Neural Plasticity and Hearing-Speech Development in Children with Auditory Brainstem Implants for Congenital Hearing Loss Due to Severe Inner Ear Malformation.

Hearing and speech outcomes of pediatric patients with auditory brainstem implants (ABI) are variable, and the underlying developmental mechanism remains unexplored. This study aims to evaluate the effectiveness of ABI in pediatric patients with congenital non-tumor hearing loss and elucidate the role of cortical plasticity in hearing and speech development. A prospective cohort study is conducted involving 112 consecutive pediatric patients who received ABI at a tertiary university-based referral center from January 2019 to October 2023. The mean age at the time of surgery and postoperative follow-up are 3.4±1.9 years and 25.7±11.7 months (3-48 months), respectively. The average percentage of elicited electrodes (eABR%) during the operation is 72.73±17.99%. Post-activation, hearing and speech outcomes improved steadily. Younger age at implantation (<3 years), less severe inner-ear malformation, and higher intraoperative eABR% (≥60%) are significantly associated with better hearing and speech outcomes. Mismatch negativity (MMN) responses are evoked in all children aged 12-18 months. Cortical functional connectivity developed after activation, particularly within the bilateral temporal/frontal lobes. Several factors contribute to hearing and speech development in children with ABI, and cortical plasticity plays a pivotal role. MMN amplitude and brain functional connectivity may serve as cortical indices for predicting long-term outcomes.