Keywords
cochlear implant - evaluation of results (health care) - follow-up studies
Palavras-chave
implante coclear - avaliação de resultados (cuidados de saúde) - seguimentos
Introduction
In 1990, FDA (Food and Drug Administration) approved the cochlear implant (CI) to
be implanted in children as young as two years old[1]. Ever since, parallel to both the scenario of criteria-expanding scenario of CI
in the pediatric population and the technological development applied to the manufacturing
of the devices, an increasing number of children has been implanted, and, subsequently,
ongoing clinical researches and studies are conducted in order to measure the results
provided by the CI, especially as a result of the characteristics of each user and
time of device utilization.
CI is considered the most effective technological resource in the treatment of severe-to-profound
sensorineural pre-lingual hearing impairment currently available. It is an intervention
whose effects and results for the children's communication skills are obtained over
the years[2].
Short-term results, measured during the early years of IC utilization in children
with pre-lingual hearing impairment, have been thoroughly described in the literature.
Generally speaking, the results of these studies showed clear benefits with the use
of CI, whether in the receptive or expressive language, in the process of academic
learning, or in passion, social and emotional areas. However, although there is a
consensus, particularly with regard to an improvement in environmental sound perception,
speech, and in other areas of language development, there is an agreement between
the studies performed in the first years of CI use regarding the diversity of results
observed in implanted children. Several factors described in the literature, such
as etiology, age at implantation, the presence of residual hearing, auditory rehabilitation,
family participation in the therapeutic process, can potentially contribute to a diversity
in the performance of CI-implanted children[3]
[4]
[5].
Yet, it is unclear whether this variability in results obtained in children using
the device for a short time remains after using the IC in the medium and long terms,
or whether satisfactory benefits will be achieved by CI users after many years using
the device, having their normal hearing peers as references. Studies that have evaluated
the results after 7 years of use are very scarce[6].
During the utilization of the CI device and the therapeutic process, families and
professionals working with CI-implanted children may face unusual situations and results,
filled with doubts and even annoyances. Not all implanted children are capable of
achieving the results expected by the family in the first years using the device.
Several factors may interfere with this acquisition process of auditory skills and
language by way of CI, and, eventually, lead to a delay in acquiring these skills
and in some cases, in the child's inability to reach levels of communication skills
appropriate for his/her age[7].
In addition, the development of listening and oral language skills and the pace of
development of these skills are not the same for all children[8]
[9]
[10]
[11]. What level of communication skills the child will reach and how long it will occur,
or if implanted children at older ages will be, over time, able to achieve the same
results of children implanted at younger ages, are questions whose answers are not
obtained within the first years using the device[12].
Another important factor to be considered with regard to the importance of long-term
studies is associated with the information relating to the functionality of the device
and the possible complications after years of use. During the process to decide about
a surgery and choose the CI model and trademark, information about the integrity of
devices derived from either historical data or more current evaluations is fundamental
and it must be provided in a transparent, standardized and easy-to-understand format,
with a view to helping professionals involved in counseling, the CI candidates and
their family members[13].
The studies in children after long-term CI utilization represent a way to guide professionals
and families both regarding the therapeutic process and counseling about expectations
and to better understand the factors involved in development processes of communicative,
educational and occupational skills of children who will grow up using the IC. As
the main untreated difficulties are observed over time, it can guide practitioners
to perform a previous therapeutic intervention in order to contribute to greater adaptation
to society[6]
[14]
[15]
[16].
Considering the importance of long-term studies with CI children, the aim of this
study was to determine whether, after several years using CI, satisfactory outcomes
were obtained in relation to the communication skills of adolescents and young adults
who grew up with the electronic device. A systematic literature review was conducted
in order to gather the available evidence in the literature to answer clinical questions.
This study was approved by the Ethical Committee for Analysis of Research Projects-CAPPesq
with the research protocol N° 0685/08.
