Cochlear implantation is now a well-established treatment for children and adults with severe to profound deafness. Increasing awareness, acceptance, and earlier diagnosis due to the introduction of newborn hearing screening has led to an increase in the number of children with complex or additional needs being referred to cochlear implant teams for assessment.
It is estimated that some 30–40% of children with severe to profound deafness have complex or additional needs. In the context of cochlear implantation (CI) these complex or additional needs can be defined as disabilities additional to the hearing loss which impact on any part of the implantation process, which might include candidacy, pre-implant assessment, surgery, or post-operative habilitation/rehabilitation. However, many children currently managed within paediatric CI programmes have some level of special needs which do not necessitate significant departure from standard care.
A meeting was held in Basel, Switzerland in March 2012 in collaboration with Cochlear UK to discuss the management of these children. This supplement to Cochlear Implants International represents a collection of the papers presented at this meeting. The aim of the meeting was to discuss management of children with relatively severe conditions, particularly where outcomes are uncertain or difficult to assess.
The meeting addressed the following issues: (i) What are additional needs? (ii) Who should or should not be implanted? (iii) How should these children be assessed for implantation? (iv) When should implantation be performed? (v) How should the sound processor be programmed? (vi) What are the habilitation issues? (vi) How should outcomes be measured?
Characteristics of the ‘target’ population
A wide range of conditions may impact on the CI process but neurological conditions such as cerebral palsy (CP), dual sensory deprivation occurring in deaf–blind children, auditory neuropathy and behavioural issues such as autism are all important examples of complex needs.
The paper by Aziz and Vassallo explores the diagnosis and assessment of children with CP. CP is not a single entity but a collection of disorders with different causes and consequences, due to (non-progressive) damage to the developing brain before 2–4 years of age. It is relatively common (c. 2.5/1000 births), with an incidence of hearing loss of around 5–10% (depending on level) and a 50% incidence of cognitive impairment that is difficult to identify early. Diagnosis and management of the wide range of disabilities in CP is often complex and time consuming. Cognitive and motor impairment may affect both the ability to assess the child's hearing before implantation and their response to the implant during programming.
The complexity of the multifactorial nature of potential disabilities is discussed by Bowcott (Bristol) in her paper on communication in normally hearing children with CP and other conditions, from a speech and language therapist perspective. Motor skills assessment is extremely important in these children and a range of non-verbal methods of communication are used, some of which require special equipment. It is vital that we understand the nature of these needs that exist even in the absence of hearing loss. Understanding the expected speech and language outcomes in normally hearing children with neurological conditions provides a useful benchmark against which to assess the outcome of CI in this group. It also highlights the failure of current outcome measures for CI in providing a fair assessment for outcomes in this disadvantaged group.
The clinical presentation of autism spectrum disorder (ASD) is discussed by Jennifer Robertson (Dublin), who presents data suggesting prevalence of about 0.75% in Ireland, with boys affected more than girls (4:1 ratio). Incidence of ASD is considerably higher (5%) among the hearing impaired population, however. Children with ASD have significant difficulties with certain aspects of communication and so pose unique challenges for the CI process.
Cochlear implant assessment and candidacy
Children with complex needs often pose difficulties in all three of the areas of pre-implant assessment (i.e. audiological, medical/surgical, and psycho-social). Greater emphasis on objective audiological measures is required in this population especially where the child has significant motor or cognitive impairment preventing normal behavioural testing. However, behavioural thresholds are still required for hearing aid fitting where appropriate and to rule out auditory neuropathy spectrum disorder (ANSD), and test methodology must often be modified according to a child's developmental status. ANSD is believed to account for up to 10–15% of hearing losses identified by neonatal screening, and identification of ANSD can result in some delay in implantation due to the need for behavioural thresholds. Midgley (Bristol) discusses the assessment, management, and eventual outcomes for 21 children with ANSD. Of 36 ears where the auditory brainstem response was initially absent only 13 were subsequently found to have a severe or profound hearing loss and of these only five have required a cochlear implant.
Barker and Bathgate (London) outline the modifications required for speech and language therapy (SLT) and clinical psychology assessments, respectively, when assessing children with special needs. The most common additional disabilities encountered at their centre include ANSD, learning difficulties, and dyspraxia. SLT assessments are typically performed without formal language measures, but place more emphasis on consultation with local professionals in order to clarify communicative abilities. Clinical psychology assessments often use different developmental scales and may include visual impairment assessment and screening for ASD.
Assessment was also covered by several individual case presentations. Ford (London) describes a complex case of a child with Trisomy 3P syndrome with learning difficulties and with a Mondini defect on the better ear. He suffered deterioration of his hearing over several years and eventually gained no practical benefit from his hearing aid. CI assessment took about 2 years in total, during which time extensive work was required to clarify his hearing status and communicative intent, to desensitize him to equipment and develop conditioned responses to sound. He was eventually implanted at 14 years of age with a good outcome.
