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Median nerve compression

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Introduction


Carpal tunnel syndrome (CTS) is a relatively common condition that causes pain, numbness and a burning or tingling sensation in the hand and fingers. Symptoms of CTS can range from mild to severe.

The carpal tunnel

The carpal tunnel is a small tunnel that runs from the bottom of the wrist to the lower palm.

Several tendons that help to move the fingers pass through the carpal tunnel. So does the median nerve, which controls sensation and movement of your hand.

On the inner side of the wrist the carpal tunnel is enclosed within tissue called the transverse carpal ligament.

In cases of CTS, the space inside the tunnel is made smaller by the increased tissue pressure and a build-up of fluid in the tissue (oedema). This places pressure on the median nerve. The pressure is increased further when the wrist and fingers are bent (flexion). Compression of the median nerve causes the symptoms of pain and numbness.

See Carpal tunnel - Symptoms for more information.

How common is CTS?

CTS is more common in women than men. In the UK each year, around 60 to 120 women out of every 100,000 are affected by the condition compared with 35 to 60 men out of every 100,000.

The two most common age-ranges for developing CTS are between 50 to 54 and 75 to 84.

CTS is also a common condition during pregnancy, affecting up to 50% of pregnant women. It is thought that this may be due to the fluid retention that often occurs during pregnancy, which places additional pressure on the carpal tunnel and causes symptoms.

Outlook

The outlook for CTS depends on the severity of the symptoms. People with mild to moderate symptoms usually respond well to non-surgical treatments, such as wrist splints and corticosteroid injections. In more severe cases of CTS, surgery is usually required to reduce the pressure on the median nerve.

See Carpal tunnel syndrome - Treatment for more information about the treatment options for CTS.

Cases of CTS during pregnancy are usually less severe than those where the cause is unknown cause (idiopathic). It is less likely that CTS during pregnancy will require surgical treatment.

CTS in pregnant women often gets better with three months of the baby being born. However, in some women, symptoms can continue for over a year.

If CTS is recognised early it can usually be treated. However, if it is left untreated it can lead to chronic weakness of the hand, numbness and nerve damage.


Symptoms of carpal tunnel syndrome


Main symptoms

The main symptoms of carpal tunnel syndrome (CTS) affect the median nerve, which passes through the carpal tunnel in the wrist and controls the movement of the hand. The three main symptoms are:

  • tingling
  • numbness
  • pain

These symptoms occur in:

  • the thumb
  • the index finger
  • the middle finger
  • half of the ring finger

Other symptoms

Other possible symptoms of CTS include:

  • a dull ache and discomfort in the hand, forearm or upper arm
  • a burning, prickling sensation (paraesthesia) in the hand that is similar to pins and needles
  • dry skin, swelling or changes in the skin colour of the hand
  • becoming much less sensitive to touch (hypoaesthesia)
  • weakness in the thumb when trying to bend it at a right angle, away from the palm (abduction)
  • weakness and wasting away (atrophy) of the muscles in the thumb

The symptoms of CTS are often worse after using the affected hand. Any repetitive actions of the hand or wrist can aggravate the symptoms, as can keeping your arm or hand in the same position for a prolonged period of time. The symptoms of CTS can also be worse at night and may wake you up.

In more severe cases of CTS, you may experience pain that leads from your hand up to your forearm and elbow.

Using your hands

If you have CTS, your hand may become weak and you may find it difficult to grip certain objects. Your dexterity, which is the ability to use your hands effectively to carry out certain tasks, is often impaired by CTS. You may also find it difficult to use the affected fingers to carry out specific tasks, such as typing.

Numbness
Numbness refers to a lack of sensation in a part of the body.
Pain
Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged.

