Speech and Hearing after Cochlear Implantation in Children with Inner Ear Malformation and Cochlear Nerve Deficiency

Despite wide possibilities of morphological deformities, our series have shown prevalence of several malformation types, IP-II (incomplete partition type II) being most frequent followed by IP-I (incomplete partition type I) and CC (common cavity). The speech perception and production outcomes after cochlear implantation were best in IP-II, which were comparable to those in controls without malformation, followed by IP-I and CC. It is important to note, however, that significant improvement in speech perception was observed even in CC anomaly, which is the severest malformation included in the present study. The number of functioning electrodes was less than default in some ears with CC and IP-I deformities, and adjustments of the current level and pulse width were necessary in some electrodes in these groups. The electrophysiological and audiometric data in CC deformity indicated that auditory neuronal elements are mainly distributed in the anteroinferior part of the cavity. Both the relative diameter of the vestibulocochlear nerve and the presence or absence of reproducible electrically evoked brainstem responses were significantly associated with cochlear implant outcomes in patients with cochlear nerve deficiency.