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Vestibular Schwannoma Position Relative to Internal Auditory Canal Helps Predict Postoperative Facial Function

by Linda Kossoff •

What is the impact of vestibular schwannoma (VS) position relative to the internal auditory canal (IAC) on postoperative facial nerve function and extent of surgical resection?

BOTTOM LINE

VS position relative to the IAC axis can be used along with tumor size to predict postoperative facial outcomes.

BACKGROUND: Treatment of VS, a benign tumor commonly arising from the vestibular branch of the eighth cranial nerve, must balance hearing/facial function preservation with tumor removal or cessation of growth. Facial paralysis risk following surgical resection in patients with VS has been correlated with tumor size, position, and growth direction.

STUDY DESIGN: Retrospective chart review.

SETTING: Department of Otolaryngology–Head and Neck Surgery, Southern California Permanente Medical Group, San Diego, Calif.

SYNOPSIS: Researchers reviewed the charts of 127 patients who underwent retrosigmoid (17%) and/or translabyrinthine (82%) resection of tumors, with a greatest tumor dimension of >25 mm, including both IAC and cerebellopontine angle components. Tumor measurements included greatest dimension, dimension anterior to the IAC axis, dimension posterior to the IAC axis, and a ratio of posterior-to-anterior dimension (PA ratio). Short term, 76 (60%) patients had good facial function, and 51 (40%) had poor function. Long term, 90 (71%) patients had good facial function; 37 (29%) had poor function. Ninety-two (72%) patients underwent gross total resection of their tumors. Although patients with good function had larger PA ratios than patients with poor function, early and long term, greatest dimension was the more significant independent predictor of facial outcomes. Patients with poor facial function in early follow-up who recovered to good function long term had significantly larger PA ratios and smaller anterior dimensions than patients who did not recover. Findings suggest that PA ratio and anterior dimension could be considered with tumor size when predicting facial outcomes. Study limitations included its retrospective nature and the limited number of patients included.

CITATION: Hobson CE, Saliba J, Vorasubin N, et al. Vestibular schwannoma cerebellopontine angle position impacts facial outcome. Laryngoscope. 2022;132:1093-1098.