Effects of nasal obstruction on Eustachian tube function and middle ear pressure

To evaluate the relationship between nasal obstruction and otitis media, 10 ferrets were studied before and after either unilateral (n = 5) or bilater al (n = 5) nasal obstruction. Observations included otomicroscopic assessme nts of middle ear status, tympanometric recordings of middle ear pressure a nd forced-response, inflation-deflation and continuous monitoring tests of Eustachian tube function. During the 6-8 week post-obstruction follow-up pe riod no animal developed evidence of otitis media. Abnormal positive middle ear pressures lasting for the period of follow-up occurred only in the ani mals with bilateral nasal obstruction. Eustachian tube function test result s showed these pressures to be generated during swallowing. No changes in t he passive function of the tube were documented in either group, but change s in active function consistent with alterations in the pressure gradient b etween the middle ear and the nasopharynx were observed in both groups.