Portuguese Version

Year:  2003  Vol. 69   Ed. 6 - (5º)

Artigo Original

Pages: 760 to 764

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Cochlear implant in deaf children due to meningites

Author(s): Maria C. Bevilacqua1,
Adriane L. M. Moret2,
Orozimbo A. Costa Filho3,
Leandra T. Nascimento4,
Marcos R. Banhara5

Keywords: meningites, cochlear implant, deafness, children

Abstract:
Meningitis is the main cause of acquired sensorineural hearing loss in children. The patient may also present motor disorders, visual, vestibular, language and attention deficits as well as inability for learning. Characteristically the hearing loss due to meningitis is bilateral profound sensorineural symmetric and descendent and it is more common in males and in children under 5 years old and it brings severe implications in the emotional, social and development. Aim: To compare the performance of two groups of pre-lingually deaf implanted children, with age varying from 1 year and 10 months to 6 years, with hearing loss due to meningitis and other varied causes. Study design: Transversal cohorte. Material and Method: 63 profoundly deaf implanted children were evaluated, 25 (40%) were male and 38 (60%) were females. In 12 cases (19%) the hearing loss was caused by meningitis and in 51 cases (81%) hearing loss was due to a variety of causes. All participants were submitted to ear nose throat examination and clinical and objective audiological evaluation. Conclusions: the occurrence of partial insertion was higher in the meningitis group. There were no statically significant differences on word and phoneme recognition as well as in the questionnaire for evaluation of the hearing (MAIS) and language (MUSS) skills between the groups.

INTRODUCTION

Meningitis is the main cause of acquired sensorineural hearing loss and patients may present simultaneous motor deficit, visual disorder, language disorder, vestibular deficit, attention deficit and learning inability1. Characteristically, post-meningitic hearing loss is bilateral profound sensorineural, symmetric and descendent, more common in male patients and in children aged below 5 years 2, and it brings severe implications not only to social and emotional development of subjects affected by it, but also severe affections to the oral language that had already been acquired and to further acquisition oral language 3. Among the causes of meningitis, pneumococcus has the worst hearing prognosis causing permanent loss in up to 30% of the surviving patients 4.

Cochlear implant is an option for rehabilitation of patients that have severe to profound sensorineural hearing loss after meningitis, who have not benefited from the use of hearing aids. However, the occurrence of central neurological sequels in cases of post-meningitic loss and consequent delays in language development after the cochlear implant evidence the need to formulate rehabilitation strategies that encompass not only specific skills but also general cognitive skills 5.

Some studies have demonstrated that deafness secondary to meningitis provides in some cases a non-satisfactory result as in patients implanted owing to other pathologies. Based on this assumption, authors conducted a comparative study of the results of 29 adults submitted to cochlear implant surgery post-meningitis with another group of 28 patients with other etiologies of hearing loss also submitted to cochlear implant between the years of 1990 and 2001 at Hospital de Reabilitação de Anomalias Craniofaciais, University of Sao Paulo, Bauru. The surgical and radiological findings such as degree of ossification of the cochlea and consequent amount of electrode insertion of the implant, type of implant, results of preoperative audiometric exams and, finally, data related to postoperative results were assessed. The ossification found in 69% of the cases in the post-meningitis group negatively influenced the results leading to greater number of complications and greater number of partial insertions of implants, but apparently it did not influence the auditory result 4.

Histopathology and pathophysiology of the temporal bones in patients that had meningitis revealed involvement of the inner ear cells and acoustic nerve, ossification of cochlear and membranous labyrinth 6 and fewer cells in the spiral ganglion of the temporal bones of subjects with longer duration of total deafness in their lifespan 7. Studies concluded that ossification is a common picture in children with post-meningitis disease; ossification of lateral semicircular canal visualized by computed tomography (CT scan) is more sensitive a measure to predict ossification than evidence of cochlear involvement, and absence of ossification of CT scan is not guarantee of its absence during surgery 8. Better results of speech perception with cochlear implant in children with post-meningitis hearing loss were found when we used cochlear implant Double Array by Nucleus and Med-El Combi 40+ GB in cases of cochlear ossification 9, 10.

The analysis of speech perception and production in children with congenital hearing loss and post-meningitic deaf children were divided into 3 groups: 70 children with congenital hearing loss, 22 children with hearing loss caused by meningitis before the age of 2 years, and 14 children with hearing loss caused by meningitis after the age of 2 years. The group of children with hearing loss caused by meningitis after the age of 2 years demonstrated speech perception significantly better than the other two groups. Speech production in this group was apparently better but not statistically significant different from the other two groups. There were no statistically significant differences concerning speech perception and production 11.

