title: Transient evoked otoacoustic emissions pattern as a prognostic indicator for hearing preservation in acoustic neuroma surgery.
abstract: OBJECTIVE
  To determine whether pre-operative transient otoacoustic emission (TEOAE) patterns are predictive of successful hearing preservation in acoustic neuroma surgery.
  
  
  METHODS
  Retrospective observational study.
  
  
  METHODS
  Tertiary referral medical center.
  
  
  METHODS
  A convenience sample was identified in whom pre-operative TEOAE data were available in patients undergoing acoustic neuroma surgery from 1993-2004. Ninety-three patients were identified who met this inclusion criterion.
  
  
  METHODS
  Subjects underwent attempted hearing preservation surgery via middle cranial fossa or retrosigmoid approaches. Routine audiometry, ABR, and TEOAE.
  
  
  METHODS
  Pre- and post-operative pure tone and speech results were categorized into hearing classes A, B, C, and D as described in the American Academy of Otolaryngology guidelines (1995). Hearing preservation was defined by maintenance of the pre-operative hearing class or downgrade to within one hearing class post-op. Pre-operative TEOAE results were divided into five frequency bands and described as positive in each band if there was a response above the noise floor with >50% reproducibility.
  
  
  RESULTS
  Hearing was preserved in 51 patients (55%). Of these, 11 (22%) had positive TEOAE response in all five frequency bands measured (1, 1.5, 2, 3, 4 kHz), whereas 40 (78%) had TEOAE responses ranging from 0 to 4 frequency bands. 42 patients failed to preserve their hearing. Of these, only three (7%) had positive TEOAE in all five frequency bands, and 39 (93%) had TEOAE responses ranging from 0 to 4 frequency bands (p<0.05). Other variables of prognostic significance to hearing preservation in our series included smaller tumor size, tumor location within the IAC, better pre-operative hearing, and shorter latencies on ABR. Logistic regression was then used to compare the prognostic value of TEOAE against these variables. In our series, ABR latencies and 5 frequency band response on TEOAE showed the highest significant correlation to hearing preservation (p<0.05).
  
  
  CONCLUSIONS
  A robust pre-operative TEOAE frequency band pattern may be used as a favorable prognostic indicator for potential hearing preservation in acoustic neuroma surgery. The prognostic value may be enhanced when combined with other prognostic factors such as tumor size, tumor location, pre-operative ABR and audiometric results.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Ana H
authors.initials: AH
authors.lastname: Kim
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Edwards
authors.forename: Steven A
authors.initials: SA
authors.lastname: Telian
authors.forename: Paul R
authors.initials: PR
authors.lastname: Kileny
authors.forename: H Alexander
authors.initials: HA
authors.lastname: Arts
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001309:Auditory Threshold; D005155:Facial Nerve Diseases / Q000209:etiology; D005260:Female; D034381:Hearing Loss / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000150:complications / Q000601:surgery*; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome