Thoughts from a Former Program Director
Many former residents quote phrases and axioms, valid at the time but long since discarded, as new concepts are recognized. This is similar to citing long-ago literature to support a premise that should have been dropped but is current usage with a practitioner.
I, of course, have a periodic revelation—some would say “epiphany”—that often changes my techniques and alters my frequently exposed clinical aphorisms. In other words, I learn something new every day. I must, or else the residents and medical students will get ahead of me.
Of course, there are some eternal verities or principles that are “forever,” but these are not to be confused with unveiling truths, new knowledge, and enlightenment, which appear from time to time.
A recent speaking exposition on the history of electrodiagnosis of carpal tunnel syndrome was illuminating. Fifty years ago, one of our British forebears (Gilliatt) was quoted as saying that electromyography was too cumbersome to be useful in a diagnostic outpatient clinic to diagnose carpal tunnel syndrome. Less than 10 years later, the standard for diagnosing carpal tunnel syndrome was 5-millisecond latency of the median motor fibers to the thenar muscles. Today, this would be absurd.
Thirty years ago, the orthodromic sensory latency from the fingers to the wrist was the critical measurement. Soon, antidromic sensory latencies from the wrist to the fingers became the diagnostic criteria.
Twenty years ago, compound nerve latency between the palm and the wrist was introduced, and then as measurements became precise, amplitudes assumed primacy.
All during this time, comparison of latencies between the median nerve and those of the ulnar and radial nerves was suggested as most helpful. Even as we speak, the controversy of “most sensitive and specific” continues.
I (we) believe that the duration of the negative spike (or rise time) of the sensory nerve action potential is the most sensitive and specific! So, allow some space between “taught concepts” in residency and the “here and now” of constantly changing knowledge.