AUDIOLOGIE

Evoluţia hipoacuziei la copiii cu tulburări din spectrul neuropatiei auditive, identificată prin screening neonatal auditiv

 Evolution of hearing loss in children with auditory neuropathy spectrum disorders identified by neonatal hearing screening

Sebastian Cozma, Oana Bitere, Cristian Mârţu, Raluca Olariu, Luminiţa Rădulescu

First published: 30 noiembrie 2018

Editorial Group: MEDICHUB MEDIA

DOI: 10.26416/Orl.41.4.2018.2117

Abstract

Purpose. The aim of the study was to observe and to describe the evolution of early diagnosed hearing loss in children with neonatal auditory neuropathy spectrum disorders identified by universal neonatal hearing screening.
Materials and method. In the last years, the development of universal auditory newborn screening program, that covers all maternities in our city, allowed us to test initially over 50,000 of babies and to identify and manage newborns with auditory neuropathy spectrum disorders after clinical audiological assessments. The follow-up was done for each child periodically until 18 months for cases fitted by hearing aids and until the cochlear implantation for cases with this indication.
Results. We identified 26 children with auditory neuropathy spectrum disorders, six children with normal tonal hearing and 20 cases with different degrees of hearing loss. According to the results of our follow-up process, all children with normal tonal hearing kept their auditory status in time. All deaf children were hearing aid fitted, except the profound hearing loss with direct indication for cochlear implantation. In the group of children with hearing loss, we observed that 35% presented progressive forms and 15% presented fluctuating forms. 57% of progressive hearing loss group evolved to the profound deafness and cochlear implant indication. The greater the initial diagnosed degree of hearing loss, the more the children have progressed to profound deafness.
Conclusions. A lot of children with auditory neuropathy spectrum disorders present progressive hearing loss, the profound form being finally present in more than 45% of cases. The periodical follow-up is essential in the first 18 months in order to offer the best medical indication and to avoid the delay of appropriate intervention for hearing rehabilitation and speech development. 

Keywords
auditory neuropathy, hearing screening, newborns, progressive hearing loss

Rezumat

Obiective. Scopul studiului a fost de a observa şi de a de­scrie evo­lu­ţia hipoacuziei diagnosticate precoce la copiii cu tulburări neo­na­tale din spectrul neuropatiilor auditive iden­ti­ficate prin screeningul auditiv universal la nou-născuţi.
Ma­te­riale şi me­to­dă. În ultimii ani, dezvoltarea unui pro­gram universal de scre­ening pentru nou-născuţi, care acoperă toate maternităţile din oraşul nostru, ne-a permis testarea iniţială a peste 50.000 de copii. În urma evaluărilor clinice audiologice efectuate, au fost posibile identificarea nou-născuţilor cu tul­burări din spec­trul neuropatiei auditive şi gestionarea aces­tora din punctul de vedere al monitorizării evoluţiei şi al re­co­man­dării tratamentului necesar hipoacuziei. Urmărirea a fost efectuată periodic pentru fiecare copil până la 18 luni pentru cazurile protezate cu aparate auditive şi până la im­plan­tarea cohleară pentru cazurile cu această indicaţie.
Re­zul­tate. Am identificat 26 de copii cu tulburări din spec­trul neuropatiei auditive, şase cu auz normal şi 20 de ca­zuri cu diferite grade de hipoacuzie. Conform rezultatelor pro­cesului nostru de urmărire, toţi copiii cu auz normal au păstrat în timp pragurile auditive. Toţi copiii hipoacuzici au fost protezaţi auditiv convenţional, cu excepţia celor cu hi­po­acuzie neurosenzorială profundă, cu indicaţie directă pentru implantarea cohleară. În grupul de copii cu pierdere de auz, am observat că 35% prezentau forme progresive şi 15% prezentau forme fluctuante. Din grupul cu hipoacuzie progresivă, 57% au evoluat până la surditate profundă, pri­mind indicaţie de implant cohlear. Cu cât mai important a fost gradul hipoacuziei diagnosticate iniţial, cu atât copiii au prezentat o hipoacuzie progresivă, ajungând până la hi­po­acuzie profundă.
Concluzii. Mulţi copii cu tulburări din spec­trul neuropatiei auditive prezintă pierdere progresivă de auz, forma profundă fiind constatată în final la mai mult din 45% din cazuri. Urmărirea periodică este esenţială în primele 18 luni pentru a oferi cele mai bune indicaţii medicale şi pentru a evita întârzierea intervenţiilor necesare pentru reabilitarea auditivă şi pentru dezvoltarea limbajului.

