Carpal tunnel syndrome is a common wrist condition that causes persistent pain, tingling and numbness in the palm, fingers and thumb.
Your carpal tunnel is a narrow passageway at the base of the hand near your wrist. In carpal tunnel syndrome, 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 (see the diagram).
There are treatments for carpal tunnel syndrome, including simple self-care measures, medicines, splinting and surgery. In up to a third of people, it gets better on its own without treatment.
Symptoms of carpal tunnel syndrome can include:
- Tingling and numbness in the fingers and palm of your hand that feels like ‘pins and needles’. Some people experience a sensation that the fingers are swollen, even if they look normal in size.
- Pain in your wrist or hand, which can radiate up the arm to your elbow or down to your fingers. Pain can vary from a dull, aching sensation, through to a burning feeling, or a sharp, piercing or shooting pain, like a very bad cramp.
- 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 pain and discomfort can often be relieved by shaking out the hands (like you are flicking water off your hands).
Symptoms usually come on slowly and get progressively worse over time. The symptoms 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.
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.
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. Women aged between 40 and 60 years are at highest risk.
- A family history of carpal tunnel syndrome.
Some people develop carpal tunnel syndrome without having any known risk factors.
Diagnosis and tests
If you are experiencing symptoms, see your GP (general practitioner) as soon as possible. A prompt diagnosis of carpal tunnel syndrome means you can start treatment. Early treatment not only eases symptoms, but helps reduce the risk of long-term (possibly permanent) damage to the median nerve.
Your doctor will ask you to describe your symptoms and what tends to make them better or worse.
Your doctor will also want to examine your hands and arms, shoulders and neck to assess whether your symptoms are related to your daily activities or due to some other underlying condition.
As part of the physical examination they may:
- 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; and
- conduct physical tests by asking you to place your hands and fingers in certain positions to bring on your symptoms.
In many cases, your doctor will be able to diagnose carpal tunnel syndrome based on your symptoms and physical examination. However, if the diagnosis is uncertain, 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.
- Ultrasound or magnetic resonance imaging (MRI) can be used to view the carpal tunnel and look for any changes.
Other tests (such as blood tests or x-rays) may be recommended to identify possible causes of carpal tunnel syndrome, such as diabetes, bone fractures or arthritis.
Treatment for carpal tunnel syndrome
Up to 1 in 3 people with carpal tunnel syndrome get better without any specific medical treatment. In people with an underlying cause (such as diabetes or an underactive thyroid gland), carpal tunnel syndrome may get better when the underlying cause is treated.
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.
- Corticosteroids. If initial treatments don’t control symptoms, your doctor may recommend corticosteroids to reduce inflammation in the carpal tunnel. Corticosteroids can be given as an injection directly into the wrist.
Surgery is often recommended if symptoms continue despite these treatments. Your doctor can refer you to a specialist hand surgeon.
A procedure called a carpal tunnel release (or surgical release) may be recommended to treat severe or ongoing carpal tunnel syndrome that is not responding to other treatments. During this procedure, the transverse carpal ligament (which forms the roof of the carpal tunnel) is cut. This makes more space in the carpal tunnel and releases the pressure on the median nerve.
The procedure can be done as an open procedure or endoscopically, where several smaller incisions are made and the procedure is done using an endoscope (instrument with a tiny camera on the end). There are risks and benefits associated with both types of procedure – your surgeon should discuss this with you beforehand.
Surgery is usually performed as a day procedure, so you don’t need an overnight stay in hospital. The procedure can be done under general anaesthetic or local anaesthetic with light sedation.
Many people get relief from their symptoms within a week of carpal tunnel surgery, but full recovery may take several months to a year. A specialist hand physiotherapist may recommend exercises to do to help restore your wrist strength after 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.