What is 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.

Nerve

One or more fibres that transmit signals of sensation and motion between the brain or spinal cord and other parts of the body.

Causes

The median nerve sends nerve fibres 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.

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

Ligament

Short, flexible fibrous tissue that connects the bones and cartilage of joints.

Nerve

One or more fibres that transmit signals of sensation and motion between the brain or spinal cord and other parts of the body.

Tendons

Dense bands of connective tissue that attach muscles to bones.

Risk factors

People between 30-60 years of age are at greater risk of developing CTS. It is also more common in women.

In many cases, it is not clear why compression of the nerve occurs. However, there are several factors that can be associated with an increased risk of developing CTS:

  • A family history of CTS;
  • Some injuries to the hand;
  • Some repetitive hand activities (particularly those that require hard gripping and a lot of flexing of the wrist);
  • Frequently using vibrating tools; 
  • Pregnancy;
  • Menopause;
  • Some forms of arthritis (such as rheumatoid arthritis and gout);
  • Hypothyroidism;
  • Type 1 diabetes;
  • Type 2 diabetes;
  • Oedema (a build-up of fluid in the tissues);
  • Obesity (particularly with rapid weight gain), and;
  • Alcohol abuse.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

Nerve

One or more fibres that transmit signals of sensation and motion between the brain or spinal cord and other parts of the body.

Signs and symptoms 

Symptoms of CTS include:

  • Dull aching pain;
  • Burning, tingling and numbness (sometimes called paraesthesia), 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.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

Fractures

A complete or incomplete break in a bone.

Magnetic resonance imaging

A type of imaging that uses a magnetic field and low-energy radio waves, instead of X-rays, to obtain images of organs.

Nerve

One or more fibres that transmit signals of sensation and motion between the brain or spinal cord and other parts of the body.

Ultrasound

A scan that uses high-frequency soundwaves to produce images of the body’s internal structures.

X-ray

A scan that uses ionising radiation beams to create an image of the body’s internal structures.

Electrodes

A sensor that detects electrical currents.

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 immobilises 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 to help manage carpal tunnel syndrome.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 anaesthetic.

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.

Corticosteroids

A medication that resembles the cortisol hormone produced in the brain. It is used as an anti-inflammatory medication.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Ligament

Short, flexible fibrous tissue that connects the bones and cartilage of joints.

Local anaesthetic

A type of medication that, when administered to an area, creates a localised loss of sensation by blocking nerve activity.

Nerve

One or more fibres that transmit signals of sensation and motion between the brain or spinal cord and other parts of the body.

NSAIDs

Non-steroidal anti-inflammatory drugs are commonly used to manage arthritis-related pain and inflammation and other musculoskeletal disorders. NSAIDs include aspirin and ibuprofen.

Occupational therapist

A healthcare professional trained to deliver occupational therapy, which involves teaching a person self care, work and play activities to promote independence and reduce disability.

Keyhole surgery

A minimally invasive type of surgery that uses small incisions through which thin instruments and a slender camera are passed to view and perform surgery on internal tissues.

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.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Ligament

Short, flexible fibrous tissue that connects the bones and cartilage of joints.

Nerve

One or more fibres that transmit signals of sensation and motion between the brain or spinal cord and other parts of the body.

Ulnar nerve

The nerve that supplies nerve fibres to the some of the skin and muscles of the hand.

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.