INTRODUCTION

Otitis media is one of the most common diseases in childhood and it may be either symptomatic or asymptomatic4. It is one of the most frequent diseases in children, especially between the neonatal period and two years of age, with the peak of incidence at the age of 9 months. Incidence of otitis media decreases with age, especially after the age of 7 years, although it is still a frequent disease that affects youngsters, adults and the elderly13.

There are a number of reports in the literature addressing the influence of otitis media in the development of speech and language, auditory processing and school performance6,11,12,23,24,28,29. Peripheral fluctuating hearing loss, frequently found in cases of otitis media, may lead to alteration of the perception of complex auditory signs, such as speech. The degradation of the auditory sign may result in impairment of sounds representation and auditory skills, which involve understanding speech in noise, auditory memory, binaural integration and temporal processes9.

In Brazil, there is a considerably high number of children referred to assessment of central auditory processing and we noticed that many of these children report previous episodes of otitis media. Therefore, the purpose of the present study was to analyze the influence of otitis media in the performance of children who had complaints of central auditory processing.

MATERIAL AND METHOD

The present study was conducted at the Discipline of Pediatric Otorhinolaryngology, together with the Discipline of Hearing bisorders, Universidade Federal de São Paulo/ Escola Paulista de Medicina.

We studied twenty five children, aged 6 to 13 years and followed up by the Ambulatory of Pediatric Otorhinolaryngology because of complaints of central auditory processing, divided into two groups:

• Group I: 10 children with history of recurrent otitis media.

• Group II: 15 children with no history of recurrent otitis media.

The criteria for inclusion in the category of complaints concerning central auditory processing required one affirmative answer in the questionnaire by Pereira and Schochat22 (Chart 1).

As to presence of previous recurrent otitis media, we adopted three or more episodes of otitis media in six months and/or four or more episodes within the previous 12 months30.

We also considered the following criteria for inclusion of studied subjects: normal audiological battery14,17,19 of Brazilian speaking children with no evidence of neurological alterations.

Assessment of central auditory processing

All children in groups I and II were submitted to assessment of central auditory processing, in which we applied the special standardized procedures by Pereira and Schochat22, as follows:

Sound localization test (five directions)

The stimulus used for the sound localization test was a rattle noise-maker. The noise-maker was presented without visual information. We played in five directions from the head: in front, behind, above, on the left and on the right. The instructions were provided by demonstration. The child was expected to indicate the direction from where he had heard the sound.

Memory test for sequenced verbal and non-verbal sounds

For verbal sounds, we used the syllables "pa", "ta" and "ca", presented in three different sequences. The child was expected to repeat the sequence. For non-verbal sounds, we used four noise-makers presented in three different sequences. The child was expected to point the noise makers he had heard. The instructions were provided by demonstration.





Speech test in white noise

As verbal stimulus, we used a 25-one syllable word list presented simultaneously with white noise, on the same ear, at a signal-to-noise ratio of +5 dB22. Children who presented articulation problems were submitted to the test of low redundancy monotic hearing test, in which the child is expected to identify the words by pointing to pictures, in the presence of ipsilateral white noise at a signal-to-noise ratio of +5 dB22.

Dichotic digit test

We used a list of digits comprising 20 pairs of two-syllable digits in Portuguese25. The procedure we followed considered only the step of binaural integration18. Children were expected to repeat orally all presented digits, regardless of the sequence.

Non-verbal dichotic test

In the test, we used three environmental sounds (thunder, bell and slamming door) and three onomatopoeic sounds (meowing cat, barking dog and crowing cock). The sounds were combined and synchronized in order to form twelve pairs. We applied only the step of free attention, in which children had to point to the pictures of the two stimuli.

Sentence recognition test with contralateral and ipsilateral competitive message - Portuguese version of PSI

The test comprises sentences that should be recognized by picture identification, in the presence of contralateral and ipsilateral competitive message. Initially, we applied the test using contralateral competitive message at 0 dB and -40 dB on the right and left ears. Next, we presented sentences with ipsilateral competitive message, at 0 dB and -10 dB.

Statistical method

We recorded the number of correct answers for each ear and test. The performance was classified as normal or abnormal in each test. We also considered the overall result of the assessment of central auditory processing. The normal or abnormal classification was made based on the comparison of the results obtained with the standards for audiologically normal subjects22.

We conducted a statistical analysis to check statistical differences between the studied groups. We employed Fisher's and t-independent tests8. The level of significance for statistical tests was fixed at 0.05 or 5%.

