Auditory Brainstem Implant (ABI) in Children With No Cochleae or Auditory Nerves

This study is a feasibility study of the Nucleus 24 ABI in children without NF2. It will be conducted as a repeated-measures, single subject experiment in order to accommodate the known variability in cochlear implant clinical results. Data obtained in the course of this study will be compared with the existing published outcome data from children with normal hearing and with cochlear implants (CIs). These comparisons may provide additional useful information about the progress of ABI subjects' performance over time. Also, this may allow the results of the current study to be utilized to design future pivotal studies of the device in the pediatric population.

Inclusion Criteria: Group 1: Prelinguistic hearing loss (birth-5 years; age at implantation of ABI 18 months-5 years) • Pre-linguistic hearing loss (birth-5 yrs.; age at ABI 18 months-5yrs) with both: * MRI +/- CT evidence of one of the following: * Cochlear nerve deficiency * Cochlear aplasia or severe hypoplasia * Severe inner ear malformation * Post-meningitis ossification * When a cochlea is present or patent, lack of significant benefit from CI despite consistent use (\>6 mo.) * No or limited speech perception ability (limited to pattern perception on closed set testing materials using the CI) * Lack of progress in auditory skills development Group 2: Post-linguistic hearing loss (\