The changes in prevalence of secretory otitis from summer to winter were analyzed on the basis of tympanometry in 288 healthy 4-year-old children in August and November 1979 and February 1980. There was a significant increase in the frequency of secretory otitis and a significant deterioration of the tympanometric conditions from summer to winter. At each trial, half of the ears changed type, and significantly more ears deteriorated than improved. During winter secretory otitis also shows a tendency to spontaneous improvement, although this is not so pronounced as in the 2-year-old children.
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