Objective: This prospective diagnostic test study evaluated the relationship between interpretation criteria and accuracy of the Upper Limb Neurodynamic Test 1 (ULNT1) in the diagnosis of carpal tunnel syndrome.
Methods: A blind comparison with a reference criterion of typical clinical presentation and abnormal median nerve conduction was used. All subjects were first tested with nerve conduction studies and then with ULNT1. Each examiner was blinded to the results collected by the other examiners.
Results: We analyzed 47 subjects and 84 limbs. Considering ULNT1 as positive in the presence of reproduction of symptoms only in the thumb or lateral 2 fingers, we estimated sensitivity to be equal to 40% (95% confidence interval [CI], 0.256-0.564), specificity 79.59% (95% CI, 0.664-0.885), positive predictive value 58.33% (95% CI, 0.388-0.755), negative predictive value 65% (95% CI, 0.524-0.758), positive likelihood ratio 1.96 (95% CI, 1.275-3.012), and negative likelihood ratio 0.7538 (95% CI, 0.490-1.159). Considering the increase of symptoms with contralateral or decrease of symptoms with ipsilateral cervical side bending as mandatory positivity criterion, specificity improved, but sensitivity decreased.
Conclusion: Our investigation suggests that the reproduction of symptoms in the thumb or lateral 2 fingers of the affected arm during ULNT1 has weak diagnostic accuracy for carpal tunnel syndrome.
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