The results of the speech perception assessment in 71 implanted children, divided into 3 groups: children who received cochlear implant (CI) aged over 7 years, children below 7 years, and children aged 3 or less with hearing loss resultant from meningitis, indicated improvement 6 to 12 months after CI use in the whole sample. The speed of improvement was different among the groups of different age ranges. The children used cochlear implant Nucleus 22, Nucleus 24 or Med-El Combi 40+ and the children were assessed pre-surgically, 2 to 5 days after activation, 1, 3 and 6 months of use of CI and every 6 months up to 24 months of use 12.

The present study intended to conduct a comparative analysis of findings relative to degree of ossification and consequent insertion of electrodes; speech recognition index and MAIS (Meaningful Auditory Integration Scale) and MUSS (Meaningful Use of Speech Scale) questionnaires between the group of children with post-meningitis sensorineural hearing loss and the group of children with sensorineural hearing loss due to other etiologies, implanted prelingually in the age range of 1 year and 10 months to 6 years.

MATERIAL AND METHOD

The present study was conducted at Centro de Pesquisas Audiológicas (CPA), Hospital de Reabilitação de Anomalias Craniofaciais (HRAC), University of Sao Paulo (USP) - Bauru.
We assessed 63 children with bilateral profound prelingual sensorineural hearing loss, users of multichannel cochlear implant, being 25 (40%) male and 38 (60%) female subjects. In 12 cases (19%) the hearing loss was resultant from meningitis and in 51 cases (81%) it was due to other etiologies (Table 1).

In Table 1 we can visualize that 67% of the cases of post-meningitis hearing loss were detected in males.

In Table 2, we can observe data referring to type of cochlear implant and strategy of speech coding.
Patients were assessed with cochlear implant device comprising internal component and external component (speech processor, microphone, antenna and transmission cables).

The speech perception assessment comprised word and phoneme recognition index using a list of dissyllable words (consonant-vowel-consonant-vowel) 13 presented in free field at 70dB SPL at regular voice production, in an acoustic soundproof booth, and parents or accompanying people answered the MAIS questionnaire about auditory skills 14, 15.

To assess the presence of cochlear ossification we conducted 1mm section CT scan of the otic capsule before the cochlear implant surgery.

The findings in patients with sequelae of meningitis were compared to those in the control group patients, of varied etiology.

To assess everyday oral language we used MUSS questionnaire 16.
The data collected during the descriptive statistical analysis of the studied samples were later collected for inferential statistical analysis using the non-parametric test of Mann-Whitney with significance level of 0.05 (5%).

Graph 1. Distribution of cases of post-meningitis hearing loss concerning the results of CT scan (N=12).



Graph 2. Distribution of subjects concerning insertion of electrodes in cases of post-meningitis hearing loss (N=12) and other etiologies (N=51).



Graph 3. Median, minimum and maximum of word recognition indexes for the cases of post-meningitis hearing loss (N=12) and other etiologies (N=51).



Graph 4. Median, minimum and maximum of phoneme recognition indexes for the cases of post-meningitis hearing loss (N=12) and other etiologies (N=51).



Graph 5. Median, minimum and maximum scores for questionnaire MAIS for the cases of post-meningitis hearing loss (N=12) and other etiologies (N=51).



Graph 6. Median, minimum and maximum scores for questionnaire MUSS for the cases of post-meningitis hearing loss (N=12) and other etiologies (N=51).

RESULTS

In graph 1 we can see the distribution of subjects with post-meningitic hearing loss concerning the result of computed tomography.

According to Graph 1, half of the subjects with post-meningitic hearing loss presented ossification of the cochlea.

In Graph2, we can see the distribution of subjects concerning the insertion of electrodes in the cochlear implant surgery.

The insertion of electrodes was partial in 3 subjects (25%) with post-meningitis hearing loss and in 2 subjects (4%) with hearing loss of other etiology, evidencing higher occurrence of partial insertion in the group of post-meningitic hearing loss (p = 0.04).

Median, minimum and maximum word and phoneme recognition indexes for the cases of hearing loss by meningitis and other etiologies are shown in Graphs 3 and 4, respectively.

In Graphs 3 and 4, we can observe median and maximum word recognition index and median, maximum and minimum of phoneme recognition index with higher values for the group with hearing loss from other causes, but this difference was not statistically significant (p>0.05).

