Simultaneous measurement of electrocochleography and cochlear blood flow during cochlear hypoxia in rabbits.
In this study, a new monitoring system is developed to measure cochlear blood flow (CBF) and electrocochleography (ECochG) during transient ischemic episodes of the cochlea. A newly designed otic probe was used for the simultaneous recordings of laser-Doppler CBF and ECochG directly from the round window (RW). The probe enabled the recording of high amplitude compound action potentials (CAP) and cochlear microphonics (CM) with few averages. Experiments were conducted on rabbits to generate episodes of cochlear ischemia by using timed compressions of the internal auditory artery (IAA). The computer monitoring system extracted and measured CAP and CM components from ECochG in real-time. Results indicate that CM and CAP generally followed CBF during compressions and releases of IAA. Both CBF values and CAP amplitudes showed an overshoot following the reperfusion. CAP amplitude measures were found to be very sensitive to ischemia showing very rapid amplitude, latency and morphological changes. CM amplitude decreased more slowly than the CAP and CBF. Simultaneous recordings of CBF and ECochG using the otic probe provide a valuable neuromonitoring tool to investigate the dynamic behavior of the cochlea during ischemia.
Yavuz
Erdem
E
Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33124, USA. cyavuz@umsis.miami.edu
Morawski
Krzysztof
K
Telischi
Fred F
FF
Ozdamar
Ozcan
O
Delgado
Rafael E
RE
Manns
Fabrice
F
Parel
Jean-Marie
JM
D000161:Acoustic Stimulation / Q000379:methods; D000818:Animals; D001300:Audiometry, Evoked Response / Q000379:methods*; D015834:Cochlear Diseases / Q000503:physiopathology*; D003055:Cochlear Microphonic Potentials / Q000502:physiology; D000860:Hypoxia / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry / Q000379:methods; D008954:Models, Biological; D011817:Rabbits; D011930:Reaction Time / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology*; D015203:Reproducibility of Results; D012405:Round Window, Ear / Q000098:blood supply / Q000503:physiopathology