Auditory Neuropathy and Cochlear Implants: Theory and Treatment
Caroline Arendt, CCC-A; University of Michigan Cochlear Implant Program
Kelly Star, M.A., CCC-SLP; University of Michigan Cochlear Implant Program
Auditory Neuropathy, also called Auditory Dys-Synchrony or Auditory Neuropathy Spectrum Disorder, is a pattern of hearing loss that presents with normal Outer Hair Cell function and abnormal neural conduction (based on electrophysiological evidence like Oto-Acoustic Emissions, or OAE, testing). People with AN may have behavioral and speech detection thresholds anywhere from the normal to profound hearing loss range, and these levels can fluctuate over time. While pure tone hearing and speech detection may be less severe, the characteristics of poor low-frequency hearing and poor temporal processing of speech common to AN cause these individuals to have great difficulty with speech perception tasks. While the mechanism(s) that causes Auditory Neuropathy is not fully understood, scientists have suggested three possible sites of lesion – dysfunction of inner hair cells, synapse (connection) problems between inner hair cells and spiral ganglion nuclei, and problems with the axon of the acoustic nerve. Problems of AN could be related to one, two, or all three of these factors. In fact, the presenters hypothesized that what we currently call the “Auditory Neuropathy Spectrum” is really an umbrella term for a group of separate, specific disorders that we may someday be able to more clearly identify and treat differentially.
Risk factors for AN include:
Genetics: a non-syndromic mutation of the gene that leads to a decrease in otoferelin production crucial for hearing. In these cases, when this mutation (called DFNB9) can be identified, a cochlear implant is highly recommended, as spontaneous recovery and/or success with hearing aids is unlikely
Anatomical: problems with the cochlear nerve, also associated with narrow internal auditory canals. In these cases, a CI is also indicated, but with reservations for progress as would be expected in any patient with cochlear abnormalities
Neuropathic conditions: such as neurological conditions that affect not only the ear, but the whole person
Immaturity: low birth weight, immature auditory system, central nervous system immaturity
Idiopathic: unknown causes
When diagnosing AN, it is important to note that many patients with this condition have present OAE responses, and that a complete battery of OAE, ABR, and other testing is needed to confirm an AN diagnosis. Just because a baby passed a newborn hearing screen conducted through OAE testing alone (some hospitals do this and do not perform ABRs on all children) does not mean that Auditory Neuropathy is not present in that child.
While there have been some reported cases of spontaneous recovery from the symptoms of Auditory Neuropathy, there is no published research indicating the prevalence of this phenomenon. Instead, scientists suggest that, in cases of “recovery”, the condition should not be considered “cured”, but instead “transient” and should be monitored by professionals. Additionally, the long-term effects of “transient” AN are unknown – just because a child “recovers” doesn’t mean that there are not long-lasting effects from their first few months/years of auditory neural deprivation.
The presenters recommended obtaining ear-specific threshold information before fitting hearing aids on a person with AN, as their hearing thresholds often change and relying solely on ABR information may lead to an inappropriate fit. Remember that AN is more of a temporal processing problem than a hearing problem, so amplification with hearing aids may improve sound audibility, it does not make up for problems processing the temporal (timing) aspects of sound. An FM system is also recommended in these cases. For some children and adults with Auditory Neuropathy, however, hearing aids and FM systems are not enough. Regardless of the individual’s unaided hearing thresholds, if they are receiving therapy and still not making progress in speech understanding and auditory language development, they should be considered as a candidate for a CI. Of the thirty-one children with Auditory Neuropathy who have received cochlear implants through the University of Michigan’s program, the children had pre-operative hearing losses ranging from mild to profound Their post-CI progress has been commensurate with the progress expected from children with typical sensorineural hearing loss without AN, and many of these children and their families are pursuing bilateral implants.
The presenters closed by sharing what they have learned in their continuing effort to establish a standard of care for children with Auditory Neuropathy:
Early referral is essential
Therapy can help determine if progress can be made with spoken language with the child’s current hearing level/amplification
Cochlear implants may improve neural synchrony, resulting in improved speech recognition
Protocol includes examining the child’s case history for AN or risk factors for AN
Monitoring hearing, speech, and language closely is essential
Children may have better speech perception for shorter words (less timing interference)
Children with AN generally have poor speech intelligibility due to the unclear speech signal they hear (remember, you say what you hear!)
Though there is much to be discovered about this disorder, and a standard of care has yet to be established, the team at the University of Michigan has reported very promising results with cochlear implantation in their population of pediatric patients with Auditory Neuropathy.
AVT Model for Families Transitioning from Visual Language
Sarah Wainscott, Ph.D., CCC-A, LSLS Cert. AVEd; Chattering Children
While many families’ first choice for their children with hearing loss is a listening and spoken language approach, other families may come to Auditory-Verbal therapy later, after using signed languages, manually coded English systems, or Cued Speech with their children. Other culturally Deaf families may have a home language of ASL, but desire listening and spoken language for their children as well. This presentation aimed to give attendees strategies for understanding these families and providing them the appropriate guidance and coaching within a listening and spoken language framework.
