Carpal tunnel syndrome Diagnosis

  • Diagnosis

    Carpal tunnel syndrome is a painful condition caused by pressure on the nerve that serves the fingers and palm. Figure 01. The carpal tunnel is a passage in each wrist that is formed by the carpal bones and the volar carpal ligament. Carpal tunnel syndrome occurs when the median nerve, which travels from the arm to the fingers, becomes compressed within the carpal tunnel. Although the tunnel usually protects the median nerve, tissues within the tunnel can become inflamed or swollen. This inflammation results in pressure on the nerve.

    Click to enlarge: Carpal tunnel syndrome (animation)

    Figure 01. Carpal tunnel syndrome (animation)

    Carpal tunnel syndrome is usually characterized by pain or tingling. Other symptoms may include numbness or weakness in your hands that may cause you to drop objects. If this weakness continues for long periods or time, it may result in permanently atrophied muscles. Some people with carpal tunnel syndrome experience intense pain that shoots up the arm to the shoulder.

    Although some medical conditions such as diabetes can increase a person’s risk for carpal tunnel syndrome, most cases are caused by repetitive motions of the hands or wrists. Carpal tunnel syndrome is most common in middle-aged people, but is rare in young people who have not yet had long-term exposure to the repetitive motions that most often cause the condition.

    Only approximately 1% of people with carpal tunnel syndrome are injured permanently. Most patients respond well to treatment. Also, many patients who are successfully treated can avoid recurrences by changing or avoiding the action or actions that led to the condition.

    Treatment varies from wearing a brace to drug therapy or surgery. Mild carpal tunnel syndrome may be effectively treated with a brace, which is usually worn overnight. This gives the wrist a chance to rest so that the swollen tissues inside the carpal tunnel can shrink, reducing pressure on the median nerve. As symptoms become more severe, drugs or surgery may be recommended.

    Although carpal tunnel syndrome can be caused by several medical conditions, the most common cause is overuse of the wrists due to repetitive tasks. Any condition that causes the tissues within the carpal tunnel to swell can lead to carpal tunnel syndrome. Some examples are broken or dislocated wrist bones, arthritis, thyroid imbalance, diabetes, menopausal hormone changes, and pregnancy. However, the most frequent cause is repetitive tasks that require bending of the wrists or grasping with the hands. Tasks that carry a recognized risk for carpal tunnel syndrome include typing, cutting, sewing, or playing a musical instrument. Overuse of small hand tools is often associated with this condition. Use of vibrating tools, such as a jackhammer, is also considered to be a contributor.

    Tingling in the hands is an early sign of carpal tunnel syndrome. The tingling may be followed by a feeling of weakness or numbness in the hands and intense shooting pain that travels up the arm. The symptoms of carpal tunnel syndrome often first appear at night and may be pronounced enough to cause sleeplessness. One or both hands may tingle painfully. This tingling may become more frequent and often involves the thumb, index, and ring fingers.

    Hand strength and dexterity are often affected. Your fingers may feel swollen or useless, making you clumsy when performing simple tasks.You may experience weakness in your hands and be unable to firmly grip an object or make a fist.

    In some cases, patients may have trouble using touch to distinguish between hot and cold.

    Certain medical conditions can put you at risk for carpal tunnel syndrome. Physical conditions that cause the tissues in the carpal tunnel to swell may make you susceptible to carpal tunnel syndrome. Such conditions include trauma to the wrist, pregnancy, arthritis, a cyst in the area of the wrist, thyroid disease, amyloidosis (a rare condition in which protein deposits accumulate in specific areas of the body), and acromegaly (a disorder in which the production of excessive growth hormone causes parts of the body, especially the hands and feet, to become enlarged).

    People whose jobs require repetitive hand motion are most at risk Table 01. Any task that overuses the hands and wrists can cause carpal tunnel syndrome. Some high-risk repetitive tasks include typing, playing a musical instrument, using scissors, and working with garden tools.

    Table 1.  Occupations Associated With Carpal Tunnel Syndrome

    Assembly line workers
    Butchers
    Cashiers
    Musicians
    Postal workers
    Secretaries
    Sign language interpreters/instructors
    Typists
    Upholsterers
    Waitresses

    Your physician will ask you to describe your symptoms, and will try to determine their cause.

    If your physician cannot find an obvious cause of the pain, such as wrist trauma, he may perform one of three simple tests to determine the likelihood of carpal tunnel syndrome. For the first test, known as Tinel's sign, your doctor will thump your wrist just below the palm of your hand, where your median nerve is located. Carpal tunnel syndrome is a likely diagnosis if this causes or intensifies tingling, tickling, pricking, or burning sensations in your hand or wrist.

    For the second test, Phalen's sign, your doctor will instruct you to flex your wrists, palms down, and press the backs of your wrists together. If holding this position for about a minute causes or intensifies tingling, tickling, pricking, or burning sensations, you may have carpal tunnel syndrome.

    For the third test, your doctor may ask you to elevate your hand for two minutes to see whether this reproduces your symptoms.

    To refine the diagnosis and help develop a treatment plan, your doctor may suggest other tests. Electromyography (EMG) is a test that measures electrical activity of muscles using either surface electrodes or thin needles inserted into the muscles. Before undergoing EMG, tell the doctor if you have a pacemaker, if you are taking any medications that may thin the blood, or if you have hemophilia. Another test, called nerve conduction, uses small electrical shocks to find out how the nerves are working. You may experience a tingling sensation during the test. In some instances, a magnetic resonance image (MRI) of the hand may be included. An MRI is a sophisticated type of x-ray that uses magnetic energy and radio waves to create cross-sectional images or “slices” of the human body.

