Median nerve compression
Carpal tunnel syndrome (CTS) is a relatively common condition that causes a tingling sensation, numbness and sometimes pain in the hand and fingers.
Usually, these sensations develop gradually and start off being worse during the night. They tend to affect the thumb, index finger and middle finger.
Other symptoms of carpal tunnel syndrome include:
- pins and needles (paraesthesia)
- thumb weakness
- a dull ache in the hand or arm
Read more about the symptoms of carpal tunnel syndrome (CTS).
What causes carpal tunnel syndrome?
Carpal tunnel syndrome is caused by compression of one of the nerves that controls sensation and movement in the hands (median nerve).
The carpal tunnel is a narrow passage in your wrist made up of small bones and a tough band of tissue that acts as a pulley for the tendons that bend the fingers.
It isn’t known why the median nerve becomes compressed in most cases, although certain things are thought to increase the risk of CTS developing, such as:
- a family history of CTS
- pregnancy – up to about 50% of pregnant women develop CTS
- injuries to the wrist
- other health conditions, such as diabetes and rheumatoid arthritis
- strenuous, repetitive work with the hand
Read more about the causes of carpal tunnel syndrome.
Treating carpal tunnel syndrome
In some cases CTS will disappear without treatment, or simple self-care measures will reduce the symptoms.
CTS in pregnant women often gets better within three months of the baby being born, although it may need treatment. In some women, symptoms can continue for more than a year.
Non-surgical treatments, such as wrist splints and corticosteroid injections, are used to treat mild or moderate symptoms.
Surgery may be required if non-surgical treatments fails to relieve the symptoms. It may also be used if there is a risk of permanent nerve damage.
Read more about treating carpal tunnel syndrome.
Surgery relieves the symptoms of mild CTS immediately. But in those with severe nerve damage, it can take a while to recover or there may not be any improvement.
Depending on which hand was operated on and what your job involves, you will usually be able to return to work within a few weeks of surgery.
Symptoms of carpal tunnel syndrome
The main symptoms of carpal tunnel syndrome (CTS) arise from irritation to the median nerve.
The median nerve passes through the carpal tunnel in the wrist and controls some of the movements of the thumb, as well as sensation in the thumb and the next two-and-a-half fingers.
The symptoms of CTS tend to develop gradually and usually start off being worse at night or early in the morning.
The three main symptoms are:
These symptoms occur in:
- the thumb
- the index finger
- the middle finger
- half of the ring finger
However, the tingling, numbness and pain can sometimes extend outside this area.
These symptoms can be present in one or both hands, although most cases affect both hands eventually.
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 similar to pins and needles
- dry skin, swelling or changes in the skin colour of the hand
- becoming less sensitive to touch (hypoaesthesia)
- weakness and wasting away (atrophy) of the muscles at the base of 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.
In some cases of CTS, you may experience pain that leads from your hand up to your forearm and elbow.
Using your hands
People with CTS often complain of dropping objects a lot.
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 or fastening buttons.
If you have hand symptoms and want to know if they might be due to CTS, you can complete an online questionnaire about your symptoms which will tell you how likely it is that CTS is the explanation.
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, controlling movement
Any pressure on the median nerve can disrupt the nerve signals, affecting your sense of touch and hand movements. The median nerve can become compressed if the tissues inside the tunnel become swollen or the tunnel narrows over time.
In most cases, it is not known what causes the median nerve to become compressed, although a number of things increase the risk of developing CTS. These include:
- family history
- certain health conditions, such as diabetes, an underactive thyroid gland or rheumatoid arthritis
- certain injuries to the wrist
- certain activities
These risk factors are outlined below.
Research has shown that there is 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 how and why the condition is passed on through families.
Certain health conditions appear to increase your risk of developing CTS. These include:
- diabetes – a chronic (long-term) condition caused by having too much sugar (glucose) in the blood
- any kind of arthritis – a condition where the joints become painful and inflamed as a result of the immune system attacking the body
- hypothyroidism – an underactive thyroid gland
- obesity in young people
- some drugs used to treat breast cancer, such as exemestane
Less commonly, CTS develops 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.
It is not clear exactly why, but CTS is common during pregnancy. However, many cases resolve after the baby is born. It is not known whether women who have carpal tunnel syndrome during pregnancy are at greater risk of developing the condition in later life.
CTS is also common in women around the time of the menopause.
These types of injuries can also change the natural shape of the bones and ligaments in the hand, leading to increased pressure on the median nerve.
Certain activities may trigger the development of carpal tunnel syndrome. These tend to involve strenuous grip, repetitive wrist flexion (bending) and exposure to vibration. Examples include:
- playing a musical instrument
- assembly packing
- work that involves manual labour
- work with vibrating tools, such as chainsaws
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.
Although much attention is paid to typing as a possible cause of carpal tunnel syndrome, the condition is in fact less common in individuals who type all day than those who carry out more strenuous activities.
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 and look for signs of weakness in the muscles surrounding your thumb.
Your doctor may tap your wrist lightly to see if you feel tingling or numbness in your fingers, although this test is not reliable.
Flexing your wrist or holding it elevated above the head for a minute are other commonly performed simple tests for CTS, and should induce the same pain, numbness or tingling in your hand if you have the condition.
