Carpal Tunnel Syndrome Is Caused by Compression of a Specific Nerve in the Wrist

106 13
Part 1 of 10 - What Is Carpal Tunnel Syndrome?

Updated May 23, 2014.

Carpal Tunnel Syndrome

You are working at your desk, trying to ignore the tingling or numbness you've had for months in your hand and wrist. Suddenly, a sharp, piercing pain shoots through the wrist and up your arm. Just a passing cramp? More likely you have carpal tunnel syndrome, a painful progressive condition caused by compression of a key nerve in the wrist.

    Carpal tunnel syndrome occurs when the median nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist. The median nerve controls sensations to the palm side of the thumb and fingers (although not the little finger), as well as impulses to some small muscles in the hand that allow the fingers and thumb to move.

    The Carpal Tunnel

    The carpal tunnel is a narrow, rigid passageway of ligament and bones at the base of the hand that houses the median nerve and tendons. Sometimes, thickening from irritated tendons or other swelling narrows the tunnel and causes the median nerve to be compressed. The result may be pain, weakness, or numbness in the hand and wrist, radiating up the arm.

    Although painful sensations may indicate other conditions, carpal tunnel syndrome is the most common and widely known of the entrapment neuropathies in which the body's peripheral nerves are compressed or traumatized.

      Part 2 of 10 - What Are the Symptoms of Carpal Tunnel Syndrome?

      Updated May 23, 2014.

      Carpal Tunnel Syndrome Symptoms

      Symptoms of carpal tunnel syndrome usually start gradually, with frequent burning, tingling, or itching numbness in the palm of the hand and the fingers, especially the thumb and the index and middle fingers. Some carpal tunnel sufferers say their fingers feel useless and swollen, even though little or no swelling is apparent.

      The symptoms of carpal tunnel syndrome often first appear in one or both hands during the night, since many people sleep with flexed wrists.

      A person with carpal tunnel syndrome may wake up feeling the need to "shake out" the hand or wrist.

      When Carpal Tunnel Syndrome Symptoms Worsen

      As symptoms of carpal tunnel syndrome worsen, people might feel tingling during the day. Decreased grip strength may make it difficult to:
      • form a fist
      • grasp small objects
      • perform other manual tasks

      In chronic and/or untreated cases of carpal tunnel syndrome, the muscles at the base of the thumb may waste away. Some people are unable to tell between hot and cold by touch.

      Part 3 of 10 - What Are the Causes of Carpal Tunnel Syndrome?

      Updated May 23, 2014.

      Carpal Tunnel Syndrome Causes

      Carpal tunnel syndrome is often the result of a combination of factors that increase pressure on the median nerve and tendons in the carpal tunnel, rather than a problem with the nerve itself. Most likely the disorder is due to a congenital predisposition - the carpal tunnel is simply smaller in some people than in others.

      Other Contributing Factors

      • trauma or injury to the wrist that cause swelling, such as sprain or fracture

      • overactivity of the pituitary gland
      • hypothyroidism
      • rheumatoid arthritis
      • mechanical problems in the wrist joint
      • work stress
      • repeated use of vibrating hand tools
      • fluid retention during pregnancy or menopause
      • the development of a cyst or tumor in the canal

      In some cases, no cause of carpal tunnel syndrome can be identified.

      Repetitive Movements

      There is little clinical data to prove whether repetitive and forceful movements of the hand and wrist during work or leisure activities can cause carpal tunnel syndrome. Repeated motions performed in the course of normal work or other daily activities can result in repetitive motion disorders such as:

      Writer's Cramp

      Writer's cramp, a condition in which a lack of fine motor skill coordination and ache and pressure in the fingers, wrist, or forearm is brought on by repetitive activity, is not a symptom of carpal tunnel syndrome.

      Part 4 of 10 - Who Is at Risk for Developing Carpal Tunnel Syndrome?

      Updated May 23, 2014.

      Carpal Tunnel Syndrome Risk

      Women are three times more likely than men to develop carpal tunnel syndrome, perhaps because the carpal tunnel itself may be smaller in women than in men.
      • The dominant hand is usually affected first and produces the most severe pain.
      • Carpal tunnel syndrome usually occurs only in adults.

      Persons with diabetes or other metabolic disorders that directly affect the body's nerves and make them more susceptible to compression are also at high risk.

      Job Risk

      The risk of developing carpal tunnel syndrome is not confined to people in a single industry or job, but is especially common in those performing assembly line work such as:
      • manufacturing
      • sewing
      • finishing
      • cleaning
      • meat, poultry, or fish packing

      In fact, carpal tunnel syndrome is three times more common among assemblers than among data-entry personnel. A study by the Mayo Clinic found heavy computer use (up to 7 hours a day) did not increase a person's risk of developing carpal tunnel syndrome.

      Other Facts

      It is estimated that three of every 10,000 workers loses time from work because of carpal tunnel syndrome. Half of these workers missed more than 10 days of work. The average lifetime cost of carpal tunnel syndrome, including medical bills and lost time from work, is estimated to be more than $30,000 for each injured worker.

      Part 5 of 10 - How Is Carpal Tunnel Syndrome Diagnosed?

      Updated May 23, 2014.


      Early diagnosis and treatment are important to avoid permanent damage to the median nerve. Physical examination of the hands, arms, shoulders, and neck can help determine if the patient's complaints are related to daily activities or to an underlying disorder, and can rule out other painful conditions that mimic carpal tunnel syndrome. The wrist is examined for:
      • tenderness
      • swelling
      • warmth
      • discoloration

        Each finger should be tested for sensation, and the muscles at the base of the hand should be examined for strength and signs of atrophy. Routine laboratory tests and X-rays can reveal:

        The presence of carpal tunnel syndrome is suggested if one or more symptoms, such as tingling or increasing numbness, is felt in the fingers within 1 minute. Doctors may also ask patients to try to make a movement that brings on symptoms.