    Because carpal tunnel syndrome is sometimes related to other disorders, such as diabetes or amyloidosis, your doctor may evaluate you for an underlying medical condition.

    Carpal tunnel syndrome can be prevented, but at-risk people and their employers must take precautions. Because carpal tunnel syndrome is so frequently job-related, both employees and employers should be concerned about prevention. Motions required in many jobs, such as typing, working on an assembly line, and playing an instrument, are often the cause.

    People at risk for carpal tunnel syndrome should ask their employers for equipment that is designed to reduce stress on their arms and wrists. Ideally, equipment should be selected, or in some cases modified, to reduce the kinds of motions that lead to carpal tunnel syndrome. Tools and their handles can be designed or modified so that the wrist is not required to bend or twist into awkward positions, and computer keyboards should be lowered so that they are positioned just slightly above your legs. Also, use a computer keyboard especially designed to minimize repetitive stress.

    Rest frequently and stretch to ease strain on your arms and wrists, and try to avoid long periods of uninterrupted repetitive movement. Rotate jobs with another employee so that you can take a longer break from a repetitive task. If you work on an assembly line, ask your employer to vary your tasks over the course of the workday. Make sure you are working in a comfortable position. Your wrists should not be bent any more than they would be to hold a pencil for writing, and your elbows should be bent to a 90-degree angle. You should adjust your chair to a height that is comfortable for you.

    Do a five-minute warm-up before you start a repetitive task Figure 02. The American Academy of Orthopaedic Surgeons (www.aaos.org) recommends the following:

    1. Hold your arms straight out in front of you. Extend your hands, fingers pointing up, in the “stop” position. Hold for a count of five.

    2. Straighten your wrists and relax your fingers.

    3. Make a tight fist with both hands.

    4. Bend both wrists down while keeping the fists and hold for a count of five.

    5. Straighten wrists and relax fingers for a count of five.

    Repeat this exercise 10 times, then let your arms hang loosely at your sides and shake them for a few minutes.

    Click to enlarge: Warm-up exercise

    Figure 02. Warm-up exercise

    Take frequent short rests from your repetitive tasks. For example, if you are using a computer keyboard, take a 10-minute break every hour and perform exercises to relax your muscles.

    The American Occupational Therapy Association recommends these exercises for anyone who performs repetitive tasks during the workday:

    • Place the unaffected hand beneath your fingers and gently but firmly push them back. Hold for 10 seconds every hour.
    • Open and close your hand fully, squeezing it into a fist. Make the fist 10 times over 10 seconds every hour.

    See your doctor for a professional diagnosis if pain is severe and numbness persists even after rest, or if your grip becomes weak. It is important to diagnose and treat carpal tunnel syndrome. The symptoms of the disorder may lead to permanent loss of hand function if prolonged.

  • Prevention and Screening

    Carpal tunnel syndrome can be prevented, but at-risk people and their employers must take precautions. Because carpal tunnel syndrome is so frequently job-related, both employees and employers should be concerned about prevention. Motions required in many jobs, such as typing, working on an assembly line, and playing an instrument, are often the cause.

    People at risk for carpal tunnel syndrome should ask their employers for equipment that is designed to reduce stress on their arms and wrists. Ideally, equipment should be selected, or in some cases modified, to reduce the kinds of motions that lead to carpal tunnel syndrome. Tools and their handles can be designed or modified so that the wrist is not required to bend or twist into awkward positions, and computer keyboards should be lowered so that they are positioned just slightly above your legs. Also, use a computer keyboard especially designed to minimize repetitive stress.

    Rest frequently and stretch to ease strain on your arms and wrists, and try to avoid long periods of uninterrupted repetitive movement. Rotate jobs with another employee so that you can take a longer break from a repetitive task. If you work on an assembly line, ask your employer to vary your tasks over the course of the workday. Make sure you are working in a comfortable position. Your wrists should not be bent any more than they would be to hold a pencil for writing, and your elbows should be bent to a 90-degree angle. You should adjust your chair to a height that is comfortable for you.

    Do a five-minute warm-up before you start a repetitive task Figure 02. The American Academy of Orthopaedic Surgeons (www.aaos.org) recommends the following:

    1. Hold your arms straight out in front of you. Extend your hands, fingers pointing up, in the “stop” position. Hold for a count of five.

    2. Straighten your wrists and relax your fingers.

    3. Make a tight fist with both hands.

    4. Bend both wrists down while keeping the fists and hold for a count of five.

    5. Straighten wrists and relax fingers for a count of five.

    Repeat this exercise 10 times, then let your arms hang loosely at your sides and shake them for a few minutes.

    Click to enlarge: Warm-up exercise

    Figure 02. Warm-up exercise

    Take frequent short rests from your repetitive tasks. For example, if you are using a computer keyboard, take a 10-minute break every hour and perform exercises to relax your muscles.

    The American Occupational Therapy Association recommends these exercises for anyone who performs repetitive tasks during the workday:

    • Place the unaffected hand beneath your fingers and gently but firmly push them back. Hold for 10 seconds every hour.
    • Open and close your hand fully, squeezing it into a fist. Make the fist 10 times over 10 seconds every hour.

    See your doctor for a professional diagnosis if pain is severe and numbness persists even after rest, or if your grip becomes weak. It is important to diagnose and treat carpal tunnel syndrome. The symptoms of the disorder may lead to permanent loss of hand function if prolonged.

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