SEQUELAE OF SECRETORY OTITIS-MEDIA - CHANGES IN MIDDLE-EAR BIOMECHANICS

A new method previously introduced investigating the pressure-volume r elationship of the middle ear system describes dynamic mechanical prop erties of the system: the variables measured are hysteresis, complianc e, and P-ec0 expressing the zero position of the tympanic membrane. Th e present study investigates the mechanical properties in 69 adolescen ts treated with ventilation tubes during childhood due to secretory ot itis media. The tympanic membranes displayed various degrees of atroph y, sclerosis, and retraction of the pars flaccida. Atrophy was quantit atively related to decreasing hysteresis and increasing compliance, wh ile 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 membr ane, which may be explained by a low opening pressure of the eustachia n tube or previous pressure load of the drum. Signs of retraction were not found by tympanometry. Treatment with ventilation tubes was assoc iated with a dramatic increase of tympanic membrane pathology (66%) co mpared to untreated ears (12U/a), as assessed by otomicroscopy (p < 0. 001). However, these changes specific to treatment were not found in t he corresponding mechanical variables of the middle ear system, as the effects of combined atrophy and myringosclerosis tend to counterbalan ce.