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Carpal Tunnel Syndrome

Tactile sensibility in the hand (with the exception of the little finger) is dependent on the major sensory nerve of the hand – the median nerve. At the wrist level, the medianus nerve passes through a narrow canal – the carpal tunnel – where it is intertwined with several flexor tendons of the hand.

In carpal tunnel syndrome (CTS), the medianus nerve is entrapped in the carpal tunnel. This can happen due to external pressure, such as swelling in the surrounding flexor tendons sheaths, but most often no cause can be identified. The increased pressure in the carpal tunnel results in impaired microcirculation in the median nerve and damage to the myelin sheaths, surrounding nerve fibres.

Carpal tunnel syndrome can be cured surgically by decompressing the nerve through a volar incision dividing the carpal ligament.

Clinical signs of CTS

In the early stages, carpal tunnel syndrome is characterized by nocturnal numbness and paraesthesia (”pins and needles”) in the fingers except for the little finger. The patient may “wake up because the hand has fallen asleep”. There may be no symptoms in the hand during the daytime. With time the problems may, however, become chronic and troubling also during the day. Even more advanced stages are sometimes characterized by pain and atrophy of the thenar muscles on the base of the thumb.

About 3 % of the population suffer from CTS, usually middle-aged women. The problem is also common in pregnant women at the last trimester. Many factors can contribute and increase the risk to develop CTS. One important such factor is repeated, monotonous flexion movements of the wrist.

Important to clarify the cause

Hard manual work using handheld vibrating tools can cause CTS. While the use of heavy tools combined with monotonous wrist movements may be one reason, the fact that the tools vibrate is probably an important factor in itself. Vibrations from the hand can be transferred to the carpal tunnel and affect the median nerve, which may already be stressed as a result of monotonous wrist movements

It is important to clarify which problems are caused by vibrations and carpal tunnel syndrome respectively. A surgical procedure aimed at decompressing the median nerve in the carpal tunnel may be curative in the case of problems caused by nerve entrapment, but will have no effect on vibration-induced injuries to nerves in the hand and fingers.


Clinical Benefit – nerve entrapment

Carpal tunnel syndrome belongs to the category of nerve entrapment which is a neurological disorder where a nerve or nerve trunks are clamped and thus exposed to external pressure.

Neural compressions are well-known clinical conditions that often can be difficult to distinguish from sensory disturbances. Of particular interest are carpal tunnel syndrome and ulnar or nerve compression at the elbow or wrist level.

The clinical benefit with VibroSense Meter II (VSM II) is to help physicians diagnose nerve entrapment such as carpal tunnel syndrome. 

Target Profile for VSM II and nerve entrapment:

Target group

Clinical targets

Clinical use

Occupational health care with vibration exposed workers

Differential diagnosis, DIG I, II bilaterally. Complement to clinical examination and possible neurography.

Hand and orthopaedic surgeons

Complement to clinical examination and possible neurography

Primary care

Examination of unclear neuropathy in the hands or leg. Complement to clinical examination for suspected nerve compression in leg,  hand, arm or neck