a summary by Laurie Moses
Millions of children visit their doctor each year for a problem that is commonly known as an ear infection, and countless others suffer silently because their symptoms are not recognized (Hemmer & Ratner, 1994). An inflammation of the middle ear and often the mastoid process and Eustachian tube is termed otitis media and is second only to the common cold as the most common illness of early childhood (Medley, Roberts, & Zeisel, 1995). Unlike the common cold, however, incidents of otitis media are often accompanied by temporary mild to moderate hearing loss and auditory deprivation (Finitzo, Gunnarson, & Clark, 1990). The American Academy of Pediatrics (as cited in Stewart, Anae, & Gipe, 1989) reports that growing evidence indicates a correlation between middle-ear disease with hearing impairment and delays in the development of speech and cognitive skills. These issues are of concern to physicians, educators, and parents of children who suffer regular occurrences of otitis media because the disease is most common during the period of early childhood when speech and language skills are developing (Roberts, Burchinal, Koch, Footo, & Henderson, 1988).
One aspect of the illness that should be of particular concern is that some children suffer from otitis media without experiencing recognizable symptoms (Paden, 1994). These children may, therefore, never see a physician and may never receive the medical interventions necessary to clear the infection and restore normal hearing. Although the fluctuating hearing loss that accompanies the illness has long been recognized by researchers and other professionals in the field, recent research has indicated that the relationship between otitis media and hearing loss may be more complex than was previously assumed (Paden, 1994). Research in the area has included examinations of the effect of temporary hearing loss due to otitis media on central auditory processing, binaural interaction, hearing threshold, and speech and language development (Finitzo et al., 1990; Hall & Grose, 1994). In order to better understand these results, it is important to first examine the definition, epidemiology, and medical management of otitis media as well as the various methods for evaluating and defining hearing loss in children suffering from the disease.
Otitis media can be classified into several categories including acute otitis media and otitis media with effusion. Acute otitis media refers to a clinically identifiable infection of the middle ear during which the eardrum may appear red and swollen with puss-like fluid visible behind the eardrum. This type of ear infection has a sudden onset and short duration of symptoms which may include fever, congestion, and pain (Medley et al., 1995). Otitis media with effusion is also a relatively common childhood disease which is characterized by the accumulation of fluid in the middle ear space (Hall & Grose, 1994). This category has no acute symptoms but may produce some more subtle signs such as inattention and irritability (Medley et al., 1995). This condition often occurs secondary to an upper respiratory infection in children with poor Eustachian tube function (Hall & Grose, 1994). The fluid present in the middle ear during an episode of otitis media with effusion is non-infectious, and the illness itself is not contagious. It can, however, be contracted from bacteria, germs, and viruses that are themselves easily spread in settings like daycares (Medley et al., 1995). A healthy Eustachian tube allows fluid to drain into the nose and throat, but when agents such as bacteria and germs spread up the tube from the mouth and nose into the middle ear, the Eustachian tube may swell and close off the drainage pathway. This trapping of fluid is known as effusion and can remain even after the acute episode is resolved. In some children, the exchange between acute otitis media and otitis media with effusion is almost constant (Medley et al., 1995).
Although otitis media is not exclusively a childhood illness, it is extremely common in children between birth and two years of age (Hemmer & Ratner, 1994). Estimates of prevalence vary, but many studies substantiate that most children do experience at least one episode of otitis media in early childhood, and at least one study has estimated that between 75% and 95% of all children are affected (Paden, 1994). Another study by Hardy and Fowler (as cited in Medley et al., 1995) found that 17% of children in the United States between birth and six years of age suffered from repeated ear infections. Otitis media peaks in occurrence between six and eighteen months of age and declines after the third year (Paden, 1994). Many factors seem to play a role in determining which children will have a higher incidence of the illness including family history of otitis media, attendance in group childcare, frequency of upper respiratory infections, bottle feeding in a reclined position, and frequent exposure to secondhand smoke (Medley et al., 1995). Also, according to Teele (as cited in Medley et al., 1995), early age at the time of the first occurrence and being male are also risk factors for recurrent otitis media.
