Abstract

Introduction: Auditory brain stem implantation (ABI) is an implantable electrode device to treat neural hearing loss, where cochlear implantation (CI) is not possible. ABI system consists of a receiver-stimulator, electrode array and electrode plate internally and a speech processor, microphone and transmitter coil externally. The device is kept on the cochlear nucleus and it stimulates the nucleus by which the patient perceives sound. Knowledge of the anatomical landmarks and variants in anatomy of the brainstem is vital for auditory brainstem implant surgery. Pediatric Auditory Brainstem Implantation is indicated for children with congenital cochlear aplasia, absent/hypoplastic vestibulocochlear nerve (VCN), for whom cochlear implantation is not possible.
Methodology: Retro prospective study (From 2006 till 2017) at Auditory implant centre in Madras ENT Research Foundation, which includes 24 children who had undergone ABI surgery and are being followed up for 1 year, post operatively. Aims were to study the anatomical variants and the outcomes of auditory brainstem implant implantation. To determine if different anatomical variants effect placement of ABI electrode. To assess the outcomes by Categories of auditory Performance (CAP) scores and Speech Intelligibility Ratings (SIR) scores.
Results: All the candidates had significant audiological and verbal outcomes after the auditory brainstem implantation. Though, there was difficulty in insertion of the electrode in subjects with anatomical variants, the outcomes were comparable with other subjects.

Keywords: Sensorineural hearing loss; ABI and electrodes; Anatomical variants; Cerebellar flocculus; Lateral recess; CAP and SIR scores; Outcomes