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Language development thru LSL post cochlear implantation in pre-linguistic deaf children
Cochlear implants have established a remarkable record for improving hearing and language, educational, and social outcomes in pre-linguistic deaf and hard-of-hearing children. Nonetheless, despite continuous improvements, in most cases the quality of auditory input with CIs is not sufficient for implanted children to develop age-level language without habilitation.
Nearly 20 years ago, Hodges et al.(1) and Cullington et al.(2) demonstrated that implanted children who are enrolled in auditory-verbal therapy (AVT) programs performed significantly better than those in total communication (TC) programs on common batteries of speech perception and language development respectively. More recently, Geers et al reported “compelling support…for the benefits of spoken language input for promoting verbal development in children implanted by 3 years of age.”(3)
AVT is also referred to as Listening and Spoken Language (LSL), “the application and management of the most current hearing technologies, in conjunction with specific strategies that foster listening and spoken language conversations, through artful coaching of the child’s parents”(4). One important goal of LSL intervention is that children achieve age-appropriate literacy skills by third grade.
LSL intervention begins ideally at the time the child is initially diagnosed with hearing loss. The LSL professional is essential not only for facilitating listening and spoken language development, but in conditioning the child to respond to sound in preparation for early behavioral audiometry, guiding parents in managing hearing technology, providing critical diagnostic information on the child’s functional auditory skill development and preparing the child for the CI signal. As the member of the CI team who sees the child most frequently, the LSL professional can provide diagnostic information (a process called diagnostic therapy) on the status of the hearing aid trial period which can reduce the time for resolution of candidacy.
The AG Bell Academy for Listening and Spoken Language Specialist awards LSLSTM certification with two designations, Cert. AVT and Cert. AVEd to qualified professionals who have met rigorous academic, professional, post-graduate education and mentoring requirements, and have passed a certification exam. Typically, LSLS certified practitioners are licensed audiologists, speech-language pathologists, or educators of the deaf who have acquired additional training and experience in listening and spoken language theory and practice.
Nicholas and Geers (5) have shown that children who receive AVT and are implanted at 6–12 months of age achieve significantly higher scores on all studied measures of language development than those implanted at 12-18 months. Further, the advantages of implantation at 6-12 months remain constant at 4.5 years and 10.5 years of age. (6) These findings underlie the value of early resolution of the hearing aid trial.
Conversely, Geers et al. (7) found that early exposure to sign language negatively affects CI outcomes. In a controlled, prospective nationwide study of implanted children, those with sign language exposure exhibited a statistically significant disadvantage in spoken language and reading. Only 39% of implanted children with exposure to ASL achieved age-appropriate spoken language compared to 70% of those without sign language exposure.
A 2016 systematic review by Kaipa and Danser (8) included 14 studies assessing AVT intervention with implanted children. Significant benefits of AVT over other forms of habilitation were found in all three studied domains: receptive and expressive language, speech perception, and mainstreaming. A similar systematic review of the relative efficacy of AVT and TC for language development in implanted children was completed in 2017. In that study, Shoffner (9) demonstrated statistically significant advantages of AVT over TC for measures of receptive and expressive language.
Unfortunately, many CI centers have reported lack of access to AVT/LSL services for their implanted patients. Results of an Institute for Cochlear Implant Training (ICIT) nationwide survey of CI teams, circulated by the American Cochlear Implant Alliance (ACIA) (August 2018), indicate that 34.4% of implanted children in the US receive American Sign Language, Total Communication, or no formal habilitation (n = 87 CI centers). (This membership survey cannot be considered a scientific sample.)
Also in August 2018, the AG Bell Academy (Academy) reported 610 Certified LSL professionals in the US. According to the Academy, five states have no LSLS and 14 have fewer than three LSLS per state.
Early intervention programs in public-school systems often provide habilitation at no cost to families but, for a variety of reasons, such as cost or the predilection of deaf educators for American Sign Language (ASL), many tend to maintain TC approaches and offer limited access to LSL services. Noblitt et al (10) have identified several barriers to habilitation of pediatric CI recipients and call for “efforts to expand access to care… to maximize CI benefit.”
LSL/AVT is an effective form of habilitation of deaf children with CIs. An emerging literature suggests three principles of maximizing listening and spoken language development: early identification, cochlear implantation below the age of 12 months, and LSL habilitation. Additionally, post-linguistically deafened children and adults may also benefit from LSL techniques. Our best estimate appears to suggest that approximately one-third of implanted children in the US undergo ASL, TC or informal habilitation. It is likely that CI outcomes in pre-linguistic children could be markedly improved by increasing accessibility of LSL to CI teams and their patients. Further efforts to increase the availability of LSL-oriented interventionists will be necessary.