Methodology of the Systematic Literature Review
Methodology of the Systematic Literature Review
One of the fundamental items of the methodology of systematic review is the formulation
of the research question. Considering the aim of the systematic review of the present
study, the question was: Has the Cochlear Implant effectively contributed to the development of communication
skills in adolescents and young adults who grew up with this device?”
Criteria for selecting studies
In this step, after the question was established, the search for evidence began by
determining the criteria of selection of primary studies. Based on these criteria,
it is expected that all important items or items that may have some impact on the
completion of the systematic review are found and included[17].
1. Types of Studies
The studies published in the last ten years, i.e., between 2000 and 2010 in English,
Spanish or Portuguese, were selected for analysis. Regarding the level of scientific
evidence due to scarcity of studies with evidence levels 1 and 2 in the area of Audiology,
articles with evidence levels of 3, 4 and 5 were also selected for a systematic review
of the present study[18]. [Table 1] shows the levels of scientific evidence, adapted by Cox
[19] for the area of Audiology.
Table 1.
Evaluation of level evidence.
|
Level
|
|
|
1
|
Systematic reviews and meta-analysis of randomized clinical studies or other studies
of quality.
|
|
2
|
Random controlled clinical studies.
|
|
3
|
Non-randomized intervention studies.
|
|
4
|
Cohort study; case-control study, cross-sectional studies and uncontrolled experiment.
|
|
5
|
Case studies.
|
|
6
|
Expert opinions.
|
2. Participants
Since the objective of this systematic review was to assess the long-term IC performed
in children, the main inclusion criterion related to the time using the device included
the studies conducted with adolescents or young adults using it for at least seven
years. With regard to the age when the surgery was performed and the hearing loss
started, studies with pre-lingual hearing impaired groups who underwent surgery in
adolescence or adulthood were not accepted within the inclusion criteria. Studies
with group of post-lingual hearing-impaired adults were also excluded.
3. Intervention
The methodology and the tests used in studies intended to evaluate the performance
of cochlear implant users were not considered as exclusion criteria. Studies whose
intervention was performed a group using the device for more than 7 years were selected,
in compliance with the other selection criteria related to the participants.
4. Clinical results
To evaluate the effectiveness of the Cochlear Implant device after years of utilization,
the clinical results considered to be relevant to the question of this systematic
review included the following categories of interest: results expressed in percentage
of right answers in tests of perception and speech intelligibility, results expressed
by grading scales of the development of hearing, language and speech intelligibility
skills and description of both the educational and/or professional status and the
utilization of the device.
Finding studies
1. Describers
The describers or keywords used to locate the relevant studies to answer the question
established in this systematic review are shown in [Table 2].
Table 2.
Key words in the English language found in DeCS and Portuguese match.
|
DeCS - English
|
DeCS - Portuguese
|
|
Cochlear Implantation, Child, AdolescentYoung adult, Speech Perception, Speech Intelligibility,
Language, Outcome Assessment Follow-up studies, Educational status.
|
Implante Coclear, Criança, Adolescente, Adulto jovem, Percepção da fala, Inteligibilidade
da fala Linguagem, Avaliação de resultados, Seguimentos Escolaridade.
|
2. Search strategy
The search strategy is the syntax of the strategy used to search bibliographical references
through the databases. For this study, a specific search strategy was created by using
the describers into groups with at least two key words: cochlear implantation AND
OR child OR adolescent young adult, cochlear implantation AND follow-up studies OR Outcomes. Additional terms were also used: cochlear implantation AND speech perception OR speech intelligibility OR language OR educational status.
3. Sources of study
For the bibliographical search of possible articles to be included in the systematic
review, the following search sources were viewed:
-
Electronic databases: The search for primary studies was then held in electronic data
bases: Lilacs, Medline, SciELO and Cochrane Library, Pubmed, Embase, Institute for
Scientific Information (ISI) and Science Direct. The last research performed in electronic
data bases occurred in September/2010. After this date, the “e-alert” service, available
in the databases, was triggered.
-
Records of Congress National: in the country, it stands out for its history and its
importance in the national scientific scene, the International Meeting of Audiology
(EIA). By the year 2008, the search was carried out in a manual, printed in the records
of the event. After 2008, the records of events, available on the website http://www.audiologiabrasil.org.br available were accessed.
