Carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a condition that causes pain, numbness and tingling in the fingers and hands. It is caused by compression of the median nerve in the wrist.

Causes

The median nerve sends nerve fibers to the palm side of the thumb, the index and middle fingers, as well as half of the ring finger.

CTS occurs because the median nerve is compressed in a narrow area at the base of the hand called the carpal tunnel. The carpal tunnel lies between the bones of the wrist (situated towards the back of the hand) and the transverse carpal ligament (which lies towards the palm).

As well as the median nerve, many of the tendons that help move the fingers also run through the carpal tunnel. Any swelling in this area can lead to compression of the median nerve, which can interfere with the normal transmission of signals along the nerve.

The carpal tunnel is formed by the transverse carpal ligament and bones of the wrist. 

Signs and symptoms

Symptoms of CTS include:

• Dull aching pain;
• Burning, tingling and numbness (sometimes called paresthesia), and;
• Weakness or difficulty using the hand, such as while holding, gripping or turning objects.

Symptoms mostly affect the thumb and the first three fingers, but can include the whole hand and spread up the forearm or past the elbow towards the shoulder. One or both hands can be affected.

Symptoms tend to:

• Be worse at night and may wake you up;
• Occur when you are doing activities that flex or extend the wrist (such as typing or writing), or raise the arms (such as driving), and;
• Be partially relieved by shaking or wringing your hands, or putting them under warm running water.

Methods for diagnosis

There is no one single test for CTS.

Physical examination

Your doctor will ask about your symptoms and may perform some physical tests to better gauge how extensive your symptoms are.

These tests are designed to see if symptoms occur when:

• The skin of your wrist (just above the site the median nerve passes) is tapped or pressed;
• You flex your wrists, or;
• You raise your arms.

It is important to note that not all people with CTS have symptoms when these tests are performed, so while they can be helpful in making a diagnosis, they do not always give a clear indication of whether you have the condition or not.

If it is not clear whether CTS is the cause of your symptoms, or it is suspected that you may have an underlying medical condition, further tests may be recommended.

These include:

Blood tests

Blood tests can help to identify conditions such as arthritis, diabetes and hypothyroidism that are associated with an increased risk of developing CTS.

Nerve conduction study

CTS can reduce the speed at which nerve signals travel along the median nerve. By placing electrodes on the wrist and hand, a nerve conduction study can measure this.

Electromyography

Electromyography (EMG) tests the function of the median nerve by inserting fine needles through the skin in order to measure electrical activity in the muscles of the hand.

Imaging studies

Imaging techniques such as X-ray, magnetic resonance imaging (MRI) and ultrasound may be recommended, but they are often not required for a diagnosis of CTS. They can sometimes help to identify underlying causes such as fractures and rheumatoid arthritis.

Types of treatment

Some mild cases of CTS may get better without treatment. If symptoms continue to get worse, seeking treatment can prevent irreversible damage to the median nerve that can occur with severe, long-standing CTS.

Rest

Taking steps to rest your affected hand and avoid activities that can make the CTS worse are an important part of dealing with CTS.

This can involve:

• Wearing a wrist splint that immobilizes your wrist;
• Taking care not to sleep on your wrist (wearing a wrist splint at night or hanging your arm out over the edge of the bed may help), and;
• Reviewing activities that may be causing symptoms and either avoiding them or finding new ways to do them.

An occupational therapist may be helpful in reviewing your activities either at home or in your workplace and suggesting ways you can adapt what you do, so that you have less pain and are less likely to further damage the nerve. They may also suggest products that can be helpful if you are having difficulty with some activities.

A wrist splint. 

Medications

• Non-steroidal anti-inflammatory drugs (NSAIDs), including ibuprofen, may be helpful for pain relief, and;
• Injections of corticosteroids into the carpal tunnel area can help to reduce inflammation and pain.

Surgery

In severe cases of CTS, where other treatments have not proven effective, carpal tunnel release surgery may be recommended.

In carpal tunnel release surgery, the transverse carpal ligament is cut in order to decrease pressure on the median nerve. Over time the ligament heals, but because this involves the formation of scar tissue, it will not be so tight and should increase the amount of room in the carpal tunnel.

Carpal tunnel release surgery:

• Can be performed as open or keyhole surgery;
• Is often a day procedure, not requiring an overnight stay in hospital, and;
• Is generally performed with a local anesthetic.

Depending on the type of surgery you have, whether or not the hand operated on is your dominant (or writing) hand, and the type of activities you do at work, it can take several weeks to recover and regain full use of your hand. Full healing of the area may take months and you may be directed to regularly perform some simple hand exercises to help promote recovery.

Surgery is often very successful, providing a permanent cure. However, if the median nerve has been compressed for a long time and is therefore more damaged, this may be less likely. Your doctor can discuss whether carpal tunnel release surgery may be suitable for you.

Potential complications

Untreated CTS

If CTS is not treated and continues to get worse, irreversible damage can occur to the median nerve. Over time this can lead to wastage of some of the muscles in the hand, resulting in reduced function of the hand.

Potential complications following surgery

Complications can occur following carpal tunnel release surgery and your doctor can discuss these with you.

Complications can include:

• Damage of the median or ulnar nerve;
• Infection;
• Damage to the surrounding blood vessels, leading to bleeding;
• Scarring;
• Failure to cut the transverse carpal ligament completely, so that CTS symptoms persist, and;
• New pain in the wrist that is different to the CTS symptoms.

In rare cases, CTS symptoms can come back years after surgery.

Prognosis

CTS symptoms often improve with rest and medication, but it is not uncommon to require surgery. Treatment of underlying medical conditions can help to reduce symptoms.

Surgery for CTS is often very successful.