title: Delineating the hearing loss in children with enlarged vestibular aqueduct.
abstract: OBJECTIVE
  To explore the clinical characteristics and audiologic outcomes in children with enlarged vestibular aqueduct (EVA).
  
  
  METHODS
  Retrospective study in a pediatric tertiary care facility.
  
  
  METHODS
  A total of 54 cases (82 ears) of children with EVA were identified with complete records, including otologic evaluation, imaging studies, and audiologic assessments. The diagnosis of EVA was confirmed by computerized tomography scan/magnetic resonance imaging of the temporal bone. Hearing status was assessed using behavioral testing or auditory brainstem response (ABR). Tympanometry, acoustic reflex, and vestibular evoked myogenic potential (VEMP) testing were also performed when appropriate.
  
  
  RESULTS
  Fifty-two percent of our EVA cases showed bilateral involvement, and 43% of all ears with EVA also had cochlear malformations, such as Mondini dysplasia. Sensorineural HL was initially diagnosed in 16 ears (20% of the total) with EVA whereas conductive or mixed HL was found in 66 ears (80% of the total). Further review of all EVA cases with sensorineural HL showed lack of proper bone conduction testing, so air-bone gaps were missed. Despite air-bone gaps in EVA ears, middle ear pressure and mobility were usually normal, along with present acoustic reflexes. VEMP responses were present with abnormally low thresholds.
  
  
  CONCLUSIONS
  Air-bone gap(s) can be found in most ears with EVA if both air and bone conduction thresholds are properly tested. Normal tympanometry, presence of acoustic reflex and low threshold VEMP responses suggest that the air-bone gap in EVA is due to an inner ear anomaly, similar to the "third" labyrinthine window syndrome.
authors.affiliation: Department of Otolaryngology and Communication Enhancement, Children's Hospital Boston, Boston, Massachusetts 02115, USA. guangwei.zhou@childrens.harvard.edu
authors.forename: Guangwei
authors.initials: G
authors.lastname: Zhou
authors.forename: Quinton
authors.initials: Q
authors.lastname: Gopen
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Kenna
mesh_terms: D000293:Adolescent; D001301:Audiometry, Pure-Tone; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D007759:Labyrinth Diseases / Q000150:complications* / Q000151:congenital / Q000175:diagnosis; D008279:Magnetic Resonance Imaging; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014723:Vestibular Aqueduct / Q000002:abnormalities*; D014724:Vestibular Function Tests / Q000379:methods