EFFECTS OF LOW HUMIDITY ON THE RAT MIDDLE-EAR

Secretory otitis media is common in the winter, and the possible risk factors are numerous. This study examines the effect of low humidity o n the middle ear using a Sprague-Dawley rat model: 23 test rats housed for 5 days in a low-humidity environment (10% to 12% relative humidit y) and 23 control rats housed at 50% to 55% relative humidity. Microsc opic ear examinations were graded for otitis media with effusion (OME) before testing and on test days 3 and 5. The mucosa of the middle ear s and eustachian tubes was examined histopathologically. Significantly more effusions were observed in the low-humidity group on test days 3 (P = .003) and 5 (P = .01), but no intergroup histopathologic differe nces were noted. We conclude that a low-humidity environment contribut ed to the development of OME in the test animals, and that low humidit y warrants further investigation as a contributing factor in childhood middle ear disease.