ADM, abductor digiti minimi; ALS, amyotrophic lateral sclerosis; APB, abductor pollicis brevis; ADM/APB ratio, ADM/APB CMAP amplitude ratio; CMAP, compound muscle action potential; DML, distal motor latency; MCV, motor conduction velocity; NC, normal control. All data are expressed as mean (SD). Values with significant differences printed in bold characters. *P < 0.001, between the APB and the ADM in each group. For comparisons of DML and ADM/APB ratio between the ALS patients in groups 1 and 2, and the normal controls, Bonferroni correction with a level of significance of <0.017 was used.