P335 Comparison of median nerve distal motor responses in patients with chronic inflammatory demyelinating polyneuropathy and carpal tunnel syndrome

Abstract

Objective Dispersion of distal compound muscle action potential (CMAP) is a useful finding for showing demyelination. In this study, we aimed to compare the duration and area of CMAP of median nerve between cases with Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) and Carpal Tunnel Syndrome (CTS). Material and methods Ninety-two participants (thirty patients with CDIP, 32 patients with CTS and 30 participants of normal control group) who were evaluated. The CMAP duration was measured from the onset of the initial negative potential to the terminal negative deflection back to baseline. The CMAP area calculation was performed by computerized EMG machine. Results A significant difference was not found between groups as for mean age of the groups, and distribution of genders (CIDP: 52,73 ± 12,34 years, 18 (%40) women, 12 (%60) men; CTS: 52,38 ± 11,83 years, 25 (%78,1) women, 7 (%21,9) men; control: 48,5 ± 14,41 years,22 (%79,3) women, and 8 (%26,7) men). The mean CMAP duration of patients with CIDP was significantly higher than patients with CTS (p: 0.003) and control group (p: 0.001), however there was not any significant difference between the patients with CTS and control group (p > 0.05). The mean CMAP area of patients with CIDP was significantly lower than patients with CTS (p: 0.003) and control group (p: 0.001), however there was not any significant difference between the patients with CTS and control group (p > 0.05). Conclusion These findings suggest that the duration and area of distal CMAP is a useful parameter for the differentiation of patients with CIDPand CTS.