Electrophysiological monitoring of hearing function during cochlear perilymphatic perfusions

Abstract

Conclusion: The cochlear perilymphatic perfusion produces, by itself, significant effects in the cochlear physiology that could be associated with the surgical procedure. These effects need to be well characterized to allow a reliable quantification of the effects of the experimental agent being tested. Objectives: The study focused on the accurate description of the electrophysiological effects on the cochlear potential recordings of perilymphatic perfusions. Methods: Two successive cochlear perilymphatic perfusions were carried out. The first used artificial perilymph. The second used artificial perilymph alone or a kainic acid (KA) solution in artificial perilymph. The compound action potential of the auditory nerve (CAP-AN) was recorded: (1) before the first perfusion, (2) after the first perfusion and (3) after the second perfusion, and compared between groups. Results: The first intracochlear perfusion with artificial perilymph produced significant effects in the CAP-AN that could be related to the surgical procedure. These effects were analysed separately from the effects produced by the KA. In particular, the KA administered intracochlearly produced a significant increase in the latency and a decrease in the amplitude of the CAP-AN N1 wave compared with the controls that were perfused twice with artificial perilymph.

Keywords::

• Hypoacusia
• excitotoxic amino acids
• rat
• kainic acid
• cochlear decompression
• cochlear evoked potentials
• compound action potential of the auditory nerve
• electrocochleography
• artificial perilymph

Acknowledgments

The authors acknowledge the collaboration of Prof. Pilar Zuluaga (Department Section of Statistics and Operations Research, School of Medicine, Universidad Complutense, Madrid, Spain) in the statistical evaluation of the present work. Also, the authors wish to acknowledge the technical contribution of Ms Teresa Rodriguez for her magnificent work in the processing of samples for the morphological study carried out in this project. This work was financed with grants from the Complutense University Research Team ‘Cátedra de Neurobiología de la Audición' (ref. 910915).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.