Clearance of effusion material from the attic space--an experimental study in the rat

Rat serum with Evan's blue added as a tracer was instilled into the attic through a pars flaccida perforation in rats. At intervals the drainage of the effusion-like material was observed through a hole in the tympanic bulla. The distribution of ciliary cells was studied in the middle ear using light microscopic and scanning electronmicroscopic techniques. It was noted that the effusion material was propelled from the attic to the inlet of the Eustachian tube mainly by hydrostatic forces. It is also concluded that this mechanism might apply in Homo sapiens and that the drainage position of the head may be of importance in preventing and treating otitis media with effusion (OME).