Delayed facial nerve palsy after vestibular schwannoma resection: risk factors, extent and prognosis.

Introduction: Facial nerve palsies may develop during the postoperative period of microsurgical removal of vestibular schwannomas (VSs), even after normal facial function for days or weeks after surgery. The aim of this study was to identify the pathomechanism and predictive factors of delayed palsy.

Material and method: The clinical data of 193 patients who underwent vestibular schwannoma surgery between 2012 and 2021 were retrospectively analyzed. A total of 134 patients were included. The patients showed intact facial nerve function up to 24 h after surgery. All patients (n = 20) with palsy from postoperative day 4 were included and collectively referred to as delayed facial nerve palsy (DFNP). Various factors were checked using a binomial regression analysis.

Results: The mean age of patients with DFNP was 57.8 years (55% female, 45% male). 70% had VS with KOOS ≥ 3, and 60% underwent surgery via a translabyrinthine approach Among the 16 patients with DFNP-related neurotropic pathogens, 25% were seropositive for herpes simplex virus. Most patients (n = 9/20) experienced onset of palsy between postoperative days 6 and 10. Of the four variables included in the significance test, three were significant: KOOS ≥ 3 (p < .04), ipsilateral vestibular organ failure (p < .05), and age group (p < .03). After therapy, 100% of patients recovered almost complete facial nerve function. The parameters mentioned above (KOOS classification and ipsilateral vestibular dysfunction) could be proven risk factors for the occurrence of DFNP.