A prospective questionnaire study of patients with suspected carpal tunnel syndrome referred to a university hospital electrodiagnostic laboratory: a comparison of self-reported symptoms and NCS findings

Abstract

The primary objective of this prospective questionnaire study was to determine whether self-reported symptoms were predictive of nerve conduction study (NCS) results. The population consisted of 211 unselected patients with clinically suspected carpal tunnel syndrome (CTS) who were physician referred for confirmatory NCS. These patients were administered a pre-NCS questionnaire. Patients reported 350 symptomatic hands, and 72 asymptomatic hands. A comparison of symptom lateralization and bilateral NCS results was performed. Standardized electrophysiologic criteria were applied. In symptomatic hands, 49.2% of NCS studies reported median mononeuropathy, while, 50.8% were negative. In asymptomatic hands, 37.5% of NCS studies showed median mononeuropathy, the remaining 62.5% were negative. Overall accuracy of NCS compared to symptoms was 51.4%, with a sensitivity of 86.4%, specificity of 20.1%, positive predictive value of 49.1% and negative predictive value of 62.5%. These comparisons do not support a strong relationship between clinical symptoms and NCS results in this patient group.