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Carpal Tunnel Syndrome
Carpal tunnel syndrome
(CTS) is a condition brought on by increased pressure on the median
nerve at the wrist. In effect, it is a pinched nerve at the wrist.
Symptoms may include numbness, tingling, and pain in the arm, hand,
and fingers. There is a space in the wrist called the carpal tunnel
where the median nerve and nine tendons pass from the forearm into
the hand (see Figure 1). Carpal tunnel syndrome happens when pressure
builds up from swelling in this tunnel and puts pressure on the nerve.
When the pressure from the swelling becomes great enough to disturb
the way the nerve works, numbness, tingling, and pain may be felt in
the hand and fingers (see Figure 2).
Usually the cause is unknown. Pressure
on the nerve can happen several ways: swelling of the lining of the flexor
tendons, called tenosynovitis; joint dislocations, fractures, and arthritis
can narrow the tunnel; and keeping the wrist bent for long periods of time.
Fluid retention during pregnancy can cause swelling in the tunnel and symptoms
of carpal tunnel syndrome, which often go away after delivery. Thyroid
conditions, rheumatoid arthritis, and diabetes also can be associated with
carpal tunnel syndrome. There may be a combination of causes.
Carpal tunnel syndrome symptoms
usually include pain, numbness, tingling, or a combination of the three.
The numbness or tingling most often takes place in the thumb, index, middle,
and ring fingers. The symptoms usually are felt during the night but also
may be noticed during daily activities such as driving or reading a newspaper.
Patients may sometimes notice a weaker grip, occasional clumsiness, and
a tendency to drop things. In severe cases, sensation may be permanently
lost and the muscles at the base of the thumb slowly shrink (thenaratrophy),
causing difficulty with pinch.
A detailed history including medical
conditions, how the hands have been used, and whether there were any prior
injuries is important. An x-ray may be taken to check for the other causes
of the complaints such as arthritis or a fracture. In some cases, laboratory
tests may be done if there is a suspected medical condition that is associated
with CTS. A nerve conduction study (NCV) and/or electromyogram (EMG)
may be done to confirm the diagnosis of carpal tunnel syndrome as well
as to check for other possible nerve problems.
Symptoms may often be relieved without
surgery. Identifying and treating medical conditions, changing the patterns
of hand use, or keeping the wrist splinted in a straight position may help
reduce pressure on the nerve. Wearing wrist splints at night may relieve
the symptoms that interfere with sleep. A steroid injection into the carpal
tunnel may help relieve the symptoms by reducing swelling around the nerve.
When symptoms are severe or do not improve, surgery may be needed
to make more room for the nerve. Pressure on the nerve is decreased
by cutting the ligament that forms the roof (top) of the tunnel on
the palm side of the hand (see Figure 3). Incisions for this surgery
may vary, but the goal is the same: to enlarge the tunnel and decrease
pressure on the nerve. Following surgery, soreness around the incision
may last for several weeks or months. The numbness and tingling may
disappear quickly or slowly. It may take several months for strength
in the hand and wrist to return to normal. Carpal tunnel symptoms may
not completely go away after surgery, especially in severe cases.
The carpal tunnel is found
at the base of the palm. It is formed by the bones of the wrist and
the transverse carpal ligament. Increased pressure in the tunnel affects
the function of the median nerve.
Aspects of median nerve function.
The goal of surgery is to free
the ligament to allow more room for the median nerve in the carpal
tunnel.
© 2007 American Society for Surgery of the Hand
Developed by the ASSH Public Education Committee
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carpal, tunnel, syndrome, carpal tunnel syndrome,
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