-
Other databases: considering the importance of conducting the bibliographical research
for a systematic review of different types of databases, the search on specific sites
of (national and international) dissertations and theses was performed on digital
databases. Digital Dissertation Abstracts, Brazilian Digital Library of Theses and
Dissertations, Digital Library of Theses and Dissertations of USP.
Identification, selection, data extraction and inclusion of studies
From the application of search strategy containing the describers defined, the identification
of titles was performed in different electronic databases.
In order not to take the risk of excluding important studies for the review, after
a consensus meeting, two revisers selected all the titles identified, whether accompanied
by an abstract or not, that were potentially relevant to the object of study. After
the relevant titles were selected, the articles were thoroughly retrieved and each
article was evaluated by a protocol containing the topics: type of study, participants,
interventions taken, and results found.
The included studies included the eligibility criteria set at the beginning of the
methodological protocol of this review, in order to answer the question established
in this systematic review. The main data of each retrieved article were thoroughly
collected by a standardized protocol form for this study.
Analysis and data presentation
In this systematic review, after completing the data protocol containing detailed
information of each article, the articles were then classified as: the quality of
evidence ([Table 3]) and the level of evidence ([Table 1]), adapted by Cox[19] for the area of Audiology.
Table 3.
Degree of recommendation.
|
A
|
Studies level 1 or 2 with consistent findings.
|
|
B
|
Studies of levels 3 or 4 with consistent findings or exceeded evidence (generalized
to a situation in which it is not entirely relevant) studies of levels 1 or 2.
|
|
C
|
Studies of levels 5 or exceeded evidence (generalized to a situation in which it is
not entirely relevant) of studies of levels 3 or 4.
|
|
D
|
Studies Level 6. Inconsistent or inconclusive studies of any level. Any study presenting
a high risk of bias.
|
As regards the presentation of data, relevant information of each article, as well
as the classification of the degree of recommendation were gathered in tables to be
easily consulted and accessed during the presentation and discussion of results.
Results of the Literature Review
Results of the Literature Review
As to the selection of potentially relevant studies for the systematic review
1. Results in electronic databases:
From the search strategy in different electronic databases, 282 titles with or without
summary, potentially relevant to the object of study of this systematic review, were
identified. The titles identified in each of the databases are described in [Table 4].
Table 4.
Distribution of studies identified by database.
|
Works Identified
|
N = 282
|
|
Lilacs
|
N = 1
|
|
Medline
|
N = 78
|
|
Cochrane
|
N = 0
|
|
Scielo
|
N = 1
|
|
ISI
|
N = 69
|
|
Pubmed
|
N = 79
|
|
S. Direct
|
N = 17
|
|
Embase
|
N = 37
|
Out of the 282 titles, 82 appeared in more than one electronic database. The 197 duplicate
titles were disregarded, remaining a total of 85 titles potentially relevant to systematic
review.
2. Results in Records of Congress
From the manual and digital survey referring to the records of the International Meeting
of Audiology conducted from 1985 to 2010, studies potentially relevant to this systematic
review were not found.
3. Results in other databases
Besides searching electronic databases for scientific articles, the bibliographic
research on digital databases of dissertations and theses was also conducted. From
this search, two theses found in “Digital Dissertation Abstracts” were selected.
As for the analysis of selected studies
1. Electronic databases
Out of the 85 titles selected to retrieve articles, only one cannot be recovered because
it is not available for electronic access in the country. (Svirsky et al., 2007. “The effects of age at implantation on speech intelligibility in pediatric cochlear
implant users: Clinical outcomes and sensitive periods. “). Therefore, a total of 84 articles was retrieved.
After completely reading the articles, only 15 have met the eligibility criteria of
this study and were included in the systematic literature review. Sixty-nine articles
were not included because they had one or more factors of exclusion. [Table 5] presents the criteria that led to the exclusion of the retrieved articles and in
how many articles in the exclusion criterion occurred.
