Intraoperative findings of abnormal muscle response for hemifacial spasm following botulinum neurotoxin treatment

Importance of changes in abnormal muscle responses during microvascular decompression for hemifacial spasm

“…In this study, the duration of history was not significantly correlated with the postoperative clinical course; however, HFS was immediately cured in patients who received BTX treatment before surgery. The disparity between the results of previous and current study may be attributed to the sample size and effects of previous BTX injections on facial muscles that facilitate an immediate relief of muscle twitching, as these effects persisted even when the surgery was performed after at least 6 months of receiving the last BTX injection ( Nakayama et al, 2021 ).…”

“…Analysis of the relationship between AMR findings and preoperative BTX treatment ( Nakayama et al, 2021 ) revealed that AMRs from the orbicularis oculi muscle were not obtained in more patients in the BTX group than in non-BTX group. Additionally, the AMR recordings from the orbicularis oculi muscles were poorer in patients who received more than four BTX injections than in those who received less than four BTX injections.…”

“…Typically, the zygomatic branch was stimulated, and waves from the mentalis muscle were recorded for AMR monitoring ( Lee et al, 2018 ). Only a few studies have reported AMRs recorded from the orbicularis oculi muscle by stimulating the mandibular branch ( Fukuda et al, 1997 , Fukuda et al, 2010 , Yamashita et al, 2005 , Nakayama et al, 2021 ). AMRs from the mentalis muscle have been frequently used for intraoperative monitoring to obtain more stable responses than those obtained from other muscles ( Miao et al, 2020 ).…”