MOTOR EVOKED-POTENTIALS - A NEW METHOD OF CONTROLLED FACILITATION USING QUANTITATIVE SURFACE EMG

A new method of assessing MEP facilitation using surface EMG under computer control is described. Transcranial magnetic stimulation with voluntary contraction at a value between 2 and 6% of maximal surface EMG activity produced responses with shortest latencies and largest amplitudes and power. No significant changes occurred when facilitation increased beyond this level. These results are similar to previously published studies using a force transducer, confirming the reliability of the system as an alternative method of monitoring voluntary contraction. The controlling system may potentially provide an easy, flexible, quantitative method of ensuring adequate, reproducible facilitation with minimum EMG interference for testing in a clinical setting.