Distortion product otoacoustic emissions at 6 months in term infants after perinatal hypoxia-ischaemia or with a low Apgar score

Abstract

Distortion product otoacoustic emissions (DPOAEs) were analyzed at 6 months of age in term infants who had perinatal hypoxia-ischaemia (HI) and those who had a low Agar score alone to detect any abnormalities in cochlear function and any difference between the two groups of infants. The f2 primary tone was presented at ten frequencies (0.5-10 kHz). Both the left and right ears were tested. Compared to normal term controls, both the infants after perinatal HI and those with a low Apgar score alone showed lower DPOAE pass rates, mainly at 1-4 kHz at which the pass rates were decreased significantly (P < 0.05-0.01). The general pattern of DPOAE pass rates at different frequencies was similar in the two groups of infants. The pass rates at 1, 5 and 6 kHz tended to be lower in the infants after perinatal HI than those with a low Apgar score alone, although not statistically significant. Conclusions At 6 months of age, infants after perinatal HI or with a low Apgar score alone had a relatively poor cochlear function, mainly at 1-4 kHz. There are no major differences between the two groups of infants.

Hearing outcome of early postnatal exposure to hypoxia in Sprague–Dawley rats

“…In those studies, greater hearing effects were reported at lower frequencies (1-5 kHz). 7,8 Similarly, among newborns who suffered perinatal hypoxia, reductions in distortion product otoacoustic emission (DPOAE) amplitudes were observed at frequencies between 1 and 10 kHz, although this was most noticeable at 1-2 kHz. 6 In a guinea pig model of acutely induced hypoxia, Pierson and Moller found frequency-dependent shifts in latency during hypoxia exposure, with lower frequency clicks exhibiting a greater decrease in latency than higher frequency clicks.…”

“…11 An even smaller number of studies have investigated the effects of perinatal hypoxia and/or ischaemia on children after a prolonged period (six months or one year after birth). [6][7][8] In this study, we utilised an in vivo rat model of postnatal hypoxia and looked at the physiological effects of exposure to hypoxia on hearing at maturity.…”

“…5 Clinical studies looking at the hearing outcome of asphyxiated children at six months and one year of age have reported significant hearing loss using both otoacoustic emissions and auditory brainstem response (ABR) testing. [6][7][8] However, other studies have indicated that hearing loss which occurs as a result of hypoxia is not permanent as it is reversed when normoxia resumes. 9,10 In this study on Sprague-Dawley rats, we investigated the impact of experimentally induced postnatal hypoxia on ABR thresholds, wave I latencies and wave I-V inter-peak latencies, in adulthood.…”

Cochlear function in 1‐year‐old term infants born with hypoxia‐ischaemia or low Apgar scores

“…Understanding of what frequencies on the audiogram of the cochlea are affected by hypoxia or HI is important for early intervention of infant with hearing impairment. We have previously studied DPOAEs longitudinally from birth to 6 months of age in a group of infants born with perinatal HI 21,22 . We have also studied DPOAEs longitudinally in a group of infants born with a low Apgar score alone that was due most likely to perinatal hypoxia but no clinical signs of HIE and/or other perinatal conditions 22,23 .…”

“…We have previously studied DPOAEs longitudinally from birth to 6 months of age in a group of infants born with perinatal HI 21,22 . We have also studied DPOAEs longitudinally in a group of infants born with a low Apgar score alone that was due most likely to perinatal hypoxia but no clinical signs of HIE and/or other perinatal conditions 22,23 . During the first 6 months, DPOAEs pass rates, mainly at 1–4 kHz, were decreased in these infants suggesting a decrease in cochlear function 21–23 …”