Author(s)
Heather J. Smith, BM
Jason L. Steele, BS
Nicole Ewer, BS
Mana Espahbodi, MD
Neil S. Patel, MD
Richard H. Wiggins, MD
Richard K. Gurgel, MD, MSCI
Affiliation(s)
University of Utah Department of Otolaryngology - Head & Neck Surgery;
Abstract:
Objective: To examine the relationship between vestibular schwannoma (VS) volume, greatest linear dimension, and outcomes after microsurgical resection.
Study Design: Retrospective chart review
Setting: Tertiary academic referral center
Patients: Patients with histologically-confirmed VS who underwent microsurgical resection between 2016 and 2018.
Interventions: Microsurgical resection of VS
Main Outcome Measures: Preoperative greatest linear dimension in the axial plane and tumor volume (total and anterior to a line drawn through the midpoint of the internal auditory canal) measured using manual three-dimensional volumetric analysis of heavily-weighted T2 MRI images; preoperative and postoperative House-Brackmann (HB) facial nerve function, dichotomized into HB 1-2 or HB = 3; postoperative complications.
Results: 105 subjects were identified who underwent VS resection (55.2% female, 90.5% white, mean age at surgery 46.3 ± 14.1). Median tumor volume was 0.61 cm3 (interquartile range [IQR] 0.12-4.48), and median greatest linear dimension was 1.56 cm (IQR 0.91-2.63). Twenty subjects (19%) experienced postoperative complications; 12 of these were cerebrospinal fluid (CSF) leaks. Nearly all (99.0%) patients had HB 1-2 facial nerve function preoperatively; 63.1% and 67.6% of patients had HB 1-2 facial nerve function immediately postoperatively and at the last follow-up (median follow-up 12.0 (IQR 2.25-37.00) months), respectively. On univariate logistic regression analysis, tumor volume was associated with immediate postoperative facial nerve function (OR 1.19, 95% CI 1.07-1.31), facial nerve function at last follow-up (OR 1.12, 95% CI 1.03-1.21), and incidence of CSF leak. Greatest linear dimension and anterior tumor volume were also associated with immediate and last follow-up postoperative facial nerve function on univariate analyses, but not CSF leak. On multivariate binary logistic regression including greatest linear dimension and anterior tumor volume, tumor volume was not associated with immediate postoperative facial nerve function, but remained associated with facial nerve function at last follow-up (OR 1.31, 95% CI 1.02-1.69). Greatest linear dimension was not associated with facial nerve function at either timepoint on multivariate analysis.
Conclusions: Larger VS tumor volumes were significantly associated with HB 3-6 facial nerve function at last follow up after microsurgical resection, but greatest linear dimension of the tumor was not. Larger tumor volumes were associated with CSF leak. Additional data collection from 2018 through present is ongoing.
Professional Practice Gap & Educational Need: Associations between VS diameter and postoperative facial nerve outcomes have been frequently reported in the literature. There is limited data available regarding VS tumor volume and postoperative outcomes. Using volumetric analysis to accurately measure tumor volume may help inform decision-making and patient counseling.
Learning Objective: To explore the associations between VS volume, diameter, and postoperative outcomes.
Desired Result: Attendees will have a better understanding of volumetric tumor analysis and its utility in predicting postoperative outcomes.
Level of Evidence: IV
Indicate IRB or IACUC: IRB_00045048; University of Utah