Medical intervention for children with otitis media differs based on factors such as presentation and duration of symptoms and whether the infections are recurrent (Paden, 1994). The typical course of treatment for acute symptoms is a ten-day course of antibiotics to eradicate the infection, but physicians often prescribe a longer course for children who have frequent ear infections (Medley et al., 1995). Tympanostomy tubes can be surgically placed under the tympanic membrane between the outer and middle ear to help drain the fluid and ventilate the middle ear space. These tubes, which are sometimes called pressure equalization tubes, can restore hearing immediately in most cases (Hall & Grose, 1994). Although these tubes may seem to be the answer to ending hearing loss due to otitis media with effusion, Paden (1994) points out that since pain does not always accompany the infection, episodes may occur and persist without the parents' knowledge, and, therefore, these children never reach a physician's office.
The hearing loss that accompanies middle ear effusion is generally mild to moderate and continues only as long as the fluid is present in the middle ear (Roberts et al., 1988). The hearing loss is due to the fluid pressing against and reducing movement of the eardrum so that sound is muffled (Medley et al., 1995). The extent of the hearing deficit due to effusion varies greatly among children with otitis media; some children experience little or no loss while others have quite large losses (Paden, 1994). The hearing loss suffered due to otitis media typically averages about 25 dB HL but can range from no loss to as much as 50 dB HL (Hall & Grose, 1994). Concern usually arises when a child who experienced a first onset of effusion prior to twelve months of age experiences more than three episodes per year for multiple years and when these episodes are bilateral and reduce the hearing threshold by as much as 20 - 40 dB (Hemmer & Ratner, 1994). In rare cases permanent sensorineural hearing loss can occur if the middle ear infection spreads into the inner ear (Medley et al., 1995).
Diagnosis of otitis media with effusion is determined for the purpose of medical intervention and research by use of pneumatic otoscopy and tympanometry (Paden, 1994). The illness is diagnosed by otoscopy when middle ear fluid is detected or when the mobility of the tympanic membrane is absent or markedly reduced (Roberts et al., 1988). Tympanometry is used to corroborate the diagnosis of effusion, and a Type B tympanogram with a flat or rising shape is considered to be an accurate indication of the infection (Peters, Grievink, van Bon, & Schilder, 1994).
The majority of research on otitis media during the past decade has focused on the effects of temporary hearing loss on the developing language skills of children before the age of three (Stewart et al., 1989; Medley et al., 1995). One study examined a group of 3-to-8 year olds who had histories of chronic otitis media with effusion and had all experienced initial onset of the illness prior to age 18 months (Roberts et al., 1988). The study found that, although these children did misarticulate more consonants on the Templin-Darley Screening Test than children without otitis media histories, both groups committed errors on the same sounds (Roberts et al., 1988). Peters et al. (1994) also points out several studies that suggest a relationship between educational achievement and occurrence of otitis media. A few of these studies also suggest that the fluctuating hearing losses may actually have a more negative effect on speech and language than would a continuous mild to moderate loss (Peters et al., 1994). Additional studies, including Peters et al.(1994), also indicate that otitis media is highly correlated with increased levels of hearing loss.
Other studies on the effects of otitis media on hearing have focused on the effects of early auditory deprivation on central auditory processing, development of auditory neurons, and discrimination of sounds (Finitzo et al., 1990; Paden, 1994). Finitzo et al. (1990) also points out studies that seem to indicate that hearing loss due to middle ear effusion causes deficits in processing speech and non-speech aspects of the auditory signal. Another study found that children with central auditory processing disorders have difficulty with discriminating foreground and background noise, problems with auditory attention, and a reduced ability to sequence auditory information (Finitzo et al., 1990). With respect to problems with foreground and background discrimination, one researcher points out that similarities between foreground and background noise cause greater difficulties for infants than adults under normal circumstances and would be a particular problem if the infant were experiencing mild hearing loss (Paden, 1994). Some auditory deprivation studies have been conducted on animals in order to assess the anatomical and physiological changes due to sound deprivation. In one such study, researchers found that early auditory deprivation in mice reduced the speed and duration of the central auditory responses caused by high frequency sounds (Finitzo et al., 1990). Blatchley et al. (as cited in Finitzo et al., 1990) concluded from another study of mice that auditory stimulation is important during certain critical periods of development in order to maintain a normal cell size in auditory neurons.
