Carpal tunnel syndrome

Definition

Carpal tunnel syndrome is an entrapment neuropathy of the wrist. It occurs when the median nerve, which runs through the wrist and enervates the thumb, pointer finger, middle finger and the thumb side of the ring finger, is aggravated because of compression. Symptoms include numbness, tingling and pain in the fingers the median nerve sensitizes. Some people have difficulty grasping items and may have pain radiating up the arm. Carpal tunnel syndrome is common in people who work on assembly lines, doing heavy lifting and packing involving repetitive motions. Other repetitive movements such as typing are often implicated in cause carpal tunnel syndrome, however some clinical evidence contradicts this association. Additional causes of the syndrome include pregnancy, diabetes, obesity or simply wrist anatomy in which the carpal tunnel is narrow. Treatment includes immobilization with a splint or in severe cases surgery to release the compression of the median nerve.

Description

Carpal tunnel syndrome (CTS) is caused by a compression of the median nerve in the wrist, a condition known as nerve entrapment. Nerve entrapments occur when a nerve that travels through a passage between bones and cartilage becomes irritated because a hard edge presses against it. In almost every case of nerve entrapment, one side of the passage is moveable and the repetitive rubbing exacerbates the injury.

Three sides of the carpal tunnel are made up of three bones that form a semicircle around the back of the wrist. The fourth side of the carpal tunnel is made up of the transverse carpal tunnel ligament also called the palmar carpal ligament, which runs across the wrist on the same side as the palm. This ligament is made of tissue that cannot stretch or contract, making the cross sectional area of the carpal tunnel a fixed size. Running through the carpal tunnel are nine tendons that assist the muscles that move the hand and the median nerve. The median nerve enervates the thumb, forefinger, middle finger, and the thumb side of the ring finger. The ulnar nerve that serves the little finger side of the ring finger and the little finger runs outside of the transverse carpal tunnel ligament and is therefore less likely to become entrapped in the wrist.

The tendons that run through the carpal tunnel are encased in a lubricating substance called tensynovium. This substance can become swollen when the tendons rub quickly against one another, as occurs when the finger muscles are used repeatedly. When this happens, there is less space within the carpal tunnel for the median nerve and it becomes compressed or pinched.

When a nerve is compressed, the blood supply to the nerve is interrupted. In an attempt to alleviate the problem, the body's immune system sends new cells called fibroblasts to the area to try to build new tissue. This eventually results in scar tissue around the nerve. In an area that cannot expand this only worsens the situation and puts more pressure on the nerve. A compressed nerve can be likened to an electrical wire that has been crimped. It cannot transmit electrical signals to the brain properly and the result is a feeling of numbness, tingling or pain in the areas that the nerve enervates.

Compression of the median nerve causes tingling and numbness in the thumb, forefinger, middle finger and on the thumb-side of the fourth finger. It may also cause pain in the forearm and occasionally into the shoulder. Some persons have a difficult time gripping and making a fist.

People who suffer from CTS range from those who are mildly inconvenienced and must wear a splint at night to relieve pressure on the median nerve to those who are severely debilitated and lose use of their hands. Problems associated with CTS can invade a person's life making even simple tasks such as answering the phone, reading a book or opening a door extremely difficult. In severe cases, surgery to release the median nerve is often suggested by an orthopedist. The carpal tunnel ligament is cut, relieving the pressure within the carpal tunnel. Rates of success are quite high with the surgical procedure.

Demographics

Carpal tunnel syndrome is more common in women than in men, perhaps because the carpal tunnel generally has a smaller cross section in women than in men. The ratio of women to men who suffer from CTS is about three to one. CTS is most often diagnosed in people who are between 30 and 50 years old. It is more likely to occur in people whose professions require heavy lifting and repetitive movements of the hands such as manufacturing, packing, cleaning and finishing work on textiles.

