Carpal Tunnel Syndrome

Overview, Causes, & Risk Factors

Carpal tunnel syndrome (CTS) is a condition in which the median nerve in the wrist is compressed. This causes numbness and pain in the fingers and hand.

What is going on in the body?

A ligament and the bones at the base of the palm of the hand, just beyond the wrist, form the carpal tunnel. Through this tunnel passes the median nerve and tendons going to the fingers and thumb. The median nerve conducts sensation from the palm side of the thumb and fingers, except for the little finger. It also carries impulses to small muscles in the hand, particularly at the palm side of the base of the thumb. If the pressure in the carpal tunnel increases enough, the median nerve is compressed.

What are the causes and risks of the condition?

CTS can be caused by anything that increases pressure on the nerve in the carpal tunnel. CTS has been associated with repetitive stress injury. This type of injury occurs when a part of the body is used repeatedly or overused. People who use computers or vibrating tools are at particular risk. Factory workers on assembly lines, or those who do repeated actions involving the wrist, may develop CTS.

Other factors can also increase a person’s risk for carpal tunnel syndrome. Examples include the following:

  • chronic renal failure, a form of kidney failure
  • a cyst on the tendon
  • diabetes
  • gout, a form of arthritis
  • hemodialysis, a procedure for filtering blood of people with kidney failure
  • hypothyroidism, or low levels of thyroid hormone
  • obesity
  • oral contraceptives
  • pregnancy
  • rheumatoid arthritis
  • trauma, or injury, to the wrist
  • tuberculosis
  • Carpal tunnel syndrome is more common in women than in men. It is most common in middle-aged individuals.

    Symptoms & Signs

    What are the signs and symptoms of the condition?

    CTS usually starts gradually, with a vague aching in the wrist, extending into the hand or forearm. Acute onset occurs when the compression of the nerve happens suddenly. This sudden onset is more likely to cause pain. The numbness and tingling is felt in the thumb, index finger, long finger, and half of the ring finger on the palm side. Sharp pains may radiate up through the arm or shoulder.

    Often a person will wake up at night with pain or numbness. The individual may shake or massage the wrist in order to “improve the circulation.” Similar symptoms can occur during the day, particularly when performing repetitive activities with the wrist bent. Eventually the nerve trouble can result in weakness of the thumb muscles and a tendency to drop things.

    Diagnosis & Tests

    How is the condition diagnosed?

    The diagnosis of carpal tunnel syndrome begins with a medical history and physical exam. The healthcare provider may order additional tests, including:

  • an electromyogram, or EMG, which tests the electrical activity of the muscle
  • an MRI of the wrist, which may show the compressed nerve
  • a nerve conduction velocity test, which measures electrical conduction along the median nerve
  • Prevention & Expectations

    What can be done to prevent the condition?

    Any underlying cause of CTS should be diagnosed and corrected. For example, medicine can be used to correct hypothyroidism.

    Overuse of the wrist and fingers should be avoided. A small recovery time is needed to rest and lubricate the flexor tendons. Variety is the key. Workers whose motions are repetitious and prolonged are at risk. A mixture of activities, such as typing interspersed with filing, may help to rest the affected areas. Finding a new way to use the hand, by using a different tool, may help some individuals. Using the nondominant hand more often might help to relieve stress on the dominant extremity.

    Computer workstations should be designed so that the wrists are well supported in a neutral position. Care should be taken to avoid striking the palm side of the wrist on hard surfaces. Special on-the-job equipment and training may be available.

    Early identification of symptoms is important. Early symptoms, such as tingling in the fingers, may occur several hours after the aggravating activity has stopped. Making the connection between activities and symptoms is important. This gives the person a chance to correct working conditions. This may help to prevent further or worsening symptoms.

    What are the long-term effects of the condition?

    If carpal tunnel syndrome isn’t treated, the hand may become weaker and number. Permanent numbness and weakness can result.

    What are the risks to others?

    Carpal tunnel syndrome is not contagious and poses no risk to others.

    Treatment & Monitoring

    What are the treatments for the condition?

    Underlying diseases, such as diabetes, underactive thyroid, and rheumatoid arthritis should be treated. Weight loss or reduced salt intake may be helpful.

    Repetitive use of the hand with the wrist bent must be avoided. Frequent changes of activity, with breaks for 5 minutes every hour, can help prevent overuse. Certain exercises can be done to increase flexibility in the wrist and fingers. People with CTS should not sleep on their hands or with wrists bent down. It is very important to sit properly at the computer, with good support for the wrists. Yoga-based exercises may be effective.

    For mild cases, the first treatment is to splint the wrist at night and during the day if possible. A splint keeps the wrist from moving but allows for mostly normal hand activity. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, can be used for a short time. If these do not help, a corticosteroid can be injected into the carpal tunnel. This may help permanently or only temporarily.

    Surgery, called carpal tunnel repair, is reserved for people with muscle wasting and decreased sensation. This surgery is considered only when the symptoms are no better after several months of treatment.

    What are the side effects of the treatments?

    NSAIDs can cause stomach upset or allergic reactions. Injecting corticosteroids rarely can accidentally injure the nerve. Surgery can cause bleeding, infection, nerve damage, or allergic reaction to anesthesia.

    What happens after treatment for the condition?

    After the surgery, the wrist is immobilized for a short time. Exercises help to regain mobility of the wrist and fingers. It is important to practice proper use of the wrist.

    How is the condition monitored?

    Any new or worsening symptoms should be reported to the healthcare provider.

    Article type: xmedgeneral