Home > Encyclopedia of Nursing & Allied Health > Carpal Tunnel Syndrome

Definition

Carpal tunnel syndrome is a common disorder caused by compression at the wrist of the median nerve supplying the hand, causing numbness and tingling.

Description

The carpal tunnel is an area in the wrist where the bones and ligaments create a small passageway for the median nerve. The median nerve is responsible for both sensation and movement in the hand, in particular the thumb and first three fingers. When the median nerve is compressed, an individual's hand will feel as if it has "gone to sleep." Persistent pressure causes pain that may manifest as a burning or tingling sensation in the fingers (acroparesthesia). Reduced motor ability in the hand and wrist may gradually develop as well.

Women between the ages of 30 and 60 have the highest rates of carpal tunnel syndrome; they are two to five times as likely as men to develop the disorder. It is the most frequently occurring nerve compression found in the upper part of the body, and is a very significant cause of missed work days. Research has shown that the prevalence of carpal tunnel syndrome in the general population ranges from 2.1 to 4%. At least 200,000 carpal tunnel release surgical interventions are performed every year in the United States, and is the most frequently performed surgery on the hand. The costs associated with the procedure are at least $1 billion each year. The cost to employers is also substantial because of the significant loss of work time associated with the condition.

Causes and symptoms

Compression of the median nerve in the wrist can occur during a number of different conditions, particularly those conditions which lead to changes in fluid accumulation throughout the body. Because the area of the wrist through which the median nerve passes is very narrow, any swelling in the area will lead to pressure on the median nerve. This pressure will ultimately interfere with the nerve's ability to function normally. Pregnancy, obesity, arthritis, certain thyroid conditions, diabetes, and certain pituitary abnormalities all predispose individuals to carpal tunnel syndrome. Other conditions which increase the risk for carpal tunnel syndrome include the presence of organic lesions, tumors, congenital malformations, and various injuries to the arm and wrist (including fractures, sprains, and dislocations). A type of carpal tunnel syndrome that is transmitted by hereditary means has also been found. Furthermore, activities which cause an individual to repeatedly bend the wrist inward toward the forearm can predispose to carpal tunnel syndrome. Certain jobs that require repeated strong wrist motions carry a relatively high risk of precipitating carpal tunnel syndrome. Injuries of this type are referred to as "repetitive motion" injuries, and are more frequent among people working at computer keyboards or cash registers, factory workers, and some musicians.

Symptoms of carpal tunnel syndrome include numbness, burning, tingling, and a prickly pin-like sensation over the palmar surface of the hand, and into the thumb, forefinger, middle finger, and half of the ring finger. Some individuals notice a shooting pain going from the wrist up the arm, or down into the hand and fingers. This pain can radiate into the shoulder, neck, and chest regions, in some cases. Although pain is generally increased during repetitive movement, it is typically greatest during the night. With continued median nerve compression, an individual may begin to experience muscle weakness, making it difficult to open jars and hold objects with the affected hand. Eventually, the muscles of the hand served by the median nerve may begin to grow noticeably smaller (atrophy), especially the fleshy part of the thumb. Untreated, carpal tunnel syndrome may eventually result in permanent weakness, loss of sensation, and even paralysis of the thumb and fingers of the affected hand. Noticeable differences in strength and sensory perception can develop between the affected hand and the unaffected hand.

Diagnosis

The diagnosis of carpal tunnel syndrome is made in part by checking to see whether pain or paresthesia (Phalen's sign) can be brought on by holding his or her hand in position with wrist bent for about a minute. X-rays are often taken to rule out the possibility of a tumor causing pressure on the median nerve. A health practitioner examining a patient suspected of having carpal tunnel syndrome will perform a variety of simple tests to measure muscle strength and sensation in the affected hand and arm. The practitioner will likely test for Tinel's sign (tingling or shock-like pain) by tapping the surface of the wrist over the median nerve to try to produce symptoms. A similar test known as the carpal compression test, where the thumb is placed over the patient's carpal tunnel for 30 seconds, may also be performed.

Further testing might include electromyographic or nerve conduction velocity testing to determine the exact severity of nerve damage. These tests involve stimulating the median nerve with electricity and measuring the resulting speed and strength of the muscle response, as well as recording speed of nerve transmission across the carpal tunnel. A variety of conditions need to be ruled out to confirm the diagnosis of carpal tunnel syndrome. These include osteoarthritis, blood vessel compression or occlusion, other nerve compression conditions, and tendinitis.

Treatment

Carpal tunnel syndrome is initially treated with splints, which support the wrist and prevent it from flexing inward into the position that exacerbates median nerve compression. Nurses and physical therapists often instruct the patient on how to use these splints or braces. Some people get significant relief by wearing such splints at night while sleeping, whereas others will need to wear the splints all day, especially if they are performing jobs which stress the wrist. If possible, the patient should avoid the repetitive action that may have precipitated the condition initially. Elevation of the affected arm may help some patients. Nurses often provide information on how to minimize strain on the carpal tunnel during daily activities. Physical therapists and nurses can provide information on various exercises, which may help with the symptoms associated with carpal tunnel syndrome. There is some evidence that vitamin B₆ can help symptoms in some patients who have less serious symptoms, although this treatment is currently considered controversial and should be considered an alternative form of medicine. Acetaminophen, ibuprofen, or other nonsteroidal anti-inflammatory drugs may be prescribed to decrease pain and swelling. The clinician or pharmacist can provide advice on how to most effectively use these drugs to minimize carpal tunnel symptoms. When carpal tunnel syndrome is more advanced, injection of steroids into the wrist to decrease inflammation may be necessary. This must be carefully performed to avoid damaging the median nerve. Some patients may benefit from receiving low doses of oral corticosteroids.