Current research on otitis media with effusion and hearing loss appears to be moving in the direction of examining the effects of a fluctuating mild to moderate hearing deficit on a child's ability to segregate sounds from competing noise adequately. Results of one study indicate that there may be a reduced ability for auditory segregation in children with otitis media histories but that more research is necessary in the area (Hall & Grose, 1994). Binaural fusion tests from the Willeford battery also suggest a loss integration especially in the presence of background noise that is similar to a speech message (Finitzo et al., 1990). Monaural deprivation in rats during the critical period for developing binaural interaction resulted in a complete loss of binaural interaction due to absence of ipsilateral suppression of contralateral activity at the deprived ear (Finitzo et al., 1990). Finitzo et al. (1990) concluded that this greater than normal suppression resulted in cells becoming more responsive to stimuli from the non-deprived ear. Findings such as these will undoubtedly lead to more research on auditory deprivation and its effect on binaural interaction in children with histories of otitis media.
Many current research studies are seeking ways to overcome some of the problems that have existed in past attempts to assess the effects of recurrent effusion on hearing. One past problem has been the use of retrospective studies to examine speech difficulties caused by temporary elevation of hearing thresholds due to effusion (Paden, 1994). These types of studies often rely on parental recall which, even when excellent, cannot include those cases that involved silent symptoms. Unfortunately, prospective studies that require regular examination of children's ears to determine when effusion is present may cause a different research problem because they identify infections that may have gone unnoticed in a real world situation. Researchers are currently seeking ways to work around these issues. Another problem with past research has been the failure to use uniform methods in testing hearing. According to Paden (1994), this may account for some disagreement in conclusions from different studies. Researchers also point out two other gaps in previous research that will likely be important future topics. These include more extensive studies of hearing thresholds of children with recurrent otitis media with effusion during symptom free periods (Paden, 1994) and more studies that distinguish between unilateral and bilateral effusion and compare the consequences of the two forms (Peters et al., 1994).
References
Finitzo, T., Gunnarson, A., & Clark, J. (1990). Auditory deprivation and early conductive hearing loss from otitis media. Topics in Language Disorders, 11(1), 29-42.
Hall, J.W., & Grose, J.H. (1994). Effect of otitis media with effusion comodulation masking release in children. Journal of Speech and Hearing Research, 37(6), 1441-49.
Hemmer, V.H. & Ratner, N.B. (1994). Communicative development in twins with discordant histories of recurrent otitis media. Journal of Communication Disorders, 27(2), 91-106.
Medley, L.P., Roberts, J., & Zeisel, S.A. (1995). At-risk children and otitis media with effusion: Management issues for the early childhood special educator. Topics in Early Childhood Special Education, 15(1), 44-64.
Paden, E.P. (1994). Otitis media and disordered phonologies: Some concerns and cautions. Topics in Language Disorders, 14(2), 72-83.
Peters, S.A., Grievink, E.H., van Bon, W.H., & Schilder, A.G. (1994). The effects of early bilateral otitis media with effusion on educational attainment: A prospective cohort study. Journal of Learning Disabilities, 27(2), 111-121.
Roberts, J.E., Burchinal, M.R., Koch, M.A., Footo, M.M., & Henderson, F.W. (1988). Otitis media in early childhood and its relationship to later phonological development. Journal of Speech and Hearing Disorders, 53(4), 424-432.
Stewart, J.L., Anae, A.P., & Gipe, P.N. (1989). Pacific Islander children: Prevalence of hearing loss and middle ear disease. Topics in Language Disorders, 9(3), 76-83.