13. Threshold-tracking TMS without an MEP

Transcranial magnetic stimulation (TMS) is a useful tool for quantifying cortical hyperexcitability in ALS. Short-interval intracortical inhibition (SICI) measures the suppression of descending corticomotoneuronal volleys by GABA-ergic inhibitory interneurons. Threshold-tracking TMS (tt-TMS) studies were developed to overcome the marked variability of motor evoked potentials (MEPs); tt-TMS "tracks" the stimulus intensity required to just evoke a small target MEP. Despite the success of studies using the tt-TMS technique, fasciculations can complicate recordings.

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