Microsurgical laser Doppler probe for simultaneous intraoperative monitoring of cochlear blood flow and electrocochleography from the round window

Abstract

The aim of this project is the development of a microsurgical laserDoppler (LD) probe that simultaneously monitors blood flow andElectrocochleography (ECochG) from the round window of the ear. Thedevice will prevent neurosensory hearing loss during acoustic neuromasurgery by preventing damage to the internal auditory nerve and to thecochlear blood flow supply. A commercially available 0.5 mm diameterLaser-Doppler velocimetry probe (LaserFlo, Vasamedics) was modified tointegrate an ECochG electrode. A tube for suction and irrigation wasincorporated into a sheath of the probe shaft, to facilitate cleaning ofthe round window (RW) and allow drug delivery to the round windowmembrane. The prototype microprobe was calibrated on a single vesselmodel and tested in vivo in a rabbit model. Preliminary results indicatethat the microprobe was able to measure changes in cochlear blood flow(CBF) and ECochG potentials from the round window of rabbits in vivo.The microprobe is suitable for monitoring cochlear blood flow andauditory cochlear potentials during human surgery.