Causes of carpal tunnel syndrome


The symptoms of carpal tunnel syndrome (CTS) are caused by compression (squashing) of the median nerve at the wrist. The median nerve is responsible for two main functions:

  • relaying physical sensations - such as your sense of touch from your hand to your brain
  • relaying nerve signals - from your brain to your hand, allowing you to move your hand and fingers

The compression of the median nerve can disrupt the nerve signals, affecting your sense of touch and hand movements. The median nerve can become compressed if the tendons that run through the carpal tunnel are swollen and inflamed.

Risk factors

In most cases, it is not known what causes the median nerve to become swollen and inflamed. Cases of CTS where the cause is unknown are called idiopathic. Although the exact cause of CTS is often unknown, a number of risk factors for the condition have been identified. These include:

  • family history
  • certain health conditions
  • pregnancy
  • certain injuries
  • certain activities

These risk factors are outlined below.

Family history

Research has shown that there may be a genetic link to CTS. This means you may have an increased risk of developing CTS if other members of your family have the condition or have had it in the past.

About one in four people with CTS have a close relative, such as a parent, brother or sister, who also has the condition. It is not fully understood exactly how and why the condition is passed on through families.

Health conditions

Certain health conditions appear to increase your risk of developing CTS. These include:

  • type 1 diabetes and type 2 diabetes - a chronic (long-term) condition that is caused by having too much sugar (glucose) in the blood
  • rheumatoid arthritis - a condition where the joints become painful and inflamed as a result of the immune system attacking the body
  • gout - a common type of arthritis that causes pain and swelling in one or more joints
  • hypothyroidism - an underactive thyroid gland
  • obesity - particularly in young people
  • oedema - an excess build-up of fluid in the body's tissue

Less commonly, CTS occurs when a person has an abnormal wrist structure, such as an unusually narrow carpal tunnel, or as a result of cysts, growths or swellings in the tendons or blood vessels that pass through the carpal tunnel.

Pregnancy

CTS is common during pregnancy. This is due to fluid retention (oedema), where a build-up of fluid that often occurs in the hands and arms (as well as in the legs, ankles and feet) causes swelling in these areas. Oedema can occur during pregnancy, resulting in pressure being placed on the median nerve.

Injuries

CTS can sometimes occur following a hand injury. Injuries, such as sprains (a stretched, twisted or torn ligament), a fracture (a break or crack in the bone) and crush injuries (where an external force causes an injury to a body part) can cause swelling and place pressure on the median nerve.

These types of injuries can change the natural shape of the bones and ligaments in the hand, leading to increased pressure on the median nerve and the symptoms of CTS.

Certain activities

It has been suggested that certain activities that involve repeated flexion (bending) of the wrist may cause the median nerve to become inflamed and may therefore be a risk factor for CTS. Examples of activities that may lead to CTS include:

  • playing a musical instrument
  • assembly packing
  • using a computer keyboard
  • craftwork (making decorative items by hand)
  • work that involves manual labour 

However, further research into the link between work-related hand use and CTS is required to determine whether these types of activities are a definite cause of the condition.




Diagnosing carpal tunnel syndrome


Carpal tunnel syndrome (CTS) can usually be diagnosed by your GP who will examine your hand and wrist and ask you about your symptoms.

Your GP will assess your ability to use your hand, wrist or arm. They will look for signs of weakness in the muscles surrounding your thumb, as this can indicate CTS.

Physical tests

A physical test that may be used by your GP to help diagnose CTS involves tapping your wrist lightly to see whether it produces a tingling feeling or numbness in your affected hand.

Another test involves flexing your wrist for a minute to see if you feel pain, numbness or tingling in your hand.

If you do have these sensations, this may mean that your median nerve is being compressed (squashed) and is causing your symptoms.

Further testing

Further testing is usually only required if your GP is uncertain about the diagnosis and wants to rule out other conditions that have similar symptoms. Further tests that may be used are described below.

Blood tests

If your GP thinks that your CTS may be linked to an underlying condition, they may decide to carry out a blood test. There are a number of health conditions that increase the risk of developing CTS and your GP will want to find out if you have any of them, such as:

See Carpal tunnel syndrome - Causes for more information about these conditions.

