Efferent inhibition of otoacoustic emissions in preterm neonates.
BACKGROUND
Abnormalities in auditory function of newborns may occur not only because of preterm birth, but also from the use of medications and from diseases related to prematurity.


OBJECTIVE
To analyze the inhibitory effect from stimulation of the olivocochlear efferent system on transient evoked otoacoustic emissions in preterm neonates, comparing these data with those from full-term neonates.


METHODS
This was a prospective, cross-sectional, contemporary cohort study with 125 neonates, pooled into two groups: full-term (72 full-term neonates, 36 females and 36 males, born at 37-41 weeks of gestational age); and preterm (53 neonates, 28 males and 25 females, born at ≤36 weeks of gestational age, evaluated at the corrected gestational age of 37-41 weeks). Otoacoustic emissions were recorded using linear and nonlinear click-evoked stimuli, with and without contralateral stimulation.


RESULTS
The inhibitory effect of the efferent pathway in otoacoustic emissions was different (p=0.012) between groups, and a mean reduction of 1.48dB SPL in full-term births and of 1.02dB SPL in preterm births was observed for the non-linear click-evoked stimulus.


CONCLUSIONS
The results suggest a reduced inhibitory effect of the olivocochlear efferent system on otoacoustic emissions in preterm neonates.
Speech Therapy Course, Faculdade de Medicina, Universidade de São Paulo (FM-USP), São Paulo, SP, Brazil. Electronic address: renamaca@usp.br.
Renata Mota Mamede
RM
Carvallo
Department of Physical Therapy, Speech Therapy and Occupational Therapy, Faculdade de Medicina, Universidade de São Paulo (FM-USP), São Paulo, SP, Brazil; Rehabilitation Sciences, Faculdade de Medicina, Universidade de São Paulo (FM-USP), São Paulo, SP, Brazil.
Seisse Gabriela Gandolfi
SG
Sanches
Faculdade de Medicina, Universidade de São Paulo (FM-USP), São Paulo, SP, Brazil; Unit of Neonatology, University Hospital, Faculdade de Medicina, Universidade de São Paulo (FM-USP), São Paulo, SP, Brazil.
Silvia Maria
SM
Ibidi
Rehabilitation Sciences, Faculdade de Medicina, Universidade de São Paulo (FM-USP), São Paulo, SP, Brazil.
Jordana Costa
JC
Soares
Speech Therapy Course, Medical Sciences School, Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brazil; Experimental Pathophysiology, Faculdade de Medicina, Universidade de São Paulo (FM-USP), São Paulo, SP, Brazil.
Alessandra Spada
AS
Durante
D000161:Acoustic Stimulation; D003430:Cross-Sectional Studies; D004525:Efferent Pathways / Q000503:physiopathology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006311:Hearing Disorders / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D015997:Neonatal Screening; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D011446:Prospective Studies; D012307:Risk Factors
Auditory pathways; Audição; Emissões otoacústicas espontâneas; Hearing; Newborn infant; Premature infant; Prematuro; Recém-nascido; Spontaneous otoacoustic emissions; Vias auditivas