Causes of carpal tunnel syndrome unclear

By Dr Michelle Cooper

Published 17/11/2015 | 00:00

Dr Michelle Cooper. Photo Eye Focus
Dr Michelle Cooper. Photo Eye Focus

Carpal tunnel syndrome is caused by nerve pressure within the wrist, carpal tunnel syndrome can result in pain, numbness, tingling, weakness, or muscle damage in the hand and fingers.

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There are eight small bones in the wrist. Lying over these is a ligament which creates a passageway within the wrist joint, known as the carpal tunnel. Passing through the tunnel are tendons which attach the forearm muscles to the fingers, as well as a nerve known as the median nerve. This nerve gives feeling to the thumb, index and middle fingers, as well as half of the ring finger. It also controls the movement of the muscles of the thumb.

Carpal tunnel syndrome gives way to a set of symptoms caused by compression of the median nerve within the carpal tunnel. Although common during pregnancy, it mostly affects people in their 40's and 50's. However, it can occur at any age, with women being affected two to three times more commonly than men.

SYMPTOMS

Symptoms can vary from mild to severe and one or both hands may be affected. Initially symptoms may come and go, often after use of the affected hand. Typically, symptoms are worse at night and include:

- Pain in the hand which is often of a tingling or burning sensation. The index finger and middle fingers are usually the first to be affected and the pain may travel along the forearm.

- Numbness may then develop as the condition worsens.

- Dryness of the skin may also occur.

- Weakness of some muscles of the fingers or thumb can occur in severe cases causing poor grip.

CAUSES

In most cases the causes are unclear. However:

- Some minor changes may occur in the tendons which then increase pressure within the tunnel. This pressure restricts the blood supply to the median nerve which then affects the function of the nerve, subsequently causing symptoms. Carpal tunnel is more common in manual workers and overuse of the hand seems to play a key role in the development of this condition.

- Genetic factors contribute, with 1 in 4 people affected having a close family member with carpal tunnel syndrome.

- Bone or arthritic conditions of the wrist put patients at risk of developing carpal tunnel syndrome.

- Other conditions such as pregnancy, obesity, underactive thyroid disease, diabetes and menopause are associated with carpal tunnel syndrome.

DIAGNOSIS

A nerve conduction test, where a slow speed of impulse is sent down the median nerve, can confirm the diagnosis of carpal tunnel syndrome.

TREATMENT OPTIONS

There are various treatment options available. Non-surgical methods are usually advised in mild cases. Severe cases, such as those who present with wasting of the muscles at the base of the thumb, require urgent surgery in order to prevent long term nerve damage.

- General measures including rest, weight reduction and painkillers often prove beneficial. Thankfully, symptoms abate without treatment in 1 in 4 cases.

- Removable wrist splints keep the wrist in a neutral position, thereby resting the median nerve, helping to alleviate symptoms.

- Steroidal injections often ease symptoms by reducing inflammation.

- Surgery often proves curative. Performed under general anaesthesia, it involves cutting the ligament over the wrist in order to ease the pressure within the carpal tunnel.

Further information is available from www.carpal-tunnel.net

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