Can floseal™ be applied safely during otologic surgery? Assessment of ototoxicity in a chinchilla animal model
OBJECTIVE Carbomethylcellulose (CMC) foam has been widely adopted to promote hemostasis and healing in sinus surgery. There has been interest in the use of CMC in middle ear surgery. The purpose of this study was to evaluate the safety and efficacy of CMC foam for use in middle ear surgery. STUDY DESIGN Prospective, controlled. SETTING Academic research laboratory. SUBJECTS AND METHODS Adult guinea pigs underwent experimental tympanoplasty followed by packing of the middle ear (n = 19 per group) with CMC, hyaluronic acid (HA), or gelatin sponge (GS). Auditory evoked brainstem response testing and otomicroscopy were performed before and serially for eight weeks after surgery. Tympanic membrane healing, hemostasis, and retention of packing material were assessed. RESULTS All tympanic membranes treated with CMC healed by week eight. Less postoperative bleeding was observed with CMC than with HA or GS. Surgery elevated auditory thresholds, at least temporarily, in all groups. However, CMC was associated with greater auditory threshold elevation (15-25 dB) at eight weeks across all test frequencies relative to HA or GS (P < 0.01). Residual CMC and scarring were not found in the middle ear, indicating that the hearing loss was sensorineural. No head tilt posturing suggestive of vestibulopathy was seen. CONCLUSION CMC was associated with hearing loss and may be ototoxic. Therefore, CMC should not be used in human middle ears given the presence of several nontoxic alternative materials.