Eur Arch Otorhinolaryngol DOI 10.1007/s00405-014-3377-8
OTOLOGY
Quality of life in bimodal hearing users (unilateral cochlear implants and contralateral hearing aids) A. Farinetti • S. Roman • J. Mancini K. Baumstarck-Barrau • R. Meller • J. P. Lavieille • J. M. Triglia
•
Received: 10 October 2013 / Accepted: 24 October 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract The main objective was to evaluate the bimodal self-rated benefits on auditory performance under real conditions and the quality of life in two groups of cochlearimplanted adults, with or without a contralateral hearing aid. The secondary objective was to investigate correlations between the use of a hearing aid and residual hearing on the non-implanted ear. This retrospective study was realized between 2000 and 2010 in two referral centers. A population of 183 postlingually deaf adults, implanted with a cochlear experience superior to 6 months, was selected. The Speech, Spatial, and other Qualities of Hearing Scale were administered to evaluate the auditory performances, and the Nijmegen Cochlear Implant Questionnaire to evaluate the quality of life. The population was divided into two groups: a group with unilateral cochlear implants (Cochlear Implantalone, n = 54), and a bimodal group with a cochlear implant and a contralateral hearing aid (n = 62). Both groups were similar in terms of auditory deprivation duration, duration of A. Farinetti (&) S. Roman J. M. Triglia Department of Otolaryngology Head and Neck Surgery, CHU La Timone Hospital, 264, avenue Saint Pierre, 13385 Marseille Cedex 5, France e-mail: [email protected] S. Roman e-mail: [email protected] J. M. Triglia e-mail: [email protected] J. Mancini Aix-Marseille University, Inserm, IRD, UMR912, SESSTIM, Marseille 13273, France e-mail: [email protected]
cochlear implant use, and pure-tone average on the implanted ear. There was a significant difference in terms of puretone average on low and low-to-mid frequencies on the nonimplanted ear. The scores on both questionnaires showed an improvement in the basic sound perception and quality of social activities for the bimodal group. The results suggest that the bimodal stimulation (cochlear implant and contralateral hearing aid) improved auditory perception in quiet and the quality of life domain of social activities. Keywords Binaural hearing Bimodal stimulation Cochlear implant Hearing aid Adult Quality of life
Introduction Due to advancements in electronic technology and better understanding of auditory science, many individuals with K. Baumstarck-Barrau Medical Statistics Laboratory, La Timone University, 13385 Marseille Cedex 5, France e-mail: [email protected] R. Meller J. P. Lavieille Department of Otolaryngology Head and Neck Surgery, Nord Hospital, 13915 Marseille Cedex 20, France e-mail: [email protected] J. P. Lavieille e-mail: [email protected]
J. Mancini Public Health Department, APHM, La Timone Hospital, 13385 Marseille, France
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bilateral severe to profound sensorineural hearing loss have been rehabilitated with unilateral cochlear implantation. However, people who receive a cochlear implant in one ear perceive speech easily in quiet situations, but hearing is very challenging in noisy and acoustically complex situations [1]. These patients cannot use binaural hearing to enhance speech perception and sound localization because the auditory input is only available in one ear. To improve the perception of cochlear-implanted patients, it seemed obvious to add more speech information not only by improving the devices, but also by adding a contralateral implant or hearing aid. Bilateral stimulation, in prelingually deafened children using bilateral cochlear implants, improves the development of binaural hearing to localize sound sources and recognize speech. The processing is due to the ability of the auditory brainstem to integrate information from each ear despite bilateral auditory deprivation during development, and is ton topically organized [2]. In 2004, Ching recommended bimodal stimulation (cochlear implant in one ear and a conventional hearing aid in the opposite ear) as standard management for children and adults who received a cochlear implant in one ear, and who have usable residual hearing in the opposite ear [3]. Indeed, bimodal stimulation is indicated to provide the binaural advantages experienced by normal hearing subjects, arising from the combination of head shadow diffraction, binaural summation and binaural squelch effects. These effects lead to better localization ability, speech understanding in quiet and noisy environments [3–6]. From bimodal stimulation, two types of information complement each others: acoustic and electrical signals. Acoustic amplification with a hearing aid provides low frequencies of speech, containing information of the fundamental frequencies of the talker. The high frequencies are provided by electrical stimulation, and contain important linguistic information that relate to manner and place of articulation of consonants [7]. Hearing aids can provide voice pitch information that assist with segregation of competing voices and with making voicing and tonal distinctions by users of cochlear implant. Most studies showed the advantages of bimodal stimulation based on quantitative measurements of speech understanding (word and sentence recognition in quiet and in noise) and localization under various conditions [3, 5, 8– 10]. Although, much attention has focused on speech perception performance and horizontal localization ability in adults combining a cochlear implant and hearing aid, research examining real-world auditory performance has been limited. It was only reported that wearing a hearing aid in the contralateral aid can enable to a more natural sound [3, 5, 11], and to the impression that sound is heard
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in both ears rather than exclusively near the implant. Also, a combination of electric and acoustic stimulation improves music perception by adding low-frequency spectral information [12]. So, in spite of the quantitative strengths allocated to the contralateral hearing aid in cochlear implant users, the ecological complexities of human communication need a qualitative assessment by validated questionnaires. For instance, to evaluate the real life binaural benefits, Gatehouse and Noble designed a questionnaire (the SSQ) in 2004, which implicates the aspects of temporal and spatial dynamics of hearing disability [13]. In 2006, Noble and Gatehouse showed that two hearing aids offered advantages in dynamic contexts [14]. To evaluate health-related quality of life (QoL), Hinderink designed a self-assessment quality of life questionnaire, the NCIQ. It has been showed that a cochlear implant has significant effects on the social and psychological domains [15]. In case of evidence of benefits with a bimodal stimulation in real life, the clinician could be interested in predicting such results preoperatively. The amount of residual hearing before implantation has to be investigated because of an objective parameter. The use of a contralateral hearing aid provides improved low-frequency information, resulting in better performance by the cochlear implant and the hearing aid users [9, 16–19]. This study aimed to assess the subjective benefits of a hearing aid in the opposite ear in postlingually deaf adults cochlear-implanted recipients thanks to two self-standardized questionnaires, and secondly to predict the putative benefits related to the pure-tone average on the nonimplanted ear.
