title: Contralateral suppression of linear and nonlinear transient evoked otoacoustic emissions in neonates at risk for hearing loss.
abstract: To investigate the transient evoked otoacoustic emissions (TEOAE) contralateral suppression in neonates at risk for hearing loss, 55 neonates at risk for hearing loss (risk group) and 72 full-term neonates not at such risk (control group) were bilaterally tested. In all neonates, the TEOAE were recorded in two stimulation modes (linear and nonlinear clicks), with and without contralateral acoustic stimulation. Findings revealed significant contralateral suppression of otoacoustic emissions in both groups, but the amount of TEOAE contralateral suppression was reduced for at risk group (p=0.001), supporting the hypothesis that medial olivocochlear bundle function is reduced in neonates at risk for hearing loss. The combination of contralateral acoustic stimulation and TEOAE enables easy and noninvasive study of auditory efferent function. However it should be emphasized that the reduction in TEOAE contralateral suppression in the risk group, statistically identified as a group effect, might not be detectable in individual cases. Further studies are needed in order to determine whether the lower amount of TEOAE contralateral suppression in neonates at risk for hearing loss represents a risk for developing auditory processing disorders.
  
  
  OBJECTIVE
  The reader will be introduced to the study using auditory efferent pathway activation by contralateral acoustic stimulation (CAS), resulting in the TEOAE suppression effect. The characteristics of TEOAE suppression in the neonatal population, in which it provides evidence of the reduced medial olivocochlear system function in those at risk for hearing loss, will also be addressed.
authors.affiliation: Medicine School of Santa Casa of São Paulo, Rua Dr. Cesareo Mota Junior, 61, Zip 01221-020, São Paulo - SP, Brazil. asdurant@usp.br
authors.forename: Alessandra Spada
authors.initials: AS
authors.lastname: Durante
authors.forename: Renata Mota Mamede
authors.initials: RM
authors.lastname: Carvallo
mesh_terms: D000161:Acoustic Stimulation; D001300:Audiometry, Evoked Response / Q000379:methods*; D017626:Cochlear Nucleus / Q000503:physiopathology; D004292:Dominance, Cerebral / Q000502:physiology*; D004525:Efferent Pathways / Q000503:physiopathology; D005260:Female; D006311:Hearing Disorders / Q000151:congenital* / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D009847:Olivary Nucleus / Q000503:physiopathology; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D012016:Reference Values; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted