Carpal tunnel syndrome

Carpal tunnel syndrome is a painful and progressive condition in which the median nerve (which runs from your forearm down into the palm of your hand) is compressed or squeezed as it passes through the carpal tunnel – a narrow passageway at the base of the hand near your wrist (see the diagram).

carpal tunnel

Symptoms

Many Australians suffer from carpal tunnel syndrome and experience symptoms that usually come on slowly and get progressively worse over time. Symptoms of carpal tunnel syndrome can include:

  • Tingling and numbness in the fingers and palm of your hand that feels like ‘pins and needles’;
  • Pain in your wrist or hand, which can radiate up the arm to your elbow or down to your fingers;
  • Pain that can vary from a dull, aching sensation, through to a burning feeling, or a sharp, piercing or shooting pain, like a very bad cramp;
  • The pain and discomfort can often be relieved by shaking out the hands (like you are flicking water off your hands);
  • A sensation that your fingers are swollen, even if they look normal in size; and
  • A feeling of weakness in your hands or a loss of grip strength, which can make it difficult for you to hold small objects, clench your fist, or carry out your usual tasks.

The symptoms of carpal tunnel syndrome may be worse at night, particularly if you tend to sleep with your wrists flexed, with your palm bent down towards the front of your forearm.

For most people, their dominant hand is the first to develop symptoms, although both hands can be affected.

If left untreated, the excess pressure on the median nerve can cause the muscles near the base of the thumb to waste away.

Causes

The carpal tunnel is a narrow, stiff passageway at the base of your hand that is made up of bones and ligaments. The median nerve and tendons pass through the carpal tunnel into your hand.

The median nerve is a large nerve that controls sensations to the palm side of the thumb and your first 3 fingers (but not the little finger). It also supplies movement to some of the small muscles in the hand that allow you to move your thumb and fingers.

So if the carpal tunnel narrows for any reason – or if the tendons within the tunnel become thickened or swollen – there is less space in the tunnel for the median nerve. As a result, the median nerve becomes compressed (squeezed), and the extra pressure on the nerve can lead to pain, tingling, numbness, itching and burning sensations.

Risk factors

Any factor that results in increased pressure on the median nerve as it passes through the carpal tunnel can result in carpal tunnel syndrome. Known risk factors include:

  • Trauma or injury to the hand or wrist that results in swelling, such as a sprain or a bone fracture;
  • Some diseases, such as rheumatoid arthritis, diabetes, or disorders of some glands, such as the thyroid or pituitary gland;
  • A cyst or tumour in the carpal tunnel;
  • Retaining extra body fluid during pregnancy or menopause. Carpal tunnel syndrome during pregnancy usually develops in the second and third trimesters, and normally disappears within a month after giving birth;
  • Being overweight;
  • Activities or jobs that involve repetitive movements of the wrist and hand, or using machinery or tools that cause excessive vibration;
  • Being female – women are 3 times more likely to develop carpal tunnel syndrome than men, possibly because women generally have a narrower carpal tunnel; and
  • A family history of carpal tunnel syndrome.

Some people develop carpal tunnel syndrome without having any known risk factors.

Diagnosis

It’s important to diagnose carpal tunnel syndrome and start treatment early to reduce the risk of long-term (possibly permanent) damage to the median nerve. In addition to asking you to describe your symptoms, your doctor may:

  • Examine your hands, arms, shoulders and neck to assess whether your symptoms are related to your daily activities or due to some other underlying condition;
  • Check your wrists for any swelling, tenderness, or areas that are warm or discoloured;
  • Check each finger for sensation;
  • Check the muscles at the base of your palm for strength and any signs of wasting;
  • Conduct physical tests by asking you to place your hands and fingers in certain positions to bring on your symptoms; and
  • Order further tests (such as blood tests or x-rays) to identify possible causes of carpal tunnel syndrome like diabetes, bone fractures or arthritis).

In many cases, your doctor will be able to diagnose carpal tunnel syndrome based on your symptoms and the results of physical examinations. However, if the diagnosis is uncertain, other tests may be needed. These tests can include:

  • A nerve conduction test. This test measures the speed that the median nerve transmits signals through the carpal tunnel. Electrodes are placed on the skin of the hand and wrist and a small (but safe) electric shock is given to the median nerve. A slow nerve conduction speed helps confirm a diagnosis of carpal tunnel syndrome;
  • Electromyography. This test helps determine whether the median nerve is damaged. It involves inserting a fine needle into specific muscles to measure their electrical activity; and
  • Ultrasound or magnetic resonance imaging (MRI) can be used to view the median nerve and look for any changes.

Treatment

Up to 1 in 3 people with carpal tunnel syndrome get better without any specific medical treatment. But if you are experiencing troublesome symptoms, there are a number of treatments recommended by Australian experts, including:

  • Rest. You should avoid any activities or movements that aggravate your symptoms for at least 2 weeks;
  • A cool pack can help provide relief if there is any swelling of your hand or wrist;
  • Splinting. Splinting the wrist or wearing a hand brace may be part of the initial treatment. These devices are usually worn at night to start with, to help prevent the wrist from being bent during sleep;
  • Elevating the hand and forearm on a pillow during sleep can help relieve symptoms;
  • Anti-inflammatory medicines (such as non-steroidal anti-inflammatory drugs, or NSAIDs) may be used to relieve pain and reduce any swelling or inflammation; and
  • Corticosteroids. If initial treatments don't control symptoms, your doctor may prescribe a medicine called a corticosteroid to reduce inflammation in the carpal tunnel. Corticosteroids can be taken as tablets or a corticosteroid injection directly into the wrist.

Surgery

Surgery is often recommended if symptoms continue despite other treatments. A procedure called a ‘surgical release’ is used to make more space in the carpal tunnel. The carpal ligament is cut, which releases pressure on the median nerve. Surgery is usually performed as a day procedure under local anaesthetic, so you don’t need an overnight stay in hospital.

Many people get immediate relief from their symptoms following carpal tunnel surgery, but full recovery may take several months. Physical therapy exercises after surgery help to restore wrist strength. However, some people may need to change the way they carry out daily tasks following surgery.

Surgery is not recommended for women with carpal tunnel syndrome due to pregnancy because the symptoms disappear soon after birth.

Preventing carpal tunnel syndrome

There are steps you can take that may help prevent carpal tunnel syndrome, particularly in the workplace. Tips include:

  • Warming up your fingers, wrists and forearms with stretching exercises before work;
  • Taking regular breaks;
  • Wearing a splint or a hand brace to keep your wrists straight;
  • Making sure your desk or work area is correctly adjusted to maintain a natural wrist position; and
  • Rotating repetitive jobs among workers.
Last Reviewed: 13 May 2016
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References

1. Carpal tunnel syndrome (revised Nov 2010). In eTG complete. Melbourne: Therapeutic Guidelines Limited; 2016 March. Available at: www.tg.org.au. Accessed 9 May 2016.
2. Carpal tunnel syndrome during pregnancy (revised Nov 2010). In eTG complete. Melbourne: Therapeutic Guidelines Limited; 2016 March. Available at: www.tg.org.au. Accessed 9 May 2016.
3. LeBlanc KE & Cestia W. Carpal tunnel syndrome. Am Fam Physician 2011 Apr 15;83(8):952-958.
4. Simpson MA & Day B. Painful numb hands. MJA 2011;195:388-391.
5. Carpal Tunnel Syndrome Fact Sheet. National Institute of Neurological Disorders and Stroke. Available at: www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm Accessed 10 May 2016.
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