Cochlear Implantation in Children with Cochlear Nerve Deficiency

Cochlear nerve deficiency (CND) is characterized by a small or absent cochlear nerve. It is best identified by high-resolution magnetic resonance imaging (MRI) of the internal auditory canal, as the cochlear nerves are not directly visible by high-resolution computed tomography (CT) temporal bone imaging. CND is uncommon in children with bilateral sensorineural hearing loss (SNHL), except for those with certain syndromes such as CHARGE. The presence of residual hearing does not rule out CND. CND should also be suspected when the diagnosis of auditory neuropathy/auditory synaptopathy is made on the basis of audiological findings, especially when it is unilateral. Children with bilateral CND are potential cochlear implant (CI) candidates. The implantation of children with CND requires the counseling of parents and professionals regarding a longer time course of skill emergence and the benefits of a multimodal approach to habilitation. Specialized implant programming is also necessary. In contrast to bilateral hearing loss, CND is common in congenital unilateral sensorineural hearing loss and is a contraindication to cochlear implantation. For these reasons, MRI is essential for candidacy evaluation and management of implanted children.