The Neonate Has a Temporary Conductive Hearing Loss due to Fluid in the Middle Ear

Abstract

Postnatal functional changes in the activity of the ear and auditory pathway in neonatal guinea pigs [from day of birth (postnatal day, PND = 0), PNDs 1–4, 7 and then weekly up to 7 weeks] were studied as a model of maturation of hearing in human neonates. On the day of birth there were signs of a conductive hearing loss: negative middle ear pressure, auditory nerve brainstem evoked response (ABR) threshold elevation, ABR wave 1 latency prolongation and low amplitude otoacoustic emissions. The conductive hearing loss is probably a result of the (amniotic) fluid found in the neonatal middle-ear cavity. Over the next PNDs, this conductive hearing loss was resolved. In order to confirm this neonatal conductive hearing loss and its resolution, saline was instilled into the middle ear of guinea pigs. This induced signs of a conductive hearing loss similar to those seen in the neonatal guinea pigs which disappeared with clearance of this fluid. Therefore it may be concluded that most of the changes in auditory function seen over the first PNDs are due to absorption of amniotic fluid from the middle-ear cavity.

Middle ear and cochlear disorders result in different DPOAE growth behaviour: implications for the differentiation of sound conductive and cochlear hearing loss

“…by changes in atmospheric pressure or effusion of the tympanic cavity do also have an impact on the DPOAE level (Osterhammel et al, 1993;Hauser et al, 1993;Zheng et al, 1997;Avan et al, 2000;Ueda et al, 1998;Topoloska et al, 2000;Job and Nottet, 2002;Priner et al, 2003). However, since sound is processed linearly in the middle ear (Dallos, 1973), primary tones that elicit DPOAEs and the DPOAEs themselves are suggested to be attenuated linearly in the case of a sound conduction dysfunction.…”

Morphology and Ciliary Motion of the Middle Ear Mucosa of Neonatal and Adult Gerbils

“…In neonatal guinea pigs, the conductive hearing loss caused by amniotic fluid can automatically disappear after several days [7]. Middle ear effusion is found in all newborn animals within 3 h after birth, most effusion is clear within 3 days after birth [8].…”

Avaliação da onda V da audiometria de tronco cerebral de crianças reprovadas na triagem auditiva neonatal

“…Após a triagem auditiva, realizada ainda na maternidade, é necessária a realização de diagnóstico nos casos de falha. É imprescindível que outros exames, como a audiometria de tronco cerebral, imitanciometria e observação do comportamento auditivo, sejam incorporados ao de emissões otoacústicas para que o diagnóstico de deficiência auditiva seja realmente concluído 16,28 .…”

“…Geralmente a alteração condutiva mais encontrada nesta faixa etária é alteração condutiva por secreção em ouvido médio 28 . Isto deve ser confirmado com a realização de timpanometria e, se presente, deve ser logo tratado.…”