Botulinum Toxin Type A Injection Near the Stylomastoid Foramen: A Safe and Effective Therapeutic Modality for Tinnitus in Patients With Hemifacial Spasm

Objective This study aimed to assess the efficacy and safety of botulinum toxin type A (BTX-A) injection near the stylomastoid foramen for tinnitus in patients with hemifacial spasm (HFS). Study Design Retrospective study from 2011 to 2024. Setting Tongji Hospital affiliated to Tongji University in Shanghai, China. Patients Patients with HFS combined with tinnitus. Intervention BTX-A injection near the stylomastoid foramen. Main Outcome Measures The efficacy of BTX-A was assessed based on subjective improvement reported by patients after 1 month. Adverse events were also documented. Results A total of 869 HFS patients were analyzed, including 122 with tinnitus. Among the 122 patients with tinnitus, 110 received BTX-A injections near the stylomastoid foramen, and complete follow-up data were available for 105 of them. The 3.75 U group showed a higher improvement rate (69.2 ± 14.3%) compared with the 2.5 U group (46.3 ± 25.0%, p < 0.05). The majority received a 5 U dose, with a significantly higher improvement rate (76.9 ± 15.1%) compared with the 2.5 U group ( p < 0.01). All reported adverse events were related to routine injection sites and were mild, requiring no special treatment. No adverse events related to BTX-A injection near the stylomastoid foramen were reported. Conclusion In patients with HFS-associated tinnitus, additional injection of 5 U BTX-A near the stylomastoid foramen, targeting the stapedius muscle, proved to be an effective therapy with minimal adverse effects.