Patients and methods A population of 183 postlingually deaf adults implanted between 2000 and 2010 was selected to participate in the study. The criteria of inclusion were: a post-activation delay exceeding 6 months, a profound postlingual deafness beginning after 18 years, a last implant setting measured in a time window inferior to 12 months in our institution before the inclusion. For the contralateral hearing aid users, the settings of hearing aid had to be realized by one of the three audiologists of the team and had to be almost new and recent (\6 months). The use of the hearing aid had to be permanent since the implantation (at least 12 h a day), and patients were able to adjust the volume to be comfortable in all listening situations. The pure-tone average on the non-implanted ear was 96.1 dB HL (from 51.2 to 120 dB HL) for the bimodal group (CI ? HA). The thresholds in low frequencies were 85.7 dB HL in aided conditions. All the patients underwent the same surgical procedure that
Eur Arch Otorhinolaryngol
consisted of mastoidectomy, posterior tympanotomy and a total insertion electrode array through round window. For each patient, several criteria were analyzed such as gender, age at the time of the study, age at the diagnosis of deafness, age at the implantation, duration of profound deafness, duration of the cochlear implant use as well as the type of implant. Before implantation, the pure-tone average (PTA) at 500, 1,000, and 2,000 Hz was calculated for each ear and on the non-implanted ear, the low frequencies PTA (250 and 500 Hz) and the low-to-mid frequencies (250, 500, and 1,000 Hz) were also calculated.
and social (activities and social interactions, facilities during work or studies, in traffic, functioning in the home, shopping, and watching television). The scores for each item range from 0 to 100, where 0 always represents the lower quality and 100 represents the higher quality. Missing values and the category ‘‘not applicable’’ were both treated as not completed. The subject was excluded if more than three items were not completed for any subdivision.
Procedure
Statistical analysis was completed using SPSS 15.0 software. All questionnaires responses were analyzed descriptively. We used means and standard deviations (SD) to present the descriptive statistics of the quantitative data, and proportions to describe qualitative data. Non-parametric statistics were used to correlate outcomes across the various measurements. The comparison used parametric (v2 test) or non-parametric (Mann–Whitney test) statistics as appropriate. All significance tests were two-sided and statistical significance was accepted at the 0.05 level. The effect of low frequencies (250 and 500 Hz) and low-to-mid frequencies PTAs (250, 500, and 1,000 Hz) on using a hearing aid was also examined. To control for the potential confounding effects of the patient’s main characteristics, a multivariate ANOVA was used to study the group effect on outcomes with a systematic adjustment for age at the implantation, duration of profound deafness, and PTA of the contralateral ear entered as covariates.
The SSQ and NCIQ questionnaires were sent to the patient’s home with a letter in which the purpose of the study was explained. These responses were anonymous after matching them with demographical and audiological criteria. The interview approach was self-administration, without medical help for the comprehension of any items. All patients provided signed consent to participate in the study. Two questionnaires were used in the study, as described below. The speech, spatial and qualities of hearing scale (SSQ) The SSQ is a self-reported questionnaire designed by Gatehouse and Noble (2004), to measure a broad range of hearing functions, some of which are likely to implicate the binaural system [13]. The SSQ is composed of 50 items in three sections. Each item of the scale is scored using a Likert-type scale marked from 0 to 10, where 0 always represents minimal ability and 10 represents complete ability. The first section covers various aspects of hearing and speech in quiet, noise, and more challenging contexts such as following one line of speech in the presence of competing speeches, or following two streams of conversation simultaneously. The second covers classical components of spatial hearing: direction, distance and movement judgments. It evaluates stationary and dynamics events, reflecting their reality. The third section on other qualities contains items covering the segregation of sounds, recognition, clarity/naturalness, and listening effort. The Nijmegen cochlear implant questionnaire (NCIQ) This questionnaire, designed by Hinderink in 2000, is a quantifiable, self-assessment instrument of health-related quality of life specific to cochlear implant users [15]. It is divided into three domains as follows: physical (basic and advanced sound perception), psychological (self-esteem)
Statistical analysis
