Carpal tunnel syndrome is the most common compressive neuropathy of the upper limb. It is compression of the median nerve as the nerve passes through the carpal tunnel in the wrist. Most cases of carpal tunnel syndrome are idiopathic; however, it may be a result of other underlying conditions such as diabetes.

Several risk factors may increase the risk of developing carpal tunnel syndrome. Women are at a higher risk than men, underlying conditions such as rheumatoid arthritis, as well as occupational factors such as extensive use of the computer and exposure to repetitive vibrations.

Compression of the median nerve in the carpal tunnel is a result of a decrease in the size of the canal or an increase in the size of the contact area.  Patients suffering from carpal tunnel syndrome experience pain and numbness in the thumb, index and middle fingers, and the lateral half of the ring finger, i.e., the half closest to the thumb.

Carpal tunnel syndrome is diagnosed using a physical exam and confirming the diagnosis using electrophysiologic studies. Treatment options depend on the severity of the disease and the findings from the diagnostic tests. Patients with mild to moderate symptoms are treated with conservative treatment such as NSAIDs, a night splint and corticosteroid injections. Patients who do not respond to conservative treatment options or those who present with severe symptoms are recommended to undergo surgery.

Complications of carpal tunnel syndrome include permanent injury or disability as a result of damage to the median nerve in addition to chronic hand pain, weakness and numbness. While there are no methods available to guarantee prevention from carpal tunnel syndrome, reducing stress on the hands and wrists from daily activities may help; such measures include taking periodic breaks to stretch and bend the hands and wrists when doing an activity that may stress them, such as computer work.

Carpal tunnel syndrome is a disease that develops over time which may result in permanent median nerve damage. The effectiveness of conservative treatment in halting the progression of the disease is uncertain. Relapse after surgery also occurs in a significant number of patients.  Patients with idiopathic carpal tunnel syndrome tend to have a more favorable prognosis compared to patients with carpal tunnel syndrome as a result of an underlying condition such as diabetes.

Carpal tunnel syndrome is compression of the median nerve in the carpal tunnel at the level of the wrist.The carpal tunnel is an area of the hand that is bound by the scaphoid tubercle and trapezium laterally and the pisiform and hook of hamate medially. It is covered by the transverse carpal ligament.

The disease is classified according to its cause into

• Idiopathic

Most cases have no identifiable cause.

• Internal pressure

This results from an increase in the pressure inside the carpal tunnel due to obesity, pregnancy, rheumatoid arthritis, or trauma.

• External compression

This results from external pressure due to a lipoma, which is a relatively frequent, benign soft-tissue tumor rarely located in the hand1, or a ganglion, or as a result of gout or vascular malformation.

Compression of the median nerve in the carpal tunnel area results in carpal tunnel syndrome.  Compression occurs as a result of either a decrease in the size of the canal or an increase in the size of the contact area. There are multiple risk factors that contribute to causing this compression but no one clear cause.

There are multiple risk factors for carpal tunnel syndrome which include, female gender, Caucasian race, increasing age, obesity, pregnancy, breastfeeding, use of wheelchairs and/or walking aids, hypothyroidism, rheumatoid arthritis, chronic renal failure, smoking, diabetes mellitus, alcoholism, wrist fractures, prolonged, severe force through the wrist, prolonged, extreme posture of the wrist, high amounts of repetitive movements, from painting for example, mucopolysaccharide storage disorders, athletic activities such as cycling, tennis, or sports that involve throwing a ball such as baseball, exposure to repetitive vibration such as when using power tools, and using the computer for very long periods of time.

Carpal tunnel syndrome is a result of compression of the median nerve in the carpal tunnel area caused by either a decrease in the size of the canal or an increase in the size of the contact area. This results in an increase in pressure inside the carpal tunnel. The compressed nerve causes pain and numbness. After a period of compression and increasing pressure, demyelination may begin followed by axonal degeneration, which may cause permanent damage to the nerve.

Usually, patients with carpal tunnel syndrome complain of pain in the lateral three-and-a-half digits, i.e., thumb, index and middle fingers and lateral half of the ring finger. The pain may extend to the arm and may be severe enough to wake the patient from sleep. Other symptoms include a burning feeling in the middle and index fingers14, numbness and a tingling sensation, particularly at night, in the three and a half fingers, weakness and atrophy of the thenar muscles, a decrease in pinching strength and a weak grip strength, and loss of two-point discrimination, which is the loss of the ability to feel that two nearby objects are touching the skin at the same time.Carpal tunnel syndrome commonly affects both hands4, but typically the dominant hand is affected first and more severely.

