The effects of incisional myringotomy and CO2 laser myringotomy on rat tympanic membranes

The purpose of this study was to compare closure rates and histopathological findings of carbon dioxide (CO(2)) laser myringotomies to those of incisional myringotomy. We performed CO(2) laser round myringotomy on left ears and incisional round myringotomy on the right ears of 34 rats on the same day. The incisions were 2mm in size on both ears. Examination was made with otoendoscope on days 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 25, 30, 35, 40, 45, 50 with videorecording. Two rats were sacrificed every 2 days for 25 days and every 5 days thereafter, randomly. The tympanic membranes (TM) were excised and hyalinization, fibrosis and inflammation were assessed with light microscope. Most of the CO(2) laser myringotomies healed after day 15, and all of them healed by day 50. Three of the incisional myringotomy perforations were closed at day 3, and the rest by day 15. Patency of CO(2) laser myringotomies was significantly longer than that of incisional myringotomies. Hyalinization, fibrosis and inflammation of the incisional myringotomy group were significantly less than those of the laser myringotomy group. CO(2) laser myringotomies remain patent for a longer period of time than the incisional procedure, however, they cause more tissue inflammation. We believe that CO(2) laser myringotomy is an effective method, however, additional studies are needed to identify its complications.