Houston Methodist. Leading Medicine

Hand FAQ


My surgeon thinks there's a strong chance that I have carpal tunnel syndrome. Is there any reason to go ahead with the electric tests to measure the nerve function?


Carpal tunnel syndrome is a common problem affecting the hand and wrist. Symptoms begin when the median nerve gets squeezed inside the carpal tunnel of the wrist. Carpal tunnel syndrome is also known as nerve entrapment or compressive neuropathy. Any condition that decreases the size of the carpal tunnel or enlarges the tissues inside the tunnel can produce the symptoms of carpal tunnel syndrome. To diagnose carpal tunnel syndrome, the physician relies on the patient's history, results of the clinical exam, and sometimes, additional tests such as electrodiagnostic tests. Electrodiagnostic tests include electromyograms(EMGs) and nerve conduction velocity (NCV). An electromyogram (EMG) measures the electrical activity of muscles at rest and during contraction. Nerve conduction studies measure how well and how fast the nerves can send electrical signals to the muscles. Carpal tunnel syndrome can reduce nerve signals to the muscles resulting in muscle atrophy (wasting) and weakness. There isn't strong agreement about the value of electrodiagnostic tests at this time. Some studies show that only those patients with positive findings on the electrodiagnostic tests should be treated surgically. Others suggest that clinical tests are enough to make the diagnosis. They suggest that adding the electrodiagnostic tests is unnecessary except in some cases. A new test called the CTS-6 is now available to help with this decision. The CTS-6 test can be used to determine the chances a patient has carpal tunnel syndrome. This instrument has six parts. The six items include 1) numbness in the hand and fingers supplied by the median nerve, 2) muscle atrophy and/or weakness, 3) a positive Phalen test (standard clinical test used to diagnose carpal tunnel syndrome), 4) loss of two-point discrimination (feeling two separate points touched on the skin), 5) numbness at night that wakes the patient up, and 6) a positive Tinel sign (another standard clinical test used to diagnose carpal tunnel syndrome). Each of the six items is given a point value. A total score of 12 or more suggests a strong probability (80 per cent chance) that the patient has carpal tunnel syndrome. A total score less than five indicates a very small chance (25 per cent) that the patient has carpal tunnel syndrome. With the availability of the CTS-6, there is much less need to use electrodiagnostic studies. The goal in making any diagnosis is to do so in the least amount of time, with minimal discomfort to the patient, and at the lowest cost. The right diagnosis is important in planning treatment that will bring the most successful results. But for the most part, the value added by electrodiagnostic testing is minimal when the CTS-6 score predicts carpal tunnel syndrome. Brent Graham, MD. The Value Added by Electrodiagnostic Testing in the Diagnosis of Carpal Tunnel Syndrome. In The Journal of Bone & Joint Surgery. December 2008. Vol. 90A. No. 12. Pp. 2587-2593.

*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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