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Optimizing Location of Subdermal Recording Electrodes for Intraoperative Facial Nerve Monitoring.
Lieber Po-Hung Li1,2,3,4, Joshua Kuang-Chao Chen5, Daniel H Coelho6
1Faculty of Medicine, Institute of Brain Science, National Yang-Ming Chiao-Tung University, Taipei, Taiwan.
The Laryngoscope
|March 22, 2021
Summary
Facial muscle responses to nerve stimulation vary, with the zygomatic branch showing the strongest signals. This finding can improve intraoperative facial nerve monitoring (IOFNM) by guiding electrode placement for better patient safety.
Area of Science:
- Neurosurgery
- Otolaryngology
- Electrophysiology
Background:
- Intraoperative facial nerve monitoring (IOFNM) is crucial during surgeries near the facial nerve.
- Understanding differential muscle responses to facial nerve stimulation can optimize IOFNM techniques.
Purpose of the Study:
- To investigate if distinct facial muscle groups exhibit varied responses to facial nerve stimulation.
- To enhance the efficacy of intraoperative facial nerve monitoring (IOFNM).
Main Methods:
- Peak electromyography (EMG) amplitudes were recorded from four facial muscle groups in 93 patients undergoing cochlear implantation.
- Three distinct stimulation sites were used to assess responses in the frontalis-temporal, orbicularis oculi-zygomatic, oribularis oris-buccal, and mentalis-marginal mandibular branches.
Main Results:
- The zygomatic branch consistently showed statistically greater mean peak EMG amplitudes compared to temporal, buccal, and marginal mandibular branches across all stimulation sites (P < .05).
- At a specific site (Site C), the marginal mandibular branch exhibited stronger EMG amplitudes than the temporal or buccal branches (P < .05).
- The zygomatic branch yielded the highest amplitude in 45.9% of stimulations, followed by the marginal mandibular branch (22.2%).
Conclusions:
- For IOFNM, electrode placement in the orbicularis oculi and mentalis muscles is recommended.
- Significant inter-patient variability in facial nerve response necessitates consideration of additional electrodes, particularly in cases with variant anatomy or increased injury risk.
