Exploring factors that affect the age of cochlear implantation in children

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Abstract

Objective

Early access to sound through early cochlear implantation has been widely advocated for children who do not derive sufficient benefit from acoustic amplification. Early identification through newborn hearing screening should lead to earlier intervention including earlier cochlear implantation when appropriate. Despite earlier diagnosis and the trend towards early implantation, many children are still implanted well into their preschool years. The purpose of this study was to examine the factors that affected late cochlear implantation in children with early onset permanent sensorineural hearing loss.

Methods

Data were examined for 43 children with cochlear implants who were part of a group of 71 children with hearing loss enrolled in a Canadian outcomes study. Eighteen (41.9%) of the 43 children were identified through newborn screening and 25 (58.1%) through medical referral to audiology. Medical chart data were examined to determine age of hearing loss diagnosis, age at cochlear implant candidacy, and age at cochlear implantation. Detailed reviews were conducted to identify the factors that resulted in implantation more than 12 months after hearing loss confirmation.

Results

The median age of diagnosis of hearing loss for all 43 children was 9.0 (IQR: 5.1, 15.8) months and a median of 9.1 (IQR: 5.6, 26.8) months elapsed between diagnosis and unilateral cochlear implantation. The median age at identification for the screened groups was 3.3 months (IQR: 1.4, 7.1) but age at implantation (median 15.8 months: IQR: 5.6, 37.1) was highly variable. Eighteen of 43 children (41.9%) received a cochlear implant more than 12 months after initial hearing loss diagnosis. For many children, diagnosis of hearing loss was not equivalent to the determination of cochlear implant candidacy. Detailed reviews of audiologic profiles and study data indicated that late implantation could be accounted for primarily by progressive hearing loss (11 children), complex medical conditions (4 children) and other miscellaneous factors (3 children).

Conclusions

This study suggests that a substantial number of children will continue to receive cochlear implants well beyond their first birthday primarily due to progressive hearing loss. In addition, other medical conditions may contribute to delayed decisions in pediatric cochlear implantation.

Highlights

► Despite the availability of early cochlear implantation, many children continue to receive implants well after 1 year of age. ► Reasons for late implantation were explored. ► The primary reason for late implantation was progressive hearing loss. ► Complex medical conditions may also delay cochlear implant decision-making.

Introduction

Permanent childhood hearing loss has negative effects on typical communication development. In recent years, considerable attention has been placed on the early identification and management of hearing loss [1], [2], [3], [4] on the basis that early access to hearing will improve communication outcomes. Consequently, for children with severe to profound hearing loss, early access to sound through cochlear implantation has been widely advocated [5], [6], [7], [8], [9]. Research in neuroscience supports the notion of an optimal period for auditory development [10] and consequently minimization of auditory deprivation through early cochlear implantation in children with profound deafness [11], [12], [13]. Length of cochlear implant use has been associated with changes in the cortical auditory system [11], [14], [15]. Accordingly with improved screening and diagnostic abilities, the age of cochlear implantation has decreased to include implantation at 12 months of age or even earlier in some reports [6], [8], [16], [17].

A recent study of 188 children in the United States found better language comprehension and expression in children implanted before 18 months of age compared to those implanted after 18 months [9]. Furthermore, the majority of early-implanted children achieved language levels comparable to normal hearing peers. These results are consistent with several other studies that provide support for early implantation [5], [7], [18], [19], [20], [21]. Nicholas and Geers [18] concluded that age at implantation rather than age of diagnosis was the primary predictor of language outcomes in children who developed spoken language using cochlear implants.

Investigators have therefore advocated that implantation be provided at the youngest possible age following confirmation of severe to profound hearing loss [19], [20], [22]. Typical pediatric cochlear implant candidacy criteria include a chronological age of 12 months and severe to profound sensorineural hearing loss. Reports suggest that universal newborn hearing screening leads to earlier cochlear implantation, thus providing children with enhanced opportunities for spoken language development [7], [16], [23]. Despite the apparent trend towards early implantation and the earlier identification of children with permanent hearing loss, several recent studies that include cochlear implant cohorts report average age of implantation well beyond 12 months of age. Examples from recent studies include reports of a median age of 28.5 months for the first cochlear implant [1], a mean age of 23.16 months for 76 children age 3 years, 6 months who were first fit with hearing aids at a mean age of 12.1 months [18], and a mean age of cochlear implant activation of 29.4 months for 188 children diagnosed at a mean age of 10.6 months [9].

A Canadian survey of all pediatric cochlear implant centers in the country revealed that more than 50% of the 163–184 children implanted annually from 2000 to 2005, were more than 3 years of age at implantation [24]. Although many children included in the survey data had hearing loss identified in the absence of screening, previous research has shown that children with severe to profound hearing loss are typically identified earlier than their peers with more residual hearing [25], [26]. Therefore, the late age of implantation cannot be attributed entirely to late identification. Given the trend towards earlier implantation and universal access to cochlear implant technology in a publicly funded health care system, the authors of the survey speculated that later ages at implantation were possibly due to progressive and later onset hearing loss as well as the shift in some centers towards the implantation of children with more residual hearing. Previous research suggests that children who are borderline audiologic candidates may require more decision-making time on the part of clinicians and parents [27], [28]. Despite the evidence that early implantation is desirable, there has been little systematic investigation of the reasons for late implantation.

The purpose of this study was to examine age at cochlear implantation for children with congenital or early onset deafness before 6 months of age. We further sought to examine the relationship between age of hearing loss confirmation, age of determination of cochlear implant candidacy and age at implantation as well as to identify the factors that influenced late implantation.

Section snippets

Design

Data for this study were drawn from a prospective study that examined communication outcomes as a function of age of diagnosis in 71 pre-school age children with congenital/early onset hearing loss, who were fitted with hearing aids or cochlear implants [3]. The dataset for the current investigation included the 43 children who received cochlear implants either before entry to the study or during the three-year data collection period (2003–2006).

Participants

Participants in the study were recruited from

Results

Table 1 presents the clinical characteristics for the entire group of 43 children with cochlear implants and separately for the 18 (41.9%) screened children and the 25 (58.1%) referred children. On average, for all children, permanent bilateral sensorineural hearing loss of any degree was confirmed at a median age of 9.0 (IQR: 5.1, 15.8) months and a median of 9.1 (IQR: 5.6, 26.8) months elapsed between diagnosis and cochlear implantation. The median age at which children began assessment for

Discussion

This study examined age at identification of hearing loss and cochlear implantation in pre-school age children with early onset hearing loss. A detailed analysis of the audiologic profiles and circumstances surrounding cochlear implantation was completed for the 42% (18 of 43) of children who received cochlear implants more than 12 months after hearing loss identification. The primary factors associated with late implantation were progressive hearing loss (11 children) and the presence of

Acknowledgements

This study was supported by the Canadian Language and Literacy Research Network, the Masonic Foundation of Ontario, and the University of Ottawa. Funding through a Canadian Institutes of Health Research New Investigator Award is acknowledged for E. Fitzpatrick. We would like to thank all of the participating families as well as the many research collaborators at the Children's Hospital of Eastern Ontario, the Hospital for Sick Children and the Learning to Listen Foundation. We also thank JoAnne

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