A Systematic Review of the Incidence of Cochlear Nerve Deficiency in Pediatric Single-Sided Deafness.

Objective: To evaluate the variability in cochlear nerve deficiency (CND) incidence in pediatric single-sided deafness (SSD), assess how study parameters and inclusion criteria affect these rates, and examine the diagnostic tools utilized, including magnetic resonance imaging (MRI) and computed tomography (CT), in identifying CND.

Data Sources: Databases including MEDLINE, Embase, Cochrane CENTRAL, and Web of Science.

Review Methods: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guidelines with predefined search criteria using terms related to pediatric unilateral hearing loss and CND from 2010 to January 2024. Studies were selected based on their focus on CND incidence in pediatric SSD, excluding case reports, nonhuman or adult studies, and analyses limited to bilateral deafness.

Results: Out of 518 articles screened, 17 underwent full-text review, and 10 were included. Incidence rates of CND ranged from 15.7% to 100%, with all studies using MRI and 60% using CT as an adjunct diagnostic tool. Age criteria varied: five studies included patients 18 years and older, one study included patients up to age 21 years, and four studies targeted children under 5 years, including two studies on neonates. Variability stemmed from differing inclusion criteria; studies on younger cohorts generally excluded noncongenital causes, while older children's studies were less restrictive. Additionally, two studies excluded syndromic SSD, impacting incidence rates. Larger studies show an overall incidence of 35% to 45%, which this systematic review of the literature reports as the approximate incidence of CND in SSD, with higher incidence rates observed in studies excluding syndromic causes and broader criteria linked to decreased incidence.

Conclusion: This systematic review highlights how age-specific inclusion criteria and management of syndromic causes significantly influence reported CND incidence rates in pediatric SSD, underscoring the need for standardized reporting to improve clinical understanding and treatment approaches.Level of Evidence: 1.