DISTORTION-PRODUCT OTOACOUSTIC EMISSION MONITORING OF COCHLEAR BLOOD-FLOW

Distortion-product otoacoustic emissions (DPOAEs) have been shown to b e ideally sensitive to interruptions of the cochlear blood flow, Howev er, a 15- to 30-second latency typically occurs between cessation of c irculation and measurable DPOAE level changes. DPOAEs can also be char acterized by phase measures. The aim of the present study was to deter mine in 10 rabbits the effects on DPOAE phase of repetitively compress ing the internal auditory artery. In contrast to the delays measured b y DPOAE level, phase changes were detected 1 to 5 seconds after intern al auditory artery compression. These data suggest that the essentiall y ''real time'' monitoring of cochlear function with DPOAE phase can b e used to ensure hearing preservation during surgery involving the por us acousticus and skull base.