Monopolar cautery and adverse effects on cochlear implants

IMPORTANCE The use of monopolar cautery has been widely regarded as a contraindication in the setting of a cochlear implant because of presumed risk to the implant device. There are very limited data to support this contraindication. OBJECTIVES (1) To evaluate the effects of monopolar cautery on cochlear implant devices. (2) To determine whether monopolar cautery changes the endocochlear temperature in an implanted cochlea. DESIGN Sixteen cochlear implants from 3 manufacturers (Advanced Bionics LLC, Cochlear Americas Ltd, and Med-El Ltd) were implanted into 2 unembalmed, fresh cadavers. Monopolar cautery was applied to either the tongue or abdomen at coagulation settings of 10 Wor 50Wfor 30 minutes. Impedance and integrity testing were performed before, during, and after 30 minutes of cautery. The temperature in the endocochlear perilymph was measured during cautery. After explantation, devices were returned to the manufacturer for an in-depth "failure" analysis according to each manufacturer's current protocol evaluating explanted devices. SETTING Basic science laboratory, tertiary medical center. PARTICIPANTS Cadaveric study. INTERVENTION Application of monopolar cautery to implanted cochlear implants in a cadaveric model. MAIN OUTCOME AND MEASURE (1) Changes to the implanted devices either during electrocautery or following failure analysis. (2) Changes in the intracochlear temperature. RESULTS No change in impedance, integrity testing, or failure analysis occurred at any cautery setting when applied to either the oral cavity or abdomen. The temperature of the cochlea did not increase with up to 30 minutes of cautery at a setting of 50W. Comprehensive device analysis did not show any evidence of device damage at the conclusion of the study. CONCLUSIONS AND RELEVANCE Monopolar cautery did not produce detectible damage to any of the cochlear implant devices or produce detectible temperature change in the cochlea at low or high levels of cautery in the oral cavity in this experimental model.