Saturday, February, 11, 2012

Carpal Tunnel Syndrome - Diagnosis

Table of Contents

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.

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.

Review Date: 02/17/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)