Rehabilitation and outcomes
Nicola Robertson (Cochlear UK) discusses processor programming, where some of the challenges are similar to pre-implant threshold measurement. A range of objective measures (stapedius reflex thresholds, electrically evoked auditory brainstem response (ABR) and Neural Response Telemetry) can be used to identify the profile of T/C levels across the array, though some behavioural responses are also desirable for setting the overall level. Increased current level or pulse widths are required with certain cochlear abnormalities, and there is some evidence that lower pulse rates may be indicated in some aetiologies, such as auditory nerve hypoplasia. Sound processor, microphone, and transmitter coil wearing options were also described, as some children with complex needs may have limited head control or may be wheelchair bound.
The challenges involved in habilitation/rehabilitation in children with complex needs are described by Barker and Bathgate (London), and illustrate the complex and multidisciplinary nature of rehabilitation (as well as the need for a high level of parental commitment), where a rehabilitation programme needs to be planned on a highly individual basis. The benefit of Clinical Psychologist input is also highlighted, in order to deal with issues such as social communication and behavioural difficulties.
Bunne (Oslo) presents the Norwegian experience in paediatric cochlear implantation, where at least 25% of their 400 implanted children have some additional difficulty. A wide range of syndromes was encountered and the majority of non-syndromic cases were associated with prematurity and perinatal asphyxia. The most common clinical diagnoses were CP, general developmental delay and epilepsy. In Oslo they have developed a simplified 0 (‘non-user’) to 4 (‘verbal communication’) scale to indicate general CI outcomes in children with additional difficulties. Children with impairments not expected to affect speech development (n = 22) scored highly on this scale (mean of 3.8 and median of 4), whereas five of the six non-users had cognitive impairments.
Bruce (Manchester) reviews the evidence for the role of CI in children with CP and severe to profound hearing loss, and evaluates the current outcome measures in this group of patients. Prevalence of hearing loss in CP has been reported as up to 40%, but around 10% is probably more realistic, with about 3% having losses greater than 70 dB. Many children with CP have been excluded from implantation, but in Manchester a series of 36 have been implanted at 8–110 months of age. Poorer speech reception outcomes were strongly associated with cognitive impairment, but there was no clear association with physical disability.
The case examples presented by Bowcott and Ford at the meeting also demonstrated positive outcomes in children with CP and outlined the practical challenges and difficulties with the habilitatory process. Considerably more time is required in working with these children, and therapists need to be experienced and have a good understanding of the implications of additional disabilities. Habilitation is also likely to involve a wide range of professionals.
Outcomes of 22 children with ANSD are presented by Bunne. Most were premature or suffered perinatal complications, and seven had additional disabilities, yet outcomes were comparable with other implanted children. However, as they were implanted at a mean age of 3.4 years (due to the possibility of maturation) they required considerable time to catch up. The question of maturation is also discussed by Midgley. In Avon, of 36 babies with absent ABR (neonatally), 3 eventually showed normal hearing and 20 had only mild-moderate hearing losses (confirmed by behavioural testing). Five children were implanted, mostly with good outcomes.
Outcomes in ASD are presented by Jennifer Robertson. Ten children with ASD have been implanted in Dublin at ages from 2 to 13 years (most had congenital hearing loss). Some had additional difficulties (mainly cognitive/intellectual) and the majority have been inconsistent users of their device (with two total non-users). One case example was described in detail. His progress was slow, with significant behavioural difficulties, and his educational placement was in a school for the deaf. Seven years after implantation he was able to understand common phrases, but had unintelligible speech. The overall message was that such children can benefit from implantation, but outcomes are often limited, as least on ‘standard’ measures. It is also a significant problem that ASD is often not diagnosed before implantation.
Mulla and Archbold (Nottingham) discuss the parents’ perspectives of outcomes and their measurement. ‘Standard’ assessment, based mainly on speech and language abilities, may not be adequate for special needs children, where everyday use of the device is often the major issue. Some CI centres assess special needs children in the same way as all others, and recent qualitative research suggests that parents often do not understand the purpose or the meaning of these outcome measures. Parents report a range of subjective and behavioural benefits which are not typically assessed formally. They also recognize the inadequacies of some educational environments, both in terms of physical conditions (reverberation, specialized equipment) and expertise (e.g. shortage of teachers of the deaf).
Conclusions
Children with complex or additional needs represent a significant proportion of children with a severe to profound hearing loss and will therefore become an increasing part of the workload of a paediatric CI team. Many of these children have traditionally not been implanted due to late or non-presentation, concerns about other health issues and lack of information about possible outcomes following CI. Assessment in these children is often delayed due to late presentation or difficulty in establishing the level of hearing loss and any benefit from hearing aids. More reliance on objective measures is necessary to avoid undue delay in implantation leading to poorer outcomes in this group of children who are already disadvantaged.
It is apparent that a significant number of these children do get benefit from a cochlear implant but traditional measures for assessing the outcome are unlikely to accurately reflect the actual success. There is an urgent need for new outcome measures for these children.
Acknowledgements
We would like to acknowledge the contributions from all the speakers and delegates at the meeting. We would also like to thank John Graham for his advice in organising the meeting and in preparing this supplement and to thank Cochlear UK for their sponsorship of the meeting and this supplement.