Ossicular chain reconstruction using a new tissue adhesive.

HYPOTHESIS: A new medical-grade cyanoacrylate tissue adhesive will improve the results of ossicular chain reconstruction in a rat model. BACKGROUND: An ideal tissue adhesive has long been awaited by otologists. Studies examining the older cyanoacrylates have demonstrated variable efficacy and toxicity. Octylcyanoacrylate is a new tissue adhesive that has many ideal properties for otologic surgery. METHODS: Thirteen female C-D rats were anesthetized, and preoperative auditory brainstem response (ABR) testing was performed. A left antrotomy was performed, and the incus was removed. In the adhesive group, the incus was dipped in octylcyanoacrylate and interposed between the tympanic membrane and the stapes; no adhesive was used in the control group. At 8 weeks, postoperative ABR was performed, the integrity of the ossicular chain inspected, and histopathologic analysis of the temporal bones performed. Statistical comparison of ABR results was performed with the Mann-Whitney test. RESULTS: Seven rats were randomized to the adhesive group and six to the control group, of which four survived. There were no histopathologic differences in the temporal bones of the animals other than the presence of mild foreign body reaction around the ossicular chain of the animals in the adhesive group. The ossicular chain was not intact in two of the four controls, whereas the rest were intact at 8 weeks. Postoperative air conduction ABR results (mean dB sound pressure level) (62.5 control versus 34.3 adhesive, p = 0.010) and air-bone gaps (47.5 control versus 18.9 adhesive, p = 0.008) were significantly better in the adhesive group. CONCLUSIONS: This new medical-grade tissue adhesive improves the hearing results of ossicular chain reconstruction, with no apparent histotoxicity in this animal model.

Octylcyanoacrylate: a new medical-grade adhesive for otologic surgery.

HYPOTHESIS: The adhesive octylcyanoacrylate is not associated with significant 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. Octylcyanoacrylate is a medical-grade adhesive with many properties that make it ideal for use in the ear. It is free of contaminants; it forms a strong, flexible bond; and it inhibits the growth of gram-positive organisms in culture. This is the first study to assess the ototoxicity of this new adhesive. METHODS: Fourteen adult guinea pigs were used. Preoperative auditory brainstem responses (ABRs) were determined. Bilateral antrotomies were performed, and the ears were randomized to adhesive and control (saline) groups. In the adhesive ears. 0.5 or 0.1 mL of octylcyanoacrylate was instilled into the middle ear. Eight weeks later, postoperative ABRs were determined, the animals were killed, and the temporal bones were removed. Middle ear changes were noted, and the ossicular chain was assessed. Cochlear hair cell analyses were performed. Histologic assessment of the middle ear mucosa was performed. RESULTS: There was a higher incidence of conductive hearing loss in the adhesive group secondary to fixation of the ossicular chain, but there was no significant difference in bone conduction thresholds. The median postoperative bone conduction thresholds (dB peak sound pressure level) was 15.0 in the control group and 17.5 in the adhesive group, p = 0.89. There was also no significant difference in inner hair cell counts (0.4% vs. 0.5% median hair cell loss, p = 0.72) or outer hair cell counts (3.7% vs. 3.0% median hair cell loss, p = 0.23) for the adhesive and control groups, respectively. Histopathologic analysis of the middle ear mucosa demonstrated variable mild to moderate foreign body reaction with no evidence of mucosal ulceration or 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 inner ear toxicity. This new adhesive is a promising tool for otologic surgery.

A prospective comparison of octylcyanoacrylate tissue adhesive and suture for the closure of head and neck incisions.

OBJECTIVE: To compare the tissue adhesive octylcyanoacrylate with subcuticular suture for the closure of head and neck incisions. DESIGN: A prospective comparison with a blinded assessment of cosmetic outcome. SUBJECTS: Fifty consecutive patients undergoing head and neck procedures at two University of Ottawa teaching hospitals. METHODS: Twenty-six patients underwent skin closure with monofilament suture and 24 were closed with tissue adhesive. At 4 to 6 weeks the incisions were evaluated with a validated wound scale. Photographs of the incisions were rated using a visual analogue scale by two facial-plastic otolaryngologists who were blinded to the method of skin closure. RESULTS: The adhesive provided faster skin closure (29.7 seconds vs 289.0 seconds, p < .0001), and there were no differences in complications between the two groups. The primary outcome measure was the cosmetic appearance of the incision at 4 to 6 weeks. Although the adhesive group scored higher on both cosmesis scales, the visual analogue scale (octylcyanoacrylate 58.7 mm vs suture 53.2 mm) and the wound evaluation scale (57% vs 50% optimal wound scores), there were no statistical or clinically significant differences on either scale. The two facial-plastic otolaryngologists had good intraobserver and interobserver agreement when rating the cosmetic outcomes (0.87 and 0.71 respectively). CONCLUSIONS: Octylcyanoacrylate was found to be an effective method of skin closure in clean head and neck incisions. The practical advantages of tissue adhesives are reviewed.