Results Demographical data From a population of 183 postlingually deaf adults operated between 2000 and 2010, a total of 116 patients (63.34 %) completed both questionnaires. Patients were divided into two groups according to the use of a hearing aid on the non-implanted ear and several criteria were analyzed. The entire bimodal group concerned patients who already used hearing aid on the non-implanted ear before implantation. The first group was the cochlear implant-alone group (CI, n = 54) and the bimodal group (CI ? HA, n = 62) was the second group. The demographical and clinical data of the two groups are presented in Table 1. The bimodal group did not differ from the CI-alone group with respect to demographical data (gender (p = 0.739), age (p = 0.311), age at diagnosis of deafness (p = 0.307), age at implantation (p = 0.526). There was
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Eur Arch Otorhinolaryngol Table 1 Demographic and clinical data of the two patients groups Qualitative data
Cochlear implant-alone group CI (n = 54)
Bimodal group CI ? HA (n = 62)
N
%
N
%
Males
26
41.9
21
38.9
Females
36
58.1
33
61.1
P*
Gender 0.739
Type of cochlear implant Med-el
4
6.5
7
13.0
MXM
30
48.4
26
48.1
Nucleus
28
45.2
21
38.9
Quantitative data
0.459
Mean
SD
Mean
SD
P**
Age (years)
57.8
17.3
61.3
16.2
0.311
Age at the diagnosis of deafness
25.8
19.7
30.4
20.9
0.307
Age at the implantation (years)
52.5
19.4
55.5
15.9
0.526
9.5
12.6
8.7
12.0
0.439
53.8
44.3
70.0
54.3
0.099
Duration of profound deafness (years) Duration of CI use (months) PTA implanted ear
108.4
14.9
108.7
12.1
0.758
PTA contralateral ear
105.6
13.5
96.1
18.2
0.006
96.4
20.6
85.7
24.5
0.015
100.5
16.3
90.2
20.4
0.006
Low-frequency PTA (contralateral ear) Low-to-mid frequency PTA (contralateral ear) Bold values are statistically significant at p \ 0.005
SD standard deviation, PTA pure-tone average in dB HL at 500, 1,000, 2,000 Hz, CI cochlear implant, HA hearing aid * p value, v2 test (Fisher exact test) \0.05 ** p value, Mann–Whitney test \0.05
no significative difference for the duration of profound deafness (9.5 years in the CI-alone group (SD = 12.6), and 8.7 years in the CI ? HA group (SD = 12); p = 0.439). No significant difference was found about the data linked with the implant (duration of cochlear implant use (p = 0.099) with 53.8 years in the CI-alone group (SD = 44.3) and 70 years in the CI ? HA group (SD = 54.3), type of implant (p = 0.459). All patients received either a Nucleus cochlear implant (n = 49), a Med-el cochlear implant (n = 11), or a MXM cochlear implant (n = 56) (p = 0.459). Questionnaire’s assessment The mean scores on each domain of the SSQ are listed in Table 2. The subdomain of speech hearing in quiet and all the sections of hearing qualities had better mean results for the bimodal condition compared with unilateral implantation, although statistical significance was not reached (p [ 0.05). The mean scores on each domain of the NCIQ are listed in Table 3. The CI ? HA group had better scores for all the domains. A significant difference was found only in the subdomain of basic sound perception (p = 0.007) and limitation of social activities (p = 0.031).
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There was no difference between groups for enjoying music (advanced sound perception subdomain). The rated scores were also better for the CI ? HA group for the selfesteem section, feeling at ease with company, anxiety when talking to strangers, and facility to make contact with other people. Audiological data There was no significative difference between the PTA on the implanted ear in the two groups (108.4 dB HL in the CI-alone group, and 108.7 dB HL in the CI ? HA group; p = 0.758). The CI ? HA group had significantly better pre-implant hearing levels in the non-implanted ear with a mean of 105.6 dB HL (standard deviation SD = 13.5) in the CIalone group compared with a mean hearing loss of 96.1 dB HL (SD = 18.2) in the CI ? HA group (p = 0.006). Similarly, there was a significant difference in the preimplant hearing levels between the two groups when comparing low and low-to-mid frequencies PTAs: 96.4 dB HL vs. 85.7 dB HL for low frequencies (p = 0.015), and 100.5 dB HL vs. 90.2 dB HL for low-to-mid frequencies (p = 0.006) in the CI-alone group versus the CI ? HA group, respectively (Table 1). The two groups were
Eur Arch Otorhinolaryngol Table 2 Speech spatial and other qualities of hearing scale (SSQ) questionnaire
Subdomains of SSQ
CI-alone group (n = 54)
Bimodal CI ? HA (n = 62)
Mean
Mean
SD
b
Confidence interval
P*
SD
Speech
Bold value is statistically significant at p \ 0.005 Mean ratings [and standard deviations (SD)] for each subdomain in the cochlear implant-alone (CI) and the bimodal (CI ? HA) groups CI cochlear implant, HA hearing aid * p value, Mann–Whitney test \0.05
In quiet
4.4
2.7
5.2
2.5
0.730
-0.32–1.78
0.172
In noise In speech contexts
2.1 2.6
1.8 2.3
2.3 2.7
1.9 2.2
0.224 0.137
-0.52–0.97 -0.77–1.04
0.554 0.766
Multiple speech-stream processing and switching
2.3
1.8
2.4
2.0
0.228
-0.52–0.98
0.549
Localization
3.2
2.4
3.3
2.6
-0.011
-1.03–1.01
0.983
Distance and movement
3.4
1.9
3.8
2.1
0.576
-0.25–1.41
0.174
Spatial
Qualities Identification of sounds
4.3
2.6
4.6
2.7
0.562
-0.49–1.61
0.293
Segregation
3.6
2.8
4.6
3.3
0.729
-0.58–2.02
0.274
Sound quality and naturalness
4.8
2.4
5.4
2.3
1.067
0.13–2.00
0.026
Listening effort
2.8
2.1
3.2
2.3
0.440
-0.47–1.35
0.343
significantly different in relation to the PTA on the nonimplanted ear. The mean PTA in aided conditions (bimodal group) in the low-to-mid frequency range reached 51 dB, and 49 dB in the low-frequency range.
