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.
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
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.
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.
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 the drug lidocaine can be
injected directly into the wrist or taken by mouth (in the case of
prednisone) to 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.
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
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
© 2010 Vivacare. Last updated May 28, 2010
Vivacare public information from The National Institute of Neurological Disorders and Stroke