title: Fractionated stereotactic radiotherapy of vestibular schwannomas accelerates hearing loss.
abstract: OBJECTIVE
  To evaluate long-term tumor control and hearing preservation rates in patients with vestibular schwannoma treated with fractionated stereotactic radiotherapy (FSRT), comparing hearing preservation rates to an untreated control group. The relationship between radiation dose to the cochlea and hearing preservation was also investigated.
  
  
  METHODS
  Forty-two patients receiving FSRT between 1997 and 2008 with a minimum follow-up of 2 years were included. All patients received 54 Gy in 27-30 fractions during 5.5-6.0 weeks. Clinical and audiometry data were collected prospectively. From a "wait-and-scan" group, 409 patients were selected as control subjects, matched by initial audiometric parameters. Radiation dose to the cochlea was measured using the original treatment plan and then related to changes in acoustic parameters.
  
  
  RESULTS
  Actuarial 2-, 4-, and 10-year tumor control rates were 100%, 91.5%, and 85.0%, respectively. Twenty-one patients had serviceable hearing before FSRT, 8 of whom (38%) retained serviceable hearing at 2 years after FSRT. No patients retained serviceable hearing after 10 years. At 2 years, hearing preservation rates in the control group were 1.8 times higher compared with the group receiving FSRT (P=.007). Radiation dose to the cochlea was significantly correlated to deterioration of the speech reception threshold (P=.03) but not to discrimination loss.
  
  
  CONCLUSIONS
  FSRT accelerates the naturally occurring hearing loss in patients with vestibular schwannoma. Our findings, using fractionation of radiotherapy, parallel results using single-dose radiation. The radiation dose to the cochlea is correlated to hearing loss measured as the speech reception threshold.
authors.affiliation: Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark. rune333@gmail.com
authors.forename: Rune
authors.initials: R
authors.lastname: Rasmussen
authors.forename: Magnus
authors.initials: M
authors.lastname: Claesson
authors.forename: Sven-Eric
authors.initials: SE
authors.lastname: Stangerup
authors.forename: Henrik
authors.initials: H
authors.lastname: Roed
authors.forename: Ib Jarle
authors.initials: IJ
authors.lastname: Christensen
authors.forename: Per
authors.initials: P
authors.lastname: Cayé-Thomasen
authors.forename: Marianne
authors.initials: M
authors.lastname: Juhler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003051:Cochlea / Q000528:radiation effects*; D019583:Dose Fractionation, Radiation; D005260:Female; D006309:Hearing / Q000528:radiation effects; D034381:Hearing Loss / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000473:pathology / Q000601:surgery*; D011446:Prospective Studies; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods; D012189:Retrospective Studies; D047368:Tumor Burden