Discussion The first goal of our study (cross-sectional design) was to evaluate whether the use of a hearing aid in the nonimplanted ear of cochlear-implanted users provided any subjective benefits with respect to Health-related Quality of Life, thanks to two self-standardized questionnaires. The questionnaires were filled 53.8 months and 70 months after the implantation, respectively, in the CI-alone and the bimodal group. The results suggested that the bimodal fitting (CI ? HA), in condition of aidable residual hearing, improved subjective auditory performances and quality of life. Indeed, the bimodal group had better results than the CI-alone group for all the sections of both questionnaires, although statistical significance was not reached for all sections (p [ 0.05). These binaural benefits from bimodal stimulation have been already demonstrated by previous authors, in terms of speech perception in noise, horizontal localization ability and functional performance in real life [3, 5, 20]. The use of a hearing aid with a cochlear implant added more fluency to voices, more natural sound quality [11], enhanced music enjoyment [21], helped them to identify the speaker in a group, and made it easier listening in background noise [3, 5, 23]. Binaural benefits were evident for bimodal users irrespective of listening experience.
The second goal of our study was to predict the putative benefits related to the pure-tone average on the nonimplanted ear. This can be made because all demographical data were similar in both groups, except for the PTA in the non-implanted ear. The bimodal group had significantly better pre-implant residual hearing levels on the nonimplanted ear (96.1 dB HL) than the CI-alone group (105.6 dB HL; p = 0.006), in particular in low-to-mid frequencies. Regardless of hearing mode, all users with aidable residual hearing in the non-implanted ear in pre-operative situation were expected to obtain better scores than cochlear implant-alone listeners. We might easily hypothesize that the residual hearing in future bimodal users would improve the quality of life scores, but this influence was debated. Indeed, simply putting a hearing aid into the non-implanted ear of anyone who has a unilateral cochlear implant cannot be expected to produce consistently good results. Some authors reported that the use of a hearing aid was not significantly correlated with residual hearing thresholds and with improvement of quality of life. In 2007, Ching reported that the amount of residual hearing on the three frequencies mean (500, 1,000, and 2,000 Hz) hearing threshold was not significantly correlated with higher bimodal scores [22]. On the contrary, in 2009, Fitzpatrick showed that 40 % of cochlear implant recipients with a PTA better than 100 dB (defined as eligible for hearing aids) opted for a consistent hearing aid use [23]. More recent studies reported that significant bimodal benefit could be obtained when the hearing aid provided amplification at all frequencies with aidable residual hearing, and not only at low frequencies (below 1,000 Hz) [18], and this bimodal fitting led to
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Eur Arch Otorhinolaryngol Table 3 Nijmegen cochlear implant questionnaire (NCIQ) to evaluate quality of life Subdomains of NCIQ
CI-alone group (n = 54)
Bimodal group CI ? HA (n = 62)
Mean
SD
Mean
SD
b
Confidence interval
P*
Physical Basic sound perception
43.7
24.7
56.4
20.8
11.47
2.13–20.81
0.017
Advanced sound perception
56.8
21.6
61.3
19.5
8.64
0.48–16.80
0.038
Speech perception
40.0
19.0
42.0
17.4
2.84
-4.6–10.28
0.451
49.4
15.5
51.1
15.4
5.17
-1.07–11.41
0.104
51.4
24.6
41.5
23.4
-7.87
-17.85–2.09
0.120
45.9
23.9
37.1
20.3
-6.82
-15.76–2.11
0.133
Psychological Self-esteem Social Activitiesa Social interactions
a
Bold values are statistically significant at p \ 0.005 Mean ratings [and standard deviations (SD)] for each subdomain in the cochlear implant-alone (CI) and the bimodal (CI ? HA) groups * p value, Mann–Whitney test \0.05 a
The higher the value, the lower the level of rated effort
CI cochlear implant, HA hearing aid
further increase in the quality of life [26]. Yoon et al. (2012) demonstrated that a bimodal benefit was associated with ‘‘good’’ aided PTA C55 dB HL at frequencies B1,000 Hz [17]. Regardless of these studies, a fine-tuning procedure is necessary so that the frequency response of the hearing aid is adjusted to maximize the use of residual hearing, and the gain for low-, mid- and high-input levels are adjusted to give the same overall loudness as in the implanted ear [7]. The inconsistent results found in some studies could be related to the different experience in hearing aid and implant use among individuals, the degree of hearing loss in the non-implanted ear, or the inadequacy of the hearing aid adjustment [7, 26].
Conclusion In the case of cochlear implant users with residual hearing in the contralateral ear, the possibility to gain benefits from a hearing aid should be considered in the evaluation before the implantation. Many studies reported binaural advantages in speech perception and localization ability from bimodal hearing. Moreover, our study brings an additional argument, which is the self-reported satisfactory result by bimodal stimulation in quality of life. As a consequence of these results, providing binaural–bimodal fittings should be the standard practice with a cochlear implant and aidable residual hearing in the contralateral ear. Conflict of interest of interest.