Introduction

ANSD (auditory neuropathy spectrum disorders) represent a group of auditory impairments that may be caused by pathologic processes of: internal hair cells of Corti organ, cochlear-neural synaptic space or cochlear nerve fibers. Due to particular aspects in children with auditory neuropathy spectrum disorders consisting in the degree and evolution of hearing loss, audiometric configuration, speech perception and hearing aid benefit(1-5), there is not yet a consensus in the therapeutic recommendation in newborns with auditory neuropathy(6,7,8). ANSD could be early identified after the hearing neonatal screening by a comprehensive audiological assessment.

Purpose of the study

The objectives of the current study are: to report our ANSD cases resulting from neonatal hearing screening, to identify and to describe specific patterns of hearing dynamic progress and speech development evolution in ANSD cases diagnosed immediately after our hearing neonatal screening.

Materials and method

The study included all babies referred from maternities and diagnosed with auditory neuropathy in the Audiology Department of Rehabilitation Clinical Hospital Iaşi, Romania, in the last six years. In this period, within the universal auditory newborn screening program in maternities there were tested over 50,000 babies and, after the clinical audiological assessments in the audiology department, we identified and managed newborns with auditory neuropathy spectrum disorders.

ANSD cases were diagnosed on the base of the following clinical criteria: the presence of otoacoustic emissions (at least at birth) and/or abnormal or absent ABR responses, the presence of cochlear microphonics and/or abnormal or absent ABR (auditory brainstem response), mismatches between ABR thresholds and ASSR (auditory steady state response) results or free field behavioral auditory thresholds(9-12).

The follow-up was done for each child periodically until 18 months (at least three clinical evaluations) for cases fitted by hearing aids and until the cochlear implantation surgery for cases with this indication.

The follow-up of ANSD cases included:

auditory assessment periodic control (every three or four months), including ASSR, ABR (rarefaction and condensation polarity), free-field behavioral audiometry, tympanometry, otoacoustic emissions, free-field behavioral audiometry with hearing aids or cochlear implant;

periodic reports from speech therapy specialist (describing performances with hearing aids or with cochlear implant) regarding tonal perception, message intelligibility according to age and the level of speech production.

Results and discussion

The development of universal auditory newborn screening program allowed us to test in the Department of Audiology 1034 newborns sent from maternities for otoacoustic emissions test and/or for the presence of one or more risk factors. We finally identified 26 children (3%) with auditory neuropathy spectrum disorders (Figure 1). Figure 2 shows the number of newborns identified by audiological testing during 2012 and 2016 in the first clinical phase. In our study there were diagnosed six babies with ANSD, presenting normal tonal hearing, and 20 cases were diagnosed with different degrees of hearing loss (Figure 3). In the group of children with hearing loss, we observed that seven children showed progressive forms, three presented fluctuating forms and ten children showed stable forms (Figure 4). All six cases of ANSD with normal hearing, according to the results of our follow-up process, conserved their auditory thresholds. In four cases, speech development cannot be appreciated yet (age between 8 and 15 months). In other two cases that did not develop speech production, one case showed evidence of a good evolution (Figure 5). An example of a newborn with ANSD and normal hearing is presented in Figure 6, where we can observe the presence of cochlear microphonics even 8 months later than the diagnosis moment. All deaf children were hearing aid fitted, except for those with profound hearing loss with direct indication for cochlear implantation. For mild/moderate/severe hearing loss we used the hearing aids as the first choice. At the follow-up, when we found stable hearing loss thresholds with evidence of auditory gain and good speech development, hearing aids remained the best solution, with a periodic follow-up. When we identified a progressive hearing loss (proved after hearing aid fitted), we recommended unilateral cochlear implantation (the existence of a low speech development rate was not an argument against the evidence of hearing loss progressivity).  In the group of children with hearing loss, we observed three cases with fluctuating hearing loss (Figure 7 represents the fluctuations in ASSR thresholds level in a case with auditory neuropathy). For these children, the evaluation of the limits of fluctuation determined some difficulties for hearing aid fitting, and the evaluation of speech development showed us no evidences of good evolution. Depending on the available time or age of the patient, our indication was for unilateral cochlear implant. In our group, we did not find reversible hearing loss cases. In the group of progressive hearing loss, 57% (9 cases) evolved under acoustic stimulation by hearing aids to profound deafness and cochlear implant indication (Figure 8, Figure 9). The greater the initial diagnosed degree of hearing loss, the more the children have progressed to profound deafness. In cases with bimodal stimulation, two patients refused the contralateral hearing aid after few months from the switch-on of their cochlear implant. They are included among patients with evidence of good performances in speech development (Figure 10). Two patients with cochlear implant indication refused the surgery and they are still hearing aid users, with no evidence of speech development (Figure 11). Four out of seven of cochlear implanted children showed evidence of good speech development until now – following survey is necessary. Patients with ANSD fitted by hearing aid without cochlear implant indication present different levels of progress in speech understanding and production.
 

