2001 Volume 64 Issue 1 Pages 28-34
The purpose of this study was to investigate the influences of stimulation coils and occlusal force on elicitation of motor evoked potentials (MEPs) in the masseter muscle by transcranial magnetic stimulation (TMS).Five healthy male subjects were asked to clench with light or strong force to record the MEPs in the bilateral masseter muscles by TMS with three different coils (round, figure-eight and double cone). Stimulation strengths ranged from 30 to 70% of the maximum output for each coil. We found that the:MEPs recorded in the ipsilateral masseter muscle had short latency (about 3.0 ms) and these in the bilateral masseter muscles had long latency (about 8.0 ms). MEPs in the contralateral masseter muscle were elicited only in heavy clenchings. The double cone coil elicited the MEPs highest. These results suggest that cortical MEPs by TMS were elicited most easily with heavy clenchings and in combination with the double cone coil.
