Intra-rater reliability of a transcranial magnetic stimulation technique to obtain motor evoked potentials.

The purpose of this study was to determine the intra-rater reliability of motor evoked potentials (MEP) obtained through transcranial magnetic stimulation (TMS). TMS was applied over the primary motor cortex of 16 healthy subjects. Motor thresholds, MEP latencies, and amplitudes were recorded from the contralateral upper limb on 6 occasions over 15 days. An intraclass correlation coefficient (ICC 2,1) was used to estimate reliability. The ICCs ranged from 0.60 to 0.92 for all MEP measures except amplitude (ICC = 0.01 to 0.34). MEPs obtained with the TMS technique described are generally reliable, although MEP amplitudes demonstrated less consistency.