Sequelae of secretory otitis media: changes in middle ear biomechanics

A new method previously introduced investigating the pressure volume relationship of the middle ear system describes dynamic mechanical properties of the system: the variables measured are hysteresis, compliance, and P(ec0) expressing the zero position of the tympanic membrane. The present study investigates the mechanical properties in 69 adolescents treated with ventilation tubes during childhood due to secretory otitis media. The tympanic membranes displayed various degrees of atrophy, sclerosis, and retraction of the pars flaccida. Atrophy was quantitatively related to decreasing hysteresis and increasing compliance, while myringosclerosis showed opposite effects. P(ec0) was significantly lower for the group of former secretory otitis media than for normals (p < 0.001). This reflects a retraction pattern of the tympanic membrane, which may be explained by a low opening pressure of the eustachian tube or previous pressure load of the drum. Signs of retraction were not found by tympanometry. Treatment with ventilation tubes was associated with a dramatic increase of tympanic membrane pathology (66%) compared to untreated ears (12%), as assessed by otomicroscopy (p < 0.001). However, these changes specific to treatment were not found in the corresponding mechanical variables of the middle ear system, as the effects of combined atrophy and myringosclerosis tend to counterbalance.