title: Otoacoustic emission responses of the cochlea to acute and total ischemia.
abstract: In the present experimental study, we sought to monitor distortion product otoacoustic emissions (DPOAEs) as an indicator of cochlear function, after sudden, total, and irreversible interruption of cochlear blood flow, to provide information on the time course of cochlear response to ischemia. Twenty rats with normal hearing function were included. Complete and abrupt ischemia was provided by decapitation. DPOAEs at 3-8 kHz frequencies were recorded at baseline and exactly every consecutive minute after decapitation, until emissions in all frequencies disappeared completely. Mean DPOAE values decreased significantly and progressively after decapitation for all frequencies. The mean duration of emissions was 8.20 ± 1.96 min (minimum 3 min, maximum 11 min). The longest durations of DPOAEs were observed with 4 and 5 kHz frequencies, and 3 and 6 kHz had the shortest durations. The outer hair cells exposed to acute ischemia seem to exhibit a rapid functional loss; thus, cautious handling of the cochlear vasculature and surrounding structures is necessary in surgical interventions. Additionally, our results provide some idea of the normal tolerance range of the cochlea to ischemia, which could be useful for future studies.
authors.affiliation: Department of Otorhinolaryngology, Medical Faculty, Bezmialem Vakif University, 46300 Karaelbistan, Kahramanmaraş Turkey.
authors.forename: Yavuz Selim
authors.initials: YS
authors.lastname: Yıldırım
authors.affiliation: Department of Otorhinolaryngology, Medical Faculty, Bezmialem Vakif University, Istanbul, Turkey.
authors.forename: Fadlullah
authors.initials: F
authors.lastname: Aksoy
authors.affiliation: Department of Otorhinolaryngology, Medical Faculty, Bezmialem Vakif University, Istanbul, Turkey.
authors.forename: Orhan
authors.initials: O
authors.lastname: Ozturan
authors.affiliation: Department of Otorhinolaryngology, Medical Faculty, Bezmialem Vakif University, Istanbul, Turkey.
authors.forename: Bayram
authors.initials: B
authors.lastname: Veyseller
authors.affiliation: Department of Otorhinolaryngology, Islahiye State Hospital, Gaziantep, Turkey.
authors.forename: Hasan
authors.initials: H
authors.lastname: Demirhan
keywords: Cochlear blood flow; Cochlear ischemia; Otoacoustic emissions; Outer hair cell; Rat