Abstract
Objective Delayed facial nerve palsy (DFNP) is a complication of microsurgical resection of vestibular schwannoma (VS). This study aims to clarify the definition and incidence of DFNP, as well as evaluate long-term CNVII prognosis in affected patients. Databases Reviewed PubMed, Embase, and Scopus databases. Methods A systematic literature search was conducted according to Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Full-text publications were included if they reported DFNP incidence, CNVII prognosis, demographic data, and how they defined DFNP. Results Ten studies with 2,122 patients who underwent surgical resection for VS were included. Meta-analysis demonstrated a mean incidence of DFNP of 13%, with a mean recovery to House-Brackmann (HB) I/II of 85%. Definitions of DFNP varied widely. Four studies utilized a broad definition of DFNP, without requiring any specific level of change in HB grade in the postoperative period. Two studies defined DFNP as deterioration of CNVII function by at least one HB grade, and an additional four studies defined DFNP as deterioration of CNVII function by at least two HB grades. Conclusion The prognosis of CNVII function after DFNP was favorable with 85% of patients regaining function to HB grade I/II within 12 months. Given the heterogeneity in definitions of DFNP, it remains challenging to determine the true incidence of DFNP after VS resection. Grading DFNP by degree of severity would improve studies of this entity. We propose utilizing a novel DFNP Severity Scale to more accurately track prognosis in patients with DFNP based on pre- and postoperative HB scores.