Carpal Tunnel
Syndrome
By Jonathan
Cluett, M.D., About.com Guide
Carpal tunnel
syndrome occurs when a nerve is pinched in the wrist. This nerve, called the
median nerve, is the connection from the brain and spinal cord, down to the
finger tips. In patients with carpal tunnel syndrome, the median nerve is
pinched as it passes through the wrist. Because of the compression, the nerve
does not function properly.
How does the
median nerve normally work?
Nerves are
structures that relay messages to and from your brain. The nerve sends a
message to your muscles when you want to move, and the nerve relays messages to
your brain about sensations. Nerves control specific muscles, and nerves
provide sensations for your body. The median nerve (the nerve that is affected
in carpal tunnel syndrome) supplies messages to specific muscles of the hand.
The median nerve also sends sensory information from most of the palm side of
your hand and the thumb, forefinger, middle finger, and part of the ring
finger.
The median
nerve travels from branches off the spinal cord, down the arm, and into the
wrist and hand. In the wrist, the median nerve passes through the carpal
tunnel. Carpal comes from the Greek word for 'wrist'-that's what gives the
tunnel its name. The carpal tunnel is actually made up of the wrist bones on
the bottom, and a tight ligament on the top. The ligament that makes up the top
of the carpal tunnel is not flexible, nor are the wrist bones. Coursing through
the carpal tunnel is the median nerve, as well as tendons that attach to your
fingers.
What is
carpal tunnel syndrome?
Carpal tunnel
syndrome is caused when there is pressure in the carpal tunnel that compresses
the median nerve, causing the nerve to function improperly. Because the carpal
tunnel is surrounded by bone on one side, and an inflexible ligament on the
other, if pressure builds, the nerve has nowhere to go. Simply put, in carpal
tunnel syndrome the nerve gets squished.
When carpal
tunnel syndrome occurs, the median nerve is pinched, and the normal functions
(as described above) are impaired.
Problems that can occur in carpal tunnel
syndrome include:
Pain
Numbness
Tingling
Weakness
People can
have a wide variety of carpal tunnel syndrome symptoms, but the condition
typically causes hand and wrist pain, weakness in specific muscles of the hand,
and abnormal sensations including tingling and numbness in specific areas of
the hand supplied by the pinched nerve.
The most
common symptoms of carpal tunnel syndrome are:
Hand and
finger pain
Tingling
sensations of the fingers
Numbness in
the fingers
One common
symptom of carpal tunnel syndrome is that people find shaking the hand often
relieves these symptoms. Pain may extend up the arm, and the pain from carpal
tunnel syndrome is often worst at night. Often patients find they are awakened
at night, and have to shake out their hand to get the tingling in their fingers
to resolve. Other activities including driving and typing can aggravate
symptoms of carpal tunnel syndrome.
How is the
diagnosis of carpal tunnel syndrome made?
In diagnosing
carpal tunnel syndrome, your doctor will look for changes in sensation and for
weakness in the muscles controlled by the median nerve. Several simple tests
can be done to elicit carpal tunnel syndrome symptoms to diagnose the disorder.
Two common tests are called Tinel's and Phalen's Test.
Tinel's Sign
Tinel's test
is performed by tapping the median nerve along its course in the wrist. A
positive test is found when this causes worsening of the tingling in the
fingers when the nerve is tapped.
Phalen's Sign
Phalen's test
is done by pushing the back of your hands together for one minute. This
compresses the carpal tunnel and is also positive when it causes the same
symptoms you have been experiencing with your carpal tunnel syndrome.
What other
tests can be done to make a diagnosis of carpal tunnel syndrome?
Definitive
analysis of nerve function can be performed with studies of how well an
electric impulse conducts along the nerve. A device called an EMG can detect
abnormalities in nerve impulse conduction; these nerve conduction abnormalities
are the cause of carpal tunnel syndrome symptoms. The EMG does not always need
to be performed, but may be done if a patient's symptoms are not typical of
carpal tunnel syndrome.
What causes
the carpal tunnel syndrome symptoms?
As stated
previously, the symptoms of carpal tunnel syndrome are caused by compression of
the median nerve as it courses through the carpal tunnel in the wrist. Some
systemic conditions are associated with carpal tunnel syndrome, including
diabetes, hypothyroidism, arthritis, and pregnancy.
Recently, the
computer keyboard has been the target of blame for many patients with carpal
tunnel syndrome. Whether or not typing causes carpal tunnel syndrome is still
controversial, yet it seems appropriate that anyone who spends much time at the
computer be familiar with techniques in prevention of this problem. Similarly,
other activities that depend on wrist motion such as shop work, weight lifting,
and racquet sports have been associated with carpal tunnel syndrome. Carpal
tunnel syndrome is most common in the middle aged and elderly, with over 80% of
patients over 40 years of age.
