Take care in CTS screening to ensure valid results
December 1, 1997 3 minutes read
Take care in CTS screening to ensure valid results
Poor screening can bring expensive false diagnoses
Even the strongest proponents of nerve conduction studies stress that they can be misused, resulting in high rates of false positive diagnoses and encouraging employers to act unfairly with workers. A good screening program for carpal tunnel syndrome (CTS) must be administered by specifically trained staff and must include a strong education component.
Ronald C. Bingham, MD, president of IPS Physician Services, an occupational health provider in Jackson, TN, is a big believer in the usefulness of nerve conduction studies to screen out existing and potential CTS, but he also says most of the nerve conduction studies being conducted around the country are of poor quality. He even says that the high rate of CTS diagnoses in the United States can be traced to the poor quality of the nerve conduction studies performed on the patients; a great many of those patients do not actually have CTS and simply received an inadequate test.
To provide high-quality nerve conduction studies, Bingham offers this advice:
• Use only staff that have been specially trained.
The person doing the test does not have to be a physician, though that is preferable. A well-trained technician can conduct the test competently, but all results should be reviewed and certified by a physician before releasing them to the employer.
Ideally, both the technician and the reviewing physician should be members of the American Association of Electrodiagnostic Medicine. Membership requires extensive training and offers an assurance that the tester meets minimum qualifications.
Nonmembers can be highly skilled also, but Bingham notes the association membership is an easy way to be sure of competency. Certification can also be a selling point when presenting the service to potential clients. He estimates that about one-third of those currently providing nerve conduction studies meet the minimum standards for membership in the association.
• Insist on carefully designed testing arrangements.
A well-qualified tester should know the necessary arrangements for getting valid test results with nerve conduction studies, but it still is a good idea to stress the need for accurate measurements.
The physician overseeing a technician tester should periodically confirm that the testing conditions are appropriate.
Temperature of the hand must be considered
The most common error in nerve conduction studies is failure to take into account the temperature of the hand. A cold hand will conduct more slowly than a hand of normal temperature or a warm hand, a crucial point since the test results are based on the speed with which electricity is conducted through the nerve. Bingham, who also acts as medical director for a large employer with work sites in many states, says few testers measure the temperature of the hand.
"I see all the nerve conduction studies from this employer in six states, and only one in 20 takes temperature into consideration, and that’s being overly kind," he says. "Many similar factors are routinely ignored, so you have to make sure your staff is careful if you want to depend on the test results."
• Educate the employer about the test’s meaning and limitations.
Employers have a tendency to get overly confident about the test results. You must emphasize that no medical test is perfect, and the results should be used carefully, especially when you’re talking about only a potential to develop CTS rather than existing CTS. Even if a worker has a slow nerve and may be at increased risk of developing CTS, it is wrong for employers to assume the person is not employable. Alternative positions usually are available.
"We don’t want to be in the position of telling them they should or shouldn’t withdraw job offers, for instance, but we want to be sure we’ve fully informed the employer about these test results before they do anything," Bingham says. "We know that a positive test result does not necessarily mean that they have symptoms now or ever will."
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