Table 5.
Reasons to exclude articles.
|
Reason for exclusion
|
Number of articles excluded
|
|
Utilization time of the cochlear implantation
|
41
|
|
Utilization time of the cochlear implant not included
|
9
|
|
Age at evaluation
|
11
|
|
Post-lingual adults
|
3
|
|
Pre-lingual adolescents and young adults
|
3
|
|
Objective of the study
|
19
|
|
Scarce or insufficiently detailed methodology and/or results
|
13
|
|
Expert opinion/Literature review
|
2
|
The complete references of the 15 articles included in the systematic review and the
main results collected from the protocol are described in [Tables 6] and [7], respectively.
Table 6.
Bibliographical references of studies included in the systematic review.
|
Articles included
|
|
1
|
Tyler RS. 7-year speech perception results and the effects of age, residual hearing
and preimplant speech perception in prelingually deaf children using the Nucleus and
Clarion cochlear implants. Adv Otorhinolaryngol. 2000, 57:305-10.
|
|
2
|
Waltzman SB, Cohen NL, Green J, Roland JT. Long-term effects of cochlear implants
in children. Otolaryngol Head Neck Surg. 2002, 126(5):505-511.
|
|
3
|
Manrique M, Cervera-Paz FJ, Huarte A, Molina M. Prospective long-term auditory results
of cochlear implantation in prelinguistically deafened children: the importance of
early implantation. Acta Otolaryngol Suppl. 2004, 552:55-63.
|
|
4
|
Peng SC, Spencer LJ, Tomblin JB. Speech intelligibility of pediatric cochlear implant
recipients with 7 years of device experience. J Speech Lang Hear Res. 2004, 47(6):1227-1236.
|
|
5
|
Spencer LJ; Gantz BJ; Knutson JF. Outcomes and achievement of students who grew up
with access to cochlear implants. Laryngoscope. 2004, 114(9):1576-1581.
|
|
6
|
Beadle EA et al. Long term functional outcomes and academic-occupational status in
implanted children after 10 to 14 years of cochlear implant use. Otol Neurotol. 2005,
26(6):1152-1160.
|
|
7
|
Haensel J, Engelke JC, Ottenjann W, Westhofen M. Long-term results of cochlear implant
in children. Otolaryngol Head Neck Surg. 2005, 132(3):456-8.
|
|
8
|
Connor CM. Examining the communication skills of a young cochlear implant pioneer.
J Deaf Stud Deaf Edu. 2006, 11(4):449-460.
|
|
9
|
Uziel AS, et al. Ten-year follow-up of a consecutive series of children with multichannel
cochlear implants. Otol Neurotol. 2007, 28(5):615-628.
|
|
10
|
Geers AE, Tobey E, Moog J, Brenner C. Long-term outcomes of cochlear implantation
in the preschool years: from elementary grades to high school. Int J Audiol. 2008,
47 (Suppl 2):S21-S30.
|
|
11
|
Colletti L. Long-term follow-up of infants (4-11 months) fitted with cochlear implants.
Acta Otolaryngol. 2009 Apr, 129(4):361-6.
|
|
12
|
Said, TC, Bevilacqua MC, Moret ALM. Speech perception in pre-lingual deaf users of
cochlear implant. Pró-Fono. 2010, 22(3):275-9.
|
|
13
|
Davidson LS, Geers AE, Brenner C. Cochlear implant characteristics and speech perception
skills of adolescents with long-term device use. Otol Neurotol. 2010, 31:1310-14.
|
|
14
|
Habib MG, Waltzman SB, Tajudeen B, Svirsky MA. Speech production intelligibility of
early implanted pediatric cochlear implant users. Int J Pediatr Otorhinolaryngol.
2010, 74(8):855-859.
|
|
15
|
Venail F, Vieu A, Artieres F, Mondain M, Uziel A. Educational and employment achievements
in prelingually deaf children who receive cochlear implants. Arch Otolaryngol Head
Neck Surg. 2010, 136(6):575.
|
Table 7.
