Functional and Aesthetic Outcomes of Trans-Mastoid Decompression for Facial Paralysis After Retroauricular Hyaluronic Acid Injection

Background Retroauricular hyaluronic acid (HA) injection for aesthetic enhancement can precipitate immediate-onset facial nerve palsy. The underlying mechanism remains unclear, and no consensus exists on the next step when prolonged conservative therapy fails. Objective To investigate the pathogenesis of persistent facial paralysis following retroauricular HA injection and to evaluate the functional and aesthetic outcomes of trans-mastoid facial nerve decompression in affected patients. Methods We retrospectively reviewed 17 patients (16 females, 1 male; mean age 33.65±7.91 years) who developed immediate-onset unilateral facial paralysis after retroauricular HA injection and showed no improvement after 4 weeks of conservative therapy. All patients underwent trans-mastoid facial nerve decompression. Functional outcomes were assessed pre- and 3 months post-operatively using the eFACE scale, Emotrics software, Facial Disability Index (FDI), and CSQ-3 satisfaction questionnaire. Results Post-operative eFACE scores revealed significant improvement in all static and dynamic parameters except static palpebral fissure height ( P <0.001), with dynamic indices showing the most marked recovery. Emotrics measurements demonstrated significant reductions in inter-side differences for eyebrow elevation, oral commissure height, and dental show on smiling (all P <0.001). FDI scores rose significantly for both physical function and social/well-being function ( P <0.001). Patient satisfaction was uniformly high. Conclusion Trans-mastoid facial nerve decompression is safe and effective for persistent facial paralysis secondary to retroauricular HA injection, yielding significant functional improvement and high patient satisfaction. Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .