title: The behaviour of residual tumour after the intentional incomplete excision of a vestibular schwannoma: is it such a bad thing to leave some behind?
abstract: OBJECTIVE
  To evaluate the biological behaviour of tumour remnants intentionally left in the surgical bed following the incomplete excision of vestibular schwannomas (VS) and to review the relation between extent of resection and preservation of facial nerve function.
  
  
  METHODS
  A retrospective chart review of 450 patients who underwent surgery for resection of VS over 23 years (1992-2014). Of these, 50 (11%) patients had residual tumour intentionally left on/around the facial nerve (near-total or subtotal excision) to preserve facial nerve function intra-operatively. The growth of residual tumour was evaluated using serial magnetic resonance imaging scanning; pre- and postoperative facial nerve function was assessed using the House-Brackmann grading scale.
  
  
  METHODS
  Tertiary referral neurotology unit.
  
  
  RESULTS
  Of the 42 non-NF2 cases where the tumour was intentionally incompletely excised, 28 (67%) patients underwent subtotal resection (mean follow-up 68.5 ± 39.0 months) and 14 (33%) underwent near-total resection (mean follow-up 72.9 ± 48.3 months). Three patients (all in subtotal resection group) showed regrowth. This was not statistically different from the near-total resection group (χ2= 0.92, P = 0.31). The mean overall growth for these cases was 0.68 mm ± 0.32 mm/year. 5 (one near total, four subtotal) of the eight NF2 patients (62.5%) were excluded from our analysis. In the non-NF2 group, poor facial nerve outcomes (House-Brackmann scores of III-IV) were seen in 2/14 and V-VI in 3/14 of the near total compared with 7/25 and 4/25 respectively in the subtotal group.
  
  
  CONCLUSIONS
  Given that the primary surgery for the VS was only for tumours that were relatively large or grew during conservative treatment, the low rate of tumour remnant growth (7%) is reassuring. It may be appropriate to have a lower threshold for leaving tumour on the facial nerve in non-NF2 patients where complete resection may jeopardise facial nerve function.
authors.affiliation: TWJ fellow in Otology/Neurotology, University Health Network, Toronto, ON, Canada.
authors.forename: M I
authors.initials: MI
authors.lastname: Syed
authors.affiliation: Otology/Neurotology, University Health Network, Toronto, ON, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Wolf
authors.affiliation: Otology/Neurotology, University Health Network, Toronto, ON, Canada.
authors.forename: O
authors.initials: O
authors.lastname: Ilan
authors.affiliation: Otology/Neurotology, University Health Network, Toronto, ON, Canada.
authors.forename: C O
authors.identifier: http://orcid.org/0000-0001-6901-0985
authors.initials: CO
authors.lastname: Hughes
authors.affiliation: Otology/Neurotology, University Health Network, Toronto, ON, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Chung
authors.affiliation: Neurosurgery, University Health Network, Toronto, ON, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Tymianski
authors.affiliation: Otology/Neurotology, University Health Network, Toronto, ON, Canada.
authors.forename: D D
authors.identifier: http://orcid.org/0000-0002-7607-4562
authors.initials: DD
authors.lastname: Pothier
authors.affiliation: Otology/Neurotology, University Health Network, Toronto, ON, Canada.
authors.forename: J A
authors.initials: JA
authors.lastname: Rutka
mesh_terms: D005154:Facial Nerve; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000473:pathology; D018365:Neoplasm, Residual; D009464:Neuroma, Acoustic / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery*; D018579:Patient Selection; D012189:Retrospective Studies; D016896:Treatment Outcome