Experimental Study on the Permeability of the Round Window Membrane

Abstract

Permeability of the round window membrane was investigated in normal ears and in ears with serous otitis media. Serous otitis media was produced experimentally by obstructing the eustachian tube of the guinea pig on one side. The other side served as a control. Neomycin was applied directly to the round window membrane on both sides, and the inner ear changes were observed under a light microscope. Most of the ears with serous otitis media showed no cochlear pathology or only slight chages, while moderate to severe changes were observed in all of the control ears. The results indicate that the round window membrane is permeable to neomycin, and that the transport of neomycin into the inner ear decreases in most instances of serous otitis media. The latter may be explained on the basis of fluid remaining and blocking the transport of neomycin mechanically on the surface of the round window membrane.