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.