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The authors declare that they have no conflict
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OTOLOGY
Quality of life in bimodal hearing users (unilateral cochlear implants and contralateral hearing aids) A. Farinetti • S. Roman • J. Mancini K. Baumstarck-Barrau • R. Meller • J. P. Lavieille • J. M. Triglia
•
Received: 10 October 2013 / Accepted: 24 October 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract The main objective was to evaluate the bimodal self-rated benefits on auditory performance under real conditions and the quality of life in two groups of cochlearimplanted adults, with or without a contralateral hearing aid. The secondary objective was to investigate correlations between the use of a hearing aid and residual hearing on the non-implanted ear. This retrospective study was realized between 2000 and 2010 in two referral centers. A population of 183 postlingually deaf adults, implanted with a cochlear experience superior to 6 months, was selected. The Speech, Spatial, and other Qualities of Hearing Scale were administered to evaluate the auditory performances, and the Nijmegen Cochlear Implant Questionnaire to evaluate the quality of life. The population was divided into two groups: a group with unilateral cochlear implants (Cochlear Implantalone, n = 54), and a bimodal group with a cochlear implant and a contralateral hearing aid (n = 62). Both groups were similar in terms of auditory deprivation duration, duration of A. Farinetti (&) S. Roman J. M. Triglia Department of Otolaryngology Head and Neck Surgery, CHU La Timone Hospital, 264, avenue Saint Pierre, 13385 Marseille Cedex 5, France e-mail: [email protected] S. Roman e-mail: [email protected] J. M. Triglia e-mail: [email protected] J. Mancini Aix-Marseille University, Inserm, IRD, UMR912, SESSTIM, Marseille 13273, France e-mail: [email protected]
cochlear implant use, and pure-tone average on the implanted ear. There was a significant difference in terms of puretone average on low and low-to-mid frequencies on the nonimplanted ear. The scores on both questionnaires showed an improvement in the basic sound perception and quality of social activities for the bimodal group. The results suggest that the bimodal stimulation (cochlear implant and contralateral hearing aid) improved auditory perception in quiet and the quality of life domain of social activities. Keywords Binaural hearing Bimodal stimulation Cochlear implant Hearing aid Adult Quality of life
Introduction Due to advancements in electronic technology and better understanding of auditory science, many individuals with K. Baumstarck-Barrau Medical Statistics Laboratory, La Timone University, 13385 Marseille Cedex 5, France e-mail: [email protected] R. Meller J. P. Lavieille Department of Otolaryngology Head and Neck Surgery, Nord Hospital, 13915 Marseille Cedex 20, France e-mail: [email protected] J. P. Lavieille e-mail: [email protected]
J. Mancini Public Health Department, APHM, La Timone Hospital, 13385 Marseille, France
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bilateral severe to profound sensorineural hearing loss have been rehabilitated with unilateral cochlear implantation. However, people who receive a cochlear implant in one ear perceive speech easily in quiet situations, but hearing is very challenging in noisy and acoustically complex situations [1]. These patients cannot use binaural hearing to enhance speech perception and sound localization because the auditory input is only available in one ear. To improve the perception of cochlear-implanted patients, it seemed obvious to add more speech information not only by improving the devices, but also by adding a contralateral implant or hearing aid. Bilateral stimulation, in prelingually deafened children using bilateral cochlear implants, improves the development of binaural hearing to localize sound sources and recognize speech. The processing is due to the ability of the auditory brainstem to integrate information from each ear despite bilateral auditory deprivation during development, and is ton topically organized [2]. In 2004, Ching recommended bimodal stimulation (cochlear implant in one ear and a conventional hearing aid in the opposite ear) as standard management for children and adults who received a cochlear implant in one ear, and who have usable residual hearing in the opposite ear [3]. Indeed, bimodal stimulation is indicated to provide the binaural advantages experienced by normal hearing subjects, arising from the combination of head shadow diffraction, binaural summation and binaural squelch effects. These effects lead to better localization ability, speech understanding in quiet and noisy environments [3–6]. From bimodal stimulation, two types of information complement each others: acoustic and electrical signals. Acoustic amplification with a hearing aid provides low frequencies of speech, containing information of the fundamental frequencies of the talker. The high frequencies are provided by electrical stimulation, and contain important linguistic information that relate to manner and place of articulation of consonants [7]. Hearing aids can provide voice pitch information that assist with segregation of competing voices and with making voicing and tonal distinctions by users of cochlear implant. Most studies showed the advantages of bimodal stimulation based on quantitative measurements of speech understanding (word and sentence recognition in quiet and in noise) and localization under various conditions [3, 5, 8– 10]. Although, much attention has focused on speech perception performance and horizontal localization ability in adults combining a cochlear implant and hearing aid, research examining real-world auditory performance has been limited. It was only reported that wearing a hearing aid in the contralateral aid can enable to a more natural sound [3, 5, 11], and to the impression that sound is heard
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in both ears rather than exclusively near the implant. Also, a combination of electric and acoustic stimulation improves music perception by adding low-frequency spectral information [12]. So, in spite of the quantitative strengths allocated to the contralateral hearing aid in cochlear implant users, the ecological complexities of human communication need a qualitative assessment by validated questionnaires. For instance, to evaluate the real life binaural benefits, Gatehouse and Noble designed a questionnaire (the SSQ) in 2004, which implicates the aspects of temporal and spatial dynamics of hearing disability [13]. In 2006, Noble and Gatehouse showed that two hearing aids offered advantages in dynamic contexts [14]. To evaluate health-related quality of life (QoL), Hinderink designed a self-assessment quality of life questionnaire, the NCIQ. It has been showed that a cochlear implant has significant effects on the social and psychological domains [15]. In case of evidence of benefits with a bimodal stimulation in real life, the clinician could be interested in predicting such results preoperatively. The amount of residual hearing before implantation has to be investigated because of an objective parameter. The use of a contralateral hearing aid provides improved low-frequency information, resulting in better performance by the cochlear implant and the hearing aid users [9, 16–19]. This study aimed to assess the subjective benefits of a hearing aid in the opposite ear in postlingually deaf adults cochlear-implanted recipients thanks to two self-standardized questionnaires, and secondly to predict the putative benefits related to the pure-tone average on the nonimplanted ear.
