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Carpal Tunnel Syndrome

What is carpal tunnel syndrome?
The carpal tunnel is a passageway in the wrist formed by the eight carpal (wrist) bones, which make up the floor and sides of the tunnel, and the transverse carpal ligament, a strong ligament stretching across the roof of the tunnel.

Inside the carpal tunnel are nine flexor tendons which flex (bend down) your fingers and thumb. Also running through the carpal tunnel is the median nerve, a cord about the size of a pencil containing thousands of nerve fibres supplying sensation (feeling) to you thumb middle and index fingers, and half of the ring finger. The median nerve lies directly beneath the transverse carpal ligament and comes in contact with the ligament when bending or straightening the wrist or fingers.

Carpal tunnel syndrome is caused by increased pressure in the carpal tunnel resulting in compression of the median nerve. Thickening of the tendons can restrict the space within the tunnel and cause the nerve to become pressed against the ligament forming the roof of the tunnel. When the relatively soft structure of the median nerve is pushed up against this ligament, blood flow to the nerve is restricted, causing a sensation often described as “pins and needles” to the fingers. In severe or chronic cases, numbness can occur.

What are the causes?
Carpal tunnel syndrome can be caused by a variety of problems. Certain medical conditions that may lead to compression of the median nerve include:

  • Inflammation or swelling about the tendons
  • Fluid retention
  • Wrist fractures and dislocations
  • Crushing injuries
  • Rheumatoid/degenerative arthritis
  • Diabetes
  • Enlargement of the median nerve
  • Tumours and tumour-like conditions
  • Hypothyroidism
  • Pregnancy

Certain occupational activities which involve repeated flexing of the fingers or wrist, or prolonged use of vibrating tools may cause carpal tunnel syndrome.

Non-work related activities of daily living and leisure may also provoke symptoms of carpal tunnel syndrome such as lawn-mowing, long distance driving, knitting or wood carving. Not all people involved in these types of work or other activities will develop carpal tunnel syndrome. Proper work pacing, regular rest breaks, reducing repetition and force, and the use of ergonomically designed tools and equipment can minimise the risk.

What are the signs and symptoms?
Numbness, burning or tingling of one or more digits (excluding the little finger) is the most common symptom. Often these symptoms occur at night and can waken the individual from sleep. The pain may extend up the arm, into the elbow, and as far up as the shoulder and neck.

Numbness and tingling may occur when performing everyday activities that involve flexing the wrist or grasping such as holding a telephone or driving. A decrease in sensation or feeling may result in clumsiness or weakness of the affected hand.

How is it treated?
Many patients with carpal tunnel syndrome are treated without surgery. Conservative treatment of patients with mild symptoms usually involves use of a splint and avoidance of activities that provoke symptoms.

Your doctor may prescribe a splint to be worn to restrict movement of the wrist. Depending on the severity of the condition, the splint may be worn during the day and/or night. The length of time the splint is needed varies. Usually a splint is worn until the symptoms quiet down, which may be approximately 4-6 weeks.

In some instances, a cortisone injection may be administered into the carpal canal to decrease swelling. This may greatly reduce the symptoms.

Injection of the carpal tunnel.

When conservative treatment does not achieve the desired results, or in cases involving more severe symptoms, such as extensive weakness or numbness, surgery may be recommended.

Surgery is usually performed on a day surgery basis. An incision is made in the palm of the hand and the surgeon will cut (release) the ligament forming the roof of the tunnel.

Release (division) of the transverse carpal ligament.

This relieves the pressure on the median nerve.

What about recovery?
With the blood flow to the median nerve restored, the symptoms of burning and tingling are usually relieved soon after surgery. Patients can expect soreness from the incision for 4-6 weeks and discomfort from deep pressure for as long as several months. Improvements in strength and sensation depend on the extent of nerve damage prior to treatment. Normal grip strength may not return for several months following surgery. The natural healing process and regeneration of nerve fibres will continue throughout the following 6-12 months.