Size of the mastoid air cells and otitis media.

Repetitive tympanometric screenings were performed in 79 randomized, otherwise healthy children from 2 to 7 years old. A total of nine screenings, of which three included otomicroscopy, were performed. When the children were 7 years of age, radiographs were made of their mastoid processes in Runstrøm's lateral projection. The median size of the cell system was 8.25 cm2. The cell systems were significantly larger (9 cm2) in girls than in boys (7.5 cm2). A significant correlation was found between the size of the cell system and the duration of secretory otitis media; thus, the smallest air cell systems occurred in the children with the longest episodes of secretory otitis, and the largest cell systems in children with no history of secretory otitis. Eardrum changes occurred at the ages of 5, 6, and 7 years in 21%, 32%, and 25% of the children, respectively. Children in whom the same eardrum changes were present at all three examinations had significantly smaller cell systems than those with either no changes or changes only at a few of the examinations. No differences in extent of pneumatization were found, regardless of whether the children had had episodes of acute otitis, had been treated for secretory otitis, or had had neither. In our opinion, this study supports the theory that hypocellularity is a sequela of secretory otitis rather than a cause of the disease.