title: Persistent hemifacial spasm after microvascular decompression: a risk assessment model.
abstract: OBJECTIVE
  Microvascular decompression (MVD) for hemifacial spasm (HFS) provides resolution of disabling symptoms such as eyelid twitching and muscle contractions of the entire hemiface. The primary aim of this study was to evaluate the predictive value of patient demographics and spasm characteristics on long-term outcomes, with or without intraoperative lateral spread response (LSR) as an additional variable in a risk assessment model.
  
  
  METHODS
  A retrospective study was undertaken to evaluate the associations of pre-operative patient characteristics, as well as intraoperative LSR and need for a staged procedure on the presence of persistent or recurrent HFS at the time of hospital discharge and at follow-up. A risk assessment model was constructed with the inclusion of six clinically or statistically significant variables from the univariate analyses. A receiving operator characteristic curve was generated, and area under the curve was calculated to determine the strength of the predictive model.
  
  
  RESULTS
  A risk assessment model was first created consisting of significant pre-operative variables (Model 1) (age >50, female gender, history of botulinum toxin use, platysma muscle involvement). This model demonstrated borderline predictive value for persistent spasm at discharge (AUC .60; p=.045) and fair predictive value at follow-up (AUC .75; p=.001). Intraoperative variables (e.g. LSR persistence) demonstrated little additive value (Model 2) (AUC .67). Patients with a higher risk score (three or greater) demonstrated greater odds of persistent HFS at the time of discharge (OR 1.5 [95%CI 1.16-1.97]; p=.035), as well as greater odds of persistent or recurrent spasm at the time of follow-up (OR 3.0 [95%CI 1.52-5.95]; p=.002) Conclusions: A risk assessment model consisting of pre-operative clinical characteristics is useful in prognosticating HFS persistence at follow-up.
authors.affiliation: a Department of Anesthesiology, Perioperative and Pain Medicine , Boston Children's Hospital , Boston , MA , USA.
authors.forename: Aalap
authors.initials: A
authors.lastname: Shah
authors.affiliation: b Pennsylvania Brain and Spine Institute , Butler , PA , USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Horowitz
mesh_terms: D000328:Adult; D001764:Blepharospasm / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D019569:Hemifacial Spasm / Q000601:surgery*; D006801:Humans; D008297:Male; D061145:Microvascular Decompression Surgery / Q000379:methods*; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D010351:Patient Discharge / Q000706:statistics & numerical data; D011300:Preoperative Care; D012372:ROC Curve; D012008:Recurrence; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D013997:Time Factors; D016896:Treatment Outcome
keywords: Microvascular decompression; hemifacial spasm; persistent spasm; risk stratification