HP50 : Doing a most sensitive nerve conduction study to confirm the carpal tunnel syndrome

Abstract

The aim is to estimate a lower difference of sensory interlatency between median and ulnar nerves than 0,5 ms for CTS confirmation. Introduction : The carpal tunnel syndrom (CTS) is the most common mononeuropathy usually confirmed by nerve conduction study (NCS). But, sometimes, this tool remains negative while clinical symptoms tell the opposite. Methods : It’s a transversal study. 36 Hands were collected. Inclusion criteria was a normal sensory conduction velocity of median nerve > 45 m/s. All subjects underwent Wainner and Kamath tools. The difference of sensory interlatency between median and ulnar nerves (DMU) was calculated. When this DMU is below 0,5 ms, CTS was retained. Pearson and student tests were used as statistical tools. Results : Wainner and Kamath tools showed significant results respectively with p= 0,038 et p= 0,034 when NCS confirmed CTS or not. Wainner tool distinguished 2 groups at a level 3. 23 hands (< 3), had a DMU mean value 0,14 ± 0,26 ms. 13 hands (≥ 3), had a DMU mean value 0,34±0,22 ms (p=0,027 between 2 groups). Kamath tool distinguished 2 groups at a level 2. 16 hands (≤ 2), had a DMU mean value 0,04± 0,16 ms. 20 hands (> 2), had a DMU mean value 0,35± 0,25 ms (p=0,000 between 2 groups). Conclusion: When these clinical tools (Wainner and Kamath) are positive, the DMU was lower than 0,5 ms. In this way, the estimation of a lower positive DMU value must be done by an enlarged study.