Causes and symptoms

Carpal tunnel syndrome may occur when anything causes the size of the carpal tunnel to decreases or when anything puts pressure on the median nerve. Often the cause is simply the result of an individual's anatomy; some people have smaller carpal tunnels than others. Trauma or injury to the wrist, such as bone breakage or dislocation can cause CTS if the carpal tunnel is narrowed either by the new position of the bones or by associated swelling. Development of a cyst or tumor in the carpal tunnel will also result in increased pressure on the median nerve and likely CTS. Systemic problems that result in swelling may also cause CTS such as hypothyroidism, problems with the pituitary gland, and the hormonal imbalances that occur during pregnancy and menopause. Arthritis, especially rheumatoid arthritis, may also cause CTS. Some patients with diabetes may be more susceptible to CTS because they already suffer from nerve damage. Obesity and cigarette smoking are thought to aggravate symptoms of CTS.

Much evidence suggests that one of the more common causes of CTS involves performing repetitive motions such as opening and closing of the hands or bending of the wrists or holding vibrating tools. Motions that involve weights or force are thought to be particularly damaging. For example, the types of motions that assembly line workers perform such as packing meat, poultry or fish, sewing and finishing textiles and garments, cleaning, and manufacturing are clearly associated with CTS. Other repetitive injury disorders such as data entry while working on computers are also implicated in CTS. However, some clinical data contradicts this finding. These studies show that computer use can result in bursitis and tendonitis, but not CTS. In fact, a 2001 study by the Mayo Clinic found that people who used the computer up to seven hours a day were no more likely to develop CTS than someone who did not perform the type of repetitive motions required to operate a keyboard.

The two major symptoms of carpal tunnel syndrome include numbness and tingling in the thumb, forefinger, middle finger and the thumb side of the fourth finger and a dull aching pain extending from the wrist through the shoulder. The pain often worsens at night because most people sleep with flexed wrists, which puts additional pressure on the median nerve. Eventually the muscles in the hands will weaken, in particular, the thumb will tend to lose strength. In severe cases, persons suffering from CTS are unable to differentiate between hot and cold temperatures with their hands.

Diagnosis

Diagnosis of carpal tunnel syndrome begins with a physical exam of the hands, wrists and arms. The physician will note any swelling or discoloration of the skin and the muscles of the hand will be tested for strength. If the patient reports symptoms in the first four fingers, but not the little finger, then CTS is indicated. Two special tests are used to reproduce symptoms of CTS: the Tinel test and the Phalen test. The Tinel test involves a physician taping on the median nerve. If the patient feels a shock or a tingling in the fingers, then he or she likely has carpal tunnel syndrome. In the Phalen test, the patient is asked to flex his or her wrists and push the backs of the hands together. If the patient feels tingling or numbness in the hands within one minute, then carpal tunnel syndrome is the likely cause.

A variety of electronic tests are used to confirm CTS. Nerve conduction velocity studies (NCV) are used to measure the speed with which an electrical signal is transferred along the nerve. If the speed is slowed relative to normal, it is likely that the nerve is compressed. Electromyography involves inserting a needle into the muscles of the hand and converting the muscle activity to electrical signals. These signals are interpreted to indicate the type and severity of damage to the median nerve. Ultrasound imaging can also be used to visualize the movement of the median nerve within the carpal tunnel. X rays can be used to detect fractures in the wrist that may be the cause of carpal tunnel syndrome. Magnetic resonance imaging (MRI) is also a useful tool for visualizing injury to the median nerve.

Treatment team

Treatment for carpal tunnel syndrome usually involves a physician specializing in the bones and joints (orthopedist) or a neurologist , along with physical and occupational therapists, and if necessary, a surgeon.

Treatment

Lifestyle changes are often the first type of treatment prescribed for carpal tunnel syndrome. Avoiding activities that aggravate symptoms is one of the primary ways to manage CTS. These activities include weight-bearing repetitive hand movements and holding vibrating tools. Physical or occupational therapy is also used to relieve symptoms of CTS. The therapist will usually train the patient to use exercises to reduce irritation in the carpal tunnel and instruct the patient on proper posture and wrist positions. Often a doctor or therapist will suggest that a patient wear a brace that holds the arm in a resting position, especially at night. Many people tend to sleep with their wrists flexed, which decreases the space for the median nerve within the carpal tunnel. The brace keeps the wrist in a position that maximizes the space for the nerve.

