Carpal Tunnel Syndrome

Cause

The median nerve (nervus medianus) runs from the forearm through an opening in the carpal bones to the palm of the hand. This opening is called the carpal tunnel. The flexor tendons of the fingers also run through that tunnel. The entrapment of the nerve is caused by swelling of the tissue in and around the carpal tunnel, thereby increasing pressure in the tunnel.
People who have to perform many repetitive movements with hands and wrists, for example in intensive computerwork, are at increased risk of carpal tunnel syndrome. This is probably caused by a local response of strained muscles and tendons and a potentially reduced blood flow at that location. Pregnancy, overweight and diabetes are also risk factors for the development of CTS. Symptoms may also occur at the beginning of the menopause.

Symptoms

The signs and symptoms are often of various kinds:

• Pain, tingling and numbness in the hand and fingers. The symptoms are present in the area around the thumb, index finger and middle finger, but it can also occur that the pain radiates to the forearm, elbow, upper arm and even shoulder. The pain ranges from moderate to very severe. Many people suffer from pain especially at night, causing them to wake up. Symptoms are sometimes getting worse when the hand is frequently used, such as driving, cycling, reading, wringing, writing or using the computer mouse.
• Numbness and loss of strength in the hand. The entrapped nerve can make people feel less well what they grab. Clumsiness and loss of strength can make a person just drop things out of control. It sometimes feels like the hand is swollen.
• The carpal tunnel syndrome often occurs spontaneously.
• The condition can sometimes be present in both hands.

Diagnosis

With physical examination, sensory disorders in thumb, index finger and middle finger can be detected. In particular, a stretch test of the nerve may provoke symptoms. However, often no obvious defects are found and the diagnosis is made on the basis of the symptoms. Neurological examination must ensure that we are dealing with carpal tunnel syndrome. With electromyography (EMG) for muscle examination, the diagnosis can be confirmed. On the EMG, a delay can be seen in the nerve conduction across that portion of the nerve, located in the carpal tunnel.

Treatment

The treatment depends on the severity, duration, employment conditions and preference of the patient.
For mild symptoms, (temporary) adjustment of the activities of the hand concerned is often enough to make the symptoms disappear. A plastic splint can be put on, allowing rest to the wrist and the symptoms may reduce. Another possibility is to give an injection that dissolves the local swelling of the tendons at the height of the carpal tunnel. Many patients will thus be free of symptoms. Yoga exercises and laser acupuncture may have a beneficial effect in the short term.
In case of prolonged and severe symptoms and when it is certain that the nerve is pinched, the pressure on the nerve can be taken away by surgery. This is a minor procedure, in which an incision is made in the wrist on the palm side. The transverse wristband is thereby severed. This widens the tunnel. Some surgeons perform the procedure as keyhole surgery. Here, the surgeon operates with special instruments that go into the wrist through two small incisions. The advantage is that the incisions are small and therefore leave smaller scars.

Prognosis

Approximately half of the patients whose symptoms are caused during pregnancy, are spontaneously free of symptoms after one year. But also other untreated patients can improve spontaneously, often after a variable course.
Surgery is a good and permanent treatment, which cures ninety percent of the patients. After a surgical procedure, however, the symptoms may return due to the development of scar tissue.

Considerations

In case of carpal tunnel syndrome, it is important that the nerve comes to rest:

• Pay close attention to the use of the hands and find out which movements cause pain and tingling. Try to avoid these movements for several weeks.
• Particularly, movements that require force by the hands while moving the fingers, are often not good for people with carpal tunnel syndrome. Leave activities, such as wringing, peeling potatoes or tightening screws to others.
• Holding the steer of a bicycle or car for a long time is a posture in which the nerve is also easily pinched. Try to alternate this posture and not sustain it for too long (up to half an hour).
• Ensure regular alternation while moving the arms. Divide a task that requires extensive work with the arms in shorter tasks and take breaks.
• Let the nerve rest at night by bandaging the wrist in the most comfortable position or by wearing wrist protectors at night, that are also used in inline skating.
• Look together with a physical therapist to the posture and follow the tips and exercises to improve the posture.
• Take a critical look at the work place and avoid prolonged working with bent wrists and fingers. If necessary, bring in an occupational health expert.

Facts

• In 1950, the American hand surgeon George Phalen first reported about patients with carpal tunnel syndrome.
• The term ‘carpal’ is derived from the Latin word carpus (wrist).
• The prevalence of carpal tunnel syndrome is 2.7%.
• Carpal tunnel syndrome is one of the most common neurological diseases.
• Women are at higher risk of CTS than men.
• The condition is most common in people aged 40 to 60 years.
• Carpal tunnel syndrome falls under the heading of ‘Complaints of the Arm, Neck and/or Shoulder (CANS)’.