Hearing loss associated with enlarged vestibular aqueduct and zero or one mutant allele of SLC26A4.

OBJECTIVES/HYPOTHESIS: To characterize the severity and natural history of hearing loss, and the prevalence of having a cochlear implant in a maturing cohort of individuals with enlarged vestibular aqueduct (EVA) and zero or one mutant allele of SLC26A4.

STUDY DESIGN: Prospective cohort study of subjects ascertained between 1998 and 2015 at the National Institutes of Health Clinical Center.

METHODS: Study subjects were 127 individuals (median age, 8 years; range, 0-59 years) with EVA in at least one ear.

RESULTS: Ears with EVA and zero or one mutant allele of SLC26A4 had mean 0.5/1/2/4-kHz pure-tone averages of 62.6 and 52.9 dB HL, respectively, in contrast to EVA ears with two mutant alleles of SLC26A4 (88.1 dB HL; P < .01). This association was independent of age, sex, or side of EVA (P < .001). Natural history of hearing loss was not associated with number of mutant alleles (P = .94). The prevalence of having a cochlear implant was nine (12%) of 76, two (13%) of 15, and 12 (38%) of 32 subjects with zero, one, and two mutant alleles, respectively (P = .00833). This association was not independent (P = .534) but reflected underlying correlations with age at time of first audiogram (P = .003) or severity of hearing loss (P = .000).

CONCLUSIONS: Ears with EVA and zero or one mutant allele of SLC26A4 have less severe hearing loss, no difference in prevalence of fluctuation, and a lower prevalence of cochlear implantation in comparison to ears with two mutant alleles of SLC26A4.

LEVEL OF EVIDENCE: NA Laryngoscope, 127:E238-E243, 2017.