Participants' utilization time and main results found in the studies included in the
systematic review of literature.
|
Study Age at Cl and evaluation.
|
Time of Cl use: 7 to 10 years.
|
Time of Cl use: > 10 years.
|
Results (average of right answers - in the last evaluation)
|
|
Hearing
|
Intelligibility
|
Educational/Occupational
|
|
Tyler (2000).
Age at CI: 2–8.
Age at evaluation: Unknown.
|
N = 23.
|
None.
|
– PBK: 20–30%.
|
– None.
|
– None.
|
|
Waltzman et al. (2002).
Age at CI: 13m–15.
Age at evaluation: Unknown.
|
N = 47.
|
N = 5.
|
By Group (PBK/sentences):
– G1 (Cl up to 5 years): 70.3% / 85.7%).
– G2 (Cl between 6–1 0 years):
44.3%/62.9%.
– G3 (Cl between 11–17 years of age):
1 5%/34%.
|
– None.
|
– None.
|
|
Manrique et al. (2004).
Age at CI:
Gl (0–3); G2(4–6);
G3(7–l0); G4(ll–I4).
Age at evaluation: Unknown.
|
N = 1 82.
|
None.
|
– Thresholds on field: 32–44dB.
– Disyllables:
G1=81–100%; G2= 15–49%;
G3=0–20%; G4=l–28%.
|
– None.
|
– None.
|
|
Peng et al. (2004).
Age at CI: 2.6–1 1.
Age at evaluation 9–1 8.
|
N = 24.
|
None.
|
– None.
|
Percentage of transcription /scale:
– 1 st presentation: 67.86% (5.5–100%); 2.85(1.24–4.62).
– 2nd presentation: 71.54% (5.83–100%).; 3.03 (1.29–4.83).
|
– None.
|
|
Spencer et al. (2004).
Age at CI: 2–12.
Age at evaluation: above 1 6.
|
N = 7.
|
N = 13.
|
– PBK(N = 20): 49% (0–88%).
7–10: 61.46% (24–89%).
> 10. 40.29% (0–64%).
– Hint (N = 20): 68% (1 5–94%).
7–10: 66.55%( 15–94%).
> 10.72%(45–87%).
|
– None.
|
– Universities, Community schools: N = 12.
Domestic activities: N = 2.
|
|
Beadle et al. (2005).
Age at CI: 2.5–1 I.I.
Age at evaluation 13.9–23.9.
|
None.
|
N = 30.
|
– CAP:
Categ. 7–6: N = 26.
Categ. 5. N = 2.
Categ. 4–1: N = 2.
|
– SIR:
Level 5–4: N = 23.
Level 3: N = 5.
Level 2: N = 2.
|
School for students having special needs: N = 1
– School for the deaf (N = 9), regular school (N = 7), special room (N = 6), universities
(N = 3), domestic Activities (N = 1), work (N = 4).
|
|
Haelsen et al. (2005).
Age at CI: 3–12.
Age at evaluation: Unknown.
|
None.
|
N = 16.
|
– Children in a dosed group: N = 6.
– Freiburg multisyllabic Word:
53% (10–100%).
– Monosyllables: 40% (0–1 00%).
|
– None.
|
– None.
|
|
Connor (2006).
Age at CI: 5.
Age at evaluation: Unknown.
|
None.
|
N = 1
|
– None.
|
– Transcript: After 11 years of usage: 97%.
|
– None.
|
|
Uziel et al (2007).
Age at CI: 1.9–14.
Age at evaluation: Unknown.
|
None.
|
N = 82.
|
– PBK:72%(0–100%).
– Sentences in noise: 44.5% (0–94%).
|
– Level 5–4 (SIR): N = 54.
|
– Regular School: N = 49 (3 in the elementary, 14 high school, 32 intermediary; Special
room: N = 7; Universities: N = 6; Professional training courses: N = 17; Work: N = 3.
|
|
Geers et al (2008).
Age at Cl: 1.1 1 –5.4. Age at evaluation: 15–18.4.
|
None.
|
N = 85.
|
– LNT: 57% (0–95%).