RESULTS

Table 1 shows the results concerning mean percentages of correct answers to the right and left ears of children in groups I and II, in the tests of speech in white noise, digit dichotic test, non-verbal dichotic test, PSI with contralateral and ipsilateral competitive message.

The statistical analysis did not show statistically significant differences between groups I and II, considering the percentage of correct answers for each central processing test.

The abnormal test results of groups I and II children in the tests sound localization, sequenced verbal and non-verbal memory, speech in white noise, dichotic digit test, non-verbal dichotic test and PSI are presented in Table 2.

The statistical analysis did not show any statistically significant difference between group I and group II.

Results concerning assessment of central auditory processing in groups I and II are found in Table 3. The analysis of data showed 70% of the children with central auditory processing alteration in Group I and 66.6% of altered children in group II.

DISCUSSION

Auditory processing should be considered one of the important aspects of communication disorders. The term auditory processing disorder concerns impairment of at least one of the behaviors2, as follows:

• sound localization and lateralization;

• recognition of sound pattern;

• temporal auditory aspects (temporal resolution, masking, integration and sequencing);

• hearing performance in the presence of competitive acoustic signs;

• hearing performance in the presence of degraded acoustic signs.

In Brazil, the term auditory processing is used to refer to a series of processes that involve structures of the central nervous system: auditory pathways and cortex. Disorders of auditory-processing are considered hearing disorders, represented by the inability to analyze and/or interpret sound patterns21,22.

The assessment of auditory processing was conducted by behavioral tests, considered the key aspect in the diagnosis of auditory processing disorders in adults and children5.

Therefore, auditory processing has a major role in the development of language and speech. Impairment of hearing skills is correlated with speech, reading and writing difficulties and poor social and educational performance.

Otitis media is one of the most frequently diagnosed diseases in the pediatric population all over the world9. Epidemiological studies of acute otitis media have revealed a high incidence of the disease among children. At the age of three, 71% of the children have already presented at least one episode of acute otitis media and 1/3 have presented three or more episodes4.





In Brazil, 75 % of all children will have at least one episode of otitis media before the age of 5 years. Among them, about 30% will have developed three or more episodes of acute otitis media before the age of 3 years. Among the latter, 20% to 25% will show a tendency to present episodes of recurrent otitis media27. Recurrent otitis media is characterized by frequent relapses of acute otitis media episodes. A child is defined as prone to develop otitis when he experiences three or more different episodes of acute otitis media within 6 months or four or more episodes within 12 months28.

There are a number of reports in the literature about the influence of otitis media in the development of speech and language of these children. From an auditory viewpoint, otitis media has been considered one of the main causes of peripheral hearing loss and central auditory processing disorder12,24. Even a mild hearing loss is enough to compromise the development of specific hearing functions. One of the main characteristics of recurrent otitis media is fluctuation, which leads to inconsistency in sound detection. It is a disadvantage presented to the central auditory nervous system that is undergoing a process of development, because it represents a situation of inconsistent auditory stimulation, compromising the formation of speech sounds mental representation. In addition, it is interesting to point out that there is the likelihood of otitis media being a noisy condition, because the middle ear fluid close to the cochlea may produce noise that tends to interfere in speech perception, leading to distortion of acoustic images and decrease in speed and precision of verbal message decoding15.

In the present study, we decided to study the influence of otitis media in subjects who had central auditory processing complaints, considering the large number of recurrent otitis media cases normally seen at the Discipline of Pediatric Otorhinolaryngology and Hearing Disorders.

The test of sound localization in five directions and the sequenced verbal and non-verbal memory tests were studied in normal children21 and in hearing and language disordered children21. The test of sound localization attempts to find more about the binaural interaction, and the verbal and non-verbal memory test provides information about temporal sequence of sounds.

The test of speech in white noise was studied in normal healthy subjects and in normal elderly subjects22, in subjects with conductive mild and moderate hearing loss10, and in subjects with peripheral hearing loss26. This test provides information about auditory closure.

Dichotic digit test was studied in 80 audiologically normal adult subjects and in 60 children aged 5 to 6 years and 11 to 12 years25. The dichotic tests have been recognized as important tools for the diagnosis of auditory processing disorders5, and provide information about auditory figure-ground.

Non-verbal dichotic test assesses dichotic processing of non-linguistic sounds and reference criteria were defined for children over 7 years, adolescents and adults16,10. It has also been studied in cerebral damaged adult population.

