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Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) causes numbness or tingling on the palm side of the hand, affecting the thumb and the first three fingers. It occurs when the median nerve that runs from the forearm into the palm is compressed as it passes through the narrow channel in the wrist called the carpal tunnel. CTS occurs more often in women (5.8 percent) than in men (0.6 percent). Contrary to popular belief, studies have shown that using a computer keyboard or mouse does not increase the risk of developing CTS.

For information about treatment for CTS, contact the Virginia Mason Center for Hand Surgery at (206) 341-3000.

Risk Factors for Carpal Tunnel Syndrome

Certain medical conditions and occupations may put individuals at risk of developing carpal tunnel syndrome. CTS is associated with obesity, rheumatoid arthritis, pregnancy (fluid retention), diabetes, hypothyroidism and trauma.

Another risk factor is the size of the carpal tunnel itself. Women, for example, have a smaller carpal tunnel than men.

Physical factors associated with CTS include:

  • Repetition
  • Force
  • External pressure
  • Vibration

Occupations in which people are exposed to highly repetitive flexion and extension of the wrist, such as assembly workers, or regular use of hand-held vibratory tools, such as mechanics, have a significantly higher risk of developing CTS.

Symptoms of Carpal Tunnel Syndrome

  • Numbness, tingling in first three fingers
  • Hand numbness, tingling when holding onto a book, phone or steering wheel
  • Numbness and burning of hands at night
  • Aching in the wrist, most commonly at night
  • Weakness of the thumb
  • Inability to distinguish between hot and cold temperatures (in advanced cases)

Pain during the daytime is not very common in CTS. It is usually only seen at night in advanced cases.

Diagnosing Carpal Tunnel Syndrome

A medical history, physical exam and a neurologic exam with a physician or neurologist will help confirm or rule out CTS. There are several neurologic tests available to help in the diagnosis, including:

  • Tinel's test — During this test, the physician lightly taps the wrist near the median nerve, which may create tingling in the hand.

  • Phalen's test — The physician will ask the patient to flex (bend) the affected wrist, which may cause tingling within 60 seconds.

  • Pressure provocation test — During this test, the physician will press his or her thumb on the wrist over the carpal tunnel for 60 seconds, which may cause tingling or numbness.

  • Nerve conduction studies — These are the only ways to definitively diagnose CTS. They also determine the level of severity of median nerve compromise (mild, moderate, severe) and can be helpful in determining other causes of hand discomfort and numbness.

  • Non-surgical treatment of carpal tunnel syndrome — Mild cases of CTS are treated conservatively (non-surgically) to begin with. Avoiding activities with excessive vibration, repetitive motion, forceful gripping or excessive flexion and extension of the wrist is recommended. A wrist splint or brace can be worn during the day and also at night to keep the wrist straight and relieve pressure on the carpal tunnel. A clinical study has shown that splinting may help up to 75 percent of mild-to-moderate cases, and that many patients were able to eventually dispose of the splint without recurring symptoms.

If symptoms are mild, steroid injections can be effective in treating CTS in the short term. Steroid injections may be particularly helpful for women in the third trimester of pregnancy, to provide relief through delivery (when symptoms are frequently seen). An obstetrician will determine if it is safe to have steroid injections during pregnancy.