Carpal Tunnel
Syndrome Treatment
Carpal tunnel
syndrome treatment usually begins conservatively, and moves to more aggressive
and invasive techniques if the symptoms of carpal tunnel syndrome persist.
The initial
carpal tunnel syndrome treatment steps include some medications and splints.
Anti-Inflammatory
Medications
Anti-inflammatory
medications or NSAIDs (e.g. Motrin or Advil) can decrease inflammation in the
carpal tunnel and can also decrease carpal tunnel syndrome symptoms.
Wrist Brace
The brace
helps to stabilize the carpal tunnel in its neutral position. The carpal tunnel
is at its widest diameter in this position and the nerve is least compressed.
Wearing the splint at night is especially important, as well as during
activities that tend to irritate your carpal tunnel syndrome.
What if my
carpal tunnel syndrome symptoms persist?
The next step
in carpal tunnel syndrome treatment can be a cortisone injection to the area to
decrease inflammation around the nerve. The cortisone injection is often
effective because the medication is delivered to the source of the problem;
however, steroids shoulder be injected sparingly, and if the carpal tunnel
syndrome returns, surgery may be considered.
Injections of
cortisone into the carpal tunnel work about 80% of the time. However, this
relief is often temporary, and the symptoms may return. Recent research has
shown that the carpal tunnel injection is probably an effective treatment for
at least one year in many patients. The injection can also be very helpful in
situations where the diagnosis of carpal tunnel syndrome is unclear.
If these
treatments do not work, do I need surgery?
Surgical
treatments are available and effective in the treatment of carpal tunnel
syndrome. The most common procedure is the carpal tunnel release. A carpal
tunnel release involves making an incision in the fibrous sheath around the
carpal tunnel. By releasing tension in the carpal tunnel, the pressure is
removed from the nerve.
If a carpal
tunnel release is done, it is most commonly performed by a "open"
technique. To perform an open carpal tunnel release, your surgeon makes a 4
centimeter incision down the middle of the palm. Your surgeon carefully
dissects the tissues down to the carpal tunnel. The carpal tunnel is opened up
to relieve the pressure on the nerve. The surgery only takes about 15 minutes,
and can be performed under local, regional, or general anesthesia.
What is an
endoscopic carpal tunnel release?
A carpal
tunnel release can now be done through a small incision and a camera called an
endoscope. In this procedure, a small (about 1 centimeter) incision is made by
the wrist. Through this incision, a small camera is inserted into the carpal
tunnel. A small knife attached to the camera is then used to release the carpal
tunnel.
Both
procedures are effective in the treatment of carpal tunnel syndrome. Many
surgeons prefer the open carpal tunnel release because it is easy to ensure
there is adequate relief of tension around the nerve. Furthermore, the incision
from an open carpal tunnel release tends to heal well with few problems. Some
surgeons have also reported complications of the endoscopic carpal tunnel
release due to inadvertent cutting of a nerve.
What are the
complications of a carpal tunnel release?
The most
common complications of surgical release of the carpal tunnel are injury to the
nerve and incision pain. Injury to the nerve usually results in a permanent
area of numbness around the base of the thumb; this occurs in about 5-8% of
surgeries. Prolonged pain at the site of the incision is uncommon, but can
occur in about 1-2% of cases.
Prevention of
Carpal Tunnel Syndrome
Carpal tunnel
syndrome is best managed in its early stages of the condition. If you feel the
onset of symptoms that seem consistent with carpal tunnel syndrome, you should
seek medical attention as soon as possible, and begin conservative therapy.
To prevent
these symptoms there are a few simple exercises that can easily be done at
home. By routinely performing these exercises to warm up the wrist joint,
people often avoid the symptoms of carpal tunnel syndrome.
If you are
going to be working with your hands for an extended period of time, whether it
be at the computer, in the shop, or in the gym, you should always stretch and
warm-up the joint. Furthermore, the are ways to maintain the joint in a
'wrist-neutral' position; this decreases the pressure in the carpal tunnel. A
wrist brace can help keep the wrist in this position.
At the
keyboard you can use a cushioned "wrist rest;" also, specially
modified keyboards and computer mice are being developed and tested as
alternatives to traditional equipment. Sports-related carpal tunnel syndrome
can be prevented with proper technique and braces that support the wrist during
activities.
Sources:
Adams, BD.
"Endoscopic Carpal Tunnel Release" J. Am. Acad. Ortho. Surg., May
1994; 2: 179 - 184.
Osterman AL,
Whitman M, Porta LD. "Nonoperative carpal tunnel syndrome treatment"
Hand Clin. 2002 May;18(2):279-89.