Nerve conduction study

A nerve conduction study is a test that measures how fast signals are transmitted through your nerves. During the test, electrodes (small metallic discs) are placed on your hand and wrist. The electrodes produce a small electrical current that stimulates the nerves in the wrist, fingers and forearm.

The results from the test will be used to assess any possible damage to your nerves.

Electromyography

Electromyography involves inserting fine needles into your muscles. The needles detect any natural electrical activity that is given off by your muscles. You may be able to see the activity on a monitor (an oscilloscope) or hear it through a speaker.

Electromyography provides useful information about how well your muscles are able to respond when a nerve is stimulated and can indicate whether there is any nerve damage.

Electromyography and nerve conduction studies can help to establish how severely the median nerve is being compressed and the effect it is having on your symptoms.

X-ray

If your GP suspects that you may have an injury to your hand, such as a sprain or fracture, you will need to have an X ray. An X-ray is a procedure that uses radiation to produce images of the inside of your body.

Other procedures

To thoroughly examine the structure of the median nerve in your hand, your GP may also suggest that you have:

  • an ultrasound scan - this uses high-frequency sound waves to produce an image of the inside of your body
  • a magnetic resonance imaging (MRI) scan - this is a type of scan that uses strong magnetic fields and radio waves to produce a detailed image of the inside of your body
Thyroid gland
The thyroid gland in the throat makes hormones to help control growth and metabolism (the process that turns the food we eat into energy).

Treating carpal tunnel syndrome


Moving your hand or shaking your wrist can often help to relieve the symptoms of carpal tunnel syndrome (CTS). When sleeping, the symptoms can sometimes be improved by hanging the affected arm over the side of the bed.

If your CTS symptoms persist, a range of treatments are available, including surgical and non-surgical treatment options. The aim of treatment is to relieve the pressure on the median nerve so that your symptoms improve.

If your CTS symptoms are caused by an underlying health condition, such as rheumatoid arthritis, treating that should improve your symptoms of CTS.

Non-surgical treatments

In mild to moderate cases of carpal tunnel syndrome (CTS), non-surgical treatments such as wrist splints and corticosteroid injections are often recommended.

Wrist splints

A wrist splint is worn at night to support the wrist and keep it in the same position. The splint prevents the wrist from bending, which can place pressure on the median nerve and aggravate your symptoms.

You should begin to notice an improvement in your symptoms within eight weeks of wearing the wrist splint. Wrist splints are usually available from larger pharmacies or your GP may be able to recommend a suitable supplier.

Corticosteroids

Corticosteroids are a type of medication that contains steroids. Steroids are hormones, which are powerful chemicals that have a wide range of effects on the body, including helping to reduce inflammation.

Corticosteroids may be recommended to treat CTS if using a wrist splint does not ease your symptoms. The medication will help to relieve the pressure on your median nerve and reduce inflammation of the tendon.

Corticosteroids can be taken as tablets, although for CTS it is likely that you will have a corticosteroid injection directly into your wrist. One injection is usually recommended and it must only be given by a suitably trained healthcare professional, such as your GP or a hand surgeon.

In most cases, using a corticosteroid injection is an effective method of treating CTS. However, sometimes the symptoms of CTS may return, in which case surgery may be considered as a possible treatment option.

See the Health A-Z topic about corticosteroids for more information about this type of medication.

There is a lack of evidence to support the use of non-steroidal anti-inflammatory drugs (NSAIDs) for treating CTS and diuretics to help relieve fluid retention.

Surgery

Surgery is usually only recommended for severe cases of CTS when the symptoms last for more than six months or if other non-surgical treatment options have not been effective in relieving your symptoms.

Surgery for CTS is known as carpal tunnel decompression surgery. This type of surgery is performed on an outpatient basis, which means that you will not have to stay in hospital overnight.

It is performed using local anaesthetic so that your hand and wrist will be numb but you will remain awake throughout.

