PP1401 - Beyond Adult Norms: Improving VEMP Interpretation for Pediatric Third Window Disorders

Abstract: Despite growing pediatric vestibular research and emerging age-specific normative data, diagnostic criteria for pediatric third mobile window (TMW) disorders—particularly those involving vestibular-evoked myogenic potentials (VEMP)—remain underdefined. A structured literature review was completed to identify pediatric VEMP approaches used in evaluating TMW pathology. Findings suggest that enlarged vestibular aqueduct (EVA) is reported more frequently than superior semicircular canal dehiscence (SSCD) in children, and pediatric patients consistently show higher VEMP amplitudes and lower thresholds compared to adults. These trends highlight the potential for misclassification when adult criteria are applied and reinforce the need for pediatric-specific diagnostic standards.

Summary: Third mobile window (TMW) disorders, such as enlarged vestibular aqueduct (EVA) and superior semicircular canal dehiscence (SSCD), are well characterized in adults, but their prevalence and clinical presentation in children remain less understood. Early detection in pediatrics is critical, as vestibular dysfunction can have wide-ranging developmental consequences including gross motor delays, balance impairment, and visual acuity difficulties.

Among third window disorders, EVA has been cited as the most common structural inner ear anomaly in children with permanent hearing loss (Zhou et al., 2023). Although EVA is more frequently identified, SSCD and other rare TMWs are likely underdiagnosed due to variability in pediatric imaging and a lack of standardized vestibular testing protocols.

In recent years, vestibular-evoked myogenic potentials (VEMPs)—including ocular (oVEMP) and cervical (cVEMP) testing—have become increasingly used in pediatric populations. VEMPs are essential for identifying TMW physiology; however, interpretation remains challenging because most reference norms and diagnostic criteria are derived from adult populations. This lack of pediatric-specific standards raises concern that using adult thresholds and amplitude norms may yield false-positive results in children. Thus, this research has two aims: (1) to summarize the reported prevalence of EVA and SSCD in pediatric populations, and (2) and to review the current literature regarding the diagnostic performance of various VEMP approaches (threshold-search protocols, oVEMP vs cVEMP, and air- vs bone-conducted stimuli) with those used in adults. To further support this work, the poster will include two case examples demonstrating how reliance on adult criteria may lead to false-positive results in pediatric evaluations.

A structured, librarian-assisted search strategy was designed to capture pediatric VEMP literature relevant to TMW conditions. The search was executed in Ovid MEDLINE and applied pediatric demographic terms alongside controlled vocabulary and keyword variants for VEMPs and diagnostic accuracy concepts (e.g., sensitivity, specificity, predictive values, normative data, false-positive/negative results). The search was limited to English-language publications from the past 20 years, yielding 114 citations. Early analysis of the retrieved literature indicates that enlarged vestibular aqueduct (EVA) is reported more frequently than superior semicircular canal dehiscence (SSCD) in children, though SSCD may be underrecognized given lower rates of advanced imaging and variability in clinical suspicion. Across studies, children tend to show enhanced VEMP amplitudes and reduced thresholds when compared to adult normative data. However, variability in testing paradigms, the lack of pediatric-specific norms, and the limited number of studies specifically focused on third window VEMP testing in children significantly hinder cross-study comparability and diagnostic generalizability.

Evaluating TMW disorders in children presents unique diagnostic challenges. The cases presented and the current body of medical literature underscore the need for pediatric-specific diagnostic standards to avoid misclassification and improve the accuracy of vestibular function testing in children. Establishing age-specific VEMP norms, standardizing testing protocols, and reporting diagnostic accuracy are essential for improving identification and clinical management of EVA and SSCD in pediatric populations.