Doctors may prescribe non-steroidal anti-inflammatory medications to reduce the swelling in the wrist and relieve pressure on the median nerve. Oral steroids are also useful for decreasing swelling. Some studies have shown that large quantities of vitamin B-6 can reduce symptoms of CTS, but this has not been confirmed. Injections of corticosteroids into the carpal tunnel may also be used to reduce swelling and temporarily provide some extra room for the median nerve.

Surgery can be used as a final step to relieve pressure on the median nerve and relieve the symptoms of CTS. There are two major procedures in use, both of which involve cutting the transverse carpal tunnel ligament. Dividing this ligament relieves pressure on the median nerve and allows blood flow to the nerve to increase. With time,

the nerve heals and as it does so, the numbness and pain in the arm are reduced.

Open release surgery is the standard for severe CTS. In this procedure, a surgeon will open the skin down the front of the palm and wrist. The incision will be about two inches long stretching towards the fingers from the lowest fold line on the wrist. Then next incision is through the palmar fascia, which is a thin connective tissue layer just below the skin, but above the transverse carpal ligament. Finally, being careful to avoid the median nerve and the tendons that pass through the carpal tunnel, the surgeon carefully cuts the transverse carpal ligament. This releases pressure on the median nerve.

Once the transverse carpal tunnel ligament is divided, the surgeon stitches up the palma fascia and the skin, leaving the ends of the ligament loose. Over time, the space between the ends of the ligament will be joined with scar tissue. The resulting space, which studies indicate is approximately 26% greater than prior to the surgery, is enlarged enough so that the median nerve is no longer compressed.

A second surgical method for treatment of CTS is endoscopic carpal tunnel release. In this newer technique, a surgeon makes a very small incision below the crease of the wrist just below the carpal ligament. Some physicians will make another small incision in the palm of the hand, but the single incision technique is more commonly used. The incision just below the carpal ligament allows the surgeon to access the carpal tunnel. He or she will then insert a plastic tube with a slot along one side, called a cannula, into the carpal tunnel along the median nerve just underneath the carpal ligament. Next an endoscope, which is a small fiber-optic cable that relays images of the internal structures of the wrist to a television screen, is fed through the cannula. Using the endoscope, the surgeon checks that the nerves, blood vessels and tendons that run through the carpal tunnel are not in the way of the cannula. A specialized scalpel is fed through the cannula. This knife is equipped with a hook on the end that allows the surgeon to cut as he or she pulls the knife backward. The surgeon positions this knife so that it will divide the carpal ligament as he pulls it out of the cannula. Once the knife is pulled through the cannula, the carpal ligament is severed, but the palma fascia and the skin are not cut. Just as in the open release surgery, cutting the carpal ligament releases the pressure on the median nerve. Over time, scar tissue will form between the ends of the carpal ligament. After the cannula is removed from the carpal tunnel, the surgeon will stitch the small incision in patient's wrist and the small incision in the palm if one was made.

The two different surgical techniques for treating CTS have both positive and negative attributes and the technique used depends on the individual case. In open release, the surgeon has a clear view of the anatomy of the wrist and can make sure that the division of the transverse ligament is complete. He or she can also see exactly which structures to avoid while making the incision. On the other hand, because the incision to the exterior is much larger than in endoscopic release, recovery time is usually longer. While the symptoms of CTS usually improve rapidly, the pain associated with the incision may last for several months. Many physicians feel that the recovery time associated with endoscopic release is faster than that for open release because the incision in the skin and palma fascia are so much smaller. On the other hand, endoscopic surgery is more expensive and requires training in the use of more technologic equipment. Some believe that are also risks that the carpal ligament may not be completely released and the median nerve may be damaged by the cannula, or the specialized hooked knife. Research is ongoing in an attempt to determine whether open or endoscopic release provides the safest and most successful results.

Success rates of release surgery for carpal tunnel syndrome are extremely high, with a 70–90% rate of improvement in median nerve function. There are complications associated with the surgery, although they are generally rare. These include incomplete division of the carpal ligament, pain along the incisions and weakness in the hand. Both the pain and the weakness are usually temporary. Infections following surgery for CTS are reported in less than 5% of all patients.

