(281) Intraoperative Facial Movement Predicts Postoperative Outcomes in Vestibular Schwannoma Resection

Monday, October 2, 2023

2:45 PM – 3:45 PM East Coast USA Time

Presenting Author(s)

Douglas Josiah Totten, MD, MBA

Resident Physician
Indiana University School of Medicine, Department of Otolaryngology -- Head and Neck Surgery
Indianapolis, Indiana, United States

Co-Author(s)

Evan C. Cumpston, MD

Neurotology Fellow
Indiana University School of Medicine , Department of Otolaryngology -- Head and Neck Surgery
Indianapolis, Indiana, United States
NC

Nathan Connell, MD

Physician
Mayo Clinic Health System
Eau Claire, Wisconsin, United States
LH

Lauren Howser, MD

Indiana University School of Medicine, USA
SK

Samuel Kaefer, BS

Indiana University School of Medicine, USA
MS

Mitesh Shah, MD

Indiana University School of Medicine, Department of Neurological Surgery, USA

Senior Author(s)

Rick F. Nelson, MD, PhD

Professor
Indiana University
Zionsville, Indiana, United States

Disclosure(s):

Douglas Josiah Totten, MD, MBA: No relevant relationships to disclose.

Evan C. Cumpston, MD: No relevant relationships to disclose.

Nathan Connell, MD: No relevant relationships to disclose.

Rick F. Nelson, MD, PhD: No relevant relationships to disclose.

Introduction: Intraoperative facial electromyography (EMG) is universally used during resection of vestibular schwannoma (VS) to preserve physiologic facial nerve function. Previous literature shows facial nerve stimulation at 0.05 mA with >240 uV return predicts that 85% of patient will have good postoperative facial nerve function, defined as House-Brackmann grade of I-II/VI. We routinely expose the ipsilateral hemiface to evaluate for visible facial movement with stimulation at 0.05 mA after VS resection. Here we evaluate the predictive value of intraoperative objective facial movement with long-term good facial nerve function.

Methods: Patients who underwent translabyrinthine vestibular schwannoma resection from 2011-2021 were included. Patient records were reviewed retrospectively to assess pre-operative facial nerve function, resection approach, extent of resection, and visible facial movement when the facial nerve was stimulated at 0.05 mA at the conclusion of the case. Positive predictive value (PPV) of facial movement for a good facial nerve outcome immediately postoperatively and after one year were assessed. Amplitudes for patients with poor facial nerve outcomes and good facial nerve outcomes were compared with a t-test.

Results: 87 patients (52% female) with an average age of 56 (standard deviation 14.3) had documented intraoperative facial never stimulation. Intraoperative visible facial movement with 0.05 mA stimulation at the root exit zone was observed in 73 patients. PPV of intraoperative facial movement with stimulation was 98.6% postoperatively and 88.6% at one year. Postoperatively, sensitivity was 98.6% and specificity 85.7%. At one year, sensitivity was 93.9% and specificity was indeterminate. Patients with poor initial facial nerve outcomes had significantly lower response amplitudes (226.6 mV) than patients with good outcomes (423.3 mV, p=0.038).

Conclusions: Intraoperative facial nerve stimulation with visual confirmation of facial movement, in addition to amplitude measurement, provides reliable and highly predictive assessment of postoperative facial nerve outcomes.