To evaluate the factors that limit post-cochlear implantation (CI) speech perception in prelingually deaf children.
Patients with CI were divided into two groups according to Category of Auditory Performance (CAP) scores 3 years post-CI: the poor performance group (poor performance group, CAP scores≤4, n=41) and the good performance group (good performance group, CAP scores≥5, n=85). The distribution and contribution of the potential limiting factors related to post-CI speech perception was compared.
Perinatal problems, inner ear anomalies, narrow bony cochlear nerve canal (BCNC), and intraoperative problems was significantly higher in the poor performance group than the good performance group (
This study highlights the comprehensive prediction of speech perception after CI and provides otologic surgeons with useful information for individualized preoperative counseling of CI candidates.
Since cochlear implantation (CI) became the standard procedure for managing severe to profound sensorineural hearing loss (SNHL), it has significantly enhanced speech perception in children with SNHL. Although post-CI improvement in speech perception is rapid in some patients, it is slow in others. Therefore, an investigation of patients exhibiting poor speech perception after CI is important, and the development of approaches for doing so has become a principal focus in this field.
Linguistic competence for complete speech perception is absent in most children with SNHL before and 1 year after CI. As experience in listening using the cochlear implant increases, speech perception generally improves. Pediatric cochlear implant users in particular exhibit enhanced auditory performance for up to 10 years after CI [
Speech perception in children after CI depends on several factors including demographic and hearing characteristics and the features of the implant device [
Retrospective multicenter studies have attempted to identify prognostic factors using a three-stage model of auditory performance that assesses speech perception over time [
The aim of the present study was to analyze post-CI speech perception in prelingually deaf children according to factors known to limit speech perception. Two relatively large groups were compared to provide valuable information for preoperative counseling of CI candidates.
This study was approved by the Institutional Review Board of the Clinical Research Institute of the Kyungpook National University Hospital (No. 2013-04-009-001). The requirement for informed consent was waived.
Between February 1999 and June 2009, of 242 patients who underwent CI in the Department of Otorhinolaryngology-Head and Neck Surgery at Kyungpook National University Hospital, 126 children were enrolled in the study. Patients who were followed up for less than 3 years or whose medical records were incomplete were excluded. Patients were divided into two groups according to their Category of Auditory Performance (CAP) scores 3 years post-CI. CAP is a nonlinear hierarchical scale of auditory receptive ability [
The literature was reviewed to identify well-established factors affecting CI prognosis; these are described in
Delayed CI in childhood was defined as CI performed in children between 5-years-old and 10-years-old. Perinatal problems included hyperbilirubinemia, meningitis, low birth weight, and other etiologies previously associated with SNHL. Inner ear anomalies were evaluated according to the classification system proposed by Sennaroglu [
Using the bony cochlear nerve canal (BCNC) evaluation system developed by Fatterpekar et al. [
The mean thresholds of preoperative pure tone audiograms were 101.1±10.1 dB HL in the poor performance group and 98.3±6.7 dB HL in the good performance group. Although this difference showed a trend toward significance (
The distribution of the limiting factors was compared between the two groups using the chi-square test and Student
The demographics of the experimental and good performance groups are summarized in
The distribution of limiting factors was compared between the two groups (
The experimental and good performance groups had a similar incidence of delayed CI (n=15, 36.6% and n=34, 40.0%, respectively). The mean duration of deafness in cases of delayed CI was 80.1±21.8 months in the poor performance group (n=15) and 82.8±18.0 months in the good performance group (n=34). The mean age at the time of CI was 7.7±1.9 years in the poor performance group and 7.2±1.3 years in the good performance group.
In the 19 patients with long-term deafness, the mean duration of deafness was 138.4±21.3 months in the poor performance group (n=5, 12.2%) and 136.9±15.2 months in the good performance group (n=14, 16.5%;
Eighteen patients (43.9%) in the poor performance group had perinatal problems or comorbid disorders compared with 17 (20%) in the good performance group. Febrile illness, including meningitis, was the most frequent disorder in both groups. Six patients (12.5%) in the poor performance group had comorbid disorders compared with three (3.4%) in the good performance group. Comorbid disorders in the poor performance group included Waardenburg syndrome, autism, mitochondrial myopathy, renal disease, mental restriction, developmental delay, and epilepsy. In the good performance group, two patients exhibited developmental delay and one patient had an arachnoid cyst.
