title: Distortion-product otoacoustic emissions in nonacoustic tumors of the cerebellopontine angle.
abstract: OBJECTIVE
  The goal of the present study was to compare the frequencies of cochlear and non-cochlear patterns of distortion-product otoacoustic emissions (DPOAEs) in patients with nonacoustic (non-AN) tumors of the cerebellopontine angle (CPA)/internal auditory canal with those in patients with acoustic neuroma (AN).
  
  
  METHODS
  We conducted a prospective study of patients with non-AN internal auditory canal/CPA tumors treated between 1992 and 1999 in a tertiary care setting. We collected data on behavioral pure tone average, speech discrimination score, acoustic immittance tests, DPOAEs, and tumor size. DPOAEs were divided into those with a cochlear or a noncochlear pattern. Comparisons were made with a control group of patients with AN of the CPA.
  
  
  RESULTS
  Twenty-four patients were included in the study: 12 patients in the non-AN group and 12 patients in the AN group. In the non-AN group, 5 (42%) patients had a cochlear pattern and 7 (58%) had a noncochlear pattern. In the AN group, 7 (58%) patients had a cochlear pattern and 5 (42%) had a noncochlear pattern. The differences between the non-AN and AN groups were statistically significant. In the non-AN group, patients with a cochlear-pattern DPOAE had significantly smaller tumors (P = 0.03) and a trend (P = 0.07) toward higher speech discrimination score. Age and pure tone average were not significantly different in the non-AN tumor patients. In the AN group, none of the study parameters were significantly related to the pattern of DPOAE.
  
  
  CONCLUSIONS
  ANs appear to differ from other tumors of the CPA in their propensity to cause sensory versus neural hearing loss. A larger series of patients would be useful to confirm these preliminary findings.
authors.affiliation: Department of Otolaryngology, University of Miami Ear Institute, Florida, USA.
authors.forename: Steven Ross
authors.initials: SR
authors.lastname: Mobley
authors.forename: Onur
authors.initials: O
authors.lastname: Odabasi
authors.forename: Syed
authors.initials: S
authors.lastname: Ahsan
authors.forename: Glen
authors.initials: G
authors.lastname: Martin
authors.forename: Bart
authors.initials: B
authors.lastname: Stagner
authors.forename: Fred F
authors.initials: FF
authors.lastname: Telischi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D002528:Cerebellar Neoplasms / Q000503:physiopathology*; D002530:Cerebellopontine Angle; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000503:physiopathology*; D017084:Otoacoustic Emissions, Spontaneous; D011446:Prospective Studies