Detail Article: What Is Carpal Tunnel Syndrome? What Causes Carpal Tunnel Syndrome?

Written by Stephanie Brunner (B.A.)

Carpal tunnel syndrome (CTS), also called median neuropathy at the wrist, is a medical condition in which the median nerve is compressed at the wrist. It is a relatively common condition that causes pain, numbness and a burning or stinging sensation in the hand and fingers. Symptoms of CTS can range from mild to severe.

According to the journal Plastic and reconstructive surgery (Volume 105(5)April 2000pp 1662-1665), approximately 1% of the US population and 5% of the US working population who must undergo repetitive use of their hands and wrists in daily living are affected by Carpal Tunnel Syndrome. Over 463,000 carpal surgery releases (surgeries) are performed annually in the United States, accounting for $1 billion in direct costs.

According to Medilexicon’s medical dictionary:

    Carpal tunnel syndrome is “the most common nerve entrapment syndrome, characterized by paresthesias, typically nocturnal, and sometimes sensory loss and wasting in the median nerve distribution in the hand; often bilateral and affects women more than men; due to chronic entrapment of the median nerve at the wrist within the carpal tunnel.”

The carpal tunnel

The carpal tunnel is a small tunnel bound by bones and ligaments that runs from the bottom of the wrist to the lower palm. This tunnel protects a main nerve to the hand and tendons that bend the fingers. Several tendons that help to move the fingers pass through the carpal tunnel. The median nerve also passes through the tunnel, which controls sensation and movement of the hand.

In cases of carpal tunnel syndrome (CTS), the space inside the tunnel shrinks, placing pressure on the median nerve. Pressure placed on the nerve produces the numbness, pain and, eventually, hand weakness that characterize carpal tunnel syndrome.

The condition was first noted in medical literature in the early 20th century, but the first use of the term “carpal tunnel syndrome” was in 1939.

While it might seem that carpal tunnel syndrome is a condition caused by long hours spent working on a computer keyboard, carpal tunnel syndrome actually has numerous causes.

Fortunately, proper treatment can usually relieve the pain and numbness and restore normal use of wrists and hands.

How common is CTS?

Carpal tunnel syndrome is one of the most common conditions affecting the nerves of the hand. Most cases develop in people who are between 45 and 64 years of age.

CTS is also common in pregnant women. This may be due to the fluid retention that typically occurs during pregnancy, placing additional pressure on the carpal tunnel.

Outlook

People with mild to moderate symptoms usually respond well to non-surgical treatment, such as wrist splints and corticosteroids injections. However, more severe cases usually require surgery to reduce the pressure on the median nerve.

Cases of CTS that occur during pregnancy usually resolve after the birth.

If left untreated, CTS may lead to permanent nerve damage.

What are the signs and symptoms of carpal tunnel syndrome?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom, while dilated pupils may be a sign.

Typically, carpal tunnel syndrome starts gradually with a vague aching in the wrist that can extend to the hand or forearm. Many people who have carpal tunnel syndrome have gradually increasing symptoms over time. The first symptoms of CTS may appear when sleeping, and typically include numbness and paresthesia (a burning and tingling sensation) in the thumb, index, and middle fingers. Other common carpal tunnel syndrome symptoms include:

  • Tingling or numbness in the fingers or hand, especially the thumb and index, middle or ring fingers. The little finger is not affected. Many people shake their hands to try to relieve their symptoms. As the disorder progresses, the numb feeling may become constant.
  • Pain radiating or extending from the wrist up the arm to the shoulder or down into the palm or fingers. The pain is present especially after forceful or repetitive use. This usually occurs on the palm side of the forearm.
  • A sense of weakness in the hands and a tendency to drop objects.

The symptoms of CTS are often worse at night and may disrupt sleep.

Dexterity problems

People who have CTS may find that their hands become weak and clumsy. They also might find it is difficult to grip objects with the thumb.

Similarly, there may be problems when using the affected fingers to carry out tasks that require high levels of manual dexterity, such as typing.

Keeping the hand or wrist in one position or carrying out repetitive tasks, can make the symptoms of CTS worse. However, moving the hand or shaking the wrist can often help to relieve the symptoms.

