Auditory Effects of Microperfused Lidocaine on Guinea Pig Cochlea

Woo, Hoon Young; Cho, Kyoung Rai; Choi, Jeong Hwan; Chung, Sang Won; Han, Dong Hoon; Cho, Chul Kyu

Abstract

OBJECTIVES
Lidocaine is one of the therapeutic trials to treat tinnitus. However, the exact mechanism of the effect of lidocaine remains unclear. The aim of this study was to elucidate the action site of lidocaine in the cochlea by measuring compound action potential (CAP) and transient evoked otoacoustic emission (TEOAE) amplitude in guinea pigs. METHOD: Artificial perilymph was perfused into the scala tympani of the guinea pig cochlea in the control group, and lidocaine diluted with artificial perilymph was perfused into the scala tympani of the experimental groups. Electrocochleogram (ECoG) and TEOAE were measured in each groups both before and after lidocaine perfusion. RESULTS: Artificial perilymph perfused to the scala tympani of the guinea pig cochleae did not affect either the CAP threshold or the TEOAE response. But, lidocaine perfused into the scala tympani of the guinea pig cochleae produced a dose-dependent increase in CAP threshold, but did not affect TEOAE response. CONCLUSION: This study revealed that lidocaine perfused into the scala tympani of the guinea pig cochlea affects the CAPthreshold but not the TEOAE amplitude and reproducibility. It means that the locally perfused lidocaine affects the cochlear nerve greater than the outer hair cells.