Clinical characteristics of delayed facial palsy after middle ear surgery- a descriptive study of 40 cases.

Objective: To identify probable triggers of delayed facial palsy (DFP) after middle ear surgery.

Methods: Retrospective single-center chart review of DFP cases between 2010 and 2021.

Results: Forty patients with DFP could be identified after 3,508 middle ear surgeries (1.14%). The occurrence of DFP was after tympanoplasty type 1 1.60%, after tympanoplasty type 3 without mastoidectomy 1.32%, after tympanoplasty type 3 with mastoidectomy 0.36%, and after all tympanomastoid surgery cases 0.35%. The anti-HSV-1 IgM was positive in three cases and borderline in two patients. The anti-VZV IgM was positive in three cases. Beside herpes virus reactivation, facial canal dehiscence (n = 8), bacterial infection, direct nerve microtrauma and intratympanal use of collagenous or oxidized cellulose sponges are presumed pathogenetic factors in our study.

Conclusions: The etiology of DFP is still not conclusively clarified, it has probably a heterogeneous pathogenesis and therefore requires further scientific research. Mastoidectomy may have a protecting effect against DFP. The risk may be reduced by avoiding possible promoting factors but this adverse event cannot be substantially eliminated yet. Nonetheless, we summarize practical considerations for the prevention, diagnosis, and therapy of DFP in the future.