Toward sensitive and specific electrodiagnostic techniques in early carpal tunnel syndrome

Context There remains no gold standard or even true agreement among clinicians as to which electrophysiological tests are most important and most relevant particularly in the mild and early carpal tunnel syndrome (CTS). Aim The aim of this study was to determine the sensitivity and specificity of electrodiagnostic (EDX) techniques to confirm the clinically diagnosed patients with mild CTS. Patients and methods This is a descriptive study. A total of 109 hands (68 right hands and 41 left hands) with symptoms consistent with mild idiopathic CTS, as well as 100 hands from controls, were clinically examined and underwent EDX evaluation. Results The ring-difference and thumb-difference had the highest sensitivity, with the distal sensory latency (DSL) of the median nerve coming next. Combined sensory index (CSI) test at a cutoff point more than 1.1 had 100% specificity and positive predictive value. Abnormal DSL of the median nerve had the best negative predictive value. In patients with early and mild CTS and with normal distal motor latency and DSL, the CSI at cutoff point more than 1.1 is the best EDX test that is able to detect most of these patients. Conclusion CSI and its individual components appear as the best EDX tests that help in the diagnosis of patients with early and mild idiopathic CTS