General Adult Health Information
Carpal Tunnel Syndrome
Carpal Tunnel Syndrome is a common problem that affects the hand and wrist. This condition, or syndrome, has become the focus of attention in the last few years because it may be linked to jobs that require repetitive use of the hands - such as typing, video games, and and carpentry.
Anatomy
The median nerve runs from the shoulder down into the hand. It provides
sensation to the thumb, index finger, long finger, and half of the ring finger. This nerve
also supplies a branch to the muscles of the thumb, the thenar
muscles
One of the first symptoms of Carpal Tunnel Syndrome (CTS)
is numbness (image 42K) along the median Nerve. Numbness is quickly followed by pain in the same area.
The pain can also travel up the arm to the shoulder, and, sometimes into the neck. If CTS
is allowed to progress, weakness of the thenar muscles (image 45K) can occur. This weakness results in an
inability to oppose the other fingers with the thumb and thereby hindering your grasp.
Looking at a cross section (image 46K) of the wrist allows us to see the anatomy of
the carpal tunnel (image 13K).
The carpal tunnel is an opening into the hand. The bottom of the tunnel
it is made up of the bones of the wrist. The top of the tunnel is made up of the
transverse carpal ligament. Through this tunnel, the median nerve and the flexor tendons
run into the hand. Looking closer (image
12K), we can see that the median nerve lies just under the
transverse carpal ligament.
The flexor tendons allow us to move the hand, such as when we grasp
objects. The tendons are covered by a material called Tenosynovium
(image 23K). The Tenosynovium is very
slippery. It allows the tendons to glide against each other as hand opens and closes. Any
condition which irritates or causes inflammation of the tendons
(image 42K) can result in swelling and thickening of the tenosynovium. As the tendons begin to swell and thicken, pressure builds
up in the carpal tunnel. This is because the bones and ligaments that make up the tunnel
are not able to expand and make room for the swelling. This increased pressure in the
Carpal Tunnel begins to push the median nerve against the transverse carpal ligament.
Eventually, the pressure reaches a point when the nerve can no longer function normally.
The result is pain and numbness in the hand.
There are many conditions which can irritate and inflame the
tenosynovium, and lead to carpal tunnel syndrome. Different types of arthritis can
directly cause inflammation of the tenosynovium. A fracture of the wrist bones may cause
carpal tunnel syndrome to happen later if the healed bone fragments irritate the flexor
tendons. The Key Concept (image 20K) to know is that anything which
causes abnormal pressure on the Median Nerve will result in the symptoms of pain,
numbness, and weakness of carpal tunnel syndrome.
Physicians have learned that activities that involve highly repetitive use of the hands
can result in carpal tunnel syndrome; and is thought to be caused by inflammation of the
tenosynovium due to overuse.
Diagnosis
Evaluation begins by your doctor obtaining a history of the problem,
followed by a thorough physical examination. Your description of the symptoms and the
physical examination are the most important parts in the diagnosis of carpal tunnel
syndrome. Commonly, patients will complain first of waking in the middle of the night with
pain and a feeling that the whole hand is asleep. Careful investigation usually shows that
the little finger is unaffected This can be a key piece of information to make the diagnosis.
Other complaints include numbness while using the hand for gripping activities, such as
sweeping, hammering, or driving. The major physical findings reflect that pressure is
increased in the carpal tunnel.
If more information is needed to make the diagnosis, electrical studies
of the nerves in the wrist may be requested by your doctor. Several tests are available to
see how well the Median Nerve is functioning, including the Nerve
Conduction Velocity (NCV) This test measures how fast nerve impulses are conducted through the nerve.
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