An Umbrella Review of Cochlear Implant Outcomes in Children With Auditory Neuropathy

Abstract

Purpose: The objective of this overview of systematic reviews (SRs; umbrella review) was to systematically summarize and critically appraise current evidence of cochlear implant (CI) outcomes in children with auditory neuropathy spectrum disorder (ANSD). Method: This study was guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement. The methodological quality and the risk of bias in the included SRs were assessed using A MeaSurement Tool to Assess systematic Reviews 2 checklist and the Risk of Bias in Systematic Reviews tool, respectively. Results: According to eight included SRs, children with ANSD achieve CI outcomes (speech perception performance) similar to their peers with sensorineural hearing loss. In children with postsynaptic ANSD (cochlear nerve deficiency), cochlear nerve hypoplasia is associated with better speech recognition outcomes compared with cochlear nerve aplasia, especially in the absence of additional disabilities. Except for one study, the overall quality of the included SRs was critically low, and except for three studies, evidence of a high risk of bias was identified in other included SRs. Conclusions: Current evidence supports CI benefits for children with ANSD. To improve the quality of evidence, well-designed, prospective studies with appropriate sample sizes, using valid outcome measures, clarifying matching criteria, and taking into account the role of confounding factors are essential.

Predictors of cochlear implant outcomes in pediatric auditory neuropathy: A matched case-control study

“…Children with ANSD displayed no indications of CND in MRI scan reports, suggesting a potential involvement of presynaptic mechanisms in ANSD. This finding is consistent with past studies indicating that the majority of children with presynaptic ANSD can attain speech understanding, language development, and communication outcomes equivalent to their peers with SNHL [ 7 , 28 ]. However, children with postsynaptic ANSD, comprising almost 30% of children with ANSD [ 13 ], exhibit limited benefits from CIs and cannot develop functionally useful auditory communication skills [ 26 , 27 ].…”

“…However, children with postsynaptic ANSD, comprising almost 30% of children with ANSD [ 13 ], exhibit limited benefits from CIs and cannot develop functionally useful auditory communication skills [ 26 , 27 ]. Thus, in ANSD, the lesion site along the auditory pathway carries prognostic significance, in which individuals with presynaptic ANSD or distal auditory nerve lesions (such as the involvement of inner hair cells or cochlear synapses) achieve optimal outcomes compared to children with postsynaptic involvement [ 3 , 7 , 22 ].…”

“…The lesion site causing ANSD may vary from the presynaptic site of release of glutamate in the inner hair cells (IHCs) to the cochlear synapse, the postsynaptic site of neurotransmitter stimulation, the site of initiation of the excitatory postsynaptic potential (EPSP) at the terminal dendrite, or sites along the spiral ganglion, which affect auditory signal transmission along the auditory nerve to the brain [3,4]. In ANSD, deficiency in neural transmission (due to a reduced number of activated auditory nerve fibers or deafferentation) and/or neural dyssynchrony (due to progressive demyelination) are the two basic mechanisms that contribute to the disruption of neural activity and temporal resolution deficits at the auditory brainstem level [5][6][7]. Individuals with ANSD typically show difficulty with the temporal processing of sound resulting in impaired speech perception, especially in background noise [8][9][10].…”

“…Similar to children with SNHL [23], better outcomes in children with ANSD are associated with receiving hearing interventions (CIs or HAs) before three years of age [20,24,25]. While existing evidence demonstrates the benefits of CIs for both children with SNHL and ANSD [7,17,[26][27][28][29], factors with prognostic value for intervention outcomes have been less studied [24,30,31]. This matched case-control study had two main objectives: 1) To compare children with ANSD and SNHL in open-set speech perception test scores through a matched case-control study design (1:2 ratio), and 2) To identify factors that show predictive value for post-CI speech perception outcomes.…”