July 2020 The Hearing Journal
Cochlear implantation is well established as the standard treatment option for children with severe to profound sensorineural hearing loss (SNHL), and more than half of this population receives cochlear implants (CIs) when appropriately fit amplification is unsuccessful. In 1990, CIs were approved by the U.S. Food and Drug Administration (FDA) for paediatric patients aged 24 months and older with profound SNHL who receive no auditory benefit from hearing aids. Since then, the FDA candidacy criteria have expanded to include severe to profound SNHL in children 24 months to 17 years old who score <30 percent on open-set speech tasks, profound SNHL in children as young as 9 months old, and single-sided deafness (SSD) or asymmetric hearing loss (AHL) in children 5 years and older with profound SNHL in the poorer ear. Expansion of CI candidacy for children younger than 1 year old is supported by evidence that earlier cochlear implantation is safe and associated with improvements in speech understanding and language development. Additionally, emerging evidence suggests enhancements in speech understanding in quiet and in noise for children with SSD and CI.
Despite the recent expansion of paediatric CI candidacy criteria, they continue to be more restrictive than those used for adults. Presently, any child with a hearing level better than severe to profound SNHL and/or an open set speech score greater than 30 percent is considered an off-label or non-traditional CI candidate. One study suggests a growing number of paediatric CI cases for non-traditional candidates with positive outcomes. And a recent survey of CI surgeons at various implant centres revealed 78 percent reported performing off-label CI surgeries for non-traditional indications within the past two years, including implanting children under 12 months of age, children with asymmetrical hearing loss, and children with SSD. While these numbers are encouraging, the truth remains that non-traditional paediatric CI candidates are not consistently referred to CI centres, and as a result, these children may have access to a CI at different times if at all. To complicate matters further, CI candidacy guidelines vary across manufacturer and insurer, which can lead to confusion for clinical providers who manage paediatric patients with hearing loss.
PROTOCOLS & REFERRAL CRITERIA
Identifying patients who should be considered for off-label cochlear implantation can be difficult since inconsistencies in assessment protocols exist across paediatric audiology clinics, particularly in the selection of speech perception tasks used for aided testing. The Paediatric Minimum Speech Test Battery (PMSTB) was developed in 2017 as a standardised clinical assessment protocol to aid in continuity of care and provide a guide to monitor auditory progress in the paediatric hearing loss population. Developmentally appropriate speech perception tests are administered by the audiologist, and a hierarchy of materials is used to track progression from basic tasks of pattern perception to complex tasks of listening in noise and at soft speech levels. For children who are unable to perform speech perception tasks, subjective parent or patient questionnaires can be included in the functional assessment of the child. The PMSTB should be conducted on ALL children with hearing loss to properly assess their aided benefit with hearing technology, regardless of the type of technology used. Real ear measurements alone do not provide adequate information about how a child performs with amplification. Application of the PMSTB aids clinicians and families in decision-making for the appropriate treatment of the hearing loss, and identifies those who need to be referred for a formal CI evaluation.
A variety of populations and hearing loss configurations do not always meet traditional CI candidacy criteria. However, a referral for a formal CI evaluation should not be delayed since research shows that cochlear implantation is beneficial for paediatric patients with less severe hearing loss than current indications and open-set aided speech scores of >30 percent. In fact, the literature suggests children under 3 years of age with unaided pure tone average (PTA) of >60 dB HL should be evaluated for CI candidacy since they will likely benefit more from cochlear implantation than traditional amplification. Similar referral criteria were recently outlined for the adult population in a study by Zwolan and colleagues, where they proposed patients with a PTA of >60 dB HL and unaided word recognition score of <60 percent should be referred for a CI evaluation since these referral criteria were effective in identifying CI candidates. While this study did not include the paediatric population, clinicians may wish to consider applying the 60/60 referral guideline for older children with hearing loss. Patients with AHL or bilateral hearing loss better than severe to profound levels are often overlooked for CI consideration when they have adequate spoken language skills for mainstream education. Yet these children may struggle academically even when wearing appropriately fit amplification. Evaluations with the PMSTB at soft speech and in-noise conditions are essential for this population to determine functional performance with hearing aids in more complex listening conditions.
The expanded indications for paediatric cochlear implantation extend to children with hearing loss and additional disabilities. Historically, CI centres did not readily implant children who were syndromic and/or multiply involved since language acquisition was the primary goal for CI surgery. Over time, CI surgical numbers for children with additional disabilities have increased as a result of clinics adjusting their paediatric cochlear implantation selection criteria. Approximately 30-40 percent of children with hearing loss have additional disabilities, including but not limited to vision loss, sensory disorders such as autism, syndromes, learning disorders, cognitive disorders, global developmental delay, auditory neuropathy spectrum disorder (ANSD), and birth trauma. CI outcomes vary across disorders and often vary within the same syndrome, yet results are typically favourable. When evaluating children with additional disabilities for CI candidacy, it is imperative to assess each child on an individual basis and discuss realistic expectations with the child's multidisciplinary care team since this will aid in establishing attainable post-implantation goals. In some cases, pre- and post-operative evaluations of audibility may be completed using less traditional rating systems such as Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) instead of the traditional auditory tasks outlined in the PMSTB. It is important to note that the timing of CI surgery may be delayed for children with additional disabilities due to their complex medical needs. Regardless, research shows post-operative improvements in sound awareness, speech intelligibility, language skills, quality of life, and interactions with family and peers. Therefore, clinicians should refer children with additional disabilities for a CI evaluation as soon as limited audibility with amplification is established.
In summary, when determining if a child is a CI candidate, hearing health care professionals must look beyond the unaided audiogram and real ear measurements and evaluate the auditory performance of the whole child. Early and appropriate access to auditory input is critical to the child's overall development and academic success. Therefore, children with poor audibility and/or difficulty with auditory skill development, as evidenced by aided assessments using the PMSTB, should be carefully considered for cochlear implantation even if they are non-traditional candidates. Additionally, a multi-disciplinary team approach is strongly recommended to thoroughly assess the child's medical history, speech/language development, hearing technology, family's realistic expectations, and therapeutic and educational opportunities available throughout the CI process. Removing the constraints of traditional CI criteria and evaluating children with hearing loss in a more thoughtful way will allow for improved access to paediatric cochlear implantation.