Table 2

Summary of parameters of nerve excitability testing

ParameterAbductor pollicis brevisAbductor digit minimip Value
Normal (A)ALS (B)Normal (C)ALS (D)A vs BC vs DA vs CB vs D
Strength-duration time constant (ms)0.46 (0.02)0.55 (0.03)0.40 (0.01)0.42 (0.02)0.018*0.590.049*0.0002*
Threshold electrotonus
 TEd (10–30 ms) (%)69.5 (1.2)71.6 (1.7)65.4 (1.4)66.5 (1.2)0.310.560.039*0.016*
 TEd (90–100 ms) (%)47.2 (1.2)51.2 (1.2)48.1 (1.3)51.6 (1.9)0.041*0.130.690.85
 TEh (90–100 ms) (%)−131.3 (4.6)−121.0 (5.6)−130.7 (4.9)−126.3 (5.2)0.170.540.920.49
Recovery cycle
 Refractoriness (2.0 ms) (%)78.6 (13.4)73.8 (15.8)50.2 (3.4)45.0 (6.8)0.820.50.059**0.11
 Supernormality (5.0 ms) (%)−23.6 (1.4)−28.9 (2.1)−21.2 (1.4)−25.6 (1.5)0.042*0.038*0.230.21
 Late subnormality (42 ms) (%)15.4 (0.9)14.7 (1.2)9.7 (1.2)10.2 (1.4)0.670.790.0007*0.016*
  • Data are given as mean (SEM).

  • *p<0.05; **p<0.1.

  • ALS, amyotrophic lateral sclerosis; TEd, depolarising electrotonus; TEh, hyperpolarising electrotonus.