U.S. DEPARTMENT OF HEALTH

AND HUMAN SERVICES

Public Health Service

National Institutes of Health

Carpal Tunnel 

Syndrome

1

Carpal Tunnel 

Syndrome

You’re 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.

What is carpal tunnel syndrome? 

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 — a 

narrow, rigid passageway of ligament and 

bones at the base of the hand — 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. 
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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.

What are the symptoms of carpal 

tunnel syndrome?

Symptoms 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 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. As symptoms worsen, people 

might feel tingling during the day. Decreased 

grip strength may make it difficult to form 

a fist, grasp small objects, or perform other 

manual tasks. In chronic and/or untreated 

cases, the muscles at the base of the thumb 

may waste away. Some people are unable to 

tell between hot and cold by touch. 
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What are the causes of carpal 

tunnel syndrome? 

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. There may be a congenital 

predisposition — the carpal tunnel is simply 

smaller in some people than in others. Other 

contributing factors include trauma or injury 

to the wrist that causes swelling, such as 

sprain or fracture; obesity, 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; or the development of a cyst 

or tumor in the canal. In some cases no cause 

can be identified.

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. Other 

disorders such as bursitis and tendonitis 

have been associated with repeated motions 

performed in the course of normal work or 

other daily activities. Writer’s cramp — a 

condition in which a lack of fine motor skill 

coordination and ache and pressure in the 

fingers, wrist, or forearm — may also be 

brought on by repetitive activity.
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Who is at risk of developing carpal 

tunnel syndrome?

Women are three times more likely than men to develop carpal tunnel 

syndrome, perhaps because the carpal 

tunnel itself may be smaller in some women 

than in men. The dominant hand is usually 

affected first and produces the most severe 

pain. 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. Carpal 

tunnel syndrome usually occurs only in 

adults.

In the workplace, 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 — manufacturing, sewing, 

finishing, cleaning, and meat, poultry, or fish 

packing. In fact, carpal tunnel syndrome is 

three times more common among assemblers 

than among data-entry personnel.

How is carpal tunnel syndrome diagnosed?

Early diagnosis and treatment are important to avoid permanent damage to the 

median nerve. A physical examination of the 

hands, arms, shoulders, and neck can help 

determine if the individual’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, and discoloration. Each finger should 

be tested for sensation, and the muscles at 
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the base of the hand should be examined for 

strength and signs of atrophy. Routine laboratory tests and X-rays can reveal diabetes, 

arthritis, and fractures.

Physicians can use specific tests to try to 

produce the symptoms of carpal tunnel 

syndrome. In the Tinel test, the doctor taps on 

or presses on the median nerve in the person’s 

wrist. The test is positive when tingling in 

the fingers or a resultant shock-like sensation occurs. The Phalen, or wrist-flexion, test 

involves having the individual hold his or her 

forearms upright by pointing the fingers down 

and pressing the backs of the hands together. 

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 

individuals to try to make a movement that 

brings on symptoms.

Often it is 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 (MRI) can show 

the anatomy of the wrist but to date has not 

been especially useful in diagnosing carpal 

tunnel syndrome.
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How is carpal tunnel syndrome treated?

Treatments for carpal tunnel syndrome should begin as early as possible, under a 

doctor’s direction. Underlying causes such as 

diabetes or arthritis should be treated first. 

Initial treatment 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.

Non-surgical treatments

Drugs — In special circumstances, various 

drugs can ease the pain and swelling 

associated with carpal tunnel syndrome. 

Nonsteroidal anti-inflammatory drugs, such 

as aspirin, ibuprofen, and other nonprescription pain relievers, may ease symptoms that 

have been present for a short time or have 

been caused by strenuous activity. Orally 

administered diuretics (“water pills”) can 

decrease swelling. Corticosteroids, injected 

directly into the wrist, or taken as prednisone by mouth, may reduce the pressure on 

the median nerve and provide immediate, 

temporary relief to persons with mild to 

moderate symptoms. (Caution: persons with 

diabetes and those who may be predisposed 

to diabetes should note that prolonged use of 

corticosteroids can make it difficult to regulate insulin levels. Corticosteroids should 

not be taken without a doctor’s prescription.) 

Additionally, some studies show that vitamin 

B6 (pyridoxine) supplements may ease the 

symptoms of carpal tunnel syndrome.
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Exercise — Stretching and strengthening 

exercises can be helpful in people whose 

symptoms have decreased or ended. 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.

Alternative therapies — Acupuncture and 

chiropractic care have benefited some individuals but their effectiveness remains 

unproven. An exception is yoga, which has 

been shown to reduce pain and improve 

grip strength among people with carpal 

tunnel syndrome.

Surgery

Carpal tunnel release is one of the most 

common surgical procedures in the United 

States. Generally, surgery is recommended 

if symptoms last for 6 months or if there is 

evidence of muscle damage in severe cases 

of carpal tunnel syndrome. 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 individuals require surgery on both 

hands. The following are types of carpal 

tunnel release surgery:
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Open release surgery, the traditional procedure used to correct carpal tunnel syndrome, 

consists of making an incision up to 2 inches 

in the wrist and then cutting the carpal 

ligament to enlarge the carpal tunnel. The 

procedure is generally done under local anesthesia on an outpatient basis, unless there are 

unusual medical considerations.

