Incomplete cochlear partition type II variants as an indicator of congenital partial deafness: a first report

The increased understanding on the impact of partial deafness (PD) with residual low-frequency hearing has led to new hearing rehabilitation strategies using hearing preservation techniques during cochlear implantation with the aim to make use of the combined electric acoustic stimulation (EAS) in the affected ear. As a first report, we describe minor forms of the incomplete cochlear partition type II (IP- II) involving the apical 1.5 turns, which were found in the majority of our patients presenting with congenital PD. We investigated the hearing preservation rates and hearing outcomes of these patients after EAS cochlear implantation (EAS-CI).

We present a review of a case series of 4 children and 1 adult with documented congenital PD. They all underwent audiologic and radiologic assessment for CI. Hearing preservation rates and speech perception outcomes were assessed at 1, 3, 6, 12, and 24 months after EAS-CI.

Three (75%) of the 4 pediatric patients and 1 adult patient with congenital PD showed the pattern of isolated IP-II variants involving the apical 1.5 cochlear turns with a normal basal turn, without associated inner ear anomalies. Complete hearing was preserved in all patients. Speech performance improved significantly in all patients.

As a first report, we describe minor IP-II variants identified in the majority of our patients with congenital PD; these IP-II variants could be useful as an indicator of malformation for congenital PD. Detection requires careful radiologic evaluation of the cochlea. EAS-CI is not a contraindication in these patients and should be considered early to prevent permanent speech and language deficits.