Carpal tunnel syndrome

Carpal tunnel syndrome is a disorder in which the median nerve is compressed at the wrist causing symptoms like tingling, pain, coldness, and sometimes weakness in parts of the hand. It is the best known of a class of disorders called repetitive strain injuries.

Causes

Some cases of carpal tunnel syndrome are due to work-related cumulative trauma of the wrist. It is commonly caused by strain placed on the hand, for instance gripping and typing, which are usually performed repetitively in a person's occupation. The condition was first diagnosed in Australia in the 80s when musicians started to use synthesizers heavily and people using these instruments started to get hand and wrist pain. The condition went mostly undiagnosed in the US until the mid 90s when computers became more popular in the workplace.

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There are a number of causes of carpal tunnel syndrome. They can be either traumatic, or non-traumatic.

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Repetitive stress induced carpal tunnel strain is the leading cause of carpal tunnel syndrome in most industrialized countries. In the USA for instance, repetitive stress induced carpal tunnel syndrome is the biggest single contributing factor to lost time at work. This type of carpal tunnel syndrome results in billions of dollars of workers compensation claims every year.

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Repetitive hand and wrist action often results in subcutaneous tissues becoming injured and swollen. These tissues include fascia, muscle, ligament, tendon, sheaths, retinaculum and peripheral nerve and blood vessels. In restricted passages of the body, swollen soft tissue can become compressed together creating intense pressure. Adjacent soft tissue can adhere together when compressed under these conditions over a prolonged period.

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Trauma-based causes:

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• Fractures of one of the arm bones, particularly a Colles' fracture.
• Dislocation of one of the carpal bones of the wrist.
• Hematoma forming inside the wrist, because of internal haemorrhaging.
• Deformities due to abnormal healing of old bone fractures.

Non-traumatic causes generally happen over a period of time, and are not triggered by one certain event. Examples include:

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• Tenosynovitis, which is inflammation of the joint. Part of the process of inflammation is swelling, and this compresses the nerve.
• With pregnancy and hypothyroidism, fluid is retained in tissues, which swells the joint.
• Acromegaly, a disorder of growth hormones, compresses the nerve by the abnormal growth of bones around the hand and wrist.
• Tumours (though not necessarily cancer), such as a ganglion or a lipoma, can protrude into the carpal tunnel, reducing the amount of space.
• Diabetes, rheumatoid arthritis, and obesity tend to cause swelling, thus decreasing the amount of space in the carpal tunnel.
• Idiopathic causes, which no one can explain, can also cause this disease.

Common activities that have been identified as contributing to repetitive stress induced carpal tunnel syndrome include:

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• Computer keyboarding or typing
• Playing video games
• Playing a musical instrument
• Driving a vehicle, motorcycle or flying a plane
• Pushing a lawn mower (both the pressure and the vibration are to blame)
• Any activity where hand use is vigorous and routine could contribute (surgeons, dentists)

An exhaustive list can be found in the external links below

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Often people suffering from carpal tunnel syndrome can have multiple contributing factors which are aggravated by vigorous hand activities and repetitive stress trauma to the hand.

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Proper attention to ergonomic considerations can reduce or eliminate these kinds of injuries.

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