Evaluating the Diagnostic Utility of the Flexion-Compression Test for Carpal Tunnel Syndrome
Sahitya K Denduluri, MD1; Samuel E. Ford, MD2; Susan M. Odum, PhD3; Michael B Geary, MD2; R. Glenn Gaston, MD2; Bryan J. Loeffler, MD4
1OrthoCarolina, Charlotte, CA; 2OrthoCarolina, Charlotte, NC; 3OrthoCarolina Research Institute, Charlotte, NC; 4Hand Center, OrthoCarolina, Charlotte, NC
INTRODUCTION The purpose of this study was to determine the diagnostic accuracy of the flexion-compression (F-C) test for carpal tunnel syndrome (CTS). Furthermore, we sought to understand whether the F-C test could be used to as an adjunct to the CTS-6 score. Using electrodiagnostic testing as the gold standard, we hypothesized that the F-C test would be a better diagnostic test for CTS as compared to the wrist flexion (Phalen’s) or palmar compression (Durkan’s) tests alone.
MATERIALS & METHODS We performed a prospective, cross-sectional study of patients who presented with CTS symptoms. At the first visit, all patients were administered the CTS-6 questionnaire, and then the Phalen’s, Durkan’s, and F-C tests in a particular order as determined by block randomization. A test was considered positive if the patient reported the onset or worsening of symptoms within 30 seconds (s). A CTS-6 score greater than 11 was deemed positive. Patients were then sent for electrodiagnostic testing, considered to be positive if sensory latency was greater than 3.5 milliseconds (ms), motor latency was greater than 4.2ms, or if EMG changes were present. At the follow-up visit, the three physical exam tests were repeated in a pre-determined, random order. Physicians were blinded to electrodiagnostic study results until physical exam tests were repeated. Physical exam test results from both visits were combined for analysis.
RESULTS After an a priori power analysis, 81 patients were included. The F-C test resulted in more rapid onset of symptoms (8s) than the Phalen’s (13s) or Durkan's (12s) tests. Among patients with any electrodiagnostic evidence of CTS, the positive likelihood ratio (LR+) of the Phalen’s test (1.40) was higher than the Durkan’s (1.13) and F-C (1.10) tests, but still less than that of the CTS-6 score (1.64). None of the physical exam tests had a positive likelihood ratio greater than 1 when EMG changes were present (CTS-6 LR+ 1.03). Performing any of these physical exam tests in conjunction with the CTS-6 questionnaire was not more useful than administering the CTS-6 alone.
CONCLUSIONS None of the physical exam maneuvers, including flexion-compression, were informative in diagnosing CTS, and even less useful for severe CTS. The CTS-6 questionnaire alone better predicts electrodiagnostic evidence of CTS than physical exam testing, though it only very slightly increases the post-test probability of disease. Taken together, formal electrodiagnostic testing plays an important role in accurately diagnosing CTS when compared to the tested exam maneuvers and CTS-6.
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