Transient Subacute Facial Nerve Dysfunction After Dual Modality Treatment of Large Vestibular Schwannomas

OBJECTIVES 1: Describe subacute facial nerve paralysis after salvage stereotactic radiosurgery (SRS). 2: To analyze predictors of facial nerve weakness after dual modality treatment. PATIENTS Adult patients with Vestibular Schwannoma who underwent sub-total resection (STR) followed by salvage radiation. INTERVENTIONS Microsurgical resection of VS, stereotactic radiosurgery, intensity-modulated radiotherapy, proton radiotherapy. MAIN OUTCOME MEASURES Serial facial nerve function (House-Brackmann scale). RESULTS Thirteen patients who underwent dual modality treatment for large VS were included (mean age = 43.6 years, 77% females). The mean pre-operative tumor volume was 11.7 cm3 (SD = 6.5) and the immediate mean post-operative remnant volume was 1.5 cm3 (SD = 1.4) with a mean extent of resection of 86.7% (SD = 9.5). The mean salvage-free interval was 20.8 months (SD = 13.3). All patients had excellent one-year FN outcome (HB grade 1, 2) after resection. Three patients developed subacute facial nerve weakness after salvage SRS (4.2-9.4 months after SRS). This paralysis responded to high dose systemic steroids and no surgical interventions for facial rehabilitation were required. At last follow up (mean 61.6 months, SD = 28.5), facial nerve function was favorable (HB grade 1-2 in 12 patients and HB grade 3 in 1 patient). There were no significant associations between various predictors and subacute deterioration of facial nerve function after SRS. CONCLUSIONS Sub-acute transient facial nerve dysfunction can develop infrequently over a variable time frame after post-operative salvage SRS and usually responds to steroids. Patients should be adequately counseled about potential of transient deterioration of facial nerve function after salvage SRS.