The Benefits of Bilateral Cochlear Implants for Children & Adults
Cochlear implantation is internationally recognized as the standard of care for patients with severe-to-profound hearing loss [4,28], with bilateral implantation regarded as the gold standard.
However, despite a well-established body of research highlighting the cost-effectiveness of bilateral cochlear implantation and improved quality of life outcomes, it is believed that just 4.2% of people who are eligible for cochlear implants have access to them . In many developing nations, this figure is expected to be significantly lower.
Outcomes Compared: Unilateral & Bilateral Implantation
A recent MED-EL survey identified that 18% of unilateral users said their country provides financial support for unilateral implantation only, and that 22% of current bilateral recipients surveyed had to actively pursue a second implant where funding was available . This is despite hearing experts and an ever-growing body of medical research reaching broad consensus that bilateral implantation offers clear advantages over unilateral implantation.
Studies have shown that access to binaural cues, thus enabling binaural hearing, can deliver the following benefits [1,10,19,20,29]:
- Improved speech recognition in quiet and background noise
- Enhanced sound localization
- Reduced listening effort and related fatigue
- Enriched quality of life
- Reduced head shadow effect for improved signal-to-noise ratio
- Binaural summation benefit
- Health-related quality of life
- Improved language development for children and positive impact on phonological processing skills
Parents also report their child’s responsiveness in groups, reaction time, and language acquisition to be significantly improved following bilateral implantation .
Subjective expectations of unilateral cochlear implant users also identify improved quality of life, reduced exhaustion, and better hearing in noise as the perceived potential benefits of bilateral cochlear implant use over-and-above their current listening experience .
Inter-Implant Intervals & Sequential Implantation
Robust evidence spanning decades details the long-term socio-economic and audiological outcomes that support simultaneous bilateral implantation as the recommended and safe treatment option for children .
However, the question of whether to sequentially implant existing unilateral patients is too often still discussed, with factors such as inter-implant interval, pre- or post-lingual duration of hearing loss, and unilateral performance among the core discussion topics.
“…bilateral cochlear implants (BiCI) are better than unilateral cochlear implant,
and simultaneous BiCI is preferred than the sequential cochlear implant even after
escaping the early stage of language development.” 
Importantly, research suggests that minimizing the time delay between the first and second implant is important to maximize patient outcomes [12,29]. That said, auditory deprivation is not a contraindication to cochlear implantation , and “…even after a long period of deafness and despite a prolonged inter-stage interval, sequential bilateral cochlear implantation should be considered” .
Multiple studies support this, suggesting pediatric bilateral benefits are achieved irrespective of the inter-implant interval, age, and duration of use of the second CI, with patients showing functional binaural benefit, sound localization, and improved speech perception in quiet and noise [1,16,17].
In post-lingually deafened adults, a growing body of evidence continues to highlight subjective and objective sequential benefits including speech intelligibility in quiet and noise, as well as quality of life regardless of age at implantation and inter-implant intervals [26,34].
Quality of Life Indicators Support Bilateral Cochlear Implantation
Compared to other chronic diseases such as diabetes, hypertension, angina, and heart failure, studies have shown that hearing loss has a greater impact on a person’s quality of life [14,33]. Extensive research cites social isolation, depression, cognitive decline, low self-confidence, and related health issues among the scenarios that those living with untreated hearing loss often face [27,32]. Thus, untreated hearing loss places additional hidden burdens on healthcare systems .
When evaluating Quality of Life outcomes against generic population or intervention metrices, or disease-specific measures, several studies have shown statistically significant increases in quality of life following bilateral cochlear implantation in both adults and children [5,15,22,31]. A global survey of bilateral cochlear implant users and parents also found that 99% of participants identified an improvement in their quality of life as one of the most important benefits of their bilateral implant .
Such improvements in adults have been reported across all ages, including a prospective cohort analysis of older adults ages 80+ years . In large adult study groups, statistically significant health utility gains were recorded with HUI-3 and NCIQ when comparing bilateral implantation versus unilateral implantation. When considering bilateral versus no-intervention with or without hearing aids, the health utility gain further increases. In addition, these outcomes are consistent across sequentially and simultaneously implanted patients [5,7,13,15,21,24].
Similar results are available in pediatric cohort studies, with clinicians recording statistically significant health utility gains using HUI-3 when comparing bilateral to unilateral implantation and when considering bilateral versus no treatment, with or without hearing aids [2,6,22,31].
Cost-Effectiveness of Bilateral Implantation
In children living with bilateral sensorineural hearing loss, the cost-effectiveness of bilateral intervention is clear when compared to both hearing aids and unilateral cochlear implantation [15,25]. The same has been shown for adults as a growing body of evidence indicates that bilateral cochlear implantation is cost-effective compared to no treatment, hearing aids, or unilateral implantation [11,35,36].
Importantly, simultaneous bilateral cochlear implantation is shown to be more cost-effective compared to sequential bilateral implantation in both adults and children [35,39]. In developing countries, evidence also notes the cost-effectiveness of bilateral implantation [38,41].
Achieving Universal Access to Bilateral Cochlear Implants
The decades of research outlined above provide strong evidence to support bilateral cochlear implantation. However, despite the evidence, access to bilateral cochlear implantation remains out of reach for families unable to shoulder the financial burden of private treatment in many developed and developing nations across the globe.
We encourage policymakers to engage with national and international experts, including the HEARRING Group or the Hearing Health Forum EU, to facilitate the reimbursement of bilateral cochlear implants for both children and adults.
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