|Carpel 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.
Risk factors for 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
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.
Diagnosis of of Carpal Tunnel Syndrome
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
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.
Prevention of of Carpal Tunnel Syndrome
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.