– BKB: 77%.
|
– None.
|
– None.
|
|
Colletti (2009).
Age at Cl: 4–36 months.
Age at evaluation: Unknown.
|
N = 53.
|
None.
|
– CAP: reached level 7:
Gl (4–11 m): at 24m;
G2(l2–23m):at 36m;
G3 (24–36m):at 42m.
|
– SIR: reached level 5:
Gl: N = 13(100%),
G2: N = 15 (83%),
G3: N = 15(69%).
|
– None.
|
|
Davidson et al (2010).
Age at CI: 1.8–5.4.
Age at evaluation 15.5–18.5.
|
N = 53.
|
N = 109.
|
– Thresholds on field:
3G–Freedom:27–30dB.
Esprit / Spectra :35–37dB.
– LNT (70dB/50dB):
3G/Freedom: 62.3%/53.3%.
ESprit/Spectra:56.7%/35.1 %.
– BKB (silence/noise):
3G/Freedom:82.8%/53.9%.
ESprit/Spectra:74.8%/49.1 %.
|
– None.
|
– None.
|
|
Habib et al (2010).
Age at Cl: 8–40 months.
Age at evaluation: 2.5–1 8 .
|
N = 6.
|
N = 2.
|
– None.
|
– Transcript: 80–100%.
– Correlation–transcription /scale: r = +0.79.
|
– None.
|
|
Said et al (2010).
Age at Cl: Unknown.
Age at evaluation 9.2–1 8.2.
|
N = 33 (Med–EI and Nucleus 24).
Nucleus 22: not specified.
|
Nucleus 22: not specified.
|
– Monosyllables:
N22:40%; N24:48%; Med–EI:47%.
– Disyllables:
N22:45%; N24:54%; Med–EI:54%.
– Sentences:
N22:36%; N24:47%; Med–EI:48%.
|
– None.
|
– None.
|
|
Venail et al(2010).
Age at CI: 8–18.
Age at evaluation: Unknown.
|
N = 24.
|
N = 26.
|
– None.
|
– None.
|
– Gl: Elementary (N = 20),
Intermediate – Junior High (N = 4).
– G2: Elementary (N = 2),
Intermediate (N = 1 7), High school/high school (N = 1), Professional training course
(N = 4).
– G3: High school (N = 7), University (N = 1), Professional training course (N = 8),
Work (N = 2).
– G4: University (N = 4),
Professional training course (N = 3),
Work (N = 1).
|
2. Other databases
Two theses found in “Digital Dissertation Abstracts” were selected for analysis due
to having titles potentially relevant to the object of study of this systematic review:
“The experience of adolescents with cochlear implants” (KE Kops, 2003) and “Perception and production of speech intonation in pediatric cochlear implant recipients
and children with normal hearing” ( SC Peng, 2005).
However, both were excluded after the work was evaluated in details due to not meeting
the selection criteria of this systematic review regarding the objective of study,
at the time of CI utilization, and the age when surgery was performed and the hearing
impairment started.
Discussion
Considering the importance to know the medium and long-term achieved results and the
scarcity of this type of study in the CI pediatric population, the objective was to
determine, by systematically reviewing the literature, the CI effectiveness to the
development of communication skills of adolescents and young adults who grew up using
the electronic device.
A prevalent number of studies in literature evaluated the users using the device for
as long as six years. At the end of bibliographical research, only a 15-article group,
all of which were primary, was selected for appraisal, as they met the inclusion criteria
to answer the question of this systematic review. Among the articles included, 8 were
prospective studies, 2 retrospective, 4 transverse and 1 longitudinal case study.
The studies showed a degree of recommendation C and D.
The first study evaluating the benefits of long-term IC utilization in children was
performed by Tyler (2000). At the time, only studies with children using cochlear
implants for five years after surgery had been conducted. The author found the possible
variants that could contribute to the different levels of benefits provided by the
CI to develop listening skills during the first seven years of use of the device.
