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October 18, 2000

Clinical Diagnosis of Carpal Tunnel Syndrome—Reply

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Copyright 2000 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2000

JAMA. 2000;284(15):1924-1925. doi:10-1001/pubs.JAMA-ISSN-0098-7484-284-15-jlt1018

In Reply: In answer to Dr Mackinnon and colleagues, we chose to exclude studies using asymptomatic control subjects because such studies tend to inflate the specificity of a diagnostic test and overestimate its accuracy.

Clinicians have no difficulty distinguishing a normal, asymptomatic hand from one with classic CTS. Instead, they are interested in how well bedside findings distinguish CTS from other diagnoses that cause hand dysesthesias. If the patient has no symptoms, physical examination for CTS is unnecessary. In addition, we believe it is important to distinguish patients' subjective symptoms (eg, Katz hand diagram) from the objective sensory findings (eg, hypalgesia). Katz et al included the fifth finger in their "classic" pattern because they, like others, noted that patients with CTS frequently complain of symptoms in the fifth digit.1 We included their hand diagram in our analysis because it is a bedside finding that was clearly defined, and our analysis shows it has modest diagnostic accuracy. Whether other rating schemes of hand diagrams have better accuracy is unknown. Nonetheless, in contrast to the subjective phenomenon of symptoms in the fifth finger, sensory loss is rarely demonstrated in the fifth finger in CTS,1 consistent with the classic anatomic teaching mentioned by Mackinnon et al.