An Evaluation of the Sensitivities and Specificities of the Comparative Techniques for Electrophysiological Diagnosis of Carpal Tunnel Syndrome

Abstract

Objective: The aim of this study was to determine the diagnostic value of the comparative techniques in carpal tunnel syndrome (CTS) at various electrophysiological stages. Patients and Methods: One hundred hands of 61 patients and 100 hands of 50 healthy volunteers were examined electrophysiologically. The CTS was classified in to four stages according to findings from routine nerve conduction studies. Three motor techniques and two sensory techniques were assessed. The motor techniques included the 2nd lumbricales to interossei distal motor latency difference (2LI-DMLD), the median-thenar to ulnarhypothenar latency difference (THLD) and the median-thenar to ulnar-thenar latency difference (TTLD). The two sensory techniques included the digit 1 sensory latency difference (D1SLD) and the digit 4 sensory latency difference (D4SLD). Results: From the electrophysiological assessment, we found that the CTS stage was mild in 47 hands, moderate in 47 hands and severe in 6 hands. The respective sensitivities and specificities of diagnosing CTS were 100% and 100% for D4SLD, 98% and 98% for THLD, 92% and 92% for 2LI-DMLD, 88.3% and 87% for D1SLD and 87% and 92% for TTLD. The most sensitive and specific technique were found to be D4SLD in mild cases, D4SLD and THLD in moderate cases and THLD and 2LI-DMLD in severe cases. Conclusion: Comparative techniques can be easily performed and are useful in the diagnosis of CTS. The most valuable techniques were D4SLD in mild cases, D4SLD and THLD in moderate cases and THLD and 2LI-DMLD in severe cases.