When families who have used visual languages come to Auditory-Verbal Therapy, professionals must use their LSLS principles to coach and guide the family. Though families who sign may not be the traditional candidates for AVT, goals may include improving early intervention access and efficacy, impacting a broader continuum of children, including those who sign, and increasing language and academic outcomes for school-age children. Therapists and familes need to discuss what the family believes about Auditory-Verbal Therapy and communication in general. What are the family’s priorities? What are they already doing at home that is working? What are their challenges and how can we, the professionals, help?
Ms. Wainscott divided these “transitioning children” into four groups, each with distinct needs, and suggested tips and techniques to provide high-quality services to each group.
“Infants Exposed to Sign” (families that have instituted baby signs at home)
These families may be aggressively pursuing AVT and CIs
Their children are young, they are still exploring service types and learning about their child
They view AVT as critical and wish to capitalize on their child’s critical period for language development
Parent education should focus on the process of listening and language development
Therapists should gather information on how signs are used at home (is the family really signing or is it more gestural? Does the child imitate signs or use them independently?)
Cultivate positive professional relationships with sign-based programs
Identify opportunities for language and listening at home and in the community
GOAL: For the parent to receive all information and come to the best decision possible for their family
“Signers in Transition” (children who have been educated using manual communication whose parents wish them to transition to an oral language approach)
Priority is building proficiency in spoken language
Often underserved populations: late identified, late recipients of HAs/CIs, limited service options, families not proficient in English
Trying to make up for lost time
Oral language is the target – goal levels vary by age
Families view AVT as potentially hopeful, but may be unsure about their child’s success based on their age
Families are learning about language development and making compromises
Parent education focuses on developmental processes
Gather information on how sign is used in communication and play (What is the parents’ skill level? What is the child’s skill level?)
Work on functional skills first, then build cognitive and academic language
Collaborate with the child’s current school placement
Identify opportunities for full and accurate modeling at home, school, and community (especially if family is not native English speakers)
Famlies must commit to consistent use of optimal technology and intense exposure to spoken language
Counsel parents on realistic, optimistic progress goals
Early success is critical for motivation (for both parents and child)
Outcomes vary based upon: age at transition, family commitment, availablily of language experiences, child’s language learning capacity
“Special Needs Signers” (children with hearing loss and multiple disabilities)
Priority is access to both receptive and expressive communication
Families are pursing AVT and hearing technology, but also dealing with multiple other medical needs
Consider the child’s visual, motor, and cognitive skills
Spoken language is optimal, but the child’s receptive and expressive modes may differ (child may be able to hear and comprehend, but anatomically cannot produce speech, and must respond in sign)
View AVT as the family’s primary tool for spoken language, though they may have many other tools in their box (sign, picture communication systems, assistive technology devices for communication, etc.)
Slower pace of development and AVT progression
Gain information on pre- and para-linguistic communication in the home (Does the child make eye contact? Does the child show joint attention skills?)
The primary target is making the child available to listen and coaching the parent to identify auditory-based behaviors that ARE present in the child (blinking or turning to noise, motor imitation of vocal patterns, etc.)
Collaborate with the child’s other providers
Identify language and listening opportunities at home and in the community
“Culturally Deaf” (children of Deaf adults who use ASL as their primary mode of communication and identify with Deaf Culture)
Primary decision factors for parents choosing AVT/CI are: better educational options, more access to broader society
Usually later age of implantation
School choice is still a challenge (families often tied to state residential signing Deaf schools)
ASL is still highly valued
Families view intense oral training as temporary, and parents may have their own negative attitudes based on their own experiences with traditional speech therapy
Families who choose this route may have varying experiences/reactions from the Deaf community
Deaf community has mixed perceptions of AVT (myths and facts)
Challenges include: parents with not only a different language (ASL) but a different language modality (manual vs. oral)
Practictioners must value the integrity of both languages receptively and expressively
Therapists must identify the parameters of the therapy session and language use (for example, “I will sign the parent education portions to Mom, but in therapy, I will only speak to the child and expect her to listen and respond orally)
Appropriate expectations for outcomes are crucial
GOAL: Inform and empower parents. Build rapport and relationship with parents in their native ASL, let them know that they are valued members of the AVT team. Modify parent participation tasks common to AVT (can the parents perform a Ling sound check using an iPod rather than by voice?). Give more deliberate parent education and coaching and give specific feedback on the child’s speech (for parents who may not be able to hear and evaluate their child’s voice quality). Help parents navigate the hearing world of new school systems, educational placements, and cultural/language barriers.
GOAL: Give children frequent and deliberate language exposure to a continuum of rich language experiences. These children may have reduced opportunities to pick up spoke English through incidental language. Help parents identify language models (hearing family members, community story-reading events at local libraries, community mainstream preschool programs, or, for older children, computer software designed for English language learners) to give them the spoken English exposure they may miss.