Recovery and rehabilitation

One day following surgery for carpal tunnel syndrome, a patient should begin to move his or her fingers, however gripping and pinching heavy items should be avoided for a month and a half to prevent the tendons that run through the carpal tunnel from disrupting the formation of scar tissue between the ends of the carpal ligament.

After about a month and a half, a patient can begin to see an occupational or physical therapist. Exercises, massage and stretching will all be used to increase wrist strength and range of motion. Eventually, the therapist will prescribe exercises to improve the ability of the tendons within the carpal tunnel to slide easily and to increase dexterity of the fingers. The therapist will also teach the patient techniques to avoid a recurrence of carpal tunnel syndrome in the future.

Clinical trials

There are a variety of clinical trials underway that are searching for ways to prevent and treat carpal tunnel syndrome. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) supports this research on CTS. Their website is <http://clinicaltrials.gov/search/term=Carpal+Tunnel+Syndrome>.

One trial seeks to determine which patients will benefit from surgical treatments compared to non-surgical treatments using a new magnetic resonance technique. The study is seeking patients with early, mild to moderate carpal tunnel syndrome. Contact Brook I. Martin at the University of Washington for more information. The phone number is (206) 616–0982 and the email is [email protected].

A second trial compares the effects of the medication amitriptyline, acupuncture , and placebos for treating repetitive stress disorders such as carpal tunnel syndrome. The study is located at Harvard University. For information contact Ted Kaptchuk at (617) 665–2174 or [email protected].

A third study is evaluating the effects of a protective brace for preventing carpal tunnel syndrome in people who use tools that vibrate in the workplace. The brace is designed to absorb the energy of the vibrations while remaining unobtrusive. For information on this study contact Prosper Benhaim at the UCLA Hand Center. The phone number is (310) 206–4468 and the email address is [email protected].

Prognosis

Persons with carpal tunnel syndrome can usually expect to gain significant relief from prescribed surgery, treatments, exercises, and positioning devices.

Resources

BOOKS

Johansson, Phillip. Carpal Tunnel Syndrome and Other Repetitive Strain Injuries. Brookshire, TX: Enslow Publishers, Inc. 1999.

Shinn, Robert, and Ruth Aleskovsky. The Repetitive Strain Injury Handbook. New York: Henry Holt and Company. 2000.

OTHER

"Carpal Tunnel Syndrome." American Association of Orthopaedic Surgeons. (February 11, 2004). http://orthoinfo.aaos.org/brochure/thr_report.cfm?Thread_ID=5&topcategory=Hand.

"Carpal Tunnel Syndrome Fact Sheet." National Instititute of Neurological Disorders and Stroke. (February 11, 2004). <http://www.ninds.nih.gov/healt_and_medical/disorders/carpal_tunnel.htm>.

ORGANIZATIONS

American Chronic Pain Association (ACPA). P.O. Box 850, Rocklin, CA 95677. (916) 632-0922 or (800) 533-3231. [email protected]. <http://www.theacpa.org>.

National Chronic Pain Outreach Association (NCPOA). P.O. Box 274, Millboro, VA 24460. (540) 862-9437; Fax: (540) 862-9485. [email protected]. <http://www.chronicpain.org>.

National Institute of Arthritis and Musculoskeletal and Skin Dieseases (NIAMS). National Institutes of Health, Bldg. 31, Rm. 4C05, Bethesda, MD 20892. (301) 496-8188; Fax: (540) 862-9485. [email protected]. <http://www.niams.nih.gov/index.htm>.

Juli M. Berwald, Ph.D.

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.

KEY TERMS

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.

Resources

BOOKS

Asbury, Arthur K. "Carpal Tunnel Syndrome." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998.

"Carpal Tunnel Syndrome." In Current Medical Diagnosis & Treatment 2001 edited by Lawrence M. Tierney, et al. New York: Lange, 2001.

Mercier, Lonnie R. "Carpal Tunnel Syndrome." In Ferri's Clinical Advisor, edited by Fred F. Ferri, et al. St. Louis: Mosby, 2001.

