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Carpal tunnel syndrome,
or CTS, is a condition in the wrist caused by the compression
of the median nerve. This compression can make parts of the hand numb,
tingle, or have occasional pain. CTS is a very common problem. More and
more cases are from trauma caused by repetitious movements, especially
computer use. While CTS can often be successfully treated non-operatively,
surgery may be necessary in some cases.
What is the carpal tunnel?
The carpal tunnel is a narrow channel on the palm side of
the wrist. Eight bones, called carpals, form an arch creating
three rigid walls of the channel. A tight, broad band of tissue, called
the transverse carpal ligament, covers the arch and forms
a roof over the channel. This "tunnel" is the protective passage for the
median nerve and all nine tendons that bend the fingers
and thumb.
A nerve has two functions:
- to relay information about sensations (like touch, temperature, and
pain).
- to control muscles.
The median nerve relays sensations from the thumb, the index
finger, the long finger, and the thumb side of the ring finger. This nerve
also controls several small muscles in the hand, especially muscles that
move the thumb.
What is carpal tunnel syndrome?
Carpal tunnel syndrome, or CTS, is caused by pressure or
pinching of the median nerve as it passes through the carpal tunnel
on its way to the palm of the hand. For example, there are conditions that
can irritate the covering (sheath) of the tendons and can cause this sheath
(which also passes through the tunnel) to swell. The tunnel is a rigid,
confined space, so any inflammation or swelling in the tunnel can compress
the median nerve. This leads to weak and poorly functioning hand muscles.
Symptoms may include numbness, tingling, and occasionally pain.
CTS is most often related to work activities that involve repetitive
motions, In addition to computer use, the repetitive motions of assembly
line workers, cashiers, and hairstylists put them at risk for
CTS. Other common causes of CTS are:
- infections or growths within the tunnel
that take up space and compress the median nerve.
- osteoarthritis, or other problems
with the carpals (wrist bones).
- diseases which cause inflammation
or fluid build-up like rheumatoid arthritis, diabetes, and hypothyroidism.
- pregnancy: hormonal changes may
cause fluid retention, which can increase pressure on the median nerve.
This condition usually improves after pregnancy.
Some people may be born with a condition that puts them at risk to
develop CTS. For example, a carpal tunnel that is smaller than average
leaves little room for the nerve and tendons. Anything causing swelling
around the nerve can increase the pressure on it. The median nerve can
only tolerate a small amount of pressure for a short time. Increased pressure
over time can cause the hand to "fall asleep". The longer the condition
exists, the worse the symptoms become.
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