Electrophysiologic Evaluation of Facial Nerve and Prognostic Factors in Facial Neuropathy

J Korean Assoc EMG Electrodiagn Med 2007;9(1):1-7.
Published online May 10, 2007.

Abstract

Objectives: To observe association between clinical and electrophysiologic findings and to investigate prognostic factor for facial neuropathy through long term follow up study. Methods: Thirty-three patients with facial neuropathy were retrospectively analyzed. The etiology, House-Brackmann grade and electrophysiologic findings were evaluated at the time of diagnosis and the follow up (initial vs final). The initial evaluation was performed between 5 days and 1 month after onset. The compound muscle action potentials (CMAPs) were recorded in orbicularis oris, nasalis, orbicularis oculi muscles. The amplitude ratio of lesion side to normal side were obtained in each muscle recordings and the average of the amplitude ratio were used as an amplitude ratio of the lesion side. The relation of House-Brackmann grade and the CMAP ratio was investigated. The prognosis according to the etiology and amplitude ratio (initial) were analyzed. Results: House-Brackmann grade and the amplitude ratio were well correlated. The CMAP ratios less than 10% showed poor outcome whereas those more than 10% had a good outcome. The patients with CMAPs ratio above 30% recovered completely. Bell’s palsy and Ramsay-Hunt syndrome revealed favorable outcome. Conclusion: House-Brackmann grade tends to show correlation with electrophysiologic findings. The CMAP ratios obtained between 5 days and 1 month after onset would be useful in predicting outcome of facial palsy.

Key Words: Facial nerve paralysis, House-Brackmann grade, Compound muscle action potentials, Prognosis