Carpal Tunnel Syndrome
What
is carpal tunnel syndrome?
What are the symptoms of carpal tunnel syndrome?
What are the causes of carpal tunnel syndrome?
Who is at risk of developing carpal tunnel syndrome?
How is carpal tunnel syndrome diagnosed?
How can carpal tunnel syndrome be treated?
How can carpal tunnel syndrome be prevented?
What research is being done?
Where can I go for more information?
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 ¾ houses the
median nerve and tendons. Sometimes, thickening from irritated tendons
or other swelling narrows the tunnel and causes the median nerve
to be compressed. The result may be pain, weakness, or numbness
in the hand and wrist, radiating up the arm. Although painful sensations
may indicate other conditions, carpal tunnel syndrome is the most
common and widely known of the entrapment neuropathies in which
the body's peripheral nerves are compressed or traumatized.
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.
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. Most likely
the disorder is due to a congenital predisposition - the carpal
tunnel is simply smaller in some people than in others. Other contributing
factors include trauma or injury to the wrist that cause swelling,
such as sprain or fracture; overactivity of the pituitary gland;
hypothyroidism; rheumatoid arthritis; mechanical problems in the
wrist joint; work stress; repeated use of vibrating hand tools;
fluid retention during pregnancy or menopause; or the development
of a cyst or tumor in the canal. In some cases no cause can be identified.
Causes
of carpal tunnel syndrome
There
is little clinical data to prove whether repetitive and forceful
movements of the hand and wrist during work or leisure activities
can cause carpal tunnel syndrome. Repeated motions performed
in the course of normal work or other daily activities can result
in repetitive motion disorders such as bursitis and tendonitis.
Writer's cramp - a condition in which a lack of fine motor skill
coordination and ache and pressure in the fingers, wrist, or forearm
is brought on by repetitive activity - is not a symptom of carpal
tunnel syndrome.
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 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.
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. A 2001 study by the Mayo Clinic found heavy computer
use (up to 7 hours a day) did not increase a person's risk of developing
carpal tunnel syndrome.
During
1998, an estimated three of every 10,000 workers lost time from
work because of carpal tunnel syndrome. Half of these workers
missed more than 10 days of work. The average lifetime cost of carpal
tunnel syndrome, including medical bills and lost time from work,
is estimated to be about $30,000 for each injured worker.
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 patient's complaints
are related to daily activities or to an underlying disorder, and
can rule out other painful conditions that mimic carpal tunnel syndrome.
The wrist is examined for tenderness, swelling, warmth, and discoloration.
Each finger should be tested for sensation, and the muscles at the
base of the hand should be examined for strength and signs of atrophy.
Routine laboratory tests and X-rays can reveal 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 patient'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 patient
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 patients 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.
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
such as prednisone or lidocaine, injected directly into the wrist
or taken by mouth, can relieve pressure on the median nerve and
provide immediate, temporary relief to persons with mild or intermittent
symptoms. (Caution: persons with diabetes and those who may be predisposed
to diabetes should note that prolonged use of corticosteroids can
make it difficult to regulate insulin levels. Corticosterioids 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.
Exercise
- Stretching and strengthening exercises can be helpful in people
whose symptoms have abated. These exercises may be supervised by
a physical therapist, who is trained to use exercises to treat physical
impairments, or an occupational therapist, who is trained in evaluating
people with physical impairments and helping them build skills to
improve their health and well-being.
Alternative
therapies - Acupuncture and chiropractic care have benefited
some patients but their effectiveness remains unproved. An exception
is yoga, which has been shown to reduce pain and improve grip strength
among patients with carpal tunnel syndrome.
Surgery
Carpal
tunnel release is one of the most common surgical procedures
in the United States. Generally recommended if symptoms last for
6 months, surgery involves severing the band of tissue around the
wrist to reduce pressure on the median nerve. Surgery is done under
local anesthesia and does not require an overnight hospital stay.
Many patients require surgery on both hands. The following are types
of carpal tunnel release surgery:
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 ½" 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, full recovery
from carpal tunnel surgery can take months. Some patients may
have infection, nerve damage, stiffness, and pain at the scar. Occasionally
the wrist loses strength because the carpal ligament is cut. Patients
should undergo physical therapy after surgery to restore wrist strength.
