Influence of argon laser stapedotomy on cochlear potentials. III. Extracochlear recorded DC potential

During laser stapedotomy there is an extracochlear recordable DC deflection, which may hamper the recording of the Cochlear Microphonics (CM), or the Compound Action Potential (CAP). The investigation of the nature of this DC potential, its distribution as well as its recovery is the subject of the present paper. In contrast to the laser induced temperature alteration, this DC deflection spreads across the surface of the cochlea. Since the DC deflection only occurs during laser impact and not when perforating the cochlea with steel instruments, the most probable explanation is a heat destruction of the molecular structure of the bone.