Inner ear anomalies were more frequent in the poor performance group than the good performance group (
The mean BCNC width on the side of the cochlear implant was significantly smaller in the poor performance group (1.67±0.99 mm) than the good performance group (2.16±0.58 mm,
Intraoperative problems included perilymph gusher, incomplete electrode insertion, cochlear ossification, and absence of a neural response (14 patients [34.1%] in the poor performance group and 15 [17.6%] in the good performance group,
In a multiple logistic regression, the odds ratios for perinatal problems and narrow BCNC in the poor performance group compared with the good performance group were 4.878 (95% confidence interval, 0.067 to 0.625;
In this study, the limiting factors affecting post-CI speech perception were compared in poor performers and good performers
The existence of a critical period for language development in children has been well documented; their best opportunity to learn language is during their first 5 years of life. The critical period for CI, in terms of language development, in children with profound SNHL is <3.5–5 years of age. Considering that even in adults with prelingual deafness significantly improved speech perception scores after CI compared with preimplantation scores in the study by Teoh et al. [
Speech understanding in patients with long-term prelingual deafness significantly improved after CI in several studies, although performance levels varied widely. Nonetheless, long-term deafness negatively affects post-CI speech perception. Arisi et al. [
Age at the time of CI affects speech perception in children after CI, and younger children displayed more rapid post-CI improvement than older children in one study [
Perinatal problems differed significantly between the experimental and good performance groups. The most common problems were infections such as meningitis and hyperbilirubinemia and prematurity (low birth weight). Philippon et al. [
Numerous inner ear anomalies cause unwanted postsurgical outcomes. They are associated with the cochleostomy site, inadequate electrode placement and stability, facial nerve injury, perilymph leakage, and post-CI meningitis. It is universally accepted that children with more severe inner ear anomalies have poorer hearing outcomes after CI than those with less severe anomalies. Papsin [
At present, children with additional disabilities routinely undergo CI, with the aim of enhancing their interactions with the environment by improving their understanding of language and speech development. Pyman et al. [
A perilymph gusher is the pulsatile egress of clear fluid for up to 1 minute during cochleostomy. It differs from perilymph leakage, which commonly occurs after cochleostomy associated with CI, and is generally nonpulsatile. The likelihood of a perilymph gusher increases when cochleovestibular anomalies are present. However, Adunka et al. [
Estimation of cochlear nerve integrity may be of fundamental importance when selecting candidates for surgery. The frequency of narrow BCNCs was significantly different and was a significant limiting factor between the two groups. Therefore, BCNC width might substantially effect speech perception after CI, although studies of the relationship between BCNC and post-CI outcome are rare [
Most patients in this study wore the hearing aid immediately after SNHL was diagnosed, which might indirectly support the importance of early diagnosis of SNHL.
Since postoperative factors such as the number of active electrodes, insertion depth, and MAP data were not unavailable for all patients, we focused on the preoperative and intraoperative factors related to speech perception after CI to increase the reliability of the data. The findings in our study may provide otologic surgeons with useful information for individualized preoperative counseling of CI candidates and their families.
In summary, this study evaluated the effects of several limiting factors on speech perception after CI. The different distributions of the limiting factors between the experimental and good performance groups should not be interpreted as differences in their contribution to post-CI speech perception. This study highlights the complexity and difficulties associated with the prediction of speech perception after CI based on limiting factors.
▪ This study evaluated the effects of limiting gactors on speech perception after cochlear implantation (CI).
▪ The distribution of limiting factor is different from the contribution to post-CI outcome.
▪ The post-CI outcome should be comprehensively predicted based on the limiting factors.
No potential conflict of interest relevant to this article was reported.
This work was supported by Biomedical Research Institute grant, Kyungpook National University Hospital, Daegu, Republic of Korea in 2015.
Limiting factors affecting CI outcome
Factor | Description |
---|---|
Delayed CI in childhood | CI between 5 and 10 years old |
Perinatal problems | Low birth weight, meningitis, hyperbilirubinemia, etc. |
Inner ear anomalies | Criteria defined by Sennaroglu [ |
Hearing aid nonuse or short term use | Duration of use less than 3 months |
Comorbid disorders | Autism, mental restriction, etc. |
Long-term deafness | Duration of deafness ≥10 years before CI |
Bony cochlear nerve canal | Measurement defined by Fatterpekar et al. [ |
Narrow bony cochlear nerve canal in case of the width ≤1.40 mm | |
Intraoperative problems | Perilymph gusher, incomplete electrode insertion, cochlear ossification, absence of neural response |
CI, cochlear implantation.
Demographics for the poor performance group and the good performance group
Variable | Poor performance group (n=41) | Good performance group (n=85) |
---|---|---|
Male:female | 26:15 | 50:35 |
Right:left | 21:20 | 47:38 |
Device | Nucleus | Nucleus |
Mean age at the time of CI (yr) | 11.5±1.8 | 11.5±1.3 |
CAP score | 0 (n=1) | 5 (n=25) |
2 (n=4) | 6 (n=45) | |
4 (n=36) | 7 (n=15) |
CI, cochlear implantation; CAP, categories of auditory performance.
Comparison of limiting factors between 2 groups
Factor | Poor performance group (n=41) | Good performance group (n=85) | |
---|---|---|---|
Delayed cochlear implantation in childhood | 15 (36.6) | 34 (40.0) | 0.713 |
Perinatal problems | 18 (43.9) | 17 (20.0) | 0.010 |
Inner ear anomalies | 14 (34.1) | 9 (10.6) | 0.003 |
Hearing aid nonuse or short-term use | 1 (2.4) | 2 (2.4) | 0.976 |
Comorbid disorders | 5 (12.2) | 3 (3.5) | 0.112 |
Long-term deafness | 5 (12.2) | 14 (16.5) | 0.605 |
Narrow bony cochlear nerve canal | 11 (26.8) | 3 (3.5) | 0.001 |
Intraoperative problems | 14 (34.1) | 15 (17.6) | 0.045 |
Values are presented as number (%).
Estimation of limiting factors
Factor | Exp (B) (95% confidence interval) | Odds ratio | |
---|---|---|---|
Delayed cochlear implantation in childhood | 0.260 | 1.875 (0.628–5.598) | - |
Perinatal problems | 0.005 | 0.205 (0.067–0.625) | 4.878 |
Inner ear anomalies | 0.120 | 0.356 (0.097–1.311) | - |
Poor hearing aid compliance | 0.731 | 1.703 (0.082–35.426) | - |
Comorbid disorders | 0.065 | 0.165 (0.025–1.116) | - |
Long-term deafness | 0.561 | 1.550 (0.354–6.777) | - |
Narrow bony cochlear nerve canal | 0.046 | 0.209 (0.045–0.972) | 4.785 |
Intraoperative problems | 0.114 | 0.342 (0.090–1.296) | - |