1993 Volume 86 Issue 12 Pages 1697-1705
Antidromic facial nerve response is considered to be an indicator of nerve damage within the temporal bone in the earliest stage of facial paralysis. However, it is difficult to obtain the nerve response clinically because its small Potential with short latency can easily be interfered by initial stimulus artifacts and compound muscle action potentials.
In this study, we investigated several recording methods such as polarity of stimulus, method of stimulation, type and site of recording electrode and elimination of compound muscle action potentials to obtain a clear and analyzable response. Initial stimulus artifacts could be reduced by using pairs of pulses with alternating polarity and by stimulation via the parotid duct. A needle electrode for the active electrode and recording in the tympanic cavity improved the SIN ratio of the nerve response. Subtracting the response recorded at a lateral site of the external auditory canal from that obtained at a more medial site eliminated compound muscle action potentials. We conclude that these methods are necessary to identify the nerve response and make possible the use of this test in the early diagnosis of facial paralysis.