Some patients 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 patients recover completely.
How
can carpal tunnel syndrome be prevented?
At the workplace, workers can do on-the-job 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?
The National Institute of Neurological Disorders and Stroke (NINDS),
a part of the National Institutes of Health, is the federal government's
leading supporter of biomedical research on neuropathy, including
carpal tunnel syndrome. Scientists are studying the chronology of
events that occur with carpal tunnel syndrome in order to better
understand, treat, and prevent this ailment. By determining distinct
biomechanical factors related to pain, such as specific joint angles,
motions, force, and progression over time, researchers are finding
new ways to limit or prevent carpal tunnel syndrome in the workplace
and decrease other costly and disabling occupational illnesses.
Percutaneous
balloon carpal tunnel-plasty is an experimental technique that can
ease carpal tunnel pain without cutting the carpal ligament. In
this procedure, a ¼-inch cut is made at the base of the palm.
The doctor then inserts a balloon through a catheter under the carpal
ligament and inflates the balloon to stretch the ligament and free
the nerve. Patients in one small study of pertucaneous balloon carpal
tunnel-plasty reported relief of symptoms with no postoperative
complications; most of them were back to work within 2 two weeks.
This experimental technique is not yet widely available.
Randomized
clinical trials are being designed to evaluate the effectiveness
of educational interventions in reducing the incidence of carpal
tunnel syndrome and upper extremity cumulative trauma disorders.
Data to be collected from an NINDS-sponsored clinical study of carpal
tunnel syndrome among construction apprentices will provide a better
understanding of the specific work factors associated with the disorder,
furnish pilot data for planning future projects to study its natural
history, and assist in developing strategies to prevent its occurrence
among construction and other workers. Other research will discern
differences between the relatively new carpal compression test (in
which the examiner applies moderate pressure with both thumbs directly
on the carpal tunnel and underlying median nerve, at the transverse
carpal ligament) and the pressure provocative test (in which a cuff
placed at the anterior of the carpal tunnel is inflated, followed
by direct pressure on the median nerve) in predicting carpal tunnel
syndrome. Scientists are also investigating the use of alternative
therapies, such as acupuncture, to prevent and treat this disorder.
Where
can I go for more information?
For more information about carpal tunnel syndrome or other neuropathies
of the nervous system, you may wish to contact:
American
Academy of Orthopaedic Surgeons
6300 North River Road
Rosemont, IL 60018-4262
(847) 823-7186
(800) 346-AAOS (2267)
http://www.aaos.org
American
Chronic Pain Association (ACPA)
P.O. Box 850
Rocklin, CA 95677-0850
ACPA@pacbell.net
http://www.theacpa.org
Tel: 916-632-0922 800-533-3231
Fax: 916-632-3208
Centers for Disease Control and Prevention (CDCP)
1600 Clifton Road, N.E.
Atlanta, GA 30333
inquiry@cdc.gov
http://www.cdc.gov
Tel: 800-311-3435
National
Chronic Pain Outreach Association (NCPOA)
P.O. Box 274
Millboro, VA 24460
ncpoa@cfw.com
http://www.chronicpain.org
Tel: 540-862-9437
Fax: 540-862-9485
National Institute of Arthritis and Musculoskeletal and Skin Diseases
(NIAMS)
National Institutes of Health
Bldg. 31, Rm. 4C05
Bethesda, MD 20892-2350
NIAMSInfo@mail.nih.gov
http://www.nih.gov/niams
Tel: 301-496-8188 877-22-NIAMS (226-4267)
Occupational
Safety & Health Administration
US Department of Labor
200 Constitution Avenue, NW
Washington, DC 20210
http://www.osha.gov
Tel: 800-321-OSHA (6742)
For
information on other neurological disorders or research programs
funded by the National Institute of Neurological Disorders and Stroke,
contact the Institute's Brain Resources and Information Network
(BRAIN) at:
BRAIN
P.O. Box 5801
Bethesda, MD 20824
(800) 352-9424
www.ninds.nih.gov
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