title: Risk Factors for Recurrence of Surgically Treated Conventional Spinal Schwannomas: Analysis of 169 Patients From a Multicenter International Database.
abstract: METHODS
  A retrospective analysis of 169 adult patients operated for a conventional spinal schwannoma from the AOSpine Multicenter Primary Spinal Tumors Database.
  
  
  OBJECTIVE
  The aim of this study is to identify risk factors for local recurrence of conventional spinal schwannoma in patients who had surgery.
  
  
  BACKGROUND
  Schwannomas account for up to 30% of all adult spinal tumors. Total resection is the gold standard for patients with sensory or motor deficits. Local recurrence is reported to be approximately 5% and usually occurs several years after surgery.
  
  
  METHODS
  Rates and time of local recurrence of spinal schwannoma were quantified. Predictive value of various clinical factors was assessed, including age, gender, tumor size, affected spinal segment, and type of surgery. Descriptive statistics and univariate regression analyses were performed.
  
  
  RESULTS
  Nine (5.32%) out the 169 patients in this study experienced local recurrence approximately 1.7 years postoperatively. Univariate analyses revealed that recurrence tended to occur more often in younger patients (39.33 ± 14.58 versus 47.01 ± 15.29 years) and in the lumbar segment (55.56%), although this did not reach significance [hazard ratio (HR) 0.96, P = 0.127; and P = 0.195, respectively]. Recurrence also arose in the cervical and sacral spine (22.22%, respectively) but not in the thoracic area. Tumors were significantly larger in patients with recurrence (6.97 ± 4.66  cm versus 3.81 ± 3.34  cm), with extent in the cranial caudal direction posing the greatest hazard (HR = 1.321, P = 0.002). The location of the tumor, whether epidural, intradural, or both (P = 0.246), was not significantly related to recurrence. Regarding surgical technique, over 4 times as many patients who underwent intralesional resection experienced a recurrence proportionally to patients who underwent en bloc resection (HR = 4.178, P = 0.033).
  
  
  CONCLUSIONS
  The pre-operative size of the conventional spinal schwannoma and intralesional resection are the main risk factors for local postoperative recurrence.
  
  
  METHODS
  3.
authors.affiliation: *Department of Surgery, Division of Neurosurgery and Spinal Program, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada †Toronto Western Research Institute and Krembil Neuroscience Center, University Health Network, Toronto, Ontario, Canada ‡Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada §National Center for Spinal Disorders and Buda Health Center, Budapest, Hungary ¶Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA ||Department of Degenerative and Oncological Spine Surgery, Rizzoli Institute, Bologna, Italy **Division of Spine, Department of Orthopaedics, University of British Columbia and Vancouver Coastal Health, Vancouver, British Columbia, Canada ††Department of Neurosurgery, MD Anderson Cancer Center, The University of Texas, Houston, Texas, USA ‡‡Department of Orthopaedic Surgery, Kanazawa Medical University, Kahokugun, Japan §§Department of Neurosurgery, University of California San Francisco, San Francisco, California, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fehlings
authors.forename: Anick
authors.initials: A
authors.lastname: Nater
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Zamorano
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Tetreault
authors.forename: Peter P
authors.initials: PP
authors.lastname: Varga
authors.forename: Ziya L
authors.initials: ZL
authors.lastname: Gokaslan
authors.forename: Stefano
authors.initials: S
authors.lastname: Boriani
authors.forename: Charles G
authors.initials: CG
authors.lastname: Fisher
authors.forename: Laurence
authors.initials: L
authors.lastname: Rhines
authors.forename: Chetan
authors.initials: C
authors.lastname: Bettegowda
authors.forename: Norio
authors.initials: N
authors.lastname: Kawahara
authors.forename: Dean
authors.initials: D
authors.lastname: Chou
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D005260:Female; D006801:Humans; D038622:Internationality; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000209:etiology* / Q000601:surgery; D009442:Neurilemmoma / Q000175:diagnosis / Q000601:surgery*; D012189:Retrospective Studies; D012307:Risk Factors; D013120:Spinal Cord Neoplasms / Q000175:diagnosis / Q000601:surgery*; D016896:Treatment Outcome; D047368:Tumor Burden; D055815:Young Adult