title: The effect of fractionated radiotherapy in sensorineural hearing loss: an animal model.
abstract: OBJECTIVE
  The purpose of this study is to assess the effect of fractionated radiotherapy on sensorineural hearing loss using an animal model.
  
  
  METHODS
  In vivo animal study.
  
  
  METHODS
  Ears of 25 guinea pigs were divided into three groups: control, irradiated with a total of 48 gray (Gy), and 71 Gy. Unilateral exposure of 48 Gy and 71 Gy fractionated irradiation was given for a 4-week period. Auditory brainstem response and distortion products otoacoustic emissions (DPOAE) were tested prior to irradiation and 1, 6, 10, and 16 weeks after completion of radiotherapy to assess the hearing threshold shift postradiotherapy over time.
  
  
  RESULTS
  No significant differences in hearing thresholds between the low dose radiation (48 Gy) and the control group (no radiation) underlined that 48 Gy caused no hearing deficits (P = 0.37). The higher dose (71 Gy) showed progressive deterioration of the hearing function over time. Three-way ANOVA interactions revealed significant group-time effects (F= 9.261; P < 0.0001). DPOAE analysis demonstrated hearing loss at 71 Gy without progression or recovery at all time points, predominantly in the higher frequencies tested.
  
  
  CONCLUSIONS
  The present study suggests that in the presence of sensorineural hearing loss due to high- dose fractionated radiotherapy, there is an initial sensorial component; however, the neural component is responsible for its progressivity.
authors: McGill Auditory Sciences Laboratory, The Montreal Children's Hospital, Montréal, Quebec, Canada; Department of Otolaryngology-Head and Neck Surgery, The Montreal Children's Hospital, Montréal, Quebec, Canada.
authors: Mario A
authors: MA
authors: Mujica-Mota
authors: Farid F
authors: FF
authors: Ibrahim
authors: Aren
authors: A
authors: Bezdjian
authors: Slobodan
authors: S
authors: Devic
authors: Sam J
authors: SJ
authors: Daniel
mesh_terms: D000818:Animals; D001301:Audiometry, Pure-Tone; D003051:Cochlea / Q000000981:diagnostic imaging / Q000473:pathology*; D004195:Disease Models, Animal; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D006168:Guinea Pigs; D006309:Hearing / Q000502:physiology*; D006319:Hearing Loss, Sensorineural / Q000473:pathology / Q000503:physiopathology / Q000532:radiotherapy*; D017084:Otoacoustic Emissions, Spontaneous; D011859:Radiography; D016896:Treatment Outcome
keywords: ABR; DPOAE; Radiotherapy; guinea pig; sensorineural hearing loss