Carpal Tunnel Syndrome - Diagnosis

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Physical Assessment Tests for Carpal Tunnel Syndrome

The doctor will perform a physical exam.

The following findings are helpful in identifying carpal tunnel syndrome:

• Less sensitivity to pain where the median nerve runs to the fingers
• Thumb weakness
• Inability to tell the difference between one and two sharp points on the fingertips (this is a late sign of carpal tunnel)

Flick Signal. One important and simple test of carpal tunnel is the "flick" signal:

• The patient is asked, "What do you do when your symptoms are worse?"
• If the patient responds with a motion that resembles shaking a thermometer, the doctor can strongly suspect carpal tunnel.

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Testing for Thumb Weakness. Two questions are useful in determining thumb weakness:

• Can the thumb rise up from the plane of the palm?
• Can the thumb stretch so that its pad rests on the little finger pad?

Provocation Tests. Certain tests can produce symptoms:

• Phalen's Test. In Phalen's test, the patient rests the elbows on a table and lets the wrists dangle with fingers pointing down and the backs of the hands pressed together. If symptoms develop within a minute, CTS is indicated. (If the test lasts for more than a minute, even patients without CTS may develop symptoms.) This test may be particularly important in determining the severity of CTS and assessing the results of treatment.
• Tinel's Sign. In the Tinel's sign test, the doctor taps over the median nerve to produce a tingling or mild shock sensation.
• Pressure Provocation Test. The doctor presses over the carpal tunnel for 30 seconds to produce tingling or shock in the median nerve.
• Tourniquet Test. This test uses an inflatable cuff that applies pressure over the median nerve to produce tingling or small shocks.
• Hand Elevation Test. The patient raises his or her hand overhead for 2 minutes to produce symptoms of CTS. The test was recently proven to be accurate and may provide useful information when combined with the Tinel's and Phalen's tests.

Electrodiagnostic Tests

Electrodiagnostic tests analyze the electric waves of nerves and muscles. These tests can help detect median nerve compression in the carpal tunnel.

Electrodiagnostic tests should be used if clinical or provocative tests are positive and the patient is considering surgery. These tests are the best methods for confirming a diagnosis of CTS. Doctors who perform these tests should be certified by the American Board of Electrodiagnostic Medicine, which uses rigorous standards in qualifying doctors. Specific electrodiagnostic tests, called nerve conduction studies and electromyography, are the most common ones performed. Nerve conduction tests can also detect other problems that cause CTS symptoms, such as pinched nerves in the neck or elbow, or thoracic outlet syndrome.