Medical information for patients

Carpal tunnel syndrome

Carpal tunnel syndrome is a condition in which pressure on a nerve (the median nerve) where it passes through the wrist into the hand, causes pain, pins and needles, weakness and numbness in the hand.


Carpal tunnel syndrome causes a number of symptoms:

The symptoms can trouble you at any time, but are most often worse at night. People often wake with the pain and find themselves shaking their hands to ease the symptoms.


The wrist is bounded on three sides by bones. The fourth side, the same side as the palm, has a thin covering across it, under which the structures lie that pass into the hand. The wrist bones are called the carpal bones, and this space is called the carpal tunnel.

Space in the carpal tunnel is limited. If anything leads to some of the space being taken up, this causes pressure to build up. The main contents of the carpal tunnel are the tendons which cause the hand to flex, but the structure in the wrist that is most sensitive to pressure is the nerve which passes into the hand (the median nerve).

Such things as swelling of the soft tissues or knobbly changes of the bones might lead to pressure building up. Often there is no obvious cause, but there are some things that seem to predispose to this:

Carpal tunnel syndrome may also be more likely to occur when the nerves to the arm are already working at a disadvantage, for example when there are pre-existing neck problems.


Your doctor will want to find out whether there is weakness of certain movements of the thumb, and will be looking for numbness affecting the thumb, forefinger, middle finger and half of the ring finger. Your doctor may also tap the wrist (on the same side as the palm of the hand) to see if this causes pins and needles or a shock sensation to the finger tips. If this happens it is known as Tinel's sign, and is said to indicate malfunction of the median nerve.

Your doctor may arrange a special electrical test to show up the speed at which the median nerve transmits impulses (nerve conduction studies). If there is pressure on the nerve at the wrist the speed of conduction through the nerve slows below the wrist.

Your doctor may ask for a blood test to look for underactivity of the thyroid gland (hypothyroidism), and possibly for an X-ray.


If you think you have carpal tunnel syndrome you should see your doctor.

Further information


Conquering carpal tunnel syndrome and other repetitive strain injuries, by Sharon J Butler
Self help book involving stretching exercises.

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