Computer simulation of antidromic facial nerve response waveform.
CONCLUSIONS
An assessment of facial nerve (FN) damage on the basis of antidromic facial nerve response (AFNR) was established by computer simulation analysis. Computer simulation has the advantage of being able to assume any type of lesion. In the near future, computer analysis should provide another experimental method which displaces animal experiments, thus circumventing the ethical dilemma associated with animal experiments.


BACKGROUND
AFNR is a promising method to monitor intratemporal FN lesions. Clinical application of AFNR showed that waveform changes reflected the site and degree of the lesion. However, the association between the waveform changes and pathologic conditions of FN remains to be clarified.


OBJECTIVE
To analyze the association between waveform changes and the degree and site of nerve degeneration or blockade with the use of computer simulation, and to speculate the degree and involvement of the intratemporal FN lesions underlying the changes of AFNR waveforms.


METHODS
AFNR waveform, latency and amplitude changes in various types of nerve conduction block in the intratemporal FN were analyzed with the use of a computer simulation program based on the solid-angle approximation theory.


RESULTS
The present computer simulation revealed a temporal increase in the peak-to-peak amplitude between 1st and 2nd waves, when the nerve blockade extends 1 mm distally from the recording site. Generally, AFNR in severe palsy cases gradually decreases in amplitude as the waveform change from biphasic to monophasic, ultimately falling into non-response. According to the computer simulation, the decay of AFNR reflects conduction blocking in 63% or more of FN fibers. The amplitude ratio of the first positive/negative wave was indicative of the site of the lesion in relation to the recording site. The ratios were <0.586 when the lesions were situated >1 mm proximal and they were >0.667 when the lesions were peripheral to the recording site.
Iwai
Mitsuru
M
Department of Otolaryngology, Kochi Medical School, Nankoku, Kochi, Japan.
Takeda
Taizo
T
Nakatani
Hiroaki
H
Kakigi
Akinobu
A
D003198:Computer Simulation; D005154:Facial Nerve / Q000503:physiopathology*; D005158:Facial Paralysis / Q000503:physiopathology*; D006801:Humans; D009407:Nerve Block; D009431:Neural Conduction / Q000502:physiology; D012815:Signal Processing, Computer-Assisted