Carpal tunnel syndrome accounts for more than 90% of the nerve compression syndromes. (1)
It is also the leading reason for hand surgery and actually, the second most common cause of all operations after back surgery.
It is also interesting to note that carpal tunnel syndrome results in the highest number of days (31 days or more) lost among all work-related hazards.
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In addition to that, it is one of the costliest occupational health problems, accounting for more than $20 billion in compensation, each year. (2)
What is carpal tunnel syndrome?
Carpal tunnel syndrome (CTS) is a medical condition that affects the hands. It occurs when there is pressure on the median nerve. (3)
The median nerve, also known as the eye of the hand, is one of the three major nerves that form the brachial plexus of the forearm. (4)
It innervates the skin of the index finger, thumb, middle finger, radial side of the ring finger, and the nail bed. It also carries sensory information of temperature, pain and touch from the hand to the brain.
What are the causes of carpal tunnel syndrome?
Carpal tunnel syndrome occurs as a result of compression of the median nerve at the carpal tunnel.
The carpal tunnel is the part on the palmar side of the wrist that acts as a passageway for anatomical structures from the forearm to the hand.
The tunnel is narrow and bounded by the bones of the wrist. Nine tendons of the forearm muscles and the median nerve pass through the carpal tunnel. (5)
The median nerve is of significant concern in carpal tunnel syndrome. It can move up to 9.6mm to allow the wrist to flex, and to a lesser extent to extend. (6)
This nerve can be compressed when there is a decrease in the size of the tunnel or swelling of the tendons. Since the carpal tunnel is only bordered by bones, the pressure that builds up has nowhere to escape to, thus ends up compressing and consequently damaging the median nerve. (7)
When there is prolonged compression of the nerve, it prevents gliding, leading to injury and even scarring. When scaring occurs, the nerve adheres to the tissues around it and becomes locked into a fixed position.
Other factors may also lead to carpal tunnel syndrome. According to the National Institute of Neurological Disorders, (8) carpal tunnel syndrome does not just occur merely because of a problem with the median nerve.
For instance, in cases of repetitive occupational motions, one of the primary risk factors for carpal tunnel syndrome, is that the lubrication function of the wrist malfunctions. When the wrist moves, it brings the muscles and tendons into action.
When the movements are too much, enough synovial fluid is not produced for lubrication. Friction results, causing inflammation and swelling at the tendon area. The swelling squeezes the median nerve, and moreover, when there is repeated inflammation, a fibrous tissue forms and hinders tendon movement.
Who is more likely to develop carpal tunnel syndrome?
According to an article published by the Orthopedic Centre of Arlington, (9) more than 8 million people are affected by carpal tunnel syndrome every year.
Out of these figures, women are twice more likely to develop carpal tunnel syndrome than men. Other risk factors are associated with any condition that causes pressure on the median nerve, at the wrist region. (10) They include:
- Being overweight or obese
- Jobs requiring repetitive wrist work and a strong grip
- Pregnancy due to hormonal changes that cause water retention and swelling of the synovium
- Inflammatory conditions such as rheumatoid arthritis
- A family history of carpal tunnel syndrome
- Previous injury (dislocation or fracture) of the wrist
- Increased age (45 to 64 years)
- Chronic illnesses such as diabetes and hypothyroidism
How does carpal tunnel syndrome manifest?
The main signs and symptoms of carpal tunnel syndrome are:
- Pain, which may also extend to the arm and shoulder.
- Tingling sensation of the thumb, index finger, middle finger and side of the ring finger. These specific fingers are affected because they receive sensory and motor innervation from the median nerve. The small finger is typically not affected.
- Dry skin on the affected arm due to decreased sweating
- After some time, there may be wasting at the base of the thumb, and the affected hand may have weak grip strength
A combination of these symptoms makes it difficult to perform simple tasks such as unscrewing bottle tops, fastening buttons and turning keys. At first, the symptoms may be relieved by shaking out the hand, but later on, they become constant.
The symptoms gradually start at night, and therefore, the discomfort is worse at night and in the morning. In most cases (more than 50%) both hands are affected. (11)
How is carpal tunnel syndrome diagnosed?
A diagnosis of carpal tunnel syndrome is made using the nature of presenting signs and symptoms, physical examination and confirmed with electrodiagnostic (EDX) tests. (12)
EDX tests either passively record the electrical activity of certain body parts or measure the response of body parts to external electrical stimuli. For the median nerve, the doctor inserts a thin needle electrode then passes a small shock to see if the electrical impulses are slowed in the carpal tunnel. (13)
During the physical examination, the doctor looks out for the following positive signs
- Phalen’s maneuver is done by gently flexing the wrist as far as possible. Then its held in that position for several minutes. If numbness results within one minute, that indicates damage of the median nerve.
- Tinel’s sign is performed by lightly tapping the skin above the flexor retinaculum. If a tingling sensation is elicited on the fingers innervated by the median nerve, the test is positive.
