title: Significance of unilateral enlarged vestibular aqueduct.
abstract: OBJECTIVE
  To describe the clinical phenotype of pediatric patients with unilateral enlarged vestibular aqueduct (EVA) and then to compare the findings to two clinically related phenotypes: bilateral EVA and unilateral hearing loss without EVA. In view of clinical observations and previously published data, we hypothesized that patients with unilateral EVA would have a much higher rate of contralateral hearing loss than patients with unilateral hearing loss without EVA.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Patients with unilateral or bilateral EVA were identified from a database of children with sensorineural hearing loss who were seen at a tertiary care institution between 1998 and 2010. Those with imaging findings consistent with well-established EVA criteria were identified. A comparative group of patients with unilateral hearing loss without EVA was also identified. The following specific outcome measurements were analyzed: 1) hearing loss phenotype, 2) laterality of EVA and hearing loss, 3) midpoint and operculum vestibular aqueduct measurements, and 4) genetic test results.
  
  
  RESULTS
  Of the 144 patients who met our inclusion criteria, 74 (51.4%) had unilateral EVA. There was a strong correlation between the presence of hearing loss and ears with EVA. Fifty-five percent of patients with unilateral EVA had hearing loss in the contralateral ear; in most of these patients, the hearing loss was bilateral. Contralateral hearing loss occurred in only 6% of patients with unilateral hearing loss without EVA. No significant differences were found in temporal bone measurements between the ears of patients with unilateral EVA and ipsilateral hearing loss and all ears with EVA and normal hearing (P = .4). There was no difference in the rate of hearing loss progression in patients with unilateral EVA between ears with or without EVA (16 of 48 [33.3%] vs. 9 of 27 [33.3%], respectively; P = 1.0). There was no difference in the rate of hearing loss progression in patients with bilateral and unilateral EVA (41 of 89 ears [46.1%] vs. 25 of 75 ears [33.3%], respectively; P = .1); however, both EVA groups had higher rates of progression compared to patients with unilateral hearing loss without EVA. There was a strong correlation between the presence of hearing loss at 250 Hz and the risk of more severe hearing loss and progressive hearing loss. Patients with bilateral EVA and SLC26A4 mutations had a higher rate of progression than patients who had no mutations (P = .02). No patients with unilateral EVA had Pendred syndrome.
  
  
  CONCLUSIONS
  Children with unilateral EVA have a significant risk of hearing loss progression. Hearing loss in the ear contralateral to the EVA is common, suggesting that unilateral EVA is a bilateral process despite an initial unilateral imaging finding. In contrast to bilateral EVA, unilateral EVA is not associated with Pendred syndrome and may have a different etiology. Temporal bone measurements, hearing loss severity, and hearing loss at 250 Hz were all correlated with the risk of progressive hearing loss. Clinicians should become knowledgeable regarding the implications of this disease process so that families can be counseled appropriately.
authors: Ear and Hearing Center, Division of Pediatric Otolaryngology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA. John.Greinwald@cchmc.org
authors: John
authors: J
authors: Greinwald
authors: Alessandro
authors: A
authors: DeAlarcon
authors: Aliza
authors: A
authors: Cohen
authors: Trina
authors: T
authors: Uwiera
authors: Keijan
authors: K
authors: Zhang
authors: Corning
authors: C
authors: Benton
authors: Mark
authors: M
authors: Halstead
authors: Jareen
authors: J
authors: Meinzen-Derr
mesh_terms: D001301:Audiometry, Pure-Tone; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005820:Genetic Testing; D006319:Hearing Loss, Sensorineural / Q000150:complications / Q000175:diagnosis / Q000209:etiology* / Q000235:genetics; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D009154:Mutation; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D000076988:Sulfate Transporters; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014723:Vestibular Aqueduct / Q000002:abnormalities
chemical_list: D026901:Membrane Transport Proteins; C085609:SLC26A4 protein, human; D000076988:Sulfate Transporters; D004247:DNA