Gamma Knife radiosurgery (GKRS) can serve as adjunctive treatment for vestibular schwannomas (VS) for residual or recurrent tumor after surgical resection. However, it is poorly understood whether prior surgical resection influences the risk of facial nerve injury from GKRS. An institutional database of GKRS treating adult VS was queried for patients with >2 years of follow-up post-GKRS. Two cohorts were identified: patients with surgical resection prior to GKRS and patients receiving only GKRS. Facial nerve function was graded with the House-Brackmann (HB) scale pre-GKRS and until last follow-up. There were 31 patients in the surgery-GKRS cohort and 107 in the GKRS-only cohort. The surgery-GKRS cohort had a significantly lower median age (57.1 vs 63.6 years) and higher median tumor volume at time of GKRS (1.96 vs 0.84 cm 3 ). Facial nerve function worsened within 2 years post-GKRS in 7/31 (22.6%) of surgery-GKRS patients and 7/107 (6.5%) of GKRS-only patients. At last follow-up, facial nerve function worsened in 5/31 (16.1%) of surgery-GKRS patients and 3/107 (2.8%) of GKRS-only patients. After controlling for patient, tumor, and radiosurgical parameters, prior surgical resection was significantly predictive of facial nerve function decrement after GKRS within 2 years and at last follow-up. Larger tumor volume was predictive of facial nerve function decrement at last follow-up. Pre-GK HB score was not predictive of new/worsened facial palsy. Patients with prior surgical resection may be at increased risk of new or worsened facial paresis after adjuvant or salvage GKRS compared to patients receiving upfront GKRS. • VS surgical resection may reduce physiologic reserve for the facial nerve • Prior resection was associated with higher risk of post-GK facial palsy for VSs • Larger tumor volume also predicted post-GK facial nerve injury • GK dose de-escalation (<13 Gy) could be warranted for VSs with prior surgery
Kumar et al. (2026) studied this question.