Two-dimensional structure analysis of hemifacial spasms and surgical outcomes of microvascular decompression.

BACKGROUND: Although studies have indicated that the small posterior fossa plays a role in hemifacial spasm (HFS), few studies have denoted the correlations between local measurements of the cerebellopontine angle and the incidence of HFS and surgical outcomes. METHODS: We retrospectively analyzed the demographic and clinical data of HSF patients who underwent microvascular decompression at our institution. Healthy controls were recruited. The divergent prognosis of HFS was defined as an ordinal variable. A multivariable ordinal regression model was generated to estimate the relationship between the variables and outcomes of HFS. RESULTS: Between 2013 and 2018, 180 patients who were enrolled in our study met the inclusion criteria. Compared with the control group (n = 94), HFS patients had a smaller internal acousticmeatus-brainstem distance (P < 0.001) on the unaffected side and a larger facial nerve-brainstem angle (P < 0.001). The regression analysis demonstrated that subgroups with more severe facial nerve compression (mild vs severe, OR = 0.269, P = 0.018; moderate vs severe, OR = 0.215, P < 0.001) and a thinner brainstem (OR = 2.368, P = 0.014) were more likely to experience better short-term outcomes, while subgroups with a thinner brainstem (OR = 5.583, P = 0.007) were more likely to experience better long-term outcomes. DISCUSSION: Structural changes occurring in patients are risk factors for HFS. The patient's local neurovascular structure and brainstem volume are factors that significantly influence short-term and long-term surgical outcomes.