Comparison study of branch versus main trunk repetitive nerve stimulation of facial nerve in normal subjects.

PURPOSE: Repetitive stimulation of the facial nerve is performed in neuromuscular junction disorders. Main nerve stimulation is currently used. There is more discomfort and artifact than stimulation of a branch. We stimulated the temporal branch of the facial nerve to the frontalis and compared the responses with that of main trunk stimulation. We compared the amplitudes and the corresponding amperage.

METHODS

Eleven normal volunteers between 18 and 65 years of age were studied. Repetitive nerve stimulation of both the main trunk and the temporal branch to the frontalis muscle was performed at a frequency of 3 Hz, and waveforms were recorded from the frontalis muscle using adhesive surface electrodes. The amplitudes and corresponding amperages were compared.

RESULTS

The amplitude comparison between the main trunk and that of the temporal branch to the frontalis yielded a paired two-tail P-value of 0.33. The comparison of corresponding stimulus intensities used yielded a paired two-tail P-value of 4.2 × 10.

CONCLUSIONS

We concluded that the stimulus intensity required to achieve similar amplitudes in small branch stimulation is much lower than that required in main trunk stimulation.