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How accurate are the history and physical examination in diagnosing carpal tunnel syndrome (CTS)?

D'Arcy CA, McGee S. Does this patient have carpal tunnel syndrome? JAMA 2000; 283:3110-17

* BACKGROUND Approximately 3% of adults in population-based studies have symptomatic CTS confirmed by electrodiagnostic studies. Clinicians use many different historical and physical findings to diagnose CTS. This study is a systematic review of the accuracy of history and physical examination findings in diagnosing CTS using electrodiagnostic studies as the gold standard.

* POPULATION STUDIED Because this is a systematic review, patients from several different populations were studied. Details were not given on the demographics of patients in the included studies, although none were performed in the family practice setting. This is a possible limitation for family physicians wishing to apply these data to their practices.

* STUDY DESIGN AND VALIDITY The authors searched MEDLINE from January 1966 to February 2000 for relevant articles. Included studies had to meet the following criteria: patients presented to the clinician for symptoms suggestive of CTS; the physical examination maneuvers were clearly described; there was an independent comparison with 1 or more electrodiagnostic parameters; and the authors could extract the data needed to calculate sensitivity, specificity, and likelihood ratios. Twelve articles met these inclusion criteria. Likelihood ratios were pooled if the overall accuracy between studies was homogeneous (ie, studies generally reported similar results). The search could have been improved by contacting the authors of studies that had insufficient data to calculate sensitivity and specificity.

* OUTCOMES MEASURED The primary outcomes were the sensitivity, specificity, and likelihood ratios for each history and physical examination finding.

* RESULTS The flick test had the best positive likelihood ratio (LR+=21.4; 95% confidence interval [CI], 10.8-42.1) and negative likelihood ratio (LR-=0.1; 95% CI, 0.0-0.1), but was only reported in a single study. It is performed as follows: When asking the patient, "What do you actually do with your hand(s) when the symptoms are at their worst?" the patient demonstrates a flicking movement of the wrist and hand similar to that used in shaking down a thermometer. Slightly to moderately useful tests for ruling in CTS include a decreased ability to perceive painful stimuli along the palmar aspect index finger when compared with the ipsilateral little finger (LR+=3.1), the Katz hand diagram with classic or probable patterns (LR+=2.4), weak thumb abduction (LR+=1.8), abnormal monofilament testing (LR+=1.5), and the Phalen sign (LR+=1.3). The confidence intervals of the LR+ and LR- of the following signs and symptoms included 1.0, signifying no diagnostic utility: nocturnal paresthesias, thenar atrophy, 2-point discrimination, abnormal vibration sense, pressure provocation test, and tourniquet test. The square wrist sign (LR-=2.7) and closed fist sign (LR-=7.3) were each only reported in 1 study but show promise. Only the Flick test had an LR- of less than 0.5.

RECOMMENDATIONS FOR CLINICAL PRACTICE

This useful systematic review found that the flick test, a classic or probable Katz hand diagram, hypalgesia, and weak thumb abduction increase the likelihood that a patient will have a positive electrodiagnostic study result for CTS. See the figures and tables in the original article for more details on performing these tests. The Tinel and Phelan tests used by many physicians are less accurate and should be discarded in favor of the tests described. The flick, abduction, and hypalgesia tests in particular can easily be adapted to the family practice setting. Use of these findings can help physicians choose the appropriate initial therapy for their patients, select patients who need further testing, and help focus the work-up on alternative diagnoses if the electrodiagnostic findings are negative.

Richard W. Lord Jr, MD Department of Family and Community Medicine Winston-Salem, North Carolina E-mail: rlord@wfubmc.edu
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Author:Lord, Richard W. Jr
Publication:Journal of Family Practice
Date:Sep 1, 2000
Words:620
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