title: The vestibular schwannoma surgery learning curve mapped by the cumulative summation test for learning curve.
abstract: OBJECTIVE
  To demonstrate and quantify the learning curve for microsurgical excision of vestibular schwannoma in a newly formed neurootologic team by using the cumulative summation test for learning curve (LC-CUSUM). To secondarily identify the factors influencing postoperative facial nerve outcome.
  
  
  METHODS
  Retrospective review.
  
  
  METHODS
  Tertiary referral center.
  
  
  METHODS
  Between 1999 and 2011, 153 consecutive cases of vestibular schwannoma excision.
  
  
  METHODS
  One-hundred and fifty-three patients underwent excision of vestibular schwannoma.
  
  
  METHODS
  Facial nerve outcomes were assessed using the House-Brackmann (HB) facial nerve grading system. Postoperative facial nerve outcomes at 12 months were analyzed using the LC-CUSUM method with HB Grades I to III being defined as successful outcomes. The factors that influence postoperative facial nerve outcome were analyzed.
  
  
  RESULTS
  The constructed learning curve shows a gradual improvement in facial nerve outcomes. The learning curve crossed the derived LC-CUSUM barrier at the 56th procedure, indicating that sufficient evidence had accumulated to demonstrate that the surgeon had achieved optimal outcomes at this point. Tumor size (p = 0.008) and surgical approach (p = 0.005) were 2 additional significant factors influencing postoperative facial nerve outcome.
  
  
  CONCLUSIONS
  The learning curve is evident in this series of microsurgical excisions of vestibular schwannoma. A newly formed team needs to perform at least 56 cases to gain sufficient experience to accomplish optimal results. Position along the learning curve, tumor size, and familiarity with a preferred surgical approach are the factors, which dominated facial nerve outcome. We recommend the use of LC-CUSUM test for learning curve analysis.
authors.affiliation: Department of Otolaryngology, Westmead Hospital, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Allen Y
authors.initials: AY
authors.lastname: Wang
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Wang
authors.forename: Mark
authors.initials: M
authors.lastname: Dexter
authors.forename: Melville
authors.initials: M
authors.lastname: Da Cruz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002983:Clinical Competence; D020220:Facial Nerve Injuries / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000009:adverse effects / Q000193:education*; D013506:Otologic Surgical Procedures / Q000009:adverse effects / Q000193:education*; D011184:Postoperative Period; D012189:Retrospective Studies; D016896:Treatment Outcome