The purpose of this study was to determine whether mitomycin C could be used to prolong the patency of the myringotomy site in the absence of ventilation tubes in rats. We examined the effect of increased exposure time and repeat application of mitomycin C to the myringotomy site. Sixty animals were separated into 4 groups: group A had a single application of mitomycin C for 10 minutes; group B had a single application for 20 minutes; group C received 2 10-minute applications separated by 1 week; and group D received 2 applications (20 and 10 minutes) separated by 1 week. Mitomycin C and bacteriostatic saline solution were applied to the right and left myringotomy sites in each rat, respectively. Experimental ears in groups A, B, C, and D remained open for a median time of 6.5, 5.5, 6.5, and 8.5 weeks, respectively. The control ears healed within 1. 5 weeks. This difference was statistically significant with P < 0.001 for each group. We conclude that mitomycin C is effective in prolonging the patency of myringotomies in rat tympanic membranes. Increased exposure time or repeat application of mitomycin C did not statistically alter the patency rate.

The purpose of this study was to determine whether topical mitomycin C could be used to prolong the patency of a myringotomy site in the absence of a ventilation tube. Mitomycin C is an antineoplastic agent used to maintain a patent trabeculectomy site in patients with glaucoma. The KTP laser was used to create bilateral myringotomies 0. 4 mm in diameter in 28 chicks (Gallus domesticus). Mitomycin C was applied to the right myringotomy site, and sterile water, used as a control, was applied to the left myringotomy site. The animals were divided into 2 groups with group A treated with freshly prepared mitomycin C and group B treated with 2-week-old mitomycin C. The patency rates of the experimental ears of groups A and B were 80% and 70%, respectively, 15 days after surgery and 33% and 7.7%, respectively, at 30 days. All myringotomy sites in the control ears were healed within 5 days. Using a logistic regression model for repeated measures, we determined the odds ratio between the experimental and control myringotomies of the combined groups to be 149.1 (P = 0.0001). We conclude that mitomycin C had a significant effect in prolonging the patency of myringotomies in chick tympanic membranes.

Cochleas from 12 guinea pigs were evaluated using light, scanning, and transmission electron microscopy after systemic administration of cis-diamminedichloroplatinum (cis-DDP). Administration of cis-DDP resulted in loss of the Preyer reflex and degeneration of outer hair cells (OHC) with increased dose. The OHC degeneration was most pronounced in the basal turns of the cochlea with greatest severity in the inner row. Ultrastructural evidence of OHC degeneration included dilatation of the parietal membranes, softening of the cuticular plate, increased vacuolization and increased numbers of lysosome-like bodies in the apical portion of the cell. Supporting cells appeared more sensitive than OHC. Alteration of supporting cell ultrastructure preceded detectable change in OHC. Injury to the supporting cells was noted with intracellular vesiculation and increased autophagocytosis.

Topically administered mitomycin C before laser myringotomy is effective in prolonging the patency of laser myringotomies in rats. The patency rate is similar to that achieved in experiments in which topical mitomycin C is placed into the myringotomy site created by the laser.

The use of MRI for the evaluation of lesions in the internal auditory canal presents a potential pitfall in the diagnosis of bony lesions of the IAC, because bone is poorly visualized with this method of imaging. The presence of marrow in an osteoma might aid in its detection, since fat in the marrow has a bright signal intensity of T1-weighted imaging. Computed tomography remains the imaging modality of choice for bony lesions of the temporal bone. We demonstrate a case of IAC osteoma in which surgical removal resulted in improvement of symptoms. The gross and microscopic appearance of the IAC osteoma in this case is similar to the characteristic findings of osteomas of the EAC. This suggests that the criteria applied to osteomas and exostoses of the EAC may also be used to differentiate bony lesions of the IAC.