Carpal tunnel syndrome

What is carpal tunnel syndrome?

Strong fibrous tissues in the wrist form a tunnel through which the tendons of the hand and the median nerve pass on their way to the fingers. This is known as the carpal tunnel (because it lies over the small carpal bones)

Anything that reduces the space in this small tunnel, such as fluid or inflammation of the tendon coatings, increases the pressure on the structures passing through it. This pressure can cause problems in the median nerve (the central nerve that supplies the lower arm and hand).

Symptoms

When the median nerve is compressed, people experience discomfort, numbness, pins and needles, and, sometimes, pain in the thumb, index, middle and side of the ring finger, next to the middle finger. This is where the median nerve endings are distributed.

Tingling often wakes people with carpal tunnel syndrome at night - vigorously shaking the hands and arms brings relief. Those affected describe dropping things, or being clumsy with simple but fiddly tasks, such as fitting a plug, because of the weakness in the hand.

Causes and risk factors

Several different risk factors for carpal tunnel syndrome have been identified. Genetics may play a part – it is more common in those with short stature (suggesting anatomy plays a part) and a family history of the condition.

Trauma to the wrist and surrounding tissues may be important. Carpal tunnel syndrome may follow a Colles fracture (a type of broken wrist) and other injuries.

Any work or leisure activity which involves repetitive movement of the wrist that can leave the tendons inflamed and swollen can predispose to the condition, including keyboard work, racquet sports etc.

Conditions which reduce space in the tissues of the wrist, such as fatty lumps, swelling of nerve capsules or arteries, may lead to carpal tunnel syndrome, as may fluid retention. Hormonal changes play a part and may explain why women are more at risk.

Treatment and recovery

Prevention is better than cure, so avoiding repetitive actions and taking regular breaks from the activity that might be the trigger is essential. If working at a computer keyboard, use a suitable wrist support and make sure the workstation is correctly positioned. Also, check your chair is at the right height.

Anti-inflammatory medicines will relieve symptoms, and often experts recommend the use of wrist splints to allow swelling to settle. If this doesn't lead to improvement, then steroid injections, or a minor operation to open up the fibrous tissues of the tunnel and release the nerve compression, may be recommended.