Any of these sensations may be the result of your median nerve being compressed. These tests are often enough to diagnose CTS if you have typical symptoms.
Further testing is usually only required if your GP is uncertain and wants to rule out other conditions that have similar symptoms. Further tests include:
A blood test can be used if the doctor suspects an underlying condition relating to CTS, such as:
Nerve conduction study
A nerve conduction study is a test that measures how fast signals are transmitted through your nerves. During the test, electrodes are placed on your hand and wrist and a small electrical current is used to stimulate the nerves in the finger, wrist and, sometimes, elbow.
The results from the test indicate how much damage there is to your nerves.
Electromyography (EMG) provides useful information about how well your muscles are able to respond when a nerve is stimulated, indicating any nerve damage.
During the test, fine needles are inserted into your muscles. The needles detect any natural electrical activity given off by your muscles.
However, electromyography is rarely used for carpal tunnel syndrome in the UK because nerve conduction studies are usually able to confirm the diagnosis and measure the degree of damage to the nerve.
An X-ray may be recommended, but usually only to aid in the diagnosis of fractures and other disorders such as rheumatoid arthritis. An X-ray is a procedure that produces images of the inside of your body.
To thoroughly examine the structure of the median nerve in your hand, your GP may also suggest you have an ultrasound scan, which uses high-frequency sound waves to produce an image of the inside of your body.
Treating carpal tunnel syndrome
Treatment for carpal tunnel syndrome (CTS) depends on the severity of the condition and how long you have had it.
In some cases, CTS will improve after a few months without treatment. Moving your hand or shaking your wrist can often help relieve the symptoms.
You should try avoid any activites that make your symptoms worse.
If you work with computer keyboards, there is little evidence that modifications at your workplace are likely to be of any help in relieving your symptoms.
If symptoms persist, there are a range of non-surgical and surgical treatments available that aim to relieve the pressure on the median nerve.
If your CTS is caused by an underlying health condition such as rheumatoid arthritis, treating the condition should improve your symptoms.
Read on to learn about the different treatments you may be offered. You can also see a summary of the pros and cons of these treatments, which allows you to easily compare your options.
Unless there is thought to be an immediate need for surgery, treatments such as wrist splints and corticosteroid injections are often recommended initially.
There is a lack of evidence to support the use of non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen for treating CTS, or for diuretics to help relieve fluid retention.
A wrist splint is worn to support the wrist and keep it in a neutral position. It should not apply direct pressure over the carpal tunnel.
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 four 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. They can also be ordered online.
Corticosteroids are a type of steroid medication. Steroids are hormones that are naturally produced in the body. They are powerful chemicals that can help reduce inflammation.
If a wrist splint does not work, corticosteroids may be recommended.
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 to begin with. If the condition responds well to one injection but then recurs, the treatment may be repeated.
Carpal tunnel release surgery
Surgery is usually recommended for cases of CTS, when other treatments have failed to relieve symptoms.
Surgery for CTS is known as carpal tunnel decompression or carpal tunnel release surgery and is performed on an outpatient basis, which means you will not have to stay in hospital overnight.
During surgery the roof of the carpal tunnel, known as the carpal ligament, is cut to reduce pressure on the median nerve in the wrist.
A local anaesthetic is used to numb your hand and wrist, but you will remain awake throughout the operation.
The surgery can be performed as open surgery, which involves making a single cut in the wrist, and is the traditional type of operation.
Some surgeons use keyhole surgery, where special instruments and a long tube with a light at one end and an eyepiece at the other are inserted through small cuts in your wrist, and sometimes your palm. This allows the surgeon to see the carpal ligament on a monitor throughout the operation.
There are no long-term differences in the outcomes of the two approaches.
Your surgeon will be able to discuss the most appropriate method of surgery with you.
Things to consider
A number of things may affect your decision to have surgery. These include:
- possible complications after surgery (see below)
- the recovery time
- how successful non-surgical treatments have been
In most cases, carpal tunnel release surgery provides a complete and permanent cure. However, as with any form of surgery there is always a small risk of complications.
Reported complications of CTS include:
- failure during surgery to fully separate the roof of the carpal tunnel, usually resulting in persistent CTS symptoms
- bleeding after the operation
- nerve injury
- persistent wrist pain, which may be different to the original symptoms
- in rare cases, the return of CTS symptoms long after apparently successful surgery
- complex regional pain syndrome – a rare but chronic (long-term) condition that causes a burning pain in one of the limbs
Following carpal tunnel release surgery, your hand will remain in a bandage for a couple of days and you may need to wear a sling. You should keep your hand raised for 48 hours 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.
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. Try to avoid using your hand for more demanding activities until it has completely recovered, which may take several weeks.
The recovery time for open release surgery is usually slightly longer than the recovery time for keyhole surgery. Studies have also shown that there is less pain during the first three months after keyhole surgery compared with open release surgery. However, both methods have proven to be equally effective in treating CTS.
‘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 carpal 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 carpal 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 carpal tunnel syndrome in both hands. My consultant suggested I have the carpal 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 ease the discomfort.
“I had the right hand done first 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 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!”