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Evidence for surviving outer hair cell function in congenitally deaf ears
Peter A Rea1, William P R Gibson
1The Sydney Cochlear Implant Centre, Department of Otolaryngology, University of Sydney, New South Wales, Australia.
The Laryngoscope
|November 7, 2003
Summary
Congenital hearing impairment in infants may stem from inner hair cell loss, indicated by abnormal potentials on electrocochleography. Otoacoustic emissions testing may be unsuitable for screening infants with hearing loss, especially those in neonatal intensive care units.
Area of Science:
- Pediatric Audiology
- Neuroscience
- Otolaryngology
Background:
- Congenital hearing impairment affects a significant number of infants.
- Inner hair cell (IHC) dysfunction is a potential cause of hearing loss.
- Round window electrocochleography (RW-ECoG) can detect cochlear dysfunction.
Purpose of the Study:
- To investigate the hypothesis that isolated inner hair cell loss causes congenital hearing impairment.
- To determine the prevalence of abnormal positive summating potentials (PSPs) in infants with hearing loss.
- To assess the implications for otoacoustic emissions (OAEs) and universal neonatal hearing screening.
Main Methods:
- A prospective cohort study involving 464 infants with suspected hearing loss.
- Assessment included round window electrocochleography (RW-ECoG) and auditory brainstem response (ABR) testing.
- Retrospective collection of otoacoustic emissions (OAEs) data.
Main Results:
- Abnormal positive potentials (PSPs) were found in 21% of hearing-impaired infants.
- PSPs were strongly associated with the presence of OAEs (83%) and neonatal intensive care unit (NICU) admission (43%).
- Prevalence of PSPs was higher in preterm infants (63%) and those with hypoxia (57%).
Conclusions:
- Inner hair cell loss, potentially due to chronic hypoxia, may cause hearing loss in over 40% of NICU infants.
- Abnormal PSPs and OAEs may arise from outer hair cell activity post-IHC loss.
- OAEs may not be a reliable screening tool for hearing loss in this vulnerable infant population.