Endoscopic surgery may allow faster functional 

recovery and less postoperative discomfort than traditional open release surgery. 

The surgeon makes two incisions (about 

1⁄2” each) in the wrist and palm, inserts a 

camera attached to a tube, observes the 

tissue on a screen, and cuts the carpal ligament (the tissue that holds joints together). 

This two-portal endoscopic surgery, generally 

performed under local anesthesia, is effective 

and minimizes scarring and scar tenderness, 

if any. One-portal endoscopic surgery for 

carpal tunnel syndrome is also available.

Although symptoms may be relieved immediately after surgery, recovery from carpal 

tunnel surgery can take months. Some individuals may have infection, nerve damage, 

stiffness, and pain at the scar. Occasionally 

the wrist loses strength because the carpal 

ligament is cut. Individuals should undergo 

physical therapy after surgery to restore wrist 

strength. Some people may need to adjust 

job duties or even change jobs after recovery 

from surgery.

Recurrence of carpal tunnel syndrome 

following treatment is rare. The majority of 

people recover completely.
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How can carpal tunnel syndrome 

be prevented?

At the workplace, workers can do on-thejob conditioning, perform stretching 

exercises, take frequent rest breaks, wear 

splints to keep wrists straight, and 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.

What research is being done?

Within the National Institutes of Health (NIH), the National Institute of 

Neurological Disorders and Stroke (NINDS) is 

the Federal government’s leading supporter 

of biomedical research on neuropathy. 

Another NIH component, the National 

Institute of Arthritis and Musculoskeletal and 

Skin Disorders (NIAMS), supports research 

on tissue damage associated with repetitive 

motion disorders, including carpal tunnel 

syndrome. Scientists supported by the NINDS 

are studying the factors that lead to longlasting neuropathies, and how the affected 

nerves are related to symptoms of pain, 

numbness, and functional loss. Researchers 

also are examining biomechanical stresses 
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that contribute to the nerve damage responsible for symptoms of carpal tunnel syndrome 

in order to better understand, treat, and 

prevent this ailment. By quantifying the 

distinct biomechanical pressures from fluid 

and anatomical structures, researchers are 

finding ways to limit or prevent carpal tunnel 

syndrome in the workplace and decrease other 

costly and disabling occupational illnesses.

Scientists funded through the NIH’s National 

Center for Complementary and Alternative 

Medicine are investigating the effects of 

acupuncture on pain, loss of median nerve 

function, and changes in the brain associated 

with carpal tunnel syndrome. In addition, a 

randomized clinical trial designed to evaluate 

the effectiveness of osteopathic manipulative treatment in conjunction with standard 

medical care is underway. Evaluations of 

these therapies and other therapies will help 

to tailor patient treatment programs.

Where can I go for more information?

T he National Institute of Neurological Disorders and Stroke conducts and 

support a wide range of research on neurological disorders, including neuropathy. For 

information on other neurological disorders 

contact in the Institute’s Brain Resources and 

Information Network (BRAIN) at:

BRAIN

P.O. Box 5801

Bethesda, MD 20824

301-496-5751

800-352-9424

www.ninds.nih.gov
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Additional information is available from the 

following organizations:

American Academy of Orthopaedic Surgeons

6300 North River Road

Rosemont, IL 60018-4262

847-823-7186

800-346-2267

www.aaos.org

American Chronic Pain Association

P.O. Box 850

Rocklin, CA 95677-0850

916-632-0922

800-533-3231

www.theacpa.org

National Center for Complementary and 

Alternative Medicine Clearinghouse

National Institutes of Health, DHHS

P.O. Box 7923

Gaithersburg, MD 20898-7923

301-519-3153

888-644-6226

www.nccam.nih.gov/health/clearinghouse

National Institute of Arthritis and 

Musculoskeletal and Skin Diseases

National Institutes of Health, DHHS

Building 31, Room 4C05

Bethesda, MD 20892-2350

301-496-8188

www.niams.nih.gov
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National Institute for Occupational Safety 

and Health (NIOSH)

Centers for Disease Control and 

Prevention, DHHS

1600 Clifton Road

Atlanta, GA 30333

404-639-3311

800-232-4636

www.cdc.gov/niosh

U.S. Department of Labor

Occupational Safety and Health 

Administration (OSHA)

Office of Public Affairs

200 Constitution Avenue, NW

Washington, DC 20210

202-693-1999

www.osha.gov

NIH . . . Turning Discovery into Health

Prepared by:

Office of Communications and Public Liaison

National Institute of Neurological 

Disorders and Stroke

National Institutes of Health

Department of Health and Human Services

Bethesda, Maryland 20892-2540

NIH Publication No. 12-4898 July 2012