Tumor Nerve of Origin and Hearing Preservation Outcomes for Patients With Small Vestibular Schwannomas Undergoing Middle Fossa Craniotomy

Objective: To evaluate hearing preservation (HP) outcomes based on tumor nerve origin for patients with small sporadic vestibular schwannomas (VS) undergoing microsurgical resection using the middle cranial fossa (MCF) approach. Study Design: Retrospective single-institution study. Setting: Tertiary academic institution. Patients: Adults 18 years or older with small sporadic VS (≤15 mm). Intervention: MCF. Main Outcome Measure: Hearing preservation is defined as a word recognition score of ≥50%. Results: Of the 189 consecutive patients who underwent surgery, 164 (89%) had intraoperative identification of the tumor nerve of origin. Of those 164 patients, 88 (54%) had inferior vestibular nerve (IVN) tumors, and 76 (46%) had superior vestibular nerve (SVN) tumors. Hearing was preserved in 83% of patients with SVN tumors compared with 49% of patients with IVN tumors. When stratified by size, the rate of HP was highest (91%) for tumors of SVN origin ≤5 mm in size. In multivariate analysis, patients with SVN tumors ≤5 mm in size had a 7.5-fold increase (95% CI: 1.60-34.9) in HP compared with patients with SVN tumors larger than 10 mm in size. There was no significant difference in facial nerve outcomes between the 2 groups. At initial follow-up, 70 (92%) patients with SVN tumors and 83 (94%) patients with IVN tumors had a HB 1/2, respectively. Conclusions: Patients with small SVN tumors have a significantly higher likelihood of HP as well as shorter operative time compared with IVN tumors, suggesting that, in appropriate candidates, early surgical intervention may be beneficial.