The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers and Robert Berkow, et al. Whitehouse Station: Merck, 1999.

Wirth, Fremont P. "Carpal Tunnel Syndrome." In Dambro: Griffith's 5-Minute Clinical Consult Philadelphia: Lippincott Williams & Wilkins, 1999.

PERIODICALS

Atroshi Isam, et al. "Prevalence for Clinically Proved Carpal Tunnel Syndrome is 4 Percent." Lakartidningen 97 no.14 (April 5, 2000):1668-70.

Franzblau, Alfred, Werner, Robert A. "What is Carpal Tunnel Syndrome?" Journal of the American Medical Association 282 no.2 (July 14, 1999):186-87.

Mackinnon, Susan E. et al."Clinical Diagnosis of Carpal Tunnel Syndrome." Journal of the American Medical Association 284 no 15 (October 18, 2000):1924-29.

ORGANIZATIONS

Association for Repetitive Motion Syndromes, P.O. Box 471973, Aurora, CO 80047-1973. 1-303-369-0803. <http://www.certifiedpst.com>.

National Institutes of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bldg. 31, Rm. 4C05, Bethesda, MD 20892-2350. 1-877-226-4267. <http://www.nih.gov>.

Mark Alan Mitchell

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 and instruct the patient on how to wear a splint or a brace. They may also 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.

KEY TERMS

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.

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.

Resources

BOOKS

Asbury, Arthur K. "Carpal Tunnel Syndrome." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998.

"Carpal Tunnel Syndrome." In Current Medical Diagnosis & Treatment 2001, edited by Lawrence M. Tierney, et al. New York: Lange, 2001.

Mercier, Lonnie R. "Carpal Tunnel Syndrome." In Ferri's Clinical Advisor, edited by Fred F. Ferri, et al. St. Louis: Mosby, 2001.

The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers and Robert Berkow, et al. Whitehouse Station: Merck, 1999.

Wirth, Fremont P. "Carpal Tunnel Syndrome." In Dambro: Griffith's 5-Minute Clinical Consult. Philadelphia: Lippincott Williams & Wilkins, 1999.

PERIODICALS

Atroshi, Isam, et al. "Prevalence for Clinically Proved Carpal Tunnel Syndrome is 4 Percent." Lakartidningen 97, no. 14 (April 5, 2000): 1668-70.

Franzblau, Alfred, and Robert A. Werner. "What is Carpal Tunnel Syndrome?" Journal of the American Medical Association 282, no. 2 (July 14, 1999): 186-87.

Mackinnon, Susan E. et al. "Clinical Diagnosis of Carpal Tunnel Syndrome." Journal of the American Medical Association 284, no. 15 (October 18, 2000): 1924-29.

ORGANIZATIONS

Association for Repetitive Motion Syndromes, P.O. Box 471973, Aurora, CO 80047-1973. (303) 369-0803. 〈http://www.certifiedpst.com〉.

National Institutes of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bldg. 31, Rm. 4C05, Bethesda, MD 20892-2350. (877) 226-4267. 〈http://www.nih.gov〉.

Carpal tunnel syndrome

Definition

Carpal tunnel syndrome is a 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."

Women between the ages of 30 and 60 have the highest rates of carpal tunnel syndrome. Research has demonstrated that carpal tunnel syndrome is a significant cause of missed work days due to pain . In 1995, about $270 million was spent on sick days taken for pain from repetitive motion injuries.

Causes & 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 to carpal tunnel syndrome. Other conditions that increase the risk for carpal tunnel syndrome include some forms of arthritis and various injuries to the arm and wrist (including fractures , sprains, and dislocations). Furthermore, activities which cause a person 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 carpal tunnel syndrome. Injuries of this type are referred to as "repetitive motion" injuries, and are more frequent among secretaries who do a lot of typing, 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 palm surface of the hand, and into the thumb, forefinger, middle finger, and half of the ring finger. Some individuals notice a shooting pain which goes from the wrist up the arm, or down into the hand and fingers. 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, or even paralysis of the thumb and fingers of the affected hand.

