title: Distortion product otoacoustic emissions in term infants after hypoxia-ischaemia.
abstract: Distortion product otoacoustic emissions (DPOAEs) were recorded in 46 term infants who suffered perinatal hypoxia-ischaemia to identify which frequencies in the cochlear audiogram are susceptible to perinatal hypoxia-ischaemia. On days 3-5 after birth, the pass rates across the frequencies of the f(2 )primary tone between 1 and 10 kHz, particularly 1-5 kHz, were all lower than those in normal term controls (X(2 )= 7.27-32.30, all P <0.01). Of the 92 ears, 15 (16.3%) failed the DPOAE test, which was significantly higher than in the controls (4.3%, X(2) = 5.81, P <0.05). At 1 month, 80 ears with a type A tympanogram were re-tested. The pass rates at most frequencies, mainly 1 and 2 kHz, were slightly further decreased. Thirteen ears (16.2%) failed the DPOAE test. These results suggest that the neonatal cochlea, mainly at the frequencies 1-5 kHz, is impaired shortly after perinatal hypoxia-ischaemia and the impairment remains at 1 month.
  
  
  CONCLUSIONS
  Perinatal hypoxia-ischaemia impairs the neonatal cochlea mainly at the frequencies 1-5 kHz and the impairment detected on days 3-5 after birth is unlikely to improve in the later neonatal period. These findings may have implications for the management of hearing impairment in infants after perinatal hypoxia-ischaemia.
authors.affiliation: Department of Paediatrics, Children's Hospital, Fudan University, Shanghai, China. zedong.jiang@paediatrics.ox.ac.uk
authors.forename: Ze Dong
authors.initials: ZD
authors.lastname: Jiang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Andrew Robert
authors.initials: AR
authors.lastname: Wilkinson
mesh_terms: D000158:Acoustic Impedance Tests; D001301:Audiometry, Pure-Tone; D016022:Case-Control Studies; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000503:physiopathology; D006801:Humans; D020925:Hypoxia-Ischemia, Brain / Q000503:physiopathology*; D007231:Infant, Newborn; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D013997:Time Factors