During surgery, the surgeon will open the roof of the carpal tunnel, known as the transverse carpal ligament, to release the ligament and reduce the pressure that is being placed on the median nerve in the wrist.

There are two ways that carpal tunnel surgery can be carried out. Surgery can either be:

  • open release surgery
  • endoscopic surgery

These two methods are described below.

Open release surgery

Open release surgery is the traditional type of surgery that is used to treat CTS. The surgeon will make an incision (cut) in the wrist and will then cut the carpal ligament. This will widen the carpal tunnel and relieve pressure on the median nerve that causes the symptoms of CTS.

Endoscopic surgery

Endoscopic surgery can be performed using two different techniques. The surgeon can either make one small incision (cut) at the wrist (one-portal endoscopic surgery) or two small incisions at the wrist and palm (two-portal endoscopic surgery).

An endoscope is a long, thin flexible tube that has a light and camera at one end. It is passed through the incision and allows the surgeon to see the carpal ligament on a monitor before they cut it to relieve the pressure on the median nerve.

Endoscopic surgery usually has a slightly faster recovery time than open surgery and may result in less scarring and tenderness. Apart from this, there is no real difference in terms of success between the two approaches.

Considerations

Your surgeon will be able to discuss the most appropriate method of surgery with you. Factors that may affect your decision to have surgery include:

  • possible complications after surgery (see below)
  • the recovery time following surgery
  • how successful non-surgical treatments have been

In most cases, surgery for CTS provides a complete and permanent cure. In a survey of 4,000 NHS patients who had surgery, 75% thought that the surgery had been completely successful. However, as with any form of surgery there is always a small risk of complications.

Reported complications of CTS include:

  • infection
  • failure during surgery to fully separate the roof of the carpal tunnel
  • bleeding after the operation
  • nerve injury
  • scarring
  • persistent wrist pain (failure to relieve CTS symptoms)
  • in rare cases, the return of CTS symptoms following surgery
  • complex regional pain syndrome - a rare, but chronic (long-term) condition that causes a burning pain in one of the limbs

After surgery

Following surgery for CTS, your hand will remain in a bandage for a couple of days and you may need to wear a sling.

Keep your hand raised for 48 hours following surgery to help reduce any swelling and stiffness in your fingers.

To help prevent stiffness, gently exercise your fingers, shoulder and elbow. You may be able to start these gentle exercises on the day of your operation.


Recovery after carpal tunnel surgery


After having surgery for carpal tunnel syndrome (CTS), you can use your hand to do light activities that do not cause excessive pain or discomfort.

However, try to avoid using your hand for more demanding activities until it has completely recovered, which may take several weeks. See the box to the left for more advice about recovering after surgery for CTS.

The recovery time for open release surgery is usually slightly longer than the recovery time for endoscopic surgery. Studies have also shown that there is less pain during the first three months after endoscopic surgery compared with open release surgery. However, both surgical methods have proven to be equally effective in treating CTS.

Open release surgery

Following open release surgery, your hand may take around six weeks to heal. Depending on the nature of your job, you should be able to return to work two to six weeks after your operation.

Endoscopic surgery

Returning to work after endoscopic surgery will depend on the nature of your job and which hand was operated on.

For example, if surgery was on your dominant hand and your work involves carrying out repetitive activities, it is likely that you will need about four weeks to recover from surgery.

If surgery was not on your dominant hand and your job does not involve repetitive activities that might affect your recovery, you may be able to return to work after one or two days.


Preventing carpal tunnel syndrome


Carpal tunnel syndrome (CTS) can be difficult to prevent because it often occurs following a wrist injury or a bone condition, such as rheumatoid arthritis.

Treating an underlying health condition that is causing CTS will help to relieve your symptoms and prevent them from recurring. For example, if you have rheumatoid arthritis, a rheumatologist (a specialist in conditions that affect the muscles and joints) may prescribe an anti-rheumatic medicine to slow down the condition's progress and prevent joint damage.

