Ototoxic Effect of Anti‐fog Solution Applied to the Guinea Pig Middle Ear

Abstract

Objectives: Recent advances in endoscopic technology have allowed an application to middle ear surgery. Anti-fog agent is necessary for endoscopy because moisture and blood may cause obscured vision. Ultrastop is one of the most commonly used anti-fog agents. The current study examined the ototoxic effect of topical application of Ultrastop in the guinea pig ear. Methods: A preliminary experimental animal study. in a university hospital. Eighteen male Hartley guinea pigs (weight, 480-620 g) were divided into 3 groups to be treated with Ultrastop, gentamicin (50 mg/mL, positive control), or saline solution (negative control). After auditory brainstem responses were measured, topical solutions of 0.2 mL were applied through a small hole made at the tympanic bulla. Posttreatment auditory brainstem responses were obtained 14 days after the treatment. The extent of middle ear damage was investigated and scored. Results: The saline-treated group showed no deterioration in auditory brainstem response threshold. The anti-fog-treated and gentamicin-treated groups showed severe deterioration in auditory brainstem response threshold. Middle ear examination revealed extensive changes in the anti-fog-treated group and medium changes in the gentamicin-treated group. Conclusions: Anti-fog solution (Ultrastop) applied topically to the guinea pig middle ear caused significant middle ear inflammation and hearing impairment. Great care must be taken to prevent anti-fog solution reaching the middle ear.