title: Growth of Primary and Remnant Vestibular Schwannomas: A Three-Year Follow-Up Study.
abstract: OBJECTIVE
  Vestibular schwannomas (VSs) are benign, slowly growing tumors. The management strategy, however, remains unclear for both primary VS and remnant VS after subtotal or partial resection. In this study, we analyzed the radiographical tumor growth to elucidate factors possibly predicting growth or regrowth of their tumors.
  
  
  METHODS
  We retrospectively analyzed the data of 76 patients with diagnoses of VS at a single tertiary academic referral center. The primary VS group consisted of 43 patients with conservative management, and the remnant VS group included 33 patients with tumor remnant after surgery. All patients were followed up with serial magnetic resonance imaging without intervention. The primary end point in this study was significant tumor growth at the end of the 3-year follow-up period.
  
  
  RESULTS
  Multivariate analysis revealed that remnant VS was less likely to grow than primary VS (odds ratio: 0.27, 95% confidence interval: 0.09-0.84). Tumor volume was correlated with tumor growth; larger tumors grew more frequently than small tumors in both primary and remnant VS groups with marginal (P = 0.05) and definite (P = 0.007) significance, respectively. The receiver operating characteristic curves plotted for tumor growth identified the optimum cutoff points of tumor volumes with greater sensitivity and specificity for remnant VS than for primary VS (sensitivity: 80% vs. 59%, specificity: 87% vs. 76%, respectively).
  
  
  CONCLUSIONS
  Small remnant VS after surgery could be conservatively managed without additional treatment, and relatively large remnant VS should be followed up with close serial imaging or might be a possible candidate for radiosurgery during the early postoperative period.
authors.affiliation: Department of Neurosurgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Tomita
authors.affiliation: Department of Neurosurgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Tosaka
authors.affiliation: Department of Neurosurgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Aihara
authors.affiliation: Department of Neurosurgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Horiguchi
authors.affiliation: Department of Neurosurgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan. Electronic address: yyoshimo@gunma-u.ac.jp.
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Yoshimoto
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009464:Neuroma, Acoustic / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D019635:Neurosurgical Procedures; D011859:Radiography; D012189:Retrospective Studies
keywords: Natural history; Recurrence; Stereotactic radiosurgery; Surgery; Vestibular schwannoma