Self-care advice

If you have CTS, you should try to minimise any activities that aggravate your symptoms.

Even though there is no clinical evidence to suggest that working with computers causes CTS, it is still important to adopt good working practices. For example, when using a computer for prolonged periods, make sure that your workstation is set up correctly and that you maintain good posture. Take regular screen breaks and perform stretching exercises.

The Directgov website provides further information and advice about safe computer use at home and work.

If you are obese or overweight, adjusting your diet and losing a reasonable amount of weight will help to alleviate the symptoms of CTS and may help to prevent the condition occurring again.

See the Health A-Z topic about Obesity - Prevention for advice about how to loose weight if you are obese.

Glossary

Joint
Joints are the connection point between two bones that allow movement.

Carpal tunnel syndrome


Treatment Pros Cons
Wrist splints
These are usually worn at night to prevent the wrist from bending and putting pressure on the median nerve
  • Available over the counter
  • No serious adverse effects
  • Can be used alongside corticosteroid injections
  • May be too bulky for daytime use, interfering with work and leisure activities
  • Needs to be worn on a long-term basis to relieve symptoms
Corticosteroid injection
Steroid medication that is injected into the wrist. Reduces tendon inflammation and pressure on the median nerve
  • Injection may also relieve arthritis symptoms
  • Can be used alongside wrist splints to help relieve symptoms
  • One injection may not be enough to relieve symptoms permanently; further injections may be required, which is time-consuming
  • There may be some discomfort following the injection
  • Reoccurrence of symptoms is common
Open release surgery
An incision is made in the wrist to access the carpal ligament, which is cut to relieve pressure on the median nerve
  • No overnight hospital stay required
  • Effective in relieving symptoms
  • Small risk of complications developing after surgery
  • Longer recovery time than with keyhole surgery
  • More pain and discomfort afterwards compared with keyhole surgery
Keyhole surgery
Same operation as above, but does not involve opening up the wrist - the ligament is cut using an instrument that is inserted through a much smaller incision in the wrist
  • No overnight hospital stay required
  • Effective in relieving symptoms
  • A less intrusive procedure than open release surgery
  • Shorter recovery time than with open release surgery
  • Less pain during the first three months compared with open release surgery
  • Small risk of complications developing after surgery
  • Not all surgeons are experienced in this technique, so availability may be limited

'I knew something was wrong when I started waking up in the night with tingling in my fingers'


Peter Taylor, 58, a customer services adviser from Norwich, first noticed tingling in his fingers a couple of years ago. Since then he has had two carpel tunnel releases and his hands feel back to normal.

"I knew something was wrong when I started waking up in the night with tingling in my fingers. It was a weird feeling and my arm also used to go numb. I was a keen cricket player and started to find it difficult holding the bat. It was as though there was no power in my shots.

"I went to my GP who suspected carpel tunnel syndrome and referred me to my local hospital for tests.

"I was sent off for a test called a 'nerve conduction study' and the results showed carpel tunnel syndrome in both hands. My consultant suggested I have the carpel tunnel release operation, but one hand at a time. I had to wait for a couple of months for a date for my operation, and during that time I was given some injections to help to ease the discomfort.

"I had the right hand done first in October 2006, with open surgery under local anaesthetic. I went in as a day patient and all the staff were fantastic. They made jokes, helping to take my mind off what was going on. At one stage the surgeon said: 'Are you OK?' I replied yes and he said, 'That's good because I've just made a 5mm long hole in your hand!'

"My hand did feel sore for a few days after the operation, but the pain soon turned into a stinging feeling and after about a week it had passed. I was given some exercises to do and was soon wriggling my fingers again.

"I had the left hand done about four months later in March 2007 and again it went without a hitch. I could hardly move my left hand when I went in for the operation, but now I've almost got complete movement in it. I'm delighted and can't thank my consultant enough!"


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