Carpal Tunnel Syndrome
What is carpal tunnel syndrome?
Do you wake up with pins and needles or numbness in your fingers? If so you may have carpal tunnel syndrome. The carpal tunnel is found in your wrist (shaded brown on the picture below). The median nerve runs through this tunnel with your finger tendons. If it is pinched as it goes through the tunnel it gives rise to carpal tunnel syndrome.
An ‘end on’ view of the carpal
tunnel at the wrist
What causes carpal tunnel syndrome?
Anything decreasing the space in the tunnel can give rise to pressure symptoms. Local injury, tenosynovitis (swelling around the tendons), arthritis, diabetes, thyroid disease and pregnancy are commonly implicated but a cause is often not identified. It is commoner in women, probably because the tunnel is already smaller.
What symptoms does carpal tunnel syndrome give rise to?
A feeling of ‘pins and needles’ or tingling in the thumb, index and middle finger is commonly described. This is usually worse at night, if reading a newspaper or driving. The fingers may feel ‘dead’. Pain in the hand, wrist or arm often occurs. Later on the hand feels clumsy and weak and dextrous tasks (doing buttons up etc) become difficult. You may find yourself inadvertently dropping things.
How is the diagnosis confirmed?
A good story and examination is often sufficient to make the diagnosis. Other conditions can mimic carpal tunnel syndrome and may need to be excluded with xrays or blood tests. If there is still doubt electrical tests of the nerves can be arranged.
What is the treatment of carpal tunnel syndrome?
Rest and treating exacerbating factors may resolve mild symptoms. A splint to hold the wrist straight at night can be helpful. A local anaesthetic and steroid injection around the nerve in the carpal tunnel can reduce swelling and relieve pressure but the effects are often short-lived.
A small operation, usually carried out under local anaesthetic as a day case, is almost guaranteed to relieve the pressure symptoms of carpal tunnel syndrome. Essentially the strap ligament that forms the top of the carpal tunnel is divided to give the nerve more room to breathe and the skin closed over the top. In severe cases finger numbness can persist following surgery but the ‘pins and needles’ sensation and night discomfort is relieved.