Diagnosis

The diagnosis of carpal tunnel syndrome is made in part by checking to see whether the patient's symptoms can be brought on by holding his or her hand with the wrist bent for about a minute. Wrist x rays are often taken to rule out the possibility of a tumor causing pressure on the median nerve. A physician 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. 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 the speed of nerve transmission across the carpal tunnel. In 2002, a report stated that three medical organizations had concluded that electrodiagnostic studies were the preferred methods of diagnosing carpal tunnel syndrome, offering the highest degrees of sensitivity and specificity.

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. Some people get significant relief by wearing such splints to sleep at night, while others will need to wear the splints all day, especially if they are performing jobs that stress the wrist.

The activity which caused the condition should be avoided whenever possible. Also, the actions of making a fist, holding objects, and typing should be reduced. The patient's work area should be modified to reduce stress on the body. This may be achieved by correct positioning and with ergonomically designed furniture. Performing hand and wrist exercises periodically throughout the day can be beneficial.

Researchers found that the carpal ligament can be lengthened or released without surgery through osteopathic manipulation and weight loading. Combining the two gives additional benefit because manipulation lengthens the ligament at one end and weight loading increases the length at the other end. Patients can be taught a stretching exercise for self-manipulation of the ligament.

A National Institute of Health (NIH) panel concluded that traditional acupuncture may be a useful alternative or complementary treatment for carpal tunnel syndrome. Studies have shown that both laser acupuncture and microamp transcutaneous electrical nerve stimulation (TENS) can significantly reduce the pain associated with carpal tunnel syndrome. Both of these therapies are painless. Greater than 90% of the patients treated reported no pain or pain that had been reduced by more than half. Patients in this study were also using Chinese herbal medicines, deep acupuncture (including needle acupuncture), moxibustion , and omega-3 fish oil capsules. All patients were able to return to work and the pain of most patients remained stable for up to two years. Persons over the age of 60 years had a poorer response.

Some studies have shown that persons with carpal tunnel syndrome are deficient in vitamin B₆ (pyridoxine ) and that supplementation with this vitamin is beneficial. Carpal tunnel syndrome should improve within two to three months by taking 100 mg three times daily. The patient should consult with his or her physician when taking high doses of this vitamin.

Chinese and homeopathic remedies include:

• arnica; 30c dose
• astra essence
• Rhus toxicodendron; 6c dose
• Ruta graveolens; 6c dose

Allopathic treatment

Ibuprofen or other nonsteroidal anti-inflammatory drugs may be prescribed to decrease pain and swelling. Diuretics may be used if the syndrome is related to the menstrual cycle. When carpal tunnel syndrome is more advanced, steroids may be injected into the wrist to decrease inflammation.

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 that 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 without the patient having to be made unconscious. 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. Recovery from this type of surgery is usually quick and without complications.

In 2002, researchers in the Netherlands reported that after studying about 80 patients over two years, surgery proved more successful than nighttime splints in freeing up compressed nerves of patients with carpal tunnel syndrome. Many patients in the splint group ended up choosing the surgery option after several months of wearing splints.

Expected results

Without treatment, continued pressure on the median nerve puts the patient at risk for permanent disability in the affected hand. Alternative medicines have been shown to reduce pain. Most people are able to control the symptoms of carpal tunnel syndrome with splinting and anti-inflammatory agents. For those who go on to require surgery, about 95% will have complete cessation of symptoms.

Prevention

Avoiding or reducing the repetitive motions that put the wrist into a bent position may help to prevent carpal tunnel syndrome. People who must work long hours at a computer keyboard, for example, may need to take advantage of recent advances in ergonomics and position the keyboard and computer components in a way that increases efficiency and decreases stress. Early use of a splint may also be helpful for persons whose jobs put them at risk of carpal tunnel syndrome.

Resources

BOOKS

Asbury, Arthur K. "Carpal Tunnel Syndrome." In Harrison's Principles of Internal Medicine. edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998.

Crouch, Tammy. Carpal Tunnel Syndrome and Repetitive Stress Injuries. Berkeley, CA: Frog, 1995.

