title: Role of intracanalicular volumetric and dosimetric parameters on hearing preservation after vestibular schwannoma radiosurgery.
abstract: OBJECTIVE
  To analyze the relationship between hearing preservation after gamma knife radiosurgery (GKR) for vestibular schwannoma (VS) and some volumetric and dosimetric parameters of the intracanalicular components of VS.
  
  
  METHODS
  This study included 82 patients with a VS treated by GKR; all patients had no NF2 disease, a Gardner-Robertson hearing class 1-4 before treatment, a marginal dose of 12 Gy, and a radiologic and audiologic follow-up > or =1 year post-GKR. The volume of both the entire tumor and the intracanalicular part of the tumor and the mean and integrated dose of these two volumes were correlated to the auditory outcomes of patients.
  
  
  RESULTS
  At last hearing follow-up, 52 patients had no hearing worsening, and 30 patients had an increase of > or =1 class on Gardner-Robertson classification. We found that hearing preservation after GKR is significantly correlated with the intracanalicular tumor volume, as well as with the integrated dose delivered to the intracanalicular tumor volume.
  
  
  CONCLUSIONS
  Some volumetric and dosimetric parameters of the intracanalicular part of the tumor influence hearing preservation after GKR of VS. Consequently, we advise the direct treatment of patients with preserved functional hearing and a VS including a small intracanalicular volume.
authors.affiliation: Gamma Knife Center, Erasme Hospital, Université Libre de Brixelles, Brussels, Belgium. nmassage@ulb.ac.be
authors.forename: Nicolas
authors.initials: N
authors.lastname: Massager
authors.forename: Ouzi
authors.initials: O
authors.lastname: Nissim
authors.forename: Carine
authors.initials: C
authors.lastname: Delbrouck
authors.forename: Daniel
authors.initials: D
authors.lastname: Devriendt
authors.forename: Philippe
authors.initials: P
authors.lastname: David
authors.forename: Françoise
authors.initials: F
authors.lastname: Desmedt
authors.forename: David
authors.initials: D
authors.lastname: Wikler
authors.forename: Sergio
authors.initials: S
authors.lastname: Hassid
authors.forename: Jacques
authors.initials: J
authors.lastname: Brotchi
authors.forename: Marc
authors.initials: M
authors.lastname: Levivier
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006309:Hearing / Q000502:physiology / Q000528:radiation effects; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000473:pathology / Q000601:surgery*; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D018709:Statistics, Nonparametric