Figure 1. Prevalence of ANSD in the hearing screened neonatal population referred to clinical audiol
Figure 1. Prevalence of ANSD in the hearing screened neonatal population referred to clinical audiol
Figure 2. Annual prevalence of ANSD in the hearing screened neonatal population referred to clinical
Figure 2. Annual prevalence of ANSD in the hearing screened neonatal population referred to clinical
Figure 3. Report of normal hearing versus hearing loss in children with ANSD
Figure 3. Report of normal hearing versus hearing loss in children with ANSD
Figure 4. Evolutive clinical forms of hearing loss in ANSD cases
Figure 4. Evolutive clinical forms of hearing loss in ANSD cases
Figure 5. Characteristics of ANSD patients with normal tonal hearing
Figure 5. Characteristics of ANSD patients with normal tonal hearing
Figure 6. ASSR and ABR response of an ANSD child with normal hearing
Figure 6. ASSR and ABR response of an ANSD child with normal hearing
Figure 7. Evolution of ASSR, ABR and OEA in a child with progressive fluctuating ANSD
Figure 7. Evolution of ASSR, ABR and OEA in a child with progressive fluctuating ANSD
Figure 8. Hearing dynamic progress under acoustic stimulation
Figure 8. Hearing dynamic progress under acoustic stimulation
Figure 9. Evolution of clinical indications based on hearing dynamic progress  under acoustic stimul
Figure 9. Evolution of clinical indications based on hearing dynamic progress under acoustic stimul
Figure 10. Contralateral hearing aid acceptance after unilateral cochlear implantation
Figure 10. Contralateral hearing aid acceptance after unilateral cochlear implantation
Figure 11. Evidence of speech understanding production progress in ANSD patients with cochlear impla
Figure 11. Evidence of speech understanding production progress in ANSD patients with cochlear impla

Conclusions

Universal hearing screening in newborns offers the chance to identify children with auditory neuropathy, requiring a different diagnosis and therapeutic approach compared to patients with regular inner ear hearing loss. Auditory neuropathy spectrum disorders cannot be diagnosed only on the base of screening auditory tests in maternity; the presence of different hearing loss risk fac­tors is an important argument to indicate clinical au­dio­logical tests. ANSD was found in 3% of the newborns referred to our audiology department for clinical audio­lo­gical tests (risk factors or “refer” result in screening tests), 23% presented normal tonal hearing and 77% presented different levels of hearing loss. We found different clinical forms of hearing loss: stable hearing level (16 cases), progressive hearing level (seven cases) and fluctuating hearing level (three cases). Because 35% of the patients with progressing hearing level switched from different degrees of hearing level to the profound one, we consider the periodical follow-up essential in the first 18 months in order to offer the best medical indication and to avoid the delay of appropriate intervention for hearing rehabilitation and speech development.  

 

Conflict of interests: The authors declare no conflict of interests.

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