FP03-6. INTRAOPERATIVE ELECTROCOCHLEOGRAPHY DURING STAPES SURGERY

William Gibson (University of Sydney, Australia)

Intraoperative electrocochleography during stapes surgery

A technique for obtaining electrocochleography (ECochG) recordings during stapes surgery is presented. A silver ball electrode is inserted into the round window niche. A click or 1kHz tone pip is used to evike the responses. The transducer is placed on the operating microscope and calibrated at the focal length. Potentials can be obtained within a few seconds- probably quicker than asking the patient to respond subjectively. 80 patients have been monitored during surgery. Loss of hearing occurred in one patient who was undergoing revision surgery. Widening of the summating potential/ action potential (SP/AP) complex appears to be an adverse sign. In subsequent surgeries when this occurred the surgery was delayed until recovery was noted. It was gratifying for the surgeon to realise that the ECochG potentials had improved after stapedectomy and that no adverse changes had occurred. ECochG monitoring provdes similar security for the surgeon as facial nerve monitoring during cholesteatoma surgery.