Operative Real-Time Monitoring System for Reconstructive Middle Ear Surgery

Positioning and coupling of middle ear prosthesis are a precondition for good postoperative hearing results, but at the same time completely dependent upon the surgeon’s subjective judgment during surgery. An electromagnetically driven measurement system that enables for in vitro and in vivo transmission measurements and thus can be used as a real-time monitoring tool in ossicular reconstruction was evaluated.

For electromagnetical excitation a magnet can be placed on the umbo of the malleus handle and driven by a magnetic field. The induced stapes displacement is picked up by laser Doppler vibrometry on the footplate. Measurements are performed on the intact ossicular chain during five cochlear implant surgeries. Additionally, two ossiculoplasties were performed under real-time transmission feedback with the monitoring system.

The electromagnetical excitation and measurement system is comparable to the gold standard with acoustical stimulation in both, the experimental setup in temporal bones as well as in vivo. The technical feasibility of the electromagnetical excitation method has been proven and it is shown that it can be used as a real-time monitoring system for ossiculoplasty in the operation room.

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