title: Clinical impact of residual lateral spread response after adequate microvascular decompression for hemifacial spasm: A retrospective analysis.
abstract: OBJECTIVE
  Residual lateral spread response (LSR) after seemingly adequate decompression for hemifacial spasms (HFSs) can provide prognostic information about the outcome of microvascular decompression (MVD). In the present study, the main objective was to evaluate the clinical and prognostic impact of residual LSR after adequate MVD for HFS.
  
  
  METHODS
  An observational study was conducted in patients who underwent MVD for HFS at the University of Pittsburgh Medical Center between January 2000 and December 2007. Clinical and neurophysiological outcomes after pre- and post-MVD, including spasm relief, amplitude and latency of LSR, and postoperative complications were collected from groups with and without residual LSR after adequate decompression. Data analysis was performed to see the impact of residual LSR on HFS outcomes.
  
  
  RESULTS
  There was no significant difference in preoperative clinical characteristics as well as postoperative complications between the two groups. The patient had significantly higher spasm relief in immediate postoperative period (p = 0.01) and at discharge (p = 0.002) when LSR disappeared during the procedure. There is no difference in spasm relief at follow-up period between the two groups (p = 0.69).
  
  
  CONCLUSIONS
  Lateral spread is an invaluable tool in MVD for HFSs. Adequate decompression in patients with residual LSR improved long-term spasm relief. Constant communication between neurophysiologists and the surgeon might be vital to achieve adequate decompression. The amplitude of residual LSR after adequate decompression does not significantly affect the long-term spasm relief.
authors.affiliation: a Department of Neurological Surgery , University of Pittsburgh , PA , USA.|b Department of Neurology , University of Pittsburgh , PA , USA.
authors.forename: Parthasarathy D
authors.initials: PD
authors.lastname: Thirumala
authors.affiliation: e Department of Neurological Surgery , Xinhua Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , P. R. China.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Wang
authors.affiliation: d Department of Anesthesia , University of Washington , WA , USA.
authors.forename: Aalap
authors.initials: A
authors.lastname: Shah
authors.affiliation: a Department of Neurological Surgery , University of Pittsburgh , PA , USA.
authors.forename: Miguel
authors.initials: M
authors.lastname: Habeych
authors.affiliation: a Department of Neurological Surgery , University of Pittsburgh , PA , USA.
authors.forename: Donald
authors.initials: D
authors.lastname: Crammond
authors.affiliation: a Department of Neurological Surgery , University of Pittsburgh , PA , USA.|c Department of Neuroscience , University of Pittsburgh , PA , USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Balzer
authors.affiliation: a Department of Neurological Surgery , University of Pittsburgh , PA , USA.
authors.forename: Raymond
authors.initials: R
authors.lastname: Sekula
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005154:Facial Nerve / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D019569:Hemifacial Spasm / Q000601:surgery*; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring; D008297:Male; D061145:Microvascular Decompression Surgery / Q000379:methods*; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology / Q000628:therapy*; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
keywords: hemifacial spasm; intraoperative monitoring; lateral spread response; microvascular decompression