        Often it's necessary to confirm the diagnosis by use of electrodiagnostic tests. In a nerve conduction study, electrodes are placed on the hand and wrist. Small electric shocks are applied and the speed with which nerves transmit impulses is measured. In electromyography, a fine needle is inserted into a muscle, electrical activity viewed on a screen can determine the severity of damage to the median nerve. Ultrasound imaging can show impaired movement of the median nerve. Magnetic resonance imaging can show the anatomy of the wrist but to date has not been especially useful in diagnosing carpal tunnel syndrome.

        Part 6 of 10 - What Other Tests Are Used for Carpal Tunnel Syndrome Diagnosis?

        Updated May 23, 2014.

        Specific Tests

        Physicians can use specific tests to try to produce the symptoms of carpal tunnel syndrome.

        The Tinel Test

        In the Tinel test, the doctor taps on or presses on the median nerve in the patient's wrist. The test is positive when tingling in the fingers or a resultant shock-like sensation occurs.

        The Phalen Test

        The Phalen, or wrist-flexion, test involves having the patient hold his or her forearms upright by pointing the fingers down and pressing the backs of the hands together.

        Part 7 of 10 - How Is Carpal Tunnel Syndrome Treated?

        Updated May 23, 2014.

        Carpal Tunnel Syndrome Treatment

        Treatment for carpal tunnel syndrome should begin as early as possible, under a doctor's direction. Underlying causes of carpal tunnel syndrome should be treated first such as:

        Initial Treatment

        Initial treatment of carpal tunnel syndrome generally involves resting the affected hand and wrist for at least 2 weeks, avoiding activities that may worsen symptoms, and immobilizing the wrist in a splint to avoid further damage from twisting or bending.

        If there is inflammation, applying cool packs can help reduce swelling.

        Alternative Therapies

        Acupuncture and chiropractic care have benefited some patients but effectiveness remains unproved. An exception is yoga, which has been shown to reduce pain and improve grip strength.

        Part 8 of 10 - Medication & Non-Surgical Carpal Tunnel Syndrome Treatment

        Updated May 23, 2014.


        In some cases, various medications can ease the pain and swelling associated with carpal tunnel syndrome.


        Symptoms that have been present for a short time or have been caused by strenuous activity may be eased by non-steroidal anti-inflammatory drugs, such as:


        Oral diuretics ("water pills") can also decrease swelling.


        Corticosteroids such as prednisone, injected directly into the wrist or taken by mouth, can relieve pressure on the median nerve and provide immediate, temporary relief to persons with mild or intermittent symptoms. (Caution: persons with diabetes and those predisposed to diabetes should note that prolonged use of corticosteroids can make it difficult to regulate insulin levels, they should not be taken without a doctor's prescription.)

        Vitamin B6

        Additionally, some studies show that vitamin B6 (pyridoxine) supplements may ease carpal tunnel syndrome symptoms.


        Stretching and strengthening exercises can be helpful in people whose symptoms have abated. These exercises may be supervised by a physical therapist, who is trained to use exercises to treat physical impairments, or an occupational therapist, who is trained in evaluating people with physical impairments and helping them build skills to improve their health and well-being.

        Updated May 23, 2014.

        Carpal Tunnel Release

        Carpal tunnel release is a common surgical procedure. Generally recommended if symptoms last for 6 months, surgery involves severing the band of tissue around the wrist to reduce pressure on the median nerve. Surgery is done under local anesthesia and does not require an overnight hospital stay. Many patients require surgery on both hands.

        Open Release

        Open release surgery, the traditional carpal tunnel correction surgery, involves making an incision up to 2 inches in the wrist and then cutting the carpal ligament to enlarge the carpal tunnel.

        The surgery is generally done outpatient under local anesthesia.

        Endoscopic Surgery

        Endoscopic surgery may allow faster functional recovery and less post-op discomfort than traditional open release surgery. A surgeon makes two incisions in the wrist and palm, inserts a camera attached to a tube, observes the tissue on a screen, and cuts the carpal ligament. This two-portal endoscopic surgery, generally performed under local anesthesia, is effective and minimizes scarring and scar tenderness. One-portal endoscopic surgery is also available.


        Although symptoms may be relieved immediately after surgery, full recovery can take months. Some patients may have:
        • infection
        • nerve damage
        • stiffness / pain at the scar

        Sometimes the wrist loses strength because the carpal ligament is cut. Patients should undergo physical therapy to restore wrist strength. Some may need to adjust duties or change jobs after recovery.

        Updated May 23, 2014.


        At the workplace, workers can:
        • do on-the-job conditioning
        • perform stretching exercises
        • take frequent rest breaks
        • wear splints to keep wrists straight
        • use correct posture and wrist position


        Wearing fingerless gloves can help keep hands warm and flexible. Workstations, tools and tool handles, and tasks can be redesigned to enable the worker's wrist to maintain a natural position during work.

        Jobs can be rotated among workers.

        Employers can develop programs in ergonomics, the process of adapting workplace conditions and job demands to the capabilities of workers. However, research has not conclusively shown that these workplace changes prevent the occurrence of carpal tunnel syndrome.


        NIH Publication No 03-4898 (edited)

        Subscribe to our newsletter
        Sign up here to get the latest news, updates and special offers delivered directly to your inbox.
        You can unsubscribe at any time

        Leave A Reply

        Your email address will not be published.