in with constant numbness and loss of the ball of the thumb. The reason for this long wait is often an excessive fear of the insufficiently informed patients. But the operation can still be carried out at the very advanced stage. A good treatment success is then possibly no longer guaranteed due to the restricted regenerative capacity of the nerves. The procedure can also be carried out on an outpatient basis in very old patients.

Is the surgical intervention to be made dependent on the extent of the nerve conduction velocity or the electroneurographic findings?
The answer to the question is no. The changes in the nerve conduction velocity often go in parallel with the extent of the clinical complaints, but this is not always the case. There are many patients who have very significant symptoms in the early stages of the disease and are very grateful when these are corrected by the operation, even if the nerve conduction velocity is relatively little changed.

How is the procedure performed and what are the risks?
The operation, which is now generally carried out on an outpatient basis and under local anesthesia, aims to permanently remove the entrapment of the nerves. For this purpose, the ligament (retinaculum flexorum) is completely severed while protecting the nerves and tendons. This can be done in two ways, namely by the traditional open method or by the endoscopic method.

In the former, a 2 - 3 cm incision is made from the wrist into the palm of the hand, the ligament is completely severed and the nerve is inspected. The technically more complex endoscopic method is carried out through one or two small incisions on the wrist and in the palm of the hand with the aid of a special probe and with a view of the screen.

The endoscopic surgeon needs special experience, otherwise the risk of nerve and vascular damage is higher than with the open method. The complications are less than 1% for both procedures when they are performed by an experienced surgeon. With the endoscopic method, due to the slightly smaller scars, an earlier load on the hand is possible, but not guaranteed.

If the patient cooperates well - this also includes moving the fingers through until the fist is completely closed after the operation - there is practically no risk of the hand becoming "stiff". The doctors who follow up the treatment must ensure that no tying bandages are applied, including plaster splints. The duration of the incapacity for work is usually 3 weeks, for some heavy physical activities or longer if the scar is more sensitive. As a rule, no special treatment measures are required after the procedure. If there is excessive bleeding or inflammatory reddening in the wound area, an immediate presentation to the surgeon is indicated, otherwise the dressing can be changed and stitches can be changed by the family doctor or another specialist.

Many patients are unsettled by the term "Sudeck syndrome". This is an extremely rare complication that can be largely avoided through early exercise treatment, i.e. movement exercises and avoidance of restricting bandages. The problem is so rare that, in the opinion of many surgeons, no special education makes sense, even if this is required by the legal side.

Can carpal tunnel syndrome recur after a successful operation?
After the ligament has been completely severed and the metacarpal nerve has been relieved, the same symptoms as before the operation are extremely rare. Often there are other problems such as B. jerky fingers or additional discomfort from the side of the cervical spine and nerve roots that cause problems for the patient. The treatment is naturally different in such cases. Another intervention on the carpal tunnel is not necessary. Electrophysiological examinations and imaging methods (magnetic resonance imaging) are suitable for delimiting such complaints.

Is carpal tunnel syndrome an occupational disease or does it have to be compensated as a consequence of an accident?
In general, the answer to the question is no. Since it is usually a congenital disorder ("narrow carpal tunnel"), an accident or a work-related overload of the hand is only a trigger. Professional activity and accidental injuries are not the cause of the development of a carpal tunnel syndrome. In special cases, however, it can be assumed that they were involved. Since the carpal tunnel syndrome is remedied by the surgical intervention, there is no question of permanent damage caused by an accident.

For more information:
Prof. Dr. med. G. Antoniadis, Neurosurgical Clinic of the University of Ulm
at the Günzburg District Hospital
[email protected]
Dr. med. H. Assmus, former practice for peripheral neurosurgery in Dossenheim
[email protected]

Videos on carpal tunnel surgery can be found here:

Open KTS operation (5.3 MB) (Dr. H. Assmus, Schriesheim)
Monoportal endoscopic KTS OP (9.8 MB) (Prof. Dr. G. Antoniadis, Günzburg)
Biportal endoscopic KTS (5.0 MB) (Dr. T. Dombert, Dossenheim)