Influence of nerve branch of origin and extracanalicular extension of the tumor on hearing after middle fossa removal of vestibular schwannoma

Abstract

Conclusion. Neither nerve branch of origin nor extracanalicular (up to 1 cm) extension of a vestibular schwannoma (VS) influence the postoperative hearing outcome in patients operated via a middle cranial fossa (MCF) approach. Objective. To test whether the nerve branch of tumor origin and an extracanalicular, up to 1 cm, tumor extension influences hearing outcome after MCF VS surgery. Patients and methods. This was a retrospective case review of 50 patients with postoperative pure-tone audiogram (PTA) performed later than 90 days after surgery. Twenty patients had a superior vestibular nerve (SVN) tumor and 27 patients had an inferior vestibular nerve (IVN) tumor. In three patients the nerve branch of origin of the VS could not be unequivocally determined. Thirty-four patients had a purely intracanalicular (IC) tumor and 16 patients had an extracanalicular extension in the cerebello-pontine angle. The differences between preoperative and postoperative air-conduction pure-tone hearing thresholds at 500, 1000, 2000, 3000, and 4000 Hz were compared between groups using the Mann–Whitney–Wilcoxon test. Results. Neither vestibular nerve branch of origin nor extracanalicular tumor extension (up to 1 cm) caused any significant difference in the degree of postoperative hearing change at any of the tested PTA frequencies.