목적: Two radiological conditions, the unilateral- and bilateral enlarged vestibular aqueduct (EVA), represent extremes in terms of genetic etiology thereby raising questions that there may be a difference in terms of the pattern of hearing progression between unilateral- and bilateral EVA. To our knowledge, there is a paucity of research on the detailed audiological profile in reference to unilateral EVA. We, herein, investigate the audiological characteristics and natural course of residual hearing in patients with EVA for future reference. 방법:We reviewed the in-house database on EVA at Seoul national university hospital. The detailed clinical and radiological profiles, including threshold shift, audiogram configuration, genetic variants, and EVA size, were retrieved. Specifically, progression of hearing loss with reference to unilateral EVA was assessed in only individuals who had follow-up audiogram at least two-time points (> 3 months). Additionally, the exclusion criteria were as follows: initial hearing threshold > 90dB and confounders, such as a history of ear surgery and temporal bone tumors. 결과:A total of 68 patients with unilateral EVA were included. The average age was 10.6 (range 0-68) at ascertainment. Right-sided unilateral EVA was predominant, comprising 63.2% (N=43). Specifically, a family history of hearing loss was noted in 4 cases (5.9%), including Waardenburg syndrome, Pendred syndrome, and Kabuki syndrome. Among the 19 patients with serial audiogram data set, unilateral- and bilateral hearing loss at the time of inclusion were observed in 12 (63.2%) and 7 (36.8%), respectively. Importantly, in cases of unilateral EVA with bilateral hearing loss, 5 (41.6%) had hearing deterioration bilaterally, revealing no association of hearing progression with the presence of EVA. Further, cases of unilateral EVA with unilateral hearing loss turned out to exhibit unilateral deterioration consistent with the affected side. In addition, no correlation of EVA size and the extent of threshold shift was identified in this study. 결론:Taken together, a subset of patients with unilateral EVA had progression of hearing loss either in a unilateral- or bilateral manner. The differential progressive nature of hearing loss, depending on initial involvement of hearing loss, is possible in unilateral EVA, which may provide implications of tailored rehabilitation and timely intervention.