Median Wrist-to-palm Motor Conduction Velocity and Median-ulnar Latency Differences in Carpal Tunnel Syndrome

Paek, Won Ky; Koh, Seong Ho; Kim, Hyun Young; Lee, Kyu Yong; Lee, Young Joo; Kim, Hee Tae; Kim, Seung Hyun; Kim, Juhan

Abstract

BACKGROUND
Carpal tunnel syndrome (CTS) is the most common type of entrapment neuropathy in clinical practice. There are patients with symptoms and signs suggestive of CTS who remain difficult to diagnose using standard electrophysiologic techniques. To date, there have been few studies concerning the efficacy of the various techniques for measuring median motor conductions in the diagnosis of CTS. The purpose of this study was to determine which motor conduction techniques are more sensitive for diagnosing CTS. METHODS: We analyzed 139 patients (221 hands) who were diagnosed with CTS for the past year in our hospital. Median motor and sensory nerve conduction velocities (MCV and SCV) with wrist (W), palm (P) and finger (F) stimulations were performed with traditional methods. W-P MCV and two motor distal latency differences between the median and ulnar nerves were measured and calculated. The sensitivity of each test was also calculated. RESULTS: The sensitivities of the nerve conduction techniques were noted in W-P MCV (71.95%), median thenar-ulnar thenar latency difference (71.95%), and median thenar-ulnar hypothenar latency difference (69.23). The sensitivities of the existing nerve conduction methods were noted in the terminal latency of the median nerve (73.30%), 2nd finger-wrist (II-W) segment (94.57%), 3rd finger-wrist (III-W) segment (92.31%), palm-wrist (P-W) segment (93.21%), and distoproximal ratio in the 3rd finger (85.07%). CONCLUSIONS: The most sensitive technique was the II-W segment SNV. MCV is also valuable and is no more difficult a method than SCV for the diagnosis of CTS. In patients with suspected CTS, studying both motor and sensory nerve conduction techniques increased the diagnostic yield.