The results of MAIS questionnaire in Graph 5, which shows median, maximum and minimum scores were higher in the group with hearing loss resultant from other etiologies, but it was not statistically significant (p>0.05).

In Graph 6, we present the median, minimum and maximum values of language skill questionnaire MUSS applied to parents whose children had hearing loss resultant from meningitis and other etiologies.
The media and maximum score in the MUSS questionnaire were higher for children with different etiologies rather than meningitis (Graph 6), but there was no statistically significant difference (p>0.05).

Table 1. Distribution of subjects concerning gender for cases of post-meningitis and other etiologies of hearing loss.



Table 2. Distribution of subjects according to type of cochlear implant and strategy of speech codification for cases of meningitis (N=12) and other etiologies (N=51).

DISCUSSION

The occurrence of ossification was higher in the group with post-meningitic hearing loss (50% of the cases) and as a consequence, the occurrence of partial insertion of electrodes was statistically significant (P=0.05) in the group representing 25% of the cases. These findings agree with the studies that referred greater occurrence of cochlear and membranous labyrinth ossification in post-meningitis auditory deficits 6, 8.

In the study, we did not find statistically significant differences concerning word and phoneme recognition index and the questionnaire of auditory skills between the groups with hearing loss post-meningitis and caused by other etiologies. Similar results concerning speech perception were reported in children implanted before the age of 3 years with post-meningitis hearing loss 12, for children who had meningitis before 2 years of age 11, when compared to the group with hearing loss of other etiologies.

As to oral language skills, assessed by questionnaire MUSS, there was no statistically significant difference between the group with post-meningitis hearing loss and the one with different etiologies.
Even though there were no statistically significant differences concerning speech perception and language between the group with post-meningitis hearing loss and the other one, we observed higher indexes for word and phoneme recognition and auditory skills (MAIS) and language (MUSS) questionnaires for the group whose hearing loss was caused by other etiologies.

The authors emphasized that the development of speech perception skills is very slow in children with post-meningitic hearing loss, but they are close to the results of other children after 18 months or so of cochlear implant use 12. It would justify a long-term study of the results of children with post-meningitis hearing loss, analyzing the influence of time on use of cochlear implant.

Meningitis has a devastating impact on the development of children. However, the indication of cochlear implant allows access to the sound environment, especially concerning word recognition, an essential condition to ensure understanding of oral language.

The delays in language development after cochlear implant need specific rehabilitation strategies 5; studies should be developed to try to have efficient strategies according to the influence of the family, cognitive status of the child and other rehabilitation factors.

CONCLUSIONS

 The occurrence of partial insertion of electrodes was significantly higher in the group with post-meningitis hearing loss;
 There were no statistically significant differences concerning word and phoneme recognition index and auditory skills (MAIS) and language skills (MUSS) questionnaires between the group of post-meningitic hearing loss and the group with hearing loss caused by other etiologies;
 Word and phoneme recognition index and auditory skills (MAIS) and language skills (MUSS) questionnaires were higher in the group with varied etiology hearing loss.

REFERENCES

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1 Full Professor, Coordinator, Course of Speech Therapy and Audiology, School of Dental Sciences of Bauru, University of Sao Paulo (FOB-USP),
Centro de Pesquisas Audiológicas (CPA) do Hospital de Reabilitação de Anomalias Craniofaciais, University of Sao Paulo (HRAC-USP).
2 Ph.D., Professor, Course of Speech Therapy and Audiology, FOB-USP.
3 Full Professor, Course of Speech Therapy and Audiology, FOB-USP, and vice-coordinator of CPA, HRAC-USP.
4 Master degree, HRAC-USP.
5 Speech Therapist, FOB-USP.
Address correspondence to: Dra. Maria Cecília Bevilacqua, CPA do Hospital de Reabilitação de Anomalias Craniofaciais -
Rua Silvio Marchione, 3-20 Bauru SP Brazil 17043-900 caixa postal 1501
Tel (55 14) 235800 - Fax (0xx14) 234-7818 - E-mail: hrac@edu.usp.br - home page: www.centrinho.usp.br
Study conducted at Centro de Pesquisas Audiológicas (CPA), Hospital de Reabilitação de Anomalias Craniofaciais, University of Sao Paulo (HRAC-USP) and School of Dental Sciences of Bauru, University of Sao Paulo (FOB-USP). Presented as conference at 16º Encontro Internacional de Audiologia, Rio de Janeiro-RJ.
Article submitted on August 01, 2003. Article accepted on September 04, 2003.

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