Nerve conduction velocities of single thenar motor axons based on the automated analysis of F waves in amyotrophic lateral sclerosis.

摘要

The motor unit number estimate (MUNE), motor unit size, and conduction velocity (CV) of thenar surface-recorded motor unit action potentials (S-MUAPs) as collected by the automated F-wave technique were analyzed in 13 patients with amyotrophic lateral sclerosis (ALS) (aged 29-78 years, mean: 61) and 10 age-matched normal subjects (aged 49-81 years, mean: 64). Totals of 96 and 100 thenar S-MUAPs were collected from ALS patients and normal subjects, respectively. There were significant differences (P < 0.001) in the mean estimated numbers and sizes of motor units between the ALS patients (MUNE: 41.9, S-MUAP size: 699.6 microV/ms) and normal subjects (MUNE: 151.2, S-MUAP size: 244.1 microV/ms). The mean S-MUAP CV was 46.3 m/s (range: 32-59) for ALS patients and 56.5 m/s (range: 43-69) for normal subjects (P < 0.001). Mean median motor nerve CVs, measured in the forearm segment, were not significantly different (P = 0.79) between ALS patients (53.4 m/s) and normal subjects (52.9 m/s), however. Thenar motor unit CVs are significantly reduced in ALS patients as compared to normal controls, and this may be due to proximal motor nerve slowing.