A Systematic Review and Meta-analysis Examining Outcomes of Cochlear Implantation in Children With Bilateral Cochlear Nerve Deficiency.

OBJECTIVE To assess hearing and speech outcomes in pediatric patients with bilateral cochlear nerve deficiency (CND) who underwent cochlear implantation (CI) and to identify factors associated with improved outcomes. DATABASES REVIEWED PubMed, Embase, Web of Science, and Cochran databases were searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. METHODS Studies that reported hearing and speech outcomes of pediatric patients with bilateral CND who underwent CI were included. Demographics, comorbidities, inner ear abnormalities, CND classification (aplasia or hypoplasia), details of diagnostic workup, and outcomes data were extracted. Outcomes were assessed using the four-level auditory performance level (APL) scale. Meta-analysis, using Cochran-Armitage tests, was performed on patients with individual data to assess factors associated with performance. RESULTS A total of 314 papers were screened, and 40 papers with 378 total patients met inclusion criteria. A total of 339 patients had patient-level data and were included in the meta-analysis. Of the 339 patients, 19% (n = 63) of patients had no measurable stimulation, 28% (n = 95) had improved detection, 22% (n = 76) achieved closed-set speech perception, and 31% (n = 105) achieved open-set speech perception. Patients with cochlear nerve aplasia (p = 0.016) and syndromes (p < 0.001) had significantly worse APL scores relative to patients with cochlear nerve hypoplasia and patients without syndromes, respectively. CONCLUSIONS While most patients with bilateral CND benefit from CI and almost one-third of patients achieved open-set speech perception, outcomes were heterogenous and one-fifth of patients did not experience measurable benefit from CI.