Preoperative Differences in Intracranial Facial Versus Vestibular Schwannomas: A Four Nerve Assessment

Abstract

Objectives Assesses whether preoperative functional testing can distinguish vestibular schwannomas from facial nerve schwannomas medial to the labyrinthine segment. Study Design Retrospective cohort. Methods Retrospectively review surgically managed intracranial facial and vestibular schwannomas between January 2015 and December 2019 at two tertiary care centers. Patients with neurofibromatosis 2 and surgery for recurrence were excluded. Preoperative functional testing to include House‐Brackmann scores, electroneuronography (ENoG), cervical vestibular evoked myogenic potentials (cVEMP), caloric testing, acoustic brainstem responses (ABRs), acoustic reflexes, and audiograms was compared between the two groups of schwannomas. Results Twelve facial and 128 vestibular schwannomas met inclusion criteria. In only one case was a facial schwannoma diagnosed preoperatively from imaging. No statistically significant difference was found in preoperative House‐Brackmann scores, ENoG, cVEMP, caloric testing, ABRs, or acoustic reflexes. Pure tone average was worse in the vestibular schwannoma group (63 dB [95% CI: 58–68 dB] vs. 46 dB [95% CI: 34–58 dB], P = .01), and the difference was more apparent in the lower frequencies. Word recognition score was better in the facial schwannoma group (66% [95% CI: 45–86%] vs. 41% [95% CI: 34–47%], P = .02). Conclusion Specialized preoperative functional evaluation of the nerves of the internal auditory canal cannot reliably predict the presence of an intracranial facial schwannoma. Hearing is better in facial schwannomas, particularly in the lower frequencies. This should raise the index of suspicion for an intracranial facial schwannoma, especially in candidates for hearing preservation vestibular schwannoma surgery. Level of Evidence 3 Laryngoscope, 131:2098–2105, 2021

Facial nerve schwannoma: Case report and brief review of the literature

“…Most common presentation of schwannoma in the internal auditory canal, labyrinth, and temporal bone is a nodular enhancement. Involvement of geniculate ganglion favors facial nerve schwannoma as opposed to vestibular schwannoma [30] . It is important to note that there is physiologic enhancement of facial nerve in its labyrinthine, geniculate, tympanic, and mastoid segments.…”

Endoscopic Over Under Cartilage Tympanoplasty Is Not Inferior to Underlay Cartilage Tympanoplasty

“…( 16 ) Code for plotting audiograms was modified from previous study. ( 17 , 18 ) The scattergram plots were created with assistance of the Stanford web-based tool. ( 19 )…”