Hearing loss in unilateral and bilateral enlarged vestibular aqueduct syndrome

Objective: To investigate any meaningful differences in hearing between patients with unilateral and bilateral enlarged vestibular aqueduct (EVA). EVA is a common radiological finding in children presenting with hearing loss. We hope to provide insight into the pathogenesis of EVA and provide further guidelines for unilateral EVA management. We hypothesized that hearing loss in unilateral EVA would be similar to that seen in bilateral EVA. Methods: A longitudinal retrospective study design was used. Three measures of hearing, pure tone average (PTA) word recognition score (WRS) and speech awareness threshold (SAT) and radiologic morphologies were tested for difference across unilateral versus bilateral ear EVA status. Linear mixed effects models were used to identify differences while accounting for time and multiple measurements per ear. Results: Using Cincinnati criteria, 89 ears fit inclusion criteria, 75 of which were from patients with bilateral EVA compared to 14 ears from patients with unilateral EVA. No significant differences across bilateral status were observed in audiological measurements. Models showed that speech recognition threshold (SRT) (p = 0.925), word recognition score (WRS)(p = 0.521) and pure tone average (PTA) of air and bone conduction from 250 to 4000 Hz (p = 0.281-0.933) were not statistically different with respect to bilateral status. Wilcoxon rank-sum tests showed no statistical difference in vestibular aqueduct width or operculum size (VA)(p = 0.234, p = 0.623). Each year after the first audiogram was associated with significantly greater SRT (p = 0.003) decreased WRS (0.014) and increased PTA (0.003.). Greater midpoint width was associated with significantly lower SRT (p = 0.004) WRS (< 0.001) and PTA (< 0.001.) Conclusion: Our results indicate no statistically significant difference in hearing ability with respect to bilateral EVA status, suggesting that unilateral EVA patients require close follow-up. Our results also demonstrate the progressive nature of EVA and a relationship between VA midpoint width and hearing loss severity.