It is a painful disorder of the hand caused by excess pressure on the median nerve as it passes through a tunnel at the wrist. The tunnel is formed by a tough membrane (transverse carpal ligament) that makes a “roof” to a natural arch produced by the carpal (wrist) bones – thus called the “carpal tunnel”. This tunnel contains nine tendons and the median nerve as they pass from the forearm to the hand. As it is naturally a small tunnel, any swelling of structures in or around the tunnel results in excess pressure on the nerve which may cause nerve dysfunction. The result is the symptoms typical of carpal tunnel syndrome – including numbness, tingling, weakness and pain in the arm, hand, and fingers.
CTS usually occurs only in adults and the development of it is often the result of many factors causing an increased pressure on the nerve. These include:
Repetitive and forceful movements of the hand and wrist during work or leisure activities can contribute to the development of CTS. However, the risk of developing CTS is not confined to people in a single industry or job, but it is especially common in those performing assembly line work – manufacturing, sewing, finishing, cleaning, meat, poultry, or packing.
The symptoms of CTS are variable and usually start gradually. They include pain, numbness, tingling, or a combination of the three affecting the palm, thumb, index, middle, and ring fingers – the little finger is spared. Pain may shoot up the arm from the wrist. The symptoms often first appear in one or both hands during the night. This is because many people sleep with flexed wrists and fluid redistribution while asleep causes swelling of the hands – both these factors result in increased pressure on the nerve. The person often wakes with the symptoms and feels the need to shake the hand or hang it over the side of the bed until it resolves.
As symptoms worsen, people develop symptoms during the day. This can progress to hand clumsiness and weakness, making it difficult to form a fist, grasp small objects or perform other manual tasks.
Chronic and/or untreated cases will cause permanent nerve damage with resultant permanent weakness and numbness in the hand.
Early diagnosis and treatment are important to avoid permanent damage to the median nerve. Fortunately, the diagnosis is usually straight forward and is made after finding a typical history and examination findings.
The detailed history should include any other medical conditions, how the hands have been used, and whether there were any prior injuries or surgery.
A physical examination of the hands, arms, shoulders, and neck can help determine if the patient’s complaints are related to daily activities or to an underlying disorder and can rule out other painful conditions that mimic CTS.
Specific tests are also used to try to produce the symptoms of CTS. In the Tinel’s test, tapping or firmly pressing on the median nerve in the patient’s wrist is performed. The test is positive when tingling in the fingers or a resultant shock-like sensation occurs. The Phalen’s test involves holding both upper limbs in a forward position and flexing the wrists by pressing the backs of the hands together. The presence of CTS is suggested if one or more symptoms, such as tingling or increasing numbness, are felt in the fingers within 1 minute. The earlier the onset of symptoms suggests a greater severity of CTS.
In some cases, laboratory tests may be done if there is a suspected medical condition that is associated with CTS.
Confirmation of CTS should be done by the use of electrodiagnostic tests. This is also good in checking for other possible nerve problems. In a nerve conduction study, electrodes are placed on the hand and wrist. Small electric shocks are applied and the speed with which nerves transmit impulses is measured. In electromyography, a fine needle is inserted into a muscle; electrical activity can determine the severity of damage to the median nerve.
X-ray’s or ultrasounds may be taken to check for the other causes of the complaints such as arthritis, fractures, tenosynovitis or tumours.
Treatments for carpal tunnel syndrome should begin as early as possible.
NON-SURGICAL – Symptoms may often be relieved without surgery.
SURGICAL – Carpal tunnel release is one of the most common hand surgical procedures.
Surgery is designed to make more room for the nerve. Pressure on the nerve is decreased by cutting the transverse carpal ligament that forms the roof of the tunnel. Incisions for this surgery may vary, but the goal is the same – to enlarge the tunnel and decrease pressure on the nerve. The procedure can be done under a general or local anaesthetic as a day only basis, unless there are unusual medical considerations.
Carpal tunnel release is highly effective in relieving the symptoms of carpal tunnel syndrome in over 95% of cases.
However, recovery periods are extremely variable. If the symptoms are only present at night and/or with certain activities, then many people notice resolution of their symptoms immediately after the operation. If the numbness is constant then the sensation may take up to 12 months before maximal recovery – and even then may be incomplete. Wasting of the muscles at the base of the thumb may never fully recover. Reduced grip strength is noted following surgery however this will largely return to normal within 6 weeks.
Carpal tunnel release surgery is a highly effective and safe operation. However, like all operations some complications can occur:
Recurrence of carpal tunnel syndrome following treatment is uncommon.
The following advice has been offered to help reduce the incidence of CTS in the workplace:
Avoid activities requiring excessive up-and-down and side-to-side movements of the wrist.
Wrist position to be maintained in a natural position during work.
Wrist splint may need to be considered in some work environments.
Position and align hands properly while working. Wrists should be parallel and elbows should be at a 90 degree angle to the work surface (i.e. desk or keyboard).
Take frequent breaks to stand, walk, and stretch.
Avoid direct pressure on the heel of the hand.
Don’t wear restrictive watchbands/jewelry or clothing with tight elastic sleeves.
Learn proper use of the computer mouse.
Use the mouse with an open, relaxed hand posture.
Don’t grip the mouse between the thumb and little finger.
Use the entire arm to move the mouse as opposed to shifting it with a side-to-side wrist motion.
Do not use a wrist rest.
Keep the mouse close to the keyboard.
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