GOAL: Complement the child’s existing educational program while still focusing on moving toward increasingly oral, increasingly inclusive placements. Incorporate your AVT therapy plan with the academic skills the child is learning in school. Make academic language a priority. Assist parents in the IEP process and communicate with, and visit, possible school placements for the child.
As professionals in Listening and Spoken Language, we possess knowledge and skills in the area of auditory development and spoken communication. When families come to us, regardless of their background or previous communication experiences, we can provide them with the best possible services for listening, language, and academic success, if that is what the family so desires.
The Auditory-Verbal Lives of Children with Multiple Challenges
For children with hearing loss in conjunction with multiple other, sometimes severe, disabiling conditions, what are the benefits of cochlear implantation and the Auditory-Verbal approach? Dr. Ritter andher team conducted a series of interviews that mixed qualitative and quantitative research to determine the factors parents considered most important when choosing CIs/AVT for their children with multiple challenges.
While much research on cochlear implants and listening and spoken language has focused on children who achieve high levels of speech intelligibility and open-set speech recognition, Dr. Ritter quoted McConkey-Robbins (2008) in arguing that, “We need to count as legitimate constructs that parents identify as making a differences, because these form the basis for hope.” So, what do parents count as legitimate? In this study, benefit #1 was “Child Affect” – parents reported that their children were happier following their cochlear implants. Parents also valued “connectedness,” receptive communication,” and improvements in relationships within their “family systems.” Surprisingly, despite the multiple medical issues and obstacles that these children and their families face, complaints about “challenges” ranked dead last in the data culled from parent interviews in this study.
Parents were interviewed on seven domains of CI/AVT benefit. While parents reported many factors that influenced their opinions of their child’s progress in each category, the parent quotes shared during this presentation spoken volumes beyond what could ever be captured by the data.
Child Affect
Reduction in self-stimulating behavior
Less effort for the child to participate in family/community interactions
Better quality attention
Child is happier overall
“He seems to be immensely happy to be socially involved in other lives. It was too hard to get him to focus, and hold focus (before the implant). Sound has definitely changed this.”
Connectedness/ Inclusion
Others interact with the child more because they know the child can hear
Child is more able to tolerate new experiences
Child’s ability to interact with others is enhanced
Child is more present, more engaged
The child has a broader social sphere and is not restricted to only those who know sign language
Child is more connected to family and peers
“At church, people will talk to her and she will smile. It takes less specialized effort to engage her, so a wider circle of people can do it successfully. She’s more present, more engaged – she’s no longer alone in the room.”
“She will turn to look at me when I make one of her favorite sounds. It is the only time she orients toward me. When she looks at me, even if it is really only to see the sound, she looks into my face and into my eyes, and I get a chance to love her with my eyes. I use her ears, to get to hear eyes, to get to her heart.”
Receptive Communication
Child turns to name
Child continues to progress in auditory comprehension (even reported progress in one subject with multiple disabilities who was over fourteen years old)
Child responds with appropriate actions to familiar songs
Child follows some routine verbal directions
Child demonstrates some open-set auditory comprehension (though many parents reported that this was inconsistent)
“I said ‘yogurt’ in conversation with my son, and happened to glance across the kitchen at my daughter and she was signing yogurt! She definitely got some, too!”
Family Systems
Family feels more “normal” to parent (Dr. Ritter shared how funny it is that parents are unafraid to use these words that professionals feel are so loaded.)
Less effort for parents and siblings to include child in family interactions
CI technology was easier for parents to manage than hearing aids
Child’s ability to interact through sounds brings the parents joy
Family has more fun with the child
Parents now feel that they have done everything possible to support the child’s optimal function
“You used to have to work so hard just to get him to look at you. Now it is effortless on our part, he’s on his own steam.”
Listening (non-linguistic)
Child responds to voices from another room
Child loves and appreciates music
Child laughs at funny sounds
Child reliability communicates when CI signal is bad or off
Child searches for environmental or voiced sound
Child removing CI headpiece is a good indicator the child’s engagement
Child independently replaces headpiece
“I am happy to see that he can at least hear his environment … and is able to dance when music comes on. I think that is what matters most, because the CI brought music into my boy’s life that was not there before.”
Expressive Communication
Child makes non-verbal efforts to engage others
Child’s vocal volume moderated to a socially acceptable level
Increase in amount and variety of vocalizations post-CI
Child uses inflection with meaning
Child imitates vocal patterns/melody
Child imitates consonant-vowel combinations
Expressive communication for these children is reported to be inconsistent
“He knows for sure that his voice has power. He has differentiated tone of voice for a long time. But now it seems more deliberate. It’s easier now to tell what his mood is from another room.”
Challenges
Child removes headpiece to get attention or to protest
Child can’t wear CI when doing some favorite things (such as roughhousing or trampoline play)
“At first she wanted nothing to do with sound and quickly learned to take it (the CI) off. We got a hat for her and my mom attached straps (helmet style) and we tied it under her chin.”
Elizabeth A. Rosenzweig 