The test of sentence recognition with the presence of insilateral and contralateral competitive message - PSI Portuguese version' was studied in normal subjects' and in subjects with learning disabilities21.

By comparing the performance of children in group I and in group 11, we did not find statistically significant differences considering the percentage of correct answers in each ear and conducted test (Table 1).

We did not find statistically significant differences by comparing the performance of children in group I and in group II considering normal or abnormal classification, for each conducted test (sound localization, sequenced verbal and non-verbal memory, PSI, digit dichotic test and non-verbal dichotic test).

Although the statistical method did not show statistically significant difference concerning abnormal tests, we do believe that there are clinical differences in the manifestations of language acquisition by these children, which will be further investigated in another study. In group 1, the lowest scores in PSI and speech in white noise indicate more marked impairment of hearing closure and figure-ground, which may interfere in language understanding. In group II, the poorer scores in dichotic digit test and sequenced memory indicate impairment of binaural integration and temporal sequence processes, which may compromise the use of symbolic language3 and expressive language.

Table 3 shows that in group I 70% of the children presented abnormal auditory processing, whereas in group II there were 66.6% of affected cases. By considering the overall number of evaluated children, 68% of the subjects presented alteration of central auditory processing.

In the specialized literature, there are a number of studies6,11,12,23,24,28,29 reporting that frequent episodes of otitis media in the first years of life are considered risk factors for language deficit, poor school performance and impaired auditory skills. According to some authors4,23,29 peripheral hearing loss in children with episodes of otitis media is intermittent, causing a great impact on the development of auditory and language skills. It seems that the hearing loss results from the degradation of complex auditory stimuli, including speech. The results of different studies that compared children with and without confirmed episodes of otitis media showed that the otitis media group presented poorer performance in auditory skills, such as figure-ground, closure, auditory memory and language, when compared to the group of children free from middle ear affection6,11,12,23,24,28,29.

We have not found any study similar to ours in the literature. Most of the studies reported in the literature investigated behavioral auditory test performance in populations with and without middle ear affection, without considering complaints of abnormal auditory processing system.

It has been stated that the performance of otitis media group, who had complaints of auditory processing, was similar to the other group's performance (no history of otitis but complaints of central auditory processing). In the present study, although we detected 70% of group I children with central auditory processing, it was quite evident that not all children with recurrent otitis media presented impairment of auditory skills that compromised the acquisition of language essential hearing skills. It is recommended that other studies be carried out in order to understand the factors that could have influenced this occurrence. This information will be useful for the development of prevention programs of speech, hearing and language disorders.

It is known that the effect of sensorial privation, such as caused by otitis media, interferes in the maturational process and, consequently, in the development of hearing skills. It is believed that otitis media is one of the determining factors of central auditory disorders. Therefore, patients should be referred to central auditory processing tests if this factor is present. Moreover, it has been observed that children with complaints related to possible central auditory processing disorders and absence of history of otitis also deserve referral to an investigation of specific hearing skills, owing to the strong correlation between complaint and central auditory processing disorder found by the present study.

CONCLUSION

The present study revealed that in a group of 25 children aged six to thirteen years with complaints of central auditory processing impairment, the presence of otitis media did not worsened their performance - central auditory function behavioral tests. Therefore, children with history of otitis media behaved similarly to those with no history of otitis regarding auditory skills, considering that they all shared complaints of central auditory processing disorders.

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* Professor, Ph.D. in Human Communication Disorders, UNIFESP-EPM.
** Master in Human Communication Disorders, UNIFESP-EPM.
*** Otorhinolaryngologist, Discipline of Pediatric Otorhinolaryngology, UNIFESP EPM.
**** Master and Ph.D. in Otorhinolaryngology, UNIFESP-EPM.
***** Ph.D., Joint Professor, Discipline of Hearing Disorders, Department of Otorhinolaryngology and Human Communication Disorders, UNIFESP EPM.
****** Full Professor, Discipline of Pediatric Otorhinolaryngology, Department of Otorhinolaryngology and Human Communication Disorders.

Study presented at I Congresso Triológico de Otorrinolaringologia, São Paulo, 1999.
Affiliation: UNIFESP/EPM.
Address correspondence to: Maria Francisca Colella dos Santos - Rua Edson, 53 - Apto. 62 - Campo Belo - 04618-030 São Paulo/SP
Tel: (55 11) 530-7516/ (55 11) 9212-9504-Fax: (55 11) 5549-7500.
Article submitted on November 21, 2000. Article accepted on March 26, 2001.