What are the causes of carpal tunnel syndrome?

The cause of carpal tunnel syndrome is pressure on the median nerve. The median nerve has a sensory function and also provides nerve signals to move the muscles (motor function). The median nerve provides sensation to the thumb, index finger, middle finger and the middle-finger side of the ring finger. The compression of the median nerve can disrupt these nerve signals, which means that both the sense of touch and the ability to move the hand can be affected.

Compression of the median nerve can occur when the tendons that run through the carpal tunnel become inflamed and swollen.

Possible causes include:

  • Other health conditions. Such as rheumatoid arthritis, certain hormonal disorders (diabetes, thyroid disorders and menopause), fluid retention due to pregnancy, or deposits of amyloid (an abnormal protein produced by cells in the bone marrow).
  • Repetitive use or injury. Repetitive flexing and extending of the tendons in the hands and wrists. This is particularly the case when done forcefully and for prolonged periods without rest. This can increase pressure within the carpal tunnel. Injury to the wrist can cause swelling that exerts pressure on the median nerve.
  • Physical characteristics. In some people, the carpal tunnel is more narrow than average.

What are the risk factors of carpal tunnel syndrome?

A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.

The exact reason why changes to the structure of the carpal tunnel occur in some people is unclear. Some research indicates that carpal tunnel syndrome can result from overuse or strain in certain job tasks that require a combination of repetitive, forceful, and awkward or stressed motions of the hands and wrists. Examples of these include:

  • Using power tools (such as chippers, grinders, chain saws or jackhammers)
  • Heavy assembly line work (such as in a meatpacking plant)

Repetitive computer use is commonly assumed to cause carpal tunnel syndrome. However, the scientific evidence for this association is not definitive.

It is not clear which activities can cause carpal tunnel syndrome. If work or hobbies are hand-intensive (involving a combination of awkward, repetitive wrist or finger motions, forceful pinching or gripping, and working with vibrating tools) there may be at higher risk of developing the condition.

Other risk factors include:

  • Certain health conditions. Conditions including thyroid problems, diabetes, obesity, rheumatoid arthritis, damage or fracture to the wrist, edema (excess fluid in the body’s tissue),heart failure, and Lyme disease (a bacterial infection that is caused by ticks), gout, lupus (a condition where the immune system attacks healthy tissue), under-active thyroid gland (hypothyroidism), can increase the risk. People with end-stage kidney disease also are more likely to develop carpal tunnel syndrome.
  • Gender. Women are three times as likely as men are to develop carpal tunnel syndrome.
  • Heredity. Individuals who have a close relative with carpal tunnel syndrome have a significantly higher risk of developing it themselves, compared to others. Some people are predisposed because of inherited physical characteristics, such as the shape of the wrist.
  • Hormonal changes. Women who are pregnant, taking oral contraceptives or going through menopause also are at increased risk, most likely due to hormonal changes. Fluid retention may be a cause of carpal tunnel syndrome during pregnancy. Fortunately, carpal tunnel syndrome related to pregnancy almost always improves after childbirth.

How is carpal tunnel syndrome diagnosed?

Carpal tunnel syndrome (CTS) can usually be diagnosed during a medical examination. The hand and wrist are checked, and symptoms are reviewed. A clue is the timing of the symptoms. Typical times when symptoms due to carpal tunnel syndrome might be experienced include while holding a phone or a newspaper, gripping a steering wheel, or waking up during the night. Physical tests

  • A common test that is used to help diagnose CTS involves tapping the wrist lightly to see if it produces a tingling feeling or numbness in the affected hand.
  • Another test involves flexing the wrist for 60 seconds to see if this produces pain, numbness or tingling in the affected hand.

A positive result for both tests would usually indicate that the median nerve is being compressed.

Additional testing

Further testing is usually only required if there is uncertainty about the diagnosis. It can be carried out in order to rule out other conditions with similar symptoms, such as cervical neuropathy (a condition where a nerve ending gets pinched or trapped by the spine).

