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
Symptoms of carpal tunnel syndrome 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.
Diagnosis of carpal tunnel
syndrome is based on the history of symptoms,
presence of risk factors, physical and neurological
examination, and diagnostic tests.
Neurological examination includes testing the
muscle that abducts the thumb away from the palm (called
the abductor pollicis brevis), as well as the ability to
bend the thumb toward the palm (flexion) and ability to
move the thumb toward the other fingers (opposition).
Tinel's sign (tapping the palm sharply produces
tingling) and Phalen's sign (pressing the backs of the
hands together for about 1 minute produces pain and
numbness) are also evaluated.
Nerve conduction velocity (NCV) and
electromyography (EMG) are used to evaluate nerve
and muscle function. NCV involves placing electrodes on
the skin above the median nerve to monitor the speed at
which an impulse travels along the nerve. EMG involves
placing small electrodes into the abductor pollicis
brevis muscle to detect abnormalities that may indicate
that the median nerve supplying the muscle is damaged.
These tests, which are often referred to as EMG/NCV
studies, may reveal delayed nerve conduction in the
Differential diagnosis includes inflammation (radiculopathy)
of nerve roots C6 and C7 in the cervical spine and
compression of the median nerve outside the carpal
Treatment for carpal tunnel syndrome involves
activity modification and rest, splinting, medication
(including injection therapy), and surgery.
Activity Modification. The first line of treatment usually involves
resting the wrist and avoiding activity and movement
that worsen symptoms. The wrist may be immobilized using
a removable splint. For most patients, wearing
the splint at night relieves symptoms, and for others,
wearing the splint while at work helps.
When the condition is work related, a work-site
evaluation may be performed. An occupational therapist,
physical therapist, or rehabilitation consultant is
often able to suggest modifications to relieve the
condition. Wrist and body positioning can often be
improved using ergonomics (science used to fit a
job to a person's anatomy and physiology). Improving
body position, stretching periodically, and changing
positions frequently may help alleviate symptoms.
Medications. Nonsteroidal anti-inflammatory drugs (NSAIDs;
e.g., ibuprofen [Advil®, Motrin®]) may be used to
relieve pain. Due to potentially severe gastrointestinal
and cardiovascular side effects, NSAIDs should
only be used as instructed.
Cortisone (a corticosteroid) may be injected
into the area around the carpal tunnel to reduce
inflammation and nerve compression. Lidocaine (a
local anesthetic) may be combined with cortisone, or
injected alone, to relieve pain. Lidocaine combined with
cortisone produces longer-lasting pain relief.
Surgery often provides permanent relief of symptoms
when other treatment measures fail. Carpal tunnel
release involves cutting the transverse carpal
ligament to relieve entrapment of the median nerve. It
is usually performed on an outpatient basis, using
local, regional, or general anesthesia.
Carpal tunnel release can be performed as open or
endoscopic surgery. In open surgery, an incision
is made through underlying tissue in the palm of the
hand to reach the carpal ligament.
In endoscopic surgery, a smaller incision is
made in the wrist and an endoscope is used to locate the
carpal ligament. Surgical instruments are inserted
through the incision or through a small incision in the
palm and the ligament is cut.
Recovery usually takes 3 to 12 months. If compression
has caused permanent nerve damage, carpal tunnel release
surgery may not be effective.
Complications associated with the surgery
include the following:
- Adverse reaction to anesthesia
- Burning pain caused by nerve damage (causalgia)
- Incomplete release of the ligament (more common
in endoscopic surgery; requires additional surgery)
Nerve damage (rare)
Laceration of a nerve, blood vessel, or tendon is
more common in the endoscopic procedure and this
approach is not recommended for patients who have small
Prognosis. Nonsurgical and surgical treatment for carpal tunnel
syndrome relieves symptoms in approximately 90% of
Maintaining proper posture, body position, and
technique when performing repetitive wrist movements may
help to prevent carpal tunnel syndrome. It is important
to relax, move around, and change positions frequently
when performing any one task for an extended period of