Carpal Tunnel Syndrome

Tingling and pain in the hand and forearm due to a compressed nerve at the wrist

  • Most common between the ages of 40 and 60
  • More common in females
  • Work that involves repetitive hand movements is a risk factor
  • Genetics is usually not a significant factor. Rarely, may run in families

The carpal tunnel is the narrow space formed by the bones of the wrist (carpal bones) and the strong ligament that lies over them. In carpal tunnel syndrome, the median nerve, which controls some hand muscles and conveys sensation from nerve endings in part of the hand, is compressed where it passes through the tunnel. This compression causes painful tingling in the hand, wrist, and forearm. Carpal tunnel syndrome is a common disorder, especially in women aged 40–60, and often affects both hands.

What are the causes?

In some cases, the underlying cause of nerve compression is not known. In others, it occurs because the soft tissues within the carpal tunnel swell, compressing the median nerve at the wrist. Such swelling may be due to diabetes mellitus, or it may occur during pregnancy. The carpal tunnel may also be narrowed by a joint disorder, such as rheumatoid arthritis, or by a wrist fracture. The syndrome is associated with work that involves repetitive hand movements, such as typing, which can result in inflammation of the tendons in the wrist (see Tendinitis and tenosynovitis). Rarely, carpal tunnel syndrome may occur as a feature of a generalized nerve disorder which may run in families.

Carpal tunnel

The carpal tunnel is formed by the bones of the wrist and the ligament over them. Compression of the median nerve in the tunnel causes carpal tunnel syndrome.

What are the symptoms?

Symptoms mainly affect specific areas of the hand, such as the thumb, the first and middle fingers, the inner side of the ring finger, and the palm of the hand. Initially, symptoms may include:

  • Burning and tingling in the hand.

  • Pain in the wrist and up the forearm.

As the condition worsens, other symptoms may gradually appear including:

  • Numbness of the hand.

  • Weakened grip.

  • Wasting of some hand muscles, particularly at the base of the thumb.

Symptoms are typically worse at night. Shaking the affected arm may temporarily relieve symptoms, but the numbness may become persistent if left untreated.

What might be done?

Your doctor may suspect carpal tunnel syndrome from your symptoms. He or she will examine your wrists and hands. Nerve conduction studies (see Nerve and muscle electrical tests) may be carried out to confirm the diagnosis. If pregnancy is the cause of carpal tunnel syndrome, the symptoms usually disappear after childbirth. In other cases, treating the cause, if it can be identified, usually relieves symptoms.

The symptoms of carpal tunnel syndrome may be relieved temporarily by nonsteroidal anti-inflammatory drugs or by wearing a wrist splint, particularly at night. In certain cases, a corticosteroid injection (see Locally acting corticosteroids) under or around the ligament may reduce swelling. If symptoms persist or recur, you may have surgery to release pressure on the nerve. After surgery, there are usually no further symptoms.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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