  • Electromyography – uses electrodes to measure the electrical activity of the muscles. A thin-needle electrode is inserted into the muscles. An instrument records the electrical activity in the muscle at rest and as the muscle contracts. This test can be used to see if any muscle damage has occurred.
  • Nerve conduction study – a test that is similar to electromyography, except the electrodes are used to study how signals are transmitted through the nerves. Two electrodes are taped to the skin. A small shock is passed through the median nerve to see if electrical impulses are slowed in the carpal tunnel. A slowing of the signals can suggest nerve compression or damage.

Imaging tests, such as MRI or X-ray, generally are not used to diagnose carpal tunnel syndrome.

Patients may be referred to a rheumatologist, neurologist, hand surgeon or neurosurgeon if the signs or symptoms indicate other medical disorders or a need for specialized treatment.

What are the treatment options for carpal tunnel syndrome?

In cases of mild symptoms of carpal tunnel syndrome, the discomfort can be eased by taking more-frequent breaks to rest hands and applying cold packs to reduce occasional swelling. If these techniques do not offer relief, carpal tunnel syndrome treatment options include:

Nonsurgical therapy

In mild to moderate cases of carpal tunnel syndrome (CTS), the symptoms should pass within six months without the need for surgical treatment or the use of medication. This is particularly likely in people who are under 30 years of age, and in pregnant women. Most people with carpal tunnel syndrome experience effective treatment with nonsurgical methods, including:

  • Wrist splinting. A splint that holds the wrist still while sleeping can help relieve nighttime symptoms of tingling and numbness. However, it may take up to eight weeks for the patient to fully appreciate the benefits. Wrist splints are usually available from the larger pharmacies. Splinting and other conservative treatments are more likely to help only mild to moderate symptoms that have been experienced for less than 10 months. It is recommended to minimize any activities that make symptoms worse.

    There is little evidence that ergonomic devices that are designed to be used when working with a keyboard, such as a wrist rest, are effective in treating the symptoms of CTS. This does not mean they do not work, but rather that further large-scale studies are needed.

  • Nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs may help relieve pain from carpal tunnel syndrome if there is an associated inflammatory condition.
  • Corticosteroids. If symptoms of CTS do not improve after three months, or if they get worse, additional treatment with corticosteroids may be required.

    Injecting the carpal tunnel with a corticosteroid may be recommended, with cortisone, to relieve pain. Corticosteroids decrease inflammation, which relieves pressure on the median nerve. Oral corticosteroids are not as effective as corticosteroid injections for treating carpal tunnel syndrome. One injection of corticosteroids usually provides significant relief from the symptoms of CTS.

If carpal tunnel syndrome results from an inflammatory arthritis, such as rheumatoid arthritis, then treating the underlying condition generally also reduces the carpal tunnel syndrome symptoms.

Surgery

Usually nonsurgical treatments are effective if there is only mild nerve impairment. When the pain or numbness of carpal tunnel syndrome persists more than six months, surgery may be the best option. Surgery is usually only recommended for severe cases of CTS, or if all other treatment options have failed.

During surgery, the surgeon will cut some of the ligament that surrounds the carpal tunnel in order to reduce the pressure on the nerve. There are two ways this can be done:

  • open surgery: the surgeon cuts through the wrist to release the nerve.
  • endoscopic surgery: the surgeon makes a smaller incision in the palm, and uses a machine called an endoscope to release the nerve.

Endoscopic surgery tends to have a slightly faster recovery time. Both approaches are generally successful. Soreness or weakness may take from several weeks to as long as a few months to resolve.

In most cases of CTS, surgery can provide a complete and lasting cure. However, as with any form of surgery, there is always a small risk of complications. Reported complications include:

  • infection
  • nerve injury
  • persistent wrist pain
  • post-operative bleeding
  • the return of CTS symptoms

After surgery:

  • Bend and extend fingers at regular intervals.
  • Do not lift heavy objects until wound has healed.
  • Start driving when feeling confident enough to safely control the car.
  • Go back to work within two or three days of the operation if it is possible to work with one hand, or wait up to six weeks if job is manual.
  • Wait six weeks before playing sports like tennis. It is possible to start swimming as soon as stitches have been removed.

