Comparison of Surgical Exposure and Outcomes Between the Subtonsillar and Infrafloccular Approaches in Microvascular Decompression for Hemifacial Spasm

BACKGROUND AND OBJECTIVES: Microvascular decompression (MVD) is a highly effective surgical intervention for hemifacial spasm (HFS). MVD is an effective surgical treatment for HFS. The conventional infrafloccular (IF) approach is widely used and has demonstrated safety and efficacy in the management of HFS. In this study, we evaluate the subtonsillar (ST) approach as an alternative to the IF approach, focusing on differences in the operative view and surgical outcomes. METHODS: A retrospective cohort study was conducted on 174 patients who underwent MVD between January 2021 and December 2024. Patients were categorized based on surgical approach: 92 underwent the IF approach and 82 the ST approach. Outcomes were assessed both intraoperatively-including mastoid air cell opening and facial nerve isolation-and postoperatively, with a focus on spasm resolution and hearing function. RESULTS: Spasm-free rates at one year were 98% in the ST group and 96% in the IF group (P = .685). The ST approach significantly reduced mastoid air cell opening (9% vs 42%, P < .001) and conductive hearing symptoms (4% vs 35%, P < .001). Facial nerve isolation was intentionally performed in 93% of ST cases vs 9% in IF cases (P < .001). Other complication rates were comparable. CONCLUSION: The ST approach provides improved inferior access for vessel manipulation and facial nerve dissection while minimizing mastoid disruption in MVD for HFS. It represents a safe and effective alternative to the IF approach with reduced auditory morbidity.