Patients and methods A population of 183 postlingually deaf adults implanted between 2000 and 2010 was selected to participate in the study. The criteria of inclusion were: a post-activation delay exceeding 6 months, a profound postlingual deafness beginning after 18 years, a last implant setting measured in a time window inferior to 12 months in our institution before the inclusion. For the contralateral hearing aid users, the settings of hearing aid had to be realized by one of the three audiologists of the team and had to be almost new and recent (\6 months). The use of the hearing aid had to be permanent since the implantation (at least 12 h a day), and patients were able to adjust the volume to be comfortable in all listening situations. The pure-tone average on the non-implanted ear was 96.1 dB HL (from 51.2 to 120 dB HL) for the bimodal group (CI ? HA). The thresholds in low frequencies were 85.7 dB HL in aided conditions. All the patients underwent the same surgical procedure that
Eur Arch Otorhinolaryngol
consisted of mastoidectomy, posterior tympanotomy and a total insertion electrode array through round window. For each patient, several criteria were analyzed such as gender, age at the time of the study, age at the diagnosis of deafness, age at the implantation, duration of profound deafness, duration of the cochlear implant use as well as the type of implant. Before implantation, the pure-tone average (PTA) at 500, 1,000, and 2,000 Hz was calculated for each ear and on the non-implanted ear, the low frequencies PTA (250 and 500 Hz) and the low-to-mid frequencies (250, 500, and 1,000 Hz) were also calculated.
and social (activities and social interactions, facilities during work or studies, in traffic, functioning in the home, shopping, and watching television). The scores for each item range from 0 to 100, where 0 always represents the lower quality and 100 represents the higher quality. Missing values and the category ‘‘not applicable’’ were both treated as not completed. The subject was excluded if more than three items were not completed for any subdivision.
Procedure
Statistical analysis was completed using SPSS 15.0 software. All questionnaires responses were analyzed descriptively. We used means and standard deviations (SD) to present the descriptive statistics of the quantitative data, and proportions to describe qualitative data. Non-parametric statistics were used to correlate outcomes across the various measurements. The comparison used parametric (v2 test) or non-parametric (Mann–Whitney test) statistics as appropriate. All significance tests were two-sided and statistical significance was accepted at the 0.05 level. The effect of low frequencies (250 and 500 Hz) and low-to-mid frequencies PTAs (250, 500, and 1,000 Hz) on using a hearing aid was also examined. To control for the potential confounding effects of the patient’s main characteristics, a multivariate ANOVA was used to study the group effect on outcomes with a systematic adjustment for age at the implantation, duration of profound deafness, and PTA of the contralateral ear entered as covariates.
The SSQ and NCIQ questionnaires were sent to the patient’s home with a letter in which the purpose of the study was explained. These responses were anonymous after matching them with demographical and audiological criteria. The interview approach was self-administration, without medical help for the comprehension of any items. All patients provided signed consent to participate in the study. Two questionnaires were used in the study, as described below. The speech, spatial and qualities of hearing scale (SSQ) The SSQ is a self-reported questionnaire designed by Gatehouse and Noble (2004), to measure a broad range of hearing functions, some of which are likely to implicate the binaural system [13]. The SSQ is composed of 50 items in three sections. Each item of the scale is scored using a Likert-type scale marked from 0 to 10, where 0 always represents minimal ability and 10 represents complete ability. The first section covers various aspects of hearing and speech in quiet, noise, and more challenging contexts such as following one line of speech in the presence of competing speeches, or following two streams of conversation simultaneously. The second covers classical components of spatial hearing: direction, distance and movement judgments. It evaluates stationary and dynamics events, reflecting their reality. The third section on other qualities contains items covering the segregation of sounds, recognition, clarity/naturalness, and listening effort. The Nijmegen cochlear implant questionnaire (NCIQ) This questionnaire, designed by Hinderink in 2000, is a quantifiable, self-assessment instrument of health-related quality of life specific to cochlear implant users [15]. It is divided into three domains as follows: physical (basic and advanced sound perception), psychological (self-esteem)
Statistical analysis
