Objective
To compare motor evoked potential stimulated by round coil with that stimulated by butterfly coil.

Method
Thirty control subjects were studied using magnetic stimulation by round coil and butterfly coil. Stimulation sites were cortex, cervical spine and lumbar spine. Recording electrodes were located on biceps brachii, abductor digiti minimi and tibialis anterior muscles.

Results
There were no significant differences between latencies of motor evoked potentials using round coil and those using butterfly coil in all tested muscles. In all muscles, amplitudes were significantly higher in stimulation with round coil than with butterfly coil. Above results were shown in both cortical and spinal motor evoked potentials.

There were significant correlations between latencies of motor evoked potentials, heights, and arm lengths.

Conclusion
We can record motor evoked potentials more easily with round coil than butterfly coil.