Carpal tunnel syndrome

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What is carpal tunnel syndrome?

The carpal tunnel is a narrow passageway inside your wrist through which certain nerves to your hands and fingers pass. Carpal tunnel syndrome occurs when a nerve becomes compressed in the carpal tunnel, causing tingling, numbness and other symptoms in the hand and arm. The condition is more common in women than in men.

Carpal tunnel is sometimes confused with wrist tendonitis, also known as repetitive strain injury (RSI).

What causes carpal tunnel syndrome?

It is caused by pressure on the median nerve, which runs from your forearm through a passageway in your wrist called the carpal tunnel. This nerve provides sensations to your thumb, index, middle fingers and part of the ring fingers on the palm side of your hand. It also moves the muscles at the base of your thumb.

If the carpal tunnel space becomes narrowed or if the median nerve becomes irritated you can develop carpal tunnel syndrome. A range of factors can cause the condition including:

  • A wrist fracture or dislocation
  • Arthritis, leading to a deformity in the small bones of the wrist
  • A genetic predisposition to a narrow carpal tunnel
  • Certain chronic illnesses, such as diabetes, which increase the risk of nerve damage and other conditions such as kidney failure and thyroid disorders
  • Inflammatory conditions such as rheumatoid arthritis which can damage the lining of the tendons in the wrist
  • Obesity
  • Fluid retention, which may occur during pregnancy or menopause
  • Repetitive or prolonged flexing of the wrist, for example due to working with vibrating tools

What are the symptoms of carpal tunnel syndrome?

Symptoms often start gradually with numbness or tingling in your thumb, index or middle fingers that may come and go. Sometime you may experience a sensation like an electric shock in these fingers. The symptoms may worsen when you hold something like a phone or steering wheel and they may disturb your sleep. Your hand may feel weak or clumsy due to numbness or loss of strength in the thumb’s pinching muscles which are controlled by the median nerve.

How is carpal tunnel syndrome diagnosed?

You should see an orthopaedic consultant if you suspect carpal tunnel syndrome as you can suffer permanent muscle and nerve damage if the condition goes untreated. The consultant will carry out a physical examination, assessing the feeling in your fingers and the strength of your hand muscles. An X-ray may be used to exclude other causes of pain, such as a fracture or arthritis. An electromyogram may be used to assess muscle damage. This involves inserting a thin needle electrode into specific muscles to assess electrical activity when the muscles contract and rest. You may also be sent for nerve conduction studies where small shocks may be passed through the median nerve to determine if the electrical impulses are slowed in the carpal tunnel.

How is carpal tunnel syndrome treated?

It is important to take frequent breaks to rest your hand and wrist. Ice packs and anti-inflammatories can be used to reduce the swelling and wearing a wrist splint at night can help relieve night-time tingling and numbness. An injection of corticosteroids into the carpal tunnel may help to relieve pain and reduce inflammation. If the condition is linked to another health problems such as arthritis, your consultant will discuss treatment options.

Depending on the severity of your carpal tunnel syndrome, you may be offered surgery to relieve pressure by cutting the ligament that is pressing on the median nerve. Surgical options include:

  • Endoscopic surgery – small incisions are made in the hand or wrist and a device called an endoscope (a tube-like instrument with a tiny camera at one end) is passed inside to allow the surgeon to see inside the carpal tunnel so that accurate cuts can be made to the ligament.
  • Open surgery – an incision is made in the palm of your hand over the carpal tunnel. Cuts are made through the ligament to free the nerve.

It can take three to four months to recover from carpal tunnel surgery and up to a year before your hand is back to full strength. Your return to work depends on the type of surgery you had, whether the surgery was on your dominant hand (the hand you use most), and your work. Your consultant will be able to advise you based on your particular situation.