Results Demographical data From a population of 183 postlingually deaf adults operated between 2000 and 2010, a total of 116 patients (63.34 %) completed both questionnaires. Patients were divided into two groups according to the use of a hearing aid on the non-implanted ear and several criteria were analyzed. The entire bimodal group concerned patients who already used hearing aid on the non-implanted ear before implantation. The first group was the cochlear implant-alone group (CI, n = 54) and the bimodal group (CI ? HA, n = 62) was the second group. The demographical and clinical data of the two groups are presented in Table 1. The bimodal group did not differ from the CI-alone group with respect to demographical data (gender (p = 0.739), age (p = 0.311), age at diagnosis of deafness (p = 0.307), age at implantation (p = 0.526). There was
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Eur Arch Otorhinolaryngol Table 1 Demographic and clinical data of the two patients groups Qualitative data
Cochlear implant-alone group CI (n = 54)
Bimodal group CI ? HA (n = 62)
N
%
N
%
Males
26
41.9
21
38.9
Females
36
58.1
33
61.1
P*
Gender 0.739
Type of cochlear implant Med-el
4
6.5
7
13.0
MXM
30
48.4
26
48.1
Nucleus
28
45.2
21
38.9
Quantitative data
0.459
Mean
SD
Mean
SD
P**
Age (years)
57.8
17.3
61.3
16.2
0.311
Age at the diagnosis of deafness
25.8
19.7
30.4
20.9
0.307
Age at the implantation (years)
52.5
19.4
55.5
15.9
0.526
9.5
12.6
8.7
12.0
0.439
53.8
44.3
70.0
54.3
0.099
Duration of profound deafness (years) Duration of CI use (months) PTA implanted ear
108.4
14.9
108.7
12.1
0.758
PTA contralateral ear
105.6
13.5
96.1
18.2
0.006
96.4
20.6
85.7
24.5
0.015
100.5
16.3
90.2
20.4
0.006
Low-frequency PTA (contralateral ear) Low-to-mid frequency PTA (contralateral ear) Bold values are statistically significant at p \ 0.005
SD standard deviation, PTA pure-tone average in dB HL at 500, 1,000, 2,000 Hz, CI cochlear implant, HA hearing aid * p value, v2 test (Fisher exact test) \0.05 ** p value, Mann–Whitney test \0.05
no significative difference for the duration of profound deafness (9.5 years in the CI-alone group (SD = 12.6), and 8.7 years in the CI ? HA group (SD = 12); p = 0.439). No significant difference was found about the data linked with the implant (duration of cochlear implant use (p = 0.099) with 53.8 years in the CI-alone group (SD = 44.3) and 70 years in the CI ? HA group (SD = 54.3), type of implant (p = 0.459). All patients received either a Nucleus cochlear implant (n = 49), a Med-el cochlear implant (n = 11), or a MXM cochlear implant (n = 56) (p = 0.459). Questionnaire’s assessment The mean scores on each domain of the SSQ are listed in Table 2. The subdomain of speech hearing in quiet and all the sections of hearing qualities had better mean results for the bimodal condition compared with unilateral implantation, although statistical significance was not reached (p [ 0.05). The mean scores on each domain of the NCIQ are listed in Table 3. The CI ? HA group had better scores for all the domains. A significant difference was found only in the subdomain of basic sound perception (p = 0.007) and limitation of social activities (p = 0.031).
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There was no difference between groups for enjoying music (advanced sound perception subdomain). The rated scores were also better for the CI ? HA group for the selfesteem section, feeling at ease with company, anxiety when talking to strangers, and facility to make contact with other people. Audiological data There was no significative difference between the PTA on the implanted ear in the two groups (108.4 dB HL in the CI-alone group, and 108.7 dB HL in the CI ? HA group; p = 0.758). The CI ? HA group had significantly better pre-implant hearing levels in the non-implanted ear with a mean of 105.6 dB HL (standard deviation SD = 13.5) in the CIalone group compared with a mean hearing loss of 96.1 dB HL (SD = 18.2) in the CI ? HA group (p = 0.006). Similarly, there was a significant difference in the preimplant hearing levels between the two groups when comparing low and low-to-mid frequencies PTAs: 96.4 dB HL vs. 85.7 dB HL for low frequencies (p = 0.015), and 100.5 dB HL vs. 90.2 dB HL for low-to-mid frequencies (p = 0.006) in the CI-alone group versus the CI ? HA group, respectively (Table 1). The two groups were
Eur Arch Otorhinolaryngol Table 2 Speech spatial and other qualities of hearing scale (SSQ) questionnaire
Subdomains of SSQ
CI-alone group (n = 54)
Bimodal CI ? HA (n = 62)
Mean
Mean
SD
b
Confidence interval
P*
SD
Speech
Bold value is statistically significant at p \ 0.005 Mean ratings [and standard deviations (SD)] for each subdomain in the cochlear implant-alone (CI) and the bimodal (CI ? HA) groups CI cochlear implant, HA hearing aid * p value, Mann–Whitney test \0.05
In quiet
4.4
2.7
5.2
2.5
0.730
-0.32–1.78
0.172
In noise In speech contexts
2.1 2.6
1.8 2.3
2.3 2.7
1.9 2.2
0.224 0.137
-0.52–0.97 -0.77–1.04
0.554 0.766
Multiple speech-stream processing and switching
2.3
1.8
2.4
2.0
0.228
-0.52–0.98
0.549
Localization
3.2
2.4
3.3
2.6
-0.011
-1.03–1.01
0.983
Distance and movement
3.4
1.9
3.8
2.1
0.576
-0.25–1.41
0.174
Spatial
Qualities Identification of sounds
4.3
2.6
4.6
2.7
0.562
-0.49–1.61
0.293
Segregation
3.6
2.8
4.6
3.3
0.729
-0.58–2.02
0.274
Sound quality and naturalness
4.8
2.4
5.4
2.3
1.067
0.13–2.00
0.026
Listening effort
2.8
2.1
3.2
2.3
0.440
-0.47–1.35
0.343
significantly different in relation to the PTA on the nonimplanted ear. The mean PTA in aided conditions (bimodal group) in the low-to-mid frequency range reached 51 dB, and 49 dB in the low-frequency range.
