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:
- Pain in the hand, which often wakes you in the night.
- Numbness or pins and needles in the hand, affecting the thumb, forefinger, middle finger and the half of the ring finger nearest to the thumb.
- Weakness of some of the movements of the thumb. Those that are worst affected may also have wasting of the muscles at the base of the thumb.
- Sometimes people feel the pain up into the lower end of their forearm.
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:
- Arthritis, for example osteoarthritis
- Various hormonal changes, including:
- Under-active thyroid gland (hypothyroidism)
- Taking the oral contraceptive pill
- Recent change in occupation or increased use of hands
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.
It may be that a change or modification of occupation will reduce the problem.
If there is an underlying hormonal cause, it may be possible to relieve the symptoms by correcting this. For example treatment of underactive thyroid with thyroid hormone, or cessation of the oral contraceptive pill.
Anti-inflammatory preparations, such as ibuprofen, may help to reduce pain, as straight pain killers (analgesics) and also by reducing swelling.
Sometimes a medication to make you pass more urine (a diuretic) may help the symptoms, by reducing the fluid in the tissues.
Splints (rather like those worn by people using rollerblades) hold the wrists in the best position to maximize the room in the carpal tunnel. These can help if worn at night, but some people find they need to wear them by day as well. Your doctor or physiotherapist may obtain these for you.
Your doctor may suggest an injection of a small dose of steroid into the carpal tunnel. This reduces inflammation and swelling in the carpal tunnel and usually settles the symptoms, partially or completely, for some time.
In some cases, your doctor may recommend a minor operation to release the pressure on the front of the wrist (carpal tunnel release).
- Arthritis Research UK Carpal tunnel syndrome information and diagrams
- Conquering carpal tunnel syndrome and other repetitive strain injuries, by Sharon J Butler
- Self help book involving stretching exercises.