Electrophysiological Study of the Frontal Branch of the Facial Nerve in Normal Subjects.

INTRODUCTION: The authors compared the electrophysiological results of the frontal branch over the main trunk stimulation of the facial nerve in normal subjects.

METHODS: Nerve conduction studies of the main trunk and frontal branch of the facial nerve were performed on both sides of 31 healthy subjects, recording the compound muscle action potential (CMAP) from the frontalis muscle.

RESULTS: A good quality CMAP was obtained in all subjects after stimulation of the frontal branch, but only in 64.5% of nerves after stimulation of the main trunk of the facial nerve. Furthermore, nerve conduction studies of the frontal branch required less intense stimuli and were better tolerated.

CONCLUSIONS: The authors suggest that stimulation of the frontal branch is a simple, reliable and well-tolerated technique to evaluate the facial nerve.