CARPEL TUNNEL SYNDROME*
Carpel tunnel syndrome occurs when the median nerve, which runs from the forearm into the palm of the hand, becomes pressed on or squeezed at the wrist. It is also referred to as median nerve entrapment neuropathy. The compression of the nerve occurs at the wrist as it travels through the carpel tunnel.
The Carpel Tunnel
The carpel tunnel is the passageway on the palmar side of the wrist that connects the forearm to the middle compartment of the deep plane of the palm. The tunnel consists of bone and connective tissue. Several tendons and nerves pass through it, in particular the median nerve. The canal is narrow and when any of the nine long flexor tendons passing through it swells or degenerates, the narrowing of the canal often results in the median nerve becoming compressed or entrapped.
The Median Nerve
The median nerve is one of the five main nerves arising from the brachial plexus (a complex of nerves in the neck). It continues down the arm to enter the forearm with the brachial artery. The median nerve is the main nerve that passes through the carpel tunnel. It innervates most of the flexor muscles in the forearm (the rest being supplied by the ulnar nerve). In the hand, the median nerve supplies motor innervation to the muscles on the thumb side of the hand and supplies sensory innervation mainly to the thumb, index and middle fingers and the radial half of the ring finger and adjacent palm.
Causes of Carpel Tunnel Syndrome (CTS)
CTS usually occurs only in adults, and it is more common in the dominant hand.
Most cases of CTS are of unknown cause, or idiopathic.
CTS is often the result of a combination of factors that increase the pressure on the median nerve and tendons in the carpel tunnel, rather than a problem with the nerve itself. Some of these factors include:
Symptoms and Signs of CTS
The main symptom of CTS is intermittent numbness in the area of the cutaneous innervation of the median nerve, namely the thumb, index and middle fingers and the radial half of the ring finger. Apart from numbness, there may be tingling ('pins and needles') or burning sensations and pain.
The symptoms usually start gradually, and often first appear in one or both hands during the night (probably because many people sleep with flexed wrists). A person with CTS may wake up feeling the need to "shake out" the hand or wrist. There may be the feeling that the fingers are useless and swollen, even though little or no swelling is apparent.
As the condition worsens, the numbness and tingling may be present during the day.
Pain in the wrists or hands may occur and can even radiate up the forearm. Decreased grip strength can also occur, making it difficult to form a fist, grasp small objects, or perform manual tasks. There may be a tendency to drop things.
In chronic and/or untreated cases, the muscles at the base of the thumb may waste away (atrophy). There may also be an inability to differentiate between hot and cold.
Diagnosis of CTS
Early diagnosis and treatment are important in order to avoid permanent damage to the median nerve.
The diagnosis is generally made from a combination of:
Treatment of CTS
Treatment for carpel tunnel syndrome should begin as early as possible. Underlying causes such as diabetes or arthritis should be treated first.
Generally accepted treatments include drugs, splinting and surgical release of the transverse carpal ligament.
Carpel tunnel syndrome is a common condition that occurs in 2.7% of the general population. The average age of people with CTS is 40-50 years.
It is straight forward to diagnose, and the outcome with appropriate treatment is generally excellent.
*Copyright 2013: The Huntly Centre.
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