Short latency facilitation between pairs of threshold magnetic stimuli studied in amyotrophic lateral sclerosis.

The aim of the present study was to investigate the effects of short latency facilitation between pairs of threshold magnetic stimuli on the motor cortex of amyotrophic lateral sclerosis (ALS) patients, at an interstimulus interval (ISI) of 1-5 ms. As compared to controls, the facilitatory effects normally recorded at ISI 1 and 3 ms were considerably reduced. This suggested that the neuronal circuitry responsible for these effects, which is supposed to be the same as those generating I-waves, is impaired in ALS.