S57. The divergence phenomenon of CMAP/SNAP in early stage of amyotrophic lateral sclerosis

Abstract

To evaluate the relationship of sensory fibers and functional status of motor fibers in patients with amyotrophic lateral sclerosis(ALS) through electrophysiological approach, and analyse the results. We retrospectively reviewed 64 case with early stage of upper limb-onset ALS admitted in our hospital from January 2010 to December 2015. Patients with ALS were graded as normal compound muscle action potential (CMAP) (23 cases) and abnormal CMAP group (41 cases) according to the CMAP of median nerve 39 healthy volunteers were included as control. Median and ulnar nerves electrophysiological study were performed using the Keypoint.net (Medoc Ltd) electromyogram device. The sensory nerve action potential (SNAP) amplitudes of Median and ulnar nerves were raised (28.80 ± 15.54) μV vs (21.06 ± 7.41) μV, t = 2.91, P < 0.01, (12.44 ± 4.64) μV vs (10.46 ± 2.77) μV, t = 2.41, P = 0.01 in ALS group, compared with control group. But the sensory conduction velocities (SCVs) had no difference. SNAP amplitudes of median nerve were raised (33.13 ± 13.33) μV vs (21.06 ± 7.41) μV, F = 6.39, P < 0.01 in the normal CMAP group, compared with the control group, but the SNAP amplitudes of ulnar nerve had no difference: Compared with the control group, the SNAP amplitudes of median nerve had no difference, but the SNAP amplitudes of ulnar nerve were raised (12.92 ± 5.01) μV vs (10.46 ± 2.78) μV, F = 3.71, P < 0.05 in abnormal CMAP group. ALS patients with onset of upper limb in the early stage may have increased SNAP in median and ulnar nerve,and show CMAP/SNAP separated phenomenon.