Language Development in Children With Cochlear Implants and Speech-language Therapy Interventions

Overview

Cochlear implantation is currently offered to children with severe to profound prelingual hearing loss for whom hearing aids alone are insufficient to provide access to oral language (HAS, 2009). Speech-language therapy should be implemented concurrently to support the development of oral language (HAS, 2006). Several speech therapy approaches can be proposed. The auditory-phonological (AP) approach, recommended by HAS (HAS, 2006), is a child-centered rehabilitation method that relies on visual aids such as Cued Speech or French Sign Language (LSF) to supplement the auditory information transmitted by cochlear implants. Auditory-Verbal Therapy (AVT), widely developed in some countries, remains innovative in France. This therapy is more parent-centered, aiming to teach caregivers how to model language to optimally stimulate their child's language development. It excludes the use of visual aids such as Cued Speech or LSF and relies solely on auditory stimulation provided by cochlear implants. When implemented, AVT should be initiated as early as possible to achieve the best language outcomes. The frequency of speech therapy sessions following implantation is also not standardized. Various international recommendations emphasize early, regular, and family-centered intervention. However, high-level evidence on the relationship between session frequency and language development is limited. A similar observation applies to parental involvement. Although it is recognized as essential for language development in implanted children's speech therapy, few studies provide a consensus on how to implement parental involvement during therapy sessions.

Hearing loss is the most common sensory disability in children worldwide. The development of hearing aids and cochlear implants now allows children to access oral language development. The latest recommendations from the French National Authority for Health (HAS, 2011) advocate for early auditory intervention as soon as hearing loss is diagnosed. In cases of severe to profound hearing loss, when hearing aids do not provide sufficient auditory access, cochlear implantation should be proposed to parents as early as possible, ideally before 12 months of age. Concurrently, speech-language therapy should be initiated to support the child's auditory and oral language development. Therapy should begin as early as the diagnosis allows, ideally within the first months of life (HAS, 2006). Various therapy approaches and modalities are currently proposed. According to HAS recommendations (2009), two main approaches are described for rehabilitating deaf children: the visuo-gestural approach and the auditory-phonological (AP) approach. The visuo-gestural approach prioritizes gestural communication without stimulating the auditory pathway and does not necessarily amplify residual hearing. Its goal is to support the child in learning a visual language, namely French Sign Language (LSF). In contrast, the AP approach aims to develop the child's oral language by stimulating the auditory pathway early, using hearing aids or cochlear implants. In AP, spoken input to the child is complemented by visual aids such as Cued Speech (CS) or signed French (FS). While no consensus exists on the preferred use of FS or CS, recommendations support interventions with complementary gestural support, excluding spoken language alone. A more recent method, Auditory-Verbal Therapy (AVT), has emerged, emphasizing parental involvement. AVT considers parents as primary agents in their child's language development. Trained speech therapists guide parents on how to optimally stimulate their child's hearing and language in everyday situations. The main goal is to teach parents to model their language in a way that supports precise perceptual and language objectives (Estabrooks, 2020). Unlike traditional therapy focused on the child, AVT centers on parental objectives: parental language modeling directly supports the child's language development. AVT relies exclusively on auditory stimulation, without gestural or visual supports, and requires early auditory intervention via hearing aids or cochlear implants. The method differs from AP by focusing on parental objectives and excluding visual supports. Early implementation is essential for optimal language outcomes (Salhi, 2019). While short-term therapy may not fully compensate for initial language delays (Dornan et al., 2007; Jackson et al., 2014), continuation can bring children to age-appropriate language levels after 2-3 years (Dornan et al., 2009, 2010). In France, AVT remains innovative: a recent survey showed that only 1% of professionals use AVT, while 68% use FS and 46% use CS (Van Bogaert, Loevenbruck \& Vilain, 2024). Parents who received AVT reported higher satisfaction and greater progress compared to other interventions. Several studies have compared perceptual and language outcomes in children receiving different therapy methods. Some studies found no significant differences, suggesting that therapy type has limited impact on language development (Yanbay et al., 2014). In these studies, intergroup variability, particularly age at implantation, was a major factor influencing outcomes (Dettman et al., 2013). Other studies indicate that AVT over 2 years post-implantation improves the likelihood of age-appropriate language outcomes, making therapy type a key determinant (Percy-Smith et al., 2018). Thomas et al. (2019) reported superior perceptual and language outcomes over seven consecutive years for children receiving AVT. Early French studies suggest AVT may enhance certain language skills, while CS exposure may be equally effective for others (Van Bogaert, 2024). Overall, existing studies provide inconsistent evidence, and heterogeneity in age at implantation remains a major limitation. In practice, the frequency of speech therapy sessions varies widely. European and American guidelines emphasize early, regular, and family-centered intervention (De Raeve et al., 2023; ACIA, 2015). In France, HAS recommends early and regular follow-up but does not specify session frequency (HAS, 2009). To date, only one study has specifically examined the number of sessions for implanted children (Mallene, 2021), and high-level evidence remains limited (De Raeve et al., 2023). Parental involvement is recognized as a key factor in speech therapy for deaf children (De Raeve et al., 2023; ACIA, 2015). Several studies show that structured parental coaching improves both parent-child communication and the child's oral language development. However, no consensus exists regarding implementation strategies for parental involvement in therapy for implanted children (Giallini et al., 2021). No French study has yet examined the impact of parental involvement on language outcomes in implanted children.