Variable long-term outcomes from cochlear implantation in children with hypoplastic auditory nerves

Abstract

This paper describes the outcomes in six children with hypoplastic cochlear nerves, demonstrated on magnetic resonance imaging who were selected for implantation because they had clear responses to sound, with hearing aids. In four of the six children the internal auditory canals were abnormally narrow; however in the remaining two the internal auditory canals were of normal width. After activation of their devices, all six children had auditory thresholds within the normal range for implanted congenitally deaf children. However the progress of all these children after 2 to 6 years of implant use turned out to be disappointing. Five of the children developed only the ability to detect the presence of sound, and were unable to discriminate accurately between speech sounds. They remain at Category of Auditory Performance (CAP) level 2: sign is their primary mode of communication. All fi ve children also remain at Speech Intelligibility Rating (SIR) level 2, with unintelligible connected speech. The sixth child was able to develop some understanding of common phrases through listening alone, however he remains at CAP level 4 and his SIR level also remains at 2. The benefi t of cochlear implantation in this group of children is likely to be considerably restricted. In specifi c cases it may be appropriate to offer a cochlear implant to a child with hypoplastic auditory nerves but careful counselling of the family about likely outcomes is essential.

Auditory neuropathy/dyssynchrony as a cause of failed neonatal hearing screening

“…However these data are the results of retrospective studies whereas AN/AD is defined by the combination of present TEOAE and absent ABR, and not the definition strictu senso as suggested by Rapin and Gravel. Consequently, this results in a higher prevalence of AN/AD in a population referred for hearing loss as described by Rance et al Because children diagnosed with AN/AD demand a different multidisciplinary approach and management, it is mandatory to distinguish these children from those with other etiologies of hearing loss [13,14]. The results of cochlear implantation may be less favorable in children with an hypoplastic cochlear nerve on MRI [13].…”

Effects of ROCK inhibitor Y27632 and EGFR inhibitor PD168393 on human neural precursors co-cultured with rat auditory brainstem explant

“…Stimulating residual SGNs electrically directly (Buchman http et al, 1999) with a cochlear implant (CI) can functionally replace damaged parts of the inner ear (Buchman et al, 1999), unlike hearing aids which make sounds louder by amplification. Regardless of the CI surgery success even when the SGNs population is relatively low (Clark et al, 1988), still insufficient number or poor condition of residual SGNs undermines CI performance (Bradley et al, 2008). Auditory brainstem implants, which stimulate electrically directly the CN in the brainstem bypassing the AN, have not yet proved to be satisfactory replacements for the AN, as the recipients do not achieve a considerable improvement in hearing (Otto et al, 2002).…”

Bilateral implantation in children with cochleovestibular nerve hypoplasia

“…Cochlear implantation of congenitally deaf children with inner ear malformations may involve difficulties in preoperative evaluation, surgical approach and postoperative followup [8,9]. Hypoplastic cochleovestibular nerve remains among the most difficult cases [10].…”

“…Minor CHARGE syndrome was confirmed by genetic research. The sequencing of the gene CHD7 found a heterozygote mutation of the splicing site of the intron 33: IVS33 + 1G > A [10,11].…”