Carpal tunnel syndrome

Constriction of the median nerve in the canal can damage the nerve, which can have various causes, including the following: Anatomical constriction, inflammation and swelling of the flexor tendon sheaths, pregnancy, forearm fractures, diabetes mellitus, polyarthritis, infections in the wrist area, hypothyroidism. Depending on the statistics, carpal tunnel syndrome occurs in up to 14% of the population. It is three times more common in women than in men. People between the ages of 40 and 60 are most frequently affected. The dominant hand usually shows symptoms first. According to a large-scale study, working at a computer is not responsible for a higher incidence of carpal tunnel syndrome. The first symptom is often the hand falling asleep at night and ants running in the fingers. Nocturnal pain that radiates into the arm and shoulder can also be the first symptom. The nocturnal symptoms can usually be alleviated at first by shaking the hand. Persistent pressure on the nerve can lead to hand weakness and muscle atrophy in the ball of the thumb. This is the only externally visible change. The loss of sensation in the fingers can progress to numbness and cause fine motor disorders. As the disease progresses, the pain fibres are damaged and the pain subsides. Symptoms such as formication can often be provoked by the position of the wrist, e.g. when reading a newspaper, driving a car or cycling, or resting the hand on a surface.

In addition to recording the symptoms described, a precise clinical examination is of great importance for making a diagnosis. The focus is on comparative testing of finger sensitivity using the following tests:

• Hoffmann-Tinel sign: Tapping the median nerve on the flexor side of the wrist triggers electrifying pain in the area supplied by the median nerve (can be triggered in approx. ¾ of patients).
• Phalen test: With the wrist flexed 60º, formication and/or electrifying pain occurs after approx. 60 seconds.
• Reversed Phalen test: The same symptoms occur as in the Phalen test when the wrist is hyperextended by 60°.
• Bottle sign: Due to muscle weakness in the ball of the thumb, a bottle cannot be gripped properly.

So-called neurophysiological examinations can also provide information about the condition of the nerve. These examinations are carried out by neurologists.

• EMG (electromyography): EMG can be used to differentiate whether more nerve or muscle is damaged. This allows the location of the damage to be determined.
• ENG (electroneurography): ENG is used to measure how quickly the median nerve transmits a stimulus.
• Ultrasound: Compression (constriction) of the median nerve can also be detected using ultrasound.

If the symptoms cannot be attributed to carpal tunnel syndrome, other causes such as polyarthritis of the finger and/or wrist or a circulatory disorder of the hand must be investigated.

Mild forms of carpal tunnel syndrome can be treated conservatively. Wearing special splints that hold the wrist in a neutral position can alleviate the symptoms, especially at night. Injections of cortisone into the carpal tunnel can reduce swelling of the tendon sheath tissue and thus the pressure in the tunnel. However, injections into the carpal tunnel are not without risk: if the cortisone is injected into the nerve, it can suffer severe damage. Taking cortisone in tablet form can also be useful in the short term, especially in cases of severe acute carpal tunnel syndrome. Around 70 % of patients initially respond to conservative therapies. In most cases, the symptoms return after a year at the latest and 50% subsequently require surgery.

The aim of the operation is to relieve the nerve and improve the blood vessels that nourish it. In the open procedure, the retinaculum is directly accessed through an approx. 3 to 4 cm long incision in the palm of the hand, which is split under visualisation and protection of the median nerve. This widens the carpal tunnel and relieves the nerve.

The operation is performed in a so-called haemostasis. The blood is "unwound" from the arm and the tourniquet is held in place with an upper arm cuff. The operation is performed with magnifying glasses.

The endoscopic procedure was introduced over 15 years ago. Smaller scars and a faster recovery of hand function were propagated. However, this procedure resulted in a higher rate of incompletely split tunnels and therefore a higher complication rate. Comparative studies have shown that the endoscopic and open techniques have practically identical results. At the Pyramid Clinic, the open procedure is used almost exclusively. The scar is almost invisible after approx. 6 months. The general risks of this procedure (e.g. infection, post-operative haemorrhage, injury to vessels and nerves) are fortunately rare. The operation can be performed under regional anaesthesia. A general anaesthetic is only required in special cases.

Short-term immobilisation of one to two weeks is the rule. Splint fixation is not mandatory and is at the discretion of the surgeon. Resumption of work depends on the respective load; light office work is possible after a few days, manual labourers (e.g. construction workers) can resume work after 6 to 12 weeks. Early functional treatment, independent movement exercises and elevation of the hand in the first few days prevent swelling and finger stiffness.

Recurrence after surgery is extremely rare and is usually due to incomplete splitting of the retinaculum or the occurrence of massive inflammation of the tendon sheaths.

If the disease has been present for a long time, the nerve may take months to fully recover. If the nerve is severely damaged beforehand (long-lasting and pronounced compression), recovery may only be partial. In such cases, however, surgery is also advisable in order to prevent the nerve damage from progressing. The final result in terms of recovery of strength and/or sensitivity is available after 6 to 12 months.