Impaired binaural hearing in children produced by a threshold level of middle ear disease

Abstract

Otitis media with effusion (OME), a form of middle ear disease, is the most common reason for young children both to visit their family doctor and to have surgery. Almost all children have at least a single episode of OME before their first birthday and annual incidence rates exceed 50% in each of the first five years. For most children, OME occurs infrequently, but about 10-15% of children have OME during more than half of their first six years. Middle ear effusions attenuate and delay sound, causing conductive sound distortion during the crucial years for language acquisition. The many studies of OME effects on language and other indices of development have produced mixed results. However, a consensus is emerging of mild language impairment in the preschool years, with subsequent performance, emotional, and behavioral difficulties. In addition to the peripheral hearing loss produced directly by the disease, binaural and other central auditory deficits can outlive the OME. It has been unclear which children are at risk of central impairment following OME, since the children studied have generally been recruited from otolaryngology clinics. Consequently, a detailed prospective history of the middle ear status of participants has not been available. By studying six-year-old children with a lifetime known history of OME, we show in this study that only those children with a cumulative OME experience of more than about half the time during the first five years consistently have residual impaired binaural hearing.

Figure 1

A. Prevalence of OME in the first six years. The data show the mean annual prevalence of OME [as measured by “B”-type tympanograms (Jerger 1970) in either or both ears] in the children in this study, divided into quartiles by overall (6-year) OME prevalence. Testing was conducted at approximately monthly intervals (adapted from Hogan et al. 1998). B. The binaural hearing task was presented as a computer game, with noise in each of two intervals (visually signaled as either frogs or penguins, in color in the actualgame), and the tone (randomly) in just one interval (Linux 2.0 penguin graphic courtesy of Larry Ewing). C. The masking level difference (MLD) involves presentation of target signals (S) and masking noise (N) that is either in-phase (N₀S₀) or out-of-phase (N₀S_π) at the two ears. When either the signal or the noise is interaurally out-of-phase, the signal is more easily detected, leading to the happy face (adapted from Moore 1997).

Figure 2

A,B. MLD at 6.7 years as a function of the total prevalence of OME in the first five years. OME prevalence was the percentage of flattympanograms, in either ear, relative to the total number of tests (see Fig. 1A). The data from A are replotted in B as the mean (±1 SEM) in each quartile of OME experience. Also shown are the data for adult listeners with unknown OME experience. C. Tone thresholds in the N₀S₀ and N₀S_π conditions for the children from the lowest three quartiles and from the highest quartile of OME experience.

Figure 3

Relation between audiometric threshold for each ear at 500 Hz and MLD. Audiometric thresholds were obtained in the same test session as the MLD. All children were free of OME, bilaterally, at the time of testing.