title: Free-running EMG monitoring during microvascular decompression for hemifacial spasm.
abstract: BACKGROUND
  The aim of this work is to determine if free-running electromyography (frEMG) can detect activity before and after microvascular decompression (MVD) treatment for hemifacial spasm (HFS), and to evaluate correlations of frEMG findings with abnormal muscle responses (AMRs) or facial motor-evoked potentials (FMEPs).
  
  
  METHODS
  To elicit nerve responses while carrying out frEMG recording before and after MVD, saline, a lactic solution, or artificial cerebrospinal fluid was injected onto the root exit zone of the facial nerve.
  
  
  RESULTS
  Significantly higher frEMG activity was observed following saline injection than for the other solutions (p < 0.01). For frEMG activity ratios of ≥ 50 %, there was a trend towards a greater likelihood of persistent AMRs. When frEMG activity decreased after MVD in the mentalis muscles, FMEP amplitude ratios were significantly smaller than when it did not (65 vs. 94 %, p < 0.05).
  
  
  CONCLUSIONS
  Changes in intraoperative frEMG, AMRs, and FMEPs likely reflect a component of the normalization of hyper-excitability of the facial nerve by MVD for HFS.
authors.affiliation: Department of Neurosurgery, Brain Research Institute, University of Niigata, 1-757 Asahimachi-dori, Chuo-ku, Niigata-City, 951-8585, Japan, mfuku529@bri.niigata-u.ac.jp.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Fukuda
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Takao
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hiraishi
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Fujii
mesh_terms: D000328:Adult; D000368:Aged; D004576:Electromyography / Q000379:methods*; D019054:Evoked Potentials, Motor; D005260:Female; D019569:Hemifacial Spasm / Q000601:surgery*; D006801:Humans; D008297:Male; D061145:Microvascular Decompression Surgery / Q000379:methods*; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods