Octylcyanoacrylate: A new medical-grade adhesive for otologic surgery

Hypothesis: The adhesive octylcyanoacrylate is not associated with signific ant inner ear toxicity in a guinea pig model. Background: Many cyanoacrylate adhesives have been investigated For use in otologic surgery, but variable ototoxicity has been reported. Octylcyanoacr ylate is a medical-grade adhesive with many properties that make it ideal f or use in the car. It is free of contaminants; it forms a strong, flexible bond, and it inhibits the growth of gram-positive organisms in culture. Thi s is the first study to assess the ototoxicity of this new adhesive. Methods: Fourteen adult guinea pigs were used. Preoperative auditory brains tem responses (ABRs) were determined. Bilateral antrotomies were performed, and the ears were randomized to adhesive and control (saline) groups. In t he adhesive ears, 0.5 or 0.1 mt of octylcyanoacrylate was instilled into th e middle ear. Eight weeks later, postoperative ABRs were determined, the an imals were killed, and the temporal bones were removed. Middle ear changes were noted, and the ossicular chain was assessed. Cochlear hair cell analys es were performed. Histologic assessment of the middle ear mucosa was perfo rmed. Results: There was a higher incidence of conductive hearing loss in the adh esive group secondary to fixation of the ossicular chain, but there was no significant difference in bone conduction thresholds. The median postoperat ive bone conduction thresholds (dB peak sound pressure level) was 15.0 in t he control group and 17.5 in the adhesive group, p = 0.89. There was also n o significant difference in inner hail cell counts (0.4% vs. 0.5% median ha ir cell loss, p = 0.72) or outer hair cell counts (3.78 vs. 3.0% median hai r cell loss, p = 0.23) for the adhesive and control groups, respectively. H istopathologic analysis of the middle ear mucosa demonstrated variable mild to moderate foreign body reaction with no evidence of mucosal ulceration o r necrosis. Conclusions: A large amount of octylcyanoacrylate placed in the middle ear of the guinea pig did not cause any morphologic or functional evidence of i nner car toxicity. This new adhesive is a promising tool for otologic surge ry.