Impact of Preoperative Botulinum Toxin Injections on Postoperative Outcomes After Redo Microvascular Decompression for Hemifacial Spasm.

[BACKGROUND AND OBJECTIVES] Many patients with hemifacial spasm (HFS) undergo botulinum toxin injections (BTI) as an initial treatment and later undergo microvascular decompression (MVD), typically a more definitive treatment. However, in some cases, spasms recur after MVD, and patients may benefit from redo MVD. The impact of preoperative BTI on spasm freedom after redo MVD remains unclear. This study aims to further investigate this relationship and determine factors which affect redo MVD outcomes.

[METHODS] In a retrospective cohort study, an adjusted ordinal logistic regression model was used to identify factors associated with spasm freedom after redo MVD of the facial nerve, including age, sex, laterality, preoperative BTI, number of prior MVDs, type of neurovascular conflict, and offending vessel.

[RESULTS] Of the 102 patients with HFS who underwent redo MVD with a minimum of 2 years of follow-up (mean 6.8 years), 75 achieved complete spasm freedom (73.5%) and 12 (11.8%) experienced >75% spasm relief. There were no significant associations between MVD outcomes and age (P = .32), sex (P = .93), laterality (P = .24), and preoperative BTI (P = .29). Notably, multiple prior MVDs predicted poorer response (P = .011). The presence of posterior inferior cerebellar artery (P = .010) and neurovascular compression (P = .00008) were associated with better spasm outcomes.

[CONCLUSION] While patients with a history of multiple prior MVDs tended to benefit less from redo MVD, the number of preoperative BTI was not associated with spasm freedom after the procedure. These findings suggest that, in cases of spasm recurrence after MVD, HFS can be managed by BTI without compromising the effectiveness of subsequent redo MVD.