Fig 1.
Preoperative temporal bone computed tomography scan (A) and intraoperative surgical inspection (B) showing bony canal dehiscence in the tympanic segment of the facial nerve (arrow).
Fig 2.
Surgical anatomy of the Landrace-Yorkshire-Duroc (LYD) pig with facial nerve (arrow).
Table 1.
The tympanic segment was the most common site of the facial nerve dehiscence and tympano-mastoidectomy were the most common procedures in this study.
Fig 3.
The linear correlation between the stimulus intensity and the response amplitude below 0.4 mA.
The response amplitude plateaued between 0.4 mA and 1.0 mA. The plateau indicates that was no significant difference between the interstimulus intensity. The minimum intensity of the stimulus that could generate a maximum response was 0.4 mA in the orbicularis oculi (244 μV) and orbicularis oris (545 μV). *P<0.05, **P<0.01, paired t-test.
Table 2.
EMG amplitude response from different stimulus intensities.
EMG amplitude response significantly increased to 0.4 mA of stimulus intensity and plateaued within 0.4–1.0 mA of stimulus intensity.
Fig 4.
Microscopic findings of continuously stimulated facial nerve (H&E, x100).
There was no evidence of necrosis and inflammation around the epi (asterisk), peri (arrow), endoneurium (dagger) of the facial nerve after 10 minutes continuous stimulation of 3.0 mA stimulus intensity.
Table 3.
Summary of the predictive role of the facial nerve IONM.
Facial nerve dehiscence was reported as 13 to 43%, and the probability of detecting a facial nerve dehiscence as IONM was reported as 89 to 100%.