Reference Values of Facial Nerve Stimulation Using Nerve Conduction Study

Abstract

Background:Electroneurography (ENoG) is an objective electro-physiologic measurement used to assess
facial nerve integrity; determine the prognosis of facial nerve injury; and guide management.
Objective:This study aimed at establishing baseline reference values of facial nerve parameters of
compound muscle action potential (CMAP) for comparison with abnormal findings of facial nerve disorders.
Methods: This cross-sectional study was conducted at the Physiology Department, Faculty of Medicine,
University of Khartoum. It involved sixty healthy volunteers (25 males & 35 females). Their mean age was
(34.1±15.98), ranged (15-65years). Pre-auricular stimulation of the facial nerve and recording from Nasalis
muscle was done bilaterally using Medelec Synergy Machine.
Results: The distance between stimulating and recording electrodes ±SD was 0.65±8.21 cm (7.56–8.86cm).
Nerve conduction study findings showed values of total right & left (120) facial nerves as well as right and
left sides values including (minimum, maximum, mean and standard deviation) of latencies, amplitudes,
durations and areas of facial CMAP.
Conclusion: The values for parameters of facial nerve stimulation are comparable to that of worldwide
literature. The variations observed here were most likely due to many factors such as: stimulating electrode
placement (pre-auricular versus post-auricular); recording electrodes placement (using different muscles
innervated by facial nerve); skin resistance; and magnitude of stimulus.