AUDITORY BRAINSTEM IMPLANT IN CHILDREN. AUDIOLOGIC EVALUATION AND RESULTS

Atas A (1), Sennaroglu G (1), Sevinc S (1), Yucel E (1) , Sennaroglu L (1), Ziyal I (2).
 
(1) Hacettepe University Department of Otolaryngology - Audiology and Speech Pathology; (2) Hacettepe University Department of, Neurosurgery, Ankara – Turkey.
 
Introduction: Auditory Brainstem Implant (ABI) has been aplied in children who are born deaf due to cochlear nerve aplasia or with severe degree of inner ear dysplasia and for whom a cochlear implant is not an option. Application of ABI is more complicated than Cochlear Implant. ABI electrodes have been placed in Cochlear Nucleus that is so near  to some important Cranial Nerves and electrically stimulation of Cochlear Nucleus has some risk of side effects. Fitting of ABI is also so important to decide which electrodes have effective auditory stimulation and which electrodes have side effects that must be closed. The children with cochlear nerve aplasia or with inner ear dysplasia also have risks of some limitations in Cochlear Nucleus as size and shape. These are increased the risk of side effects. We have no much more information about effects of long term electrically stimulation on cochlear nucleus in children.
 
Materials and Method: ABI was applied in 16  children (1.5-5 years old) with cochlear nerve aplasia and cochlear malformations. 15 Nucleus ABI-24 and 1 Medel Pulsar CI 100 ABI were used. Intaoperative EABR measurments were done in all children. Initial stimulation was carried out 6-8 weeks after the implantation in intensive care unit. The electrodes that caused side effects and nonauditory sensations were closed. Language and auditory development of children were evaluated in every three months
  
Results and discussion: The children that have been implanted with ABIs, were followed up every two weeks during the first three months and every three months later. Intraoperative EABR measurements indicated important tips for fitting. Fitting parameters and stimulation parameters were observed and found some changing. Numbers of open electrodes were increased and some electrodes that had nonauditory sensations were found to have auditory sensation. 
 
The numbers of electrodes had side effects were decreased during the following up. The results of ABIs in prelingual children show the good improvements in auditory plasticity and language development.   Especially changing some fitting parameters cause some extra improvement in children. Auditory sensations have been happened in lateral electrodes were thought the growth of cochlear nucleus after the stimulation.
 
Improvement in language and auditory developments were found in all children. We believe that careful surgery, intra and post-operative EABR measurments, fitting and rehabilitation will increase the benefits of ABI applications in children.

E-mail: atas@hacettepe.edu.tr