Purpose
Patient knowledge of the frequency with which electrodiagnostic testing (EDx) for
suspected median neuropathy at the carpal tunnel addresses nuance in the distinction
between normal and abnormal neurophysiology might help them make an informed decision
about whether or not to have this test. We reviewed a large set of consecutive EDx
for possible carpal tunnel syndrome (CTS) and associated medical records to determine
(1) the percentage of EDx measurements within 10% of threshold values; (2) discordance
between clinician and EDx diagnosis of CTS using diagnostic performance characteristics;
and (3) demographic and disease characteristics independently associated with EDx
diagnosis of median neuropathy at the carpal tunnel.
Methods
We retrospectively reviewed nerve conduction study (NCS) results of 537 consecutive
patients evaluated for possible idiopathic median neuropathy at the carpal tunnel.
We measured the number of patients within 10% of 3 NCS diagnostic thresholds; the
diagnostic performance characteristics comparing clinician and EDx diagnosis; and
patient and disease characteristics associated with EDx diagnosis of CTS.
Results
The 3 NCS parameters were within 10% of the threshold for diagnosis of median neuropathy
at the carpal tunnel in 2.6% to 33% of patients. Overall, 76% of EDx results were
interpreted as median neuropathy at the carpal tunnel, 19% as normal, and 5% as another
diagnosis (eg, cervical radiculopathy). Patients with normal EDx were significantly
younger, more likely not to report paresthesias/numbness, more likely to have prior
normal EDx, and less likely to have had a previous contralateral carpal tunnel release.
Conclusions
This data set reflecting management strategies for suspected CTS at a large institution
confirms inherent diagnostic uncertainty, relatively strong concordance between clinician
and EDx diagnosis, and the importance of focusing on paresthesia rather than pain.
These findings support the use of clinical prediction rules and may help inform a
patient’s decision regarding whether or not to have EDx.
Type of study/level of evidence
Diagnostic III.
Key words
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Article info
Publication history
Published online: February 20, 2020
Accepted:
November 27,
2019
Received:
November 9,
2018
Footnotes
No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
Identification
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© 2020 by the American Society for Surgery of the Hand. All rights reserved.