The diagnosis is carried out by taking patient history and performing a physical examination. The diagnosis is confirmed using tests.

History

The patient complains of pain and numbness in the lateral three-and-a-half fingers, the pain may cause the patient to wake up from their sleep. The symptoms are usually intermittent and are linked with activities that move the wrist such driving, reading the newspaper, and knitting.

The patient may also complain of a burning sensation or weakness or loss of power in the hand, specifically for precision grips involving the thumb.

Physical examination

Different tests may be used during the physical exam to diagnose carpal tunnel syndrome. These tests include:

• Durkan's test

It is the most sensitive test. It is used to cause compression of the median nerve in order to evoke symptoms. Steps include pressing the thumb over the carpal tunnel for the side of the palm for about 30 seconds and then releasing the pressure. The patient tests positive if the pain and numbness occur in the lateral three-and-a-half digits.

• Phalen’s test

The wrist is flexed towards the palm for about 60 seconds. The patient tests positive if the symptoms occur.

• Tinel's sign test

 Light tapping over the median nerve in the carpal tunnel region. The patient tests positive if the symptoms appear post tapping.

Imaging Studies

Imaging studies are not regarded as routine in the diagnosis of carpal tunnel syndrome. An X-ray may be helpful to exclude other causes of pain such as a fracture, dislocation or arthritis. MRI of the carpal tunnel may be useful if a space-occupying lesion in the carpal tunnel is thought to be the cause. Ultrasound may be used in some cases, as it can detect space-occupying lesions and identify abnormalities in the median nerve.

Electrodiagnostic testing

Electromyography and nerve conduction tests are the primary methods to diagnose carpal tunnel syndrome.Nerve conduction tests and electromyography measure the ability of the nervous system to conduct electrical impulses. They are used to assess nerve and muscle function to verify if neuromuscular disease is present. The tests also indicate how severe the problem is, providing information necessary to determine treatment and prognosis of the disease.

Treatment options vary depending on the severity of the problem. For patients with mild – moderate symptoms, conservative treatments such as NSAIDs are prescribed and the patient should use a wrist splint at night for a minimum of 3-weeks. Vitamins B6 and B12 may be prescribed13. A corticosteroid injection into the carpal tunnel can be used if more conservative treatments have failed.Patients with severe carpal tunnel syndrome and those who do not improve after conservative treatment are considered for surgery. Surgery involves cutting of the transverse carpal ligament.

Complications of carpal tunnel syndrome include chronic hand pain, weakness and numbness and permanent impairment or disability as a result of damage to the median nerve.

Since there is no one direct cause for carpal tunnel syndrome, there are no guaranteed methods that can be used to prevent carpal tunnel syndrome. However, there are methods that may be used to minimize stress on the hands and wrists.

Exercises to strengthen the fingers, hands, wrists, forearms, shoulders, and neck may help prevent carpal tunnel syndrome.

Reducing the force on the wrist and relaxing your grip.  Tap the keys on the keyboard or cash register lightly. For extended periods of handwriting, ensuring that the pen being used is large, with free-flowing ink, in addition to a large, soft grip adapter.

Taking frequent breaks to stretch and bend the hands and wrists periodically. Keeping the wrist in a relaxed position, not bent to the limit up or down. This can be done by putting the keyboard at elbow height or somewhat lower.

Paying attention to posture. Incorrect posture causes the shoulders to point forward, making the neck and shoulder muscles shorter which compresses nerves in the neck. This may affect the wrists, fingers and hands.

Using a computer mouse that does not strain the wrist.Ensuring that the hands remain warm since cold environments are more likely to cause hand pain and stiffness.

Carpal tunnel syndrome is a disease that progresses over time and may cause permanent median nerve damage. It is uncertain whether conservative treatment is able to stop progression of the disease. Even after surgery, a significant number of patients suffer from a relapse12.  Patients who suffer from Carpal tunnel syndrome as a result of an underlying condition such as diabetes tend to have a less favorable prognosis compared to those with no clear underlying cause.

Carpal tunnel syndrome is the most common compressive neuropathy that accounts for about 90% of all compressive neuropathies as mentioned in a review published in the American World Journal of Radiology and a study published in the British Ulster Medical Journal.