Ever since, other long-term studies were conducted in international literature. However,
considering that the FDA approved the appointment of the IC in children from two years
old, in 2010, completing 20 years of the first surgeries in children, the publication
of a greater number of articles addressing the results of long-term IC utilization
in the pediatric population was expected. According Beadle et al. (2005), possible
explanations for the still low number of such studies are due to methodological problems
and the presentation method of the results measured.
Omission of the demographic data or the results of evaluations for each user, non-standardization
of protocols and the methodology used in the testing, omission of users with poor
results, grouping of users according to different variants, problems with the study
design and inadequate follow-up, are some of the most common problems found in studies
evaluating the cochlear implant users over time (Waltzman et al. 2002; Beadle et al., 2005; Venail et al., 2010).
Another negative aspect is that not all studies have addressed all areas of interest
when monitoring of users, such as the development of listening skills, oral language,
the educational and occupational status.
In this systematic review, only two studies (Beadle et al., 2005 and Uziel et al., 2007) covers all the topics among the areas of interest. Most of the studies
addressed only one area of interest, among which six studies evaluated only the auditory
skills (Tyler,2000; Walzman et al., 2002; Manrique et al., 2004; Haelsen et al., 2005; Geers et al., 2008; Davidson et al., 2010; Said et al., 2010), three studies have examined only the speech intelligibility (Peng et al., 2004, Connor, 2006; Habib et al., 2010) and the educational and occupational status was studied by Venail et al. (2010). Combined areas, auditory/speech intelligibility skills and listening
skills/educational status were evaluated in two studies carried out by Colletti (2009) and Spencer et al. (2004), respectively.
As to the procedures used, the studies that specifically evaluated the auditory skills
used recognition tests of monosyllabic words, sentences in silence/noise and scale
of auditory skills (Tyler,2000; Walzman et al., 2002; Manrique et al., 2004; Spencer et al., 2004; Beadle et al., 2005; Haelsen et al., 2005; Uziel et al., 2007; Geers et al., 2008; Colletti, 2009; Davidson et al., 2010; Said et al., 2010). Studies in Spanish and Portuguese have also used two-syllable word
lists (Manrique et al. 2004; Said et al., 2010). Despite the methodological variables applied, we observed that most
participants in these studies achieved complex levels of auditory skills. Consequently,
most CI users were able to recognize speech without the help from orofacial reading
and, therefore, they were able to complete the evaluation procedures of speech recognition
in an open set.
Still regarding the evaluation of listening skills, only two studies performed by
Uziel et al. (2007) and Davidson et al., (2010) measured the sentence recognition in noise (S/N ratio +10 dB). Considering
the importance that the evaluation of speech perception in noise plays when evaluating
benefits and limitations of using electronic devices (Duncan and Aarts, 2006) and, due to the fact that a considerable number of users has reached levels
of auditory skills necessary for speech recognition, reaching a plateau in the tests
performed in silence, a higher number of studies with tests of speech perception in
noise was expected.
Six studies evaluated the speech intelligibility after at least 7 years of CI use.
Again, the studies used different methodologies. Among them, three used the “Speech Intelligibility Rating” - SIR scale (Beadle et al. 2005; Uziel et al. 2007; Colletti, 2009), only one study used the transcription method (Connor, 2006) and two studies measured the speech intelligibility by using the transcript
method along with a scale of five intelligibility levels (Peng et al. 2004; Habib et al., 2010). There was a wide range in the results achieved by the transcription
method, and the minimum and maximum percentages obtained by the transcription method
varied from 5.5% to 100%.
Despite the variability in the intelligibility of CI users, most participants reached
satisfactory levels in the intelligibility scales. The results suggest that after
7 years of using CI, the message orally transmitted by most children who grew up with
the device can be understood by listeners not experienced in the speech of the hearing-impaired.
However, not all users, even after 10 years using the device, failed to achieve satisfactory
results in sending the message content through oral language (Peng et al. 2004; Uziel et al. 2007; Habib et al., 2010).