Lifestyle and home remedies

  • To relieve symptoms temporarily: Quick breaks, stretching, taking aspirin or other over-the-counter NSAIDs such as ibuprofen (Advil, Motrin, others) and naproxen (Aleve, others).
  • Wear a wrist splint at night: Wearing a wrist splint at night and avoiding sleeping on hands to help ease the pain or numbness in wrists and hands. The splint should be snug but not tight. Seek medical advice if pain, numbness or weakness recurs and persists.

Alternative therapies

When an alternative therapy is said to offer little evidence that it works, this does not mean it does not work. It simply means further large-scale studies are required (it might work, or it might not work).

  • Yoga and other relaxation techniques: They may help with chronic pain that occurs with some muscle and joint conditions. Yoga postures designed for strengthening, stretching and balancing each joint in the upper body, as well as the upper body itself, may help reduce the pain and improve the grip strength of people with carpal tunnel syndrome.
  • Physical therapy (UK: physiotherapy): It offers several ways to treat and control carpal tunnel syndrome. It may include soft tissue massage, conservative stretches and exercises and techniques to directly mobilize the nerve tissue. It can also include the immobilizing braces.
  • Acupuncture and chiropractic therapy: Although some people use acupuncture or chiropractic therapy to treat carpal tunnel syndrome, these techniques have not been proved in clinical trials.
  • Vitamin supplements: Supplements of vitamin B-6 may be helpful for relieving the symptoms of carpal tunnel syndrome.
  • Ultrasound and electric stimulation and others: Ultrasound treatments also may be used, but have had variable results in studies. Electrical stimulation, magnet therapy and laser treatments have not provided the same benefits in controlled trials.

Always check with your doctor before trying any complementary or alternative treatment.

Coping and support

  • People who experience chronic pain or cannot use their hands as before may become depressed or experience low self-esteem.
  • In addition, if hand symptoms are caused or worsened by current professional or leisure activities, they may face the difficult decision of switching careers or giving up hobbies. People who have carpal tunnel syndrome may also feel that they are not actively contributing to their family if they cannot drive a car or perform ordinary household tasks.
  • Support groups for people with carpal tunnel syndrome can help find out more information about the condition. They offer advice and comfort from those who have lived with carpal tunnel syndrome.
  • Stress management and relaxation techniques also may help to deal with the psychological and emotional issues that may accompany carpal tunnel syndrome.

Prevention

There are no established strategies to prevent carpal tunnel syndrome. But the following precautions may be helpful:

  • Reduce force and relax grip. Most people use more force than needed to perform many tasks involving their hands. For instance, when tipping, hit the keys softly. For prolonged handwriting, use a big pen with an oversized, soft grip adapter and free-flowing ink. Avoid gripping the pen tightly or pressing as hard on the paper.
  • Take frequent breaks. Give hands and wrists a break by gently stretching and bending them periodically. Alternate tasks when possible. If using equipment that vibrates or that requires exerting a great amount of force, taking breaks is even more important.
  • Watch position. Avoid bending wrist all the way up or down. A relaxed middle position is best. When using a keyboard, keep it at elbow height or slightly lower.
  • Improve posture. Make sure workstation is set up correctly and you maintain good posture. Incorrect posture can cause shoulders to roll forward. When the shoulders are in this position, the neck and shoulder muscles are shortened, compressing nerves in the neck. This can affect the wrists, fingers and hands.
  • Keep hands warm. It is more likely to develop hand pain and stiffness if working in a cold environment. If the temperature at work cannot be controlled, put on fingerless gloves that keep hands and wrists warm.
  • Treating health conditions. Carpal tunnel syndrome (CTS) can be difficult to prevent because it often occurs following a wrist injury or bone condition, such as rheumatoid arthritis. If you have rheumatoid arthritis, receiving treatment for the condition will help. A specialist rheumatologist may prescribe an anti-rheumatic medicine to slow down the disease and prevent joint damage.
  • Working with computers. Even though there has not been any clinical evidence to suggest that working with computers causes CTS, it is important to adopt good working practices. Set up workstation correctly and take breaks.
  • Adjust diet if overweight. If you are overweight, adjusting diet and losing a reasonable amount of weight will help to alleviate the symptoms of CTS and prevent the condition from occurring in future.

Source: Medical News Today

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About Ahmad Ladhani

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