Discussion The first goal of our study (cross-sectional design) was to evaluate whether the use of a hearing aid in the nonimplanted ear of cochlear-implanted users provided any subjective benefits with respect to Health-related Quality of Life, thanks to two self-standardized questionnaires. The questionnaires were filled 53.8 months and 70 months after the implantation, respectively, in the CI-alone and the bimodal group. The results suggested that the bimodal fitting (CI ? HA), in condition of aidable residual hearing, improved subjective auditory performances and quality of life. Indeed, the bimodal group had better results than the CI-alone group for all the sections of both questionnaires, although statistical significance was not reached for all sections (p [ 0.05). These binaural benefits from bimodal stimulation have been already demonstrated by previous authors, in terms of speech perception in noise, horizontal localization ability and functional performance in real life [3, 5, 20]. The use of a hearing aid with a cochlear implant added more fluency to voices, more natural sound quality [11], enhanced music enjoyment [21], helped them to identify the speaker in a group, and made it easier listening in background noise [3, 5, 23]. Binaural benefits were evident for bimodal users irrespective of listening experience.
The second goal of our study was to predict the putative benefits related to the pure-tone average on the nonimplanted ear. This can be made because all demographical data were similar in both groups, except for the PTA in the non-implanted ear. The bimodal group had significantly better pre-implant residual hearing levels on the nonimplanted ear (96.1 dB HL) than the CI-alone group (105.6 dB HL; p = 0.006), in particular in low-to-mid frequencies. Regardless of hearing mode, all users with aidable residual hearing in the non-implanted ear in pre-operative situation were expected to obtain better scores than cochlear implant-alone listeners. We might easily hypothesize that the residual hearing in future bimodal users would improve the quality of life scores, but this influence was debated. Indeed, simply putting a hearing aid into the non-implanted ear of anyone who has a unilateral cochlear implant cannot be expected to produce consistently good results. Some authors reported that the use of a hearing aid was not significantly correlated with residual hearing thresholds and with improvement of quality of life. In 2007, Ching reported that the amount of residual hearing on the three frequencies mean (500, 1,000, and 2,000 Hz) hearing threshold was not significantly correlated with higher bimodal scores [22]. On the contrary, in 2009, Fitzpatrick showed that 40 % of cochlear implant recipients with a PTA better than 100 dB (defined as eligible for hearing aids) opted for a consistent hearing aid use [23]. More recent studies reported that significant bimodal benefit could be obtained when the hearing aid provided amplification at all frequencies with aidable residual hearing, and not only at low frequencies (below 1,000 Hz) [18], and this bimodal fitting led to
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Eur Arch Otorhinolaryngol Table 3 Nijmegen cochlear implant questionnaire (NCIQ) to evaluate quality of life Subdomains of NCIQ
CI-alone group (n = 54)
Bimodal group CI ? HA (n = 62)
Mean
SD
Mean
SD
b
Confidence interval
P*
Physical Basic sound perception
43.7
24.7
56.4
20.8
11.47
2.13–20.81
0.017
Advanced sound perception
56.8
21.6
61.3
19.5
8.64
0.48–16.80
0.038
Speech perception
40.0
19.0
42.0
17.4
2.84
-4.6–10.28
0.451
49.4
15.5
51.1
15.4
5.17
-1.07–11.41
0.104
51.4
24.6
41.5
23.4
-7.87
-17.85–2.09
0.120
45.9
23.9
37.1
20.3
-6.82
-15.76–2.11
0.133
Psychological Self-esteem Social Activitiesa Social interactions
a
Bold values are statistically significant at p \ 0.005 Mean ratings [and standard deviations (SD)] for each subdomain in the cochlear implant-alone (CI) and the bimodal (CI ? HA) groups * p value, Mann–Whitney test \0.05 a
The higher the value, the lower the level of rated effort
CI cochlear implant, HA hearing aid
further increase in the quality of life [26]. Yoon et al. (2012) demonstrated that a bimodal benefit was associated with ‘‘good’’ aided PTA C55 dB HL at frequencies B1,000 Hz [17]. Regardless of these studies, a fine-tuning procedure is necessary so that the frequency response of the hearing aid is adjusted to maximize the use of residual hearing, and the gain for low-, mid- and high-input levels are adjusted to give the same overall loudness as in the implanted ear [7]. The inconsistent results found in some studies could be related to the different experience in hearing aid and implant use among individuals, the degree of hearing loss in the non-implanted ear, or the inadequacy of the hearing aid adjustment [7, 26].
Conclusion In the case of cochlear implant users with residual hearing in the contralateral ear, the possibility to gain benefits from a hearing aid should be considered in the evaluation before the implantation. Many studies reported binaural advantages in speech perception and localization ability from bimodal hearing. Moreover, our study brings an additional argument, which is the self-reported satisfactory result by bimodal stimulation in quality of life. As a consequence of these results, providing binaural–bimodal fittings should be the standard practice with a cochlear implant and aidable residual hearing in the contralateral ear. Conflict of interest of interest.
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The authors declare that they have no conflict
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