In relation to occupational and educational results, the studies collected information
by interviewing the user and/or his/her family. Generally speaking, the features raised
by the authors showed that children's admission in regular schools was increasing
with the utilization time of CI and that users have reached satisfactory educational
levels. Some authors have noted that users tend to follow the educational standard
presented by their parents (Spencer et al., 2004). Although most participants in regular school or university, there
was delay in the acquisition of academic skills and recorded episodes of school failure,
particularly in teaching intermediate / medium (Spencer et al. 2004; Geers et al. 2008; Venail et al., 2010).
There were important differences between the studies related to the development pace
of communicative skills, presence of plateaus in the development, as well as the diversity
of the results obtained in the last evaluation. Such diversity was shown in all areas
evaluated by the studies, the authors assigned the results of this diversity partially
to the existence of certain factors.
Presence of residual hearing in the severe frequencies and speech understanding prior
to CI surgery were the factors associated with the best results obtained after years
using the CI to Tyler (2000) and Waltzman et al. (2002). The sensory deprivation time and age in implantation were the mostly
agreed variants among the studies regarding the successful predecessors of for CI
users. Younger age at implantation, specifically taking into consideration the age
group until two years of age, along with the use of oral communication were related
to the best pace of skill acquisition, the best results of speech perception and intelligibility
after several utilization years and the tendency to be closer to the results obtained
in individuals listeners. Instead, the worst results in all areas evaluated were obtained
by users with a greater sensory deprivation (Tyler 2000; Waltzman et al. 2002; Manrique et al. 2004; Peng et al. 2004; Spencer et al. 2004; Geers et al. 2008; Colletti, 2009; Habib et al. 2010; Said et al. 2010; Venail et al., 2010).
Based on these results, the authors stressed the importance of performing the CI early,
in order to avoid periods of sensory deprivation. The long-term results with the CI-implanted
users at different ages suggest that even after years of device utilization, the children
submitted to the IC late may not achieve the same results as the children implanted
at younger ages (Tyler, 2000; Waltzman et al. 2002; Manrique et al. 2004; Spencer et al. 2004; Geers et al. 2008; Colletti, 2009; Venail et al. 2010).
All the different models of devices evaluated provided long-term benefits to its users
and their difference was not statistically significant (Said et al., 2010). However, the use of different and more modern speech coding strategies
was an important aspect discussed in some studies and that significantly contributed
to the achievement of better results both in evaluation tests of auditory skills and
in the speech intelligibility test (Peng et al., 2004; Davidson et al., 2010 and Said et al., 2010).
The results of the studies were also positive as to the integrity question and the
long-term device operation, even after ten years of use. According to the authors,
although there is the need for reoperation, the users did not worsen in hearing perception
after being re-implanted. Out of the three studies described the occurrence of failures
in the internal device, there was the need to re-implant 9 cases in the study of Waltzman et al. (2002), 8 cases in the study of Beadle et al. (2005) and 11 cases in the article by Uziel et al. (2007).
Conclusion
After the bibliographical survey and the analysis of the scientific evidence found
on the studies included in this systematic review of literature were performed, it
was possible to imply that the authors agreed in the studies included in the present
systematic review about the conclusions regarding the benefits due to the time of
CI utilization.
The achieved results suggested that the long-term CI utilization provided the first
generation of CI children with a significant progress and levels. of language and
educational competency similar to normal hearing individuals at their age. In addition
to the CI contribution to the wide-ranging aspects inherent to the development process
of communicative and educational skills and the improvement in the quality of life,
the results of the studies revealed the functional CI effectiveness, hence consolidating
it as a notably reliable and endurable device, even after ten years of utilization.
However, certain diversity was observed in the results achieved after a period longer
than 7 years of CI utilization. For some authors, the longest time of sensorial deprivation
and the utilization of less technologically advanced devices found in the first generation
of implanted children can have firmly contributed to the existence of such a diversity.
Long-term studies with the subsequent generation s of CI children are required. It
is expected that the new generation of Cochlear Implantation users, which was submitted
to the surgical procedure at younger ages and with more advanced technological devices
can achieve still better results through the time of utilization.