PERIODICALS

Branco, Kenneth, and Margaret A. Naeser. "Carpal Tunnel Syndrome: Clinical Outcome After Low-Level Laser Acupuncture, Microamps Transcutaneous Electrical Nerve Stimulation, and Other Alternative Therapies-An Open Protocol Study." The Journal of Alternative and Complementary Medicine 5 (1999):5-26.

Brody, Jane E. "Experts on Carpal Tunnel Syndrome Say that Conservative Treatment is the Best First Approach." The New York Times. 119 (February 28, 1996): B9+.

"Carpal Tunnel Syndrome." Postgraduate Medicine 98 no. 3 (September 1995): 216.

Glazer, Sarah. "Repetitive Stress Injury: A Modern Malady." The Washington Post 110 (March 12, 1996): WH12.

"Guidelines Promote Electrodiagnostic Studies for CTS." Case Management Advisor (August 2002): S1.

Lucas, B. "Nonsurgical Technique for Carpal Tunnel Syndrome." Patient Care 33 (March 15, 1999):12.

Seiler, John Gray. "Carpal Tunnel Syndrome: Update on Diagnostic Testing and Treatment Options" Consultant. 37 no. 5 (May 1997):1233+.

"Surgery Beats Splints for Wrist Syndrome." Science News (September 28, 2002): 205.

ORGANIZATIONS

Association for Repetitive Motion Syndromes. P.O. Box 514, Santa Rosa, CA 95402. (707) 571-0397.

Belinda Rowland

Teresa G. Odle

Carpal Tunnel Syndrome

Definition

Carpal tunnel syndrome is a 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."

Women between the ages of 30 and 60 have the highest rates of carpal tunnel syndrome. Research has demonstrated that carpal tunnel syndrome is a very significant cause of missed work days due to pain. In 1995, about $270 million was spent on sick days taken for pain from repetitive motion injuries.

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 to carpal tunnel syndrome. Other conditions which increase the risk for carpal tunnel syndrome include some forms of arthritis and various injuries to the arm and wrist (including fractures, sprains, and dislocations ). Furthermore, activities which cause an individual to repeatedly bend the wrist inward toward the forearm can predispose to carpal tunnel syndrome. Certain jobs which require repeated strong wrist motions carry a relatively high risk of carpal tunnel syndrome. Injuries of this type are referred to as "repetitive motion" injuries, and are more frequent among secretaries doing a lot of typing, 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 palm surface of the hand, and into the thumb, forefinger, middle finger, and half of the ring finger. Some individuals notice a shooting pain which goes from the wrist up the arm, or down into the hand and fingers. 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, or even paralysis of the thumb and fingers of the affected hand.

Diagnosis

The diagnosis of carpal tunnel syndrome is made in part by checking to see whether the patient's symptoms can be brought on by holding his or her hand in position with wrist bent for about a minute. Wrist x rays are often taken to rule out the possibility of a tumor causing pressure on the median nerve. A physician 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. 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.

Treatment

Carpal tunnel syndrome is initially treated with splints, which support the wrist and prevent it from flexing inward into the position which exacerbates median nerve compression. Some people get significant relief by wearing such splints to sleep at night, while others will need to wear the splints all day, especially if they are performing jobs which stress the wrist. Ibuprofen or other nonsteroidal anti-inflammatory drugs may be prescribed to decrease pain and swelling. When carpal tunnel syndrome is more advanced, injection of steroids into the wrist to decrease inflammation may be necessary.

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 that ligament which 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 without the patient having to be made unconscious. 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. Recovery from this type of surgery is usually quick and without complications.

Prognosis

Without treatment, 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 with splinting and anti-inflammatory agents. For those who go on to require surgery, about 95% will have complete cessation of symptoms.

Prevention

Prevention is generally aimed at becoming aware of the repetitive motions which one must make which could 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 try to position the keyboard and computer components in a way that increases efficiency and decreases stress. Early use of a splint may also be helpful for people whose jobs increase the risk of carpal tunnel syndrome.

Resources

PERIODICALS

Seiler, John Gray. "Carpal Tunnel Syndrome: Update on Diagnostic Testing and Treatment Options." Consultant 37, no. 5 (May 1997): 1233.

KEY TERMS

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

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.