The most severe cases of carpal tunnel syndrome may require surgery to decrease the compression of the median nerve and restore its normal function. Such a repair involves cutting the ligament that crosses the wrist, thus allowing the median nerve more room and decreasing compression. This surgery is done almost exclusively on an outpatient basis and is often performed under local anesthesia. Careful injection of numbing medicines (local anesthesia) or nerve blocks (the injection of anesthetics directly into the nerve) create sufficient numbness to allow the surgery to be performed painlessly, without the risks associated with general anesthesia. Nurses provide information on what the patient should do postoperatively. Recovery from this type of surgery is usually quick and without complications. The return of muscle strength in the affected limb occurs gradually in most patients. However, when the muscle has severely atrophied in advanced cases, complete restoration of previous muscle strength is not likely. A less-invasive surgical technique using an endoscope has been developed for this procedure and is being used to a small extent.

Health care team roles

The x-ray technologist will perform the radiography that will help the practitioner determine whether a tumor or injury has occurred in the lower arm of the patient. An x ray of the neck and upper back region of the patient can help rule out any degenerative condition of the spine that could produce some of these symptoms. Likewise, an imaging technologist performing magnetic resonance imaging (MRI) could help the practitioner find abnormalities in the lower arm and hand all the way up to the upper back and neck regions of the spine. Nurses can be involved at many points of the diagnostic and therapeutic process. They may assist in the initial physical diagnostic procedures performed by a physician.

Patient education

Physical therapists can design exercises that improve posture and strengthen certain muscle groups in order to alleviate or prevent carpal tunnel strain. These therapists often design rehabilitation programs for patients who have undergone carpal tunnel release surgery. These programs have the goal of restoring muscle strength to the weakened muscles of the lower arm and hand.

Nurses may provide instruction about maintaining good posture and performing exercises that reduce strain on the carpal tunnel in patients that are at the beginning stages of carpal tunnel syndrome. They may also instruct the patient on how to wear a splint or a brace and assist the practitioner in the process of steroid injection into the carpal tunnel. Nurses assist in the carpal tunnel release surgery and in the ensuing recovery process. They also play an important role in the postoperative period by providing instructions about arm elevation and other issues, such as the use of splints. Occupational therapists can play a significant role in the prevention of carpal tunnel syndrome by providing information on good posture techniques and ergonomics while working.

Prognosis

There is a wide range of outcomes in patients with carpal tunnel syndrome. A few patients have spontaneous remission of symptoms. However, most patients need to undergo some form of therapy. Continued pressure on the median nerve puts an individual at risk for permanent disability in the affected hand. Most people are able to control the symptoms of carpal tunnel syndrome using conservative methods, such as splinting and anti-inflammatory agents. Steroid injections often produce only temporary improvement in symptoms. Most of these individuals have a recurrence of symptoms. Many women develop carpal tunnel syndrome in the third trimester of pregnancy, but symptoms usually disappear after the baby is born. Symptoms often reappear in later pregnancies in these women. Because symptoms generally resolve at the end of the pregnancy, surgery is not recommended in these women. In patients who do require surgery, about 95% will have complete cessation of symptoms.

Prevention

Prevention is generally aimed at becoming aware of the repetitive motions which put the wrist into a bent position. People who must work long hours at a computer keyboard, for example, may need to take advantage of recent advances in ergonomics, which position the keyboard and computer components in ways that increase efficiency and decrease stress. An interruption in the repetitive movement once an hour throughout the day may help prevent and reduce symptoms. Early use of a splint may also be helpful for people whose jobs increase the risk of carpal tunnel syndrome. Splints may also improve sleeping posture and prevent or reduce carpal tunnel symptoms.

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KEY TERMS

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Carpal tunnel—A passageway in the wrist, created by the bones and ligaments of the wrist, through which the median nerve passes.

Corticosteroids—Any one of several hormonal substances obtained from the adrenal gland cortex and which are classified according to biological activity.

Endoscope—A device made of a tube and an optical system for observing the inside of the body.

Electromyography—A type of test in which a nerve's function is tested by stimulating a nerve with electricity, and then measuring the speed and strength of the corresponding muscle's response.

Median nerve—A nerve which runs through the wrist and into the hand. It provides sensation and some movement to the hand, the thumb, the index finger, the middle finger, and half of the ring finger.

Osteoarthritis—A chronic disease that involves the joints and which is characterized by damaged cartilage, bone overgrowth, spur formation, and reduced function.

Tendinitis—Inflammation of a tendon.

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Mark Alan Mitchell