Efficiency of cryotherapy in avoiding myringotomy closure in rats.

Myringotomy and ventilation tube placement is an office-based procedure and represents the treatment of choice for middle ear effusions and for transtympanic drug administration. The aim of our study was to study the efficiency of low-pressure spray cryotherapy on protraction of patency time of myringotomies in rats. Bilateral myringotomies were performed with cold instruments. Afterward, one ear in each rat was randomly assigned for liquid nitrogen treatment of the perforated eardrum. Myringotomy patency was recorded daily and histological analysis of the eardrums was performed. In the myringotomy group patency time was 4.75 ± 2.93 days, while in the cryotherapy group was 11.01 ± 4.87 days. The difference is statistically significant: Student t test, p < 0.00001, 95 % CI (-8.82; -3.67). Moreover, according to Kaplan-Meier method, myringotomy survival is significantly longer in the cryotherapy group. The healing processes of the cryotreated eardrums last longer and the patency of myringotomy was longer as compared to untreated myringotomies.