Secretory otitis and pneumatization of the mastoid process: sexual differences in the size of mastoid cell system.

Seventy-nine children (41 girls and 38 boys) were subjected to tympanometry nine times from the age of 2 years to the age of 7 years. In addition, otoscopy was performed, and the children's otologic history was recorded. At the age of 7 years, roentgenograms were taken of the mastoid process, and the area of the air cell system was measured by planimetry. The smallest cell systems were found in ears with a history of secretory otitis or chronic tubal dysfunction--a finding which supports the environmental theory of pneumatization. Boys had significantly smaller cell systems (mean, 7.5 cm2; range, 2.75-16.75) than girls (mean, 9.0 cm2; range, 2.5-15.7). The degree of middle ear pathology was significantly higher in boys, as expressed by the total tympanometric score. The more pronounced middle ear pathology in boys was caused by more frequent and severe episodes of upper respiratory tract infections. The analysis of the sex differences provides substantial support of the environmental theory of pneumatization, since upper respiratory tract infections in childhood often cause tubal dysfunction and secretory otitis, conditions that disturb the normal process of pneumatization and result in hypocellularity.