Eustachian tube histopathology during experimental influenza A virus infection in the chinchilla.

The eustachian tubes of 29 influenza A virus-infected chinchillas were examined for histopathologic signs at intervals up to 21 days after inoculation to elucidate the pathologic basis of negative middle ear pressure, which occurs during viral respiratory tract infection in humans. In the animal model, eardrum inflammation and negative middle ear pressure mirrored epithelial damage in the eustachian tube and the accumulation of cellular and mucous debris in the tubal lumen. Epithelial damage was greatest in the proximal two thirds of the tube near the nasopharynx, whereas goblet cell metaplasia and increased secretory activity was greatest in the distal, tympanic one third of the tube. These results provide a morphologic correlate to the development of negative middle ear pressure, and perhaps explain the pathologic basis for purulent otitis media during viral respiratory tract infection.