Hearing habilitation with auditory brainstem implantation in two children with cochlear nerve aplasia

Patients with aplasia and hypoplasia of the cochlear nerve have no chance o f having their hearing restored by stimulating the periphery of the auditor y system using the traditional cochlear implant. A possible approach to aud itory rehabilitation may be direct electrical stimulation of the cochlear n uclei with an auditory brainstem implant (ABI). Recently, two children, age d 4 and 3 years, respectively, with bilateral severe cochlear malformations and cochlear nerve aplasia received an ABI. The present paper reports the technique and the preliminary results of this experience. The classic retro sigmoid approach was used. The correct position of the electrodes was estim ated with the aid of EABRs and neural response telemetry (NRT). No postoper ative complications were observed. High-resolution CT scans with a bone alg orithm reconstruction technique were taken postoperatively to evaluate elec trode placement before discharge, The ABI was activated 30 days after impla ntation in both patients. To date 16 and 13 electrodes, respectively, have been activated in the two children. Three months after activation the first patient had achieved good environmental sound awareness, good speech detec tion and some speech discrimination. The second child, 1 month after activa tion, had achieved good environmental sound awareness and moderate speech d etection. To the best of our knowledge this is the first report of patients with hypoplasia of the cochlea and aplasia of the cochlear nerve, aged bel ow 5 years and treated with an ABI. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.