Analysis of the Damage Mechanism Related to CO₂Laser Cochleostomy on Guinea Pig Cochlea

Abstract

Different types of lasers have been used in inner ear surgery. Therefore, it is of the utmost importance to avoid damage to the inner ear (e.g., hyperthermia and acoustic effects) caused by the use of such lasers. The aim of this study was to use a high powered fibre-enabled CO2 laser (10 W, 606 J/cm2) to perform cochleostomies on guinea pig cochlea and to investigate the possible laser-induced damage mechanisms. The temperature changes in the round window membrane, auditory evoked brainstem response, and morphological of the hair cells were measured and recorded before and after laser application. All of the outcomes differed in comparison with the control group. A rise in temperature and subsequent increased hearing loss were observed in animals that underwent surgery with a 10 W CO2 laser. These findings correlated with increased injury to the cochlear ultrastructure and a higher positive expression of E-cadherin and β-catenin in the damaged organ of Corti. We assume that enhanced cell-cell adhesion and the activated β-catenin-related canonical Wnt-signalling pathway may play a role in the protection of the cochlea to prevent further damage.

Striatin Is Required for Hearing and Affects Inner Hair Cells and Ribbon Synapses

“…In addition, striatin has been shown to colocalize with β-catenin, a junctional protein, in different tissues ( Domke et al, 2014 ; Franke et al, 2015 ; Domke and Franke, 2019 ). However, as our previous studies indicate that in the mammalian cells tested striatin did not bind or colocalize with β-catenin ( Breitman et al, 2008 ) and that in the inner ear β-catenin is barely seen in hair cells ( Liu et al, 2016 ), the possibility that striatin and β-catenin interact was not examined in the current study. Another interesting prospect is the effect of striatin on proto-cadherins.…”

Thermal variation in human temporal bone using rigid endoscope

“…Liu at al., analyzing the increase in the temperature of the round window in guinea pigs and the change in auditory evoked potential by exposure to a CO 2 laser at an intensity of 10 W, 3-mm of distance at a cochleostomy, they found an increase of 8 °C, which was enough to induce hearing loss and in the histological study of these guinea pigs, they found damage to outer hair cells. 13 This shows that little increase of temperature damages cochlear hair cells with hearing loss in animals. We consider that our work provides important information to raise awareness about the possibility of injury to the inner ear when using a 4-mm rigid endoscope in otological surgeries, especially for a longer period of time and with the tip of the endoscope close to the round window.…”