III Effects of Eustachian Tube Ligation

Abstract

Experimental production of serous effusion in the middle ear of animals has been achieved by other investigators by direct attack upon the Eustachian tube with cautery or ligation.l-" It would appear that the bullar effusion which results may be caused by one of three processes: 1) trauma to the tubal lumen may induce infection which could extend to the bulla and cause an outpouring of inflammatory exudate; 2) tubal edema or fibrosis could result in tubal obstruction followed by effusion ex vacuo; or 3) peritubal lymphatic compromise, may lead to extravasation of fluid from the bullar lymphatic vessels.In the present experiment an attempt was made to separate these factors. Accordingly, an aseptic external approach via the base of the skull without violation of the tubal lumen was carried out, followed by ligation of the Eustachian tube in order to ensure definitive obstruction without infection. The variable of lymphatic obstruction remained, and it was hoped that it might be controlled by providing middle ear ventilation through myringotomy. If bullar effusion is indeed due to diminished pressure and not to lymphatic compromise or infection, it should not occur if middle ear pressure is kept equal with that of the outside world. METHODThe tympanic membranes of healthy cats were examined under intravenous pentobarbital sodium anesthesia using a Zeiss surgical microscope for illumination and magnification. Twenty-three cats with normal-appearing drum membranes and clean ear canals were retained in the experiments.

Tympanic Neurectomy: Its Effects on the Seromucinous Glands of the Middle Ear of Cats

“…Cats were chosen because normally, their mcsotympanic mucosa contains seromucinous glands near the tym panic orifice of the Eustachian tube [9].…”

Magnetic Resonance Imaging of the Development of Otitis Media with Effusion Caused by Functional Obstruction of the Eustachian Tube

“…2 With regard to the last, numerous past studies in animals have shown that physical obstruction of the tubal lumen causes ME mucosal metaplasia and an effusion resembling in biochemical composition a transudate from the vascular compartment. [3][4][5][6][7] However, histopathologic studies of autopsy materials do not demonstrate physical obstruction of the tubal lumen in cases of OME. 8 " 10 This negative evidence was used to discount a role for tubal obstruction in the development of OME.…”

Serous otitis media in the 20th and 21st centuries: evolving views and treatments

“…Infection was considered the cause of the fluid since bacteria were found in the middle ear fluids in many experimental and clinical studies. Proud [11], in 1970, showed that the fluid would accumulate without an infection. His data ( Figure 3) also showed that a patent myringotomy prevented the accumulation of the fluid.…”