- Durkan test also known as carpal compression test, involves applying firm pressure on the palm, just above the median nerve for about 30 seconds. If the symptoms are provoked, the test is positive.
- Hand elevation test is done by lifting both hands above the head for several minutes. If the symptoms occur within two minutes, then the test is considered positive.
The medical practitioner may also order X-rays to rule out other underlying issues such as arthritis or fractures.
Blood tests may be performed to identify medical conditions associated with carpal tunnel syndrome. Thyroid hormone levels, complete blood count (CBC), blood sugar, and protein analysis are the most commonly ordered investigations.
What are the treatment options for carpal tunnel syndrome?
Early diagnosis and timely treatment of carpal tunnel increase the chances of full recovery. The treatment options are mainly medical, physical and surgical. They include:
Nonsteroidal anti-inflammatory drugs such as ibuprofen are used to relieve pain. They also inhibit inflammatory reaction on the wrist joint by decreasing prostaglandin synthesis. NSAIDs are used in combination with other treatment methods. (14) When used alone, they do not improve the overall outcome of carpal tunnel syndrome.
Wrist splinting. The splint holds the wrist joint in a neutral position to prevent bending and stress on the median nerve.
Nighttime splinting is preferred as that is when the hand is more likely to bend, and also, that is when the symptoms worsen. During the day, it is important to keep the hand moving to prevent the wrist joint from becoming stiff and muscles from atrophying due to disuse.
Wrist splinting improves the symptoms within a few weeks, (15) but it is not a lasting solution.
Corticosteroid tablets or injections are temporarily used to relieve symptoms, particularly if there is arthritis on the wrist. (16)
They may also be considered if wrist splinting has not produced any significant difference in symptoms. Injections are more effective than the tablets as they give a localized effect in reducing inflammation and swelling.
Relief of symptoms may be noted in the first 2 to 4 weeks. However, use of steroids is not recommended for long-term use as they increase the risk of nerve and tendon damage. (17)
Physiotherapy may take weeks to reverse the damage that has accrued for years, but it is very beneficial in speeding up recovery.
The physiotherapist guides one in doing exercises that are designed to reduce pressure on the median nerve, improve blood circulation and build the strength of the muscles affected.
Surgery known as open carpal tunnel release surgery is done to release pressure on the median nerve and relieve symptoms. During the procedure, the surgeon makes an incision at the base of the palm, then visualizes and cuts the transverse carpal ligament. Eventually, the gap where the ligament was fills up with scar tissue. (18) The pain and numbness start to subside immediately after surgery.
Endoscopic surgery may also be performed, where the surgeon makes one or two small incisions then uses an endoscope (telescope-like device) to see the inside of the carpal tunnel then cuts the ligament. Endoscopic surgery is less painful and has a quicker recovery period as compared to open surgery. (19)
Surgery is recommended when there is constant (not intermittent) numbness, weakness or atrophy of muscles, tumor or other growths and when other conservative interventions are not effective.
Does carpal tunnel syndrome have any complications?
If left untreated, weakness of the hand, atrophy of the thumb muscles and loss of coordination of the fingers result because of insufficient nerve stimulation.
These changes can significantly disrupt daily life, and for some people, they may not be able to return to work. It is therefore important to seek treatment early if any of the symptoms of carpal tunnel syndrome are experienced.
Other complications can be as a result of surgery. They include hypertrophic scars, joint stiffness, failure to relieve symptoms and neuromas. (20) However, all these complications are preventable.
What is the prognosis of carpal tunnel syndrome?
Many people are successful in relieving their carpal tunnel syndrome symptoms with conservative treatment options or surgical release. (21)
The recovery may be gradual, and for complete resolution of the symptoms, it may take up to one year. However, some are left with some residual nerve damage.
Long-term symptoms may also be seen in the elderly. Other factors such as smoking and chronic alcohol consumption may contribute to poor overall outcomes. In very rare cases, the symptoms of pain and numbness may return even after successful treatment.
Can carpal tunnel syndrome be prevented?
The primary goal of preventing carpal tunnel syndrome is to ensure that one minimizes stress on the hands and wrists. It can be achieved by making lifestyle changes that reduce the risk factors discussed above. Some of the ways to prevent carpal tunnel syndrome or keep it from getting worse include:
- Being physically active for 30 to 45 minutes 3 to 5 times every week
- Lose weight if obese or overweight
- Adopting an ergonomic work and living environment by
- Reduce the force of the hand’s grip
- Avoid bending the wrist all the way (up or down) but instead, maintain a middle position
- Use a big pen with a soft grip when writing
- Take frequent breaks every 2 to 3 hours
- Stretch often in between the breaks
- Keep the keyboard height at the level of the elbow or slightly lower
- Keep the elbows close to the body when typing
- Maintain the correct sitting posture with the back straight and feet flat on the ground
- If working in a cold environment, put on gloves to keep the hands and wrists warm
- Use tools that are of proper size with the hands. Consider using a vertical mouse and split keyboard to keep the hand in the handshake position.
- Treat conditions such as diabetes, arthritis, and high blood pressure