title: A nationwide study on enlargement of the vestibular aqueduct in Japan.
abstract: OBJECTIVE
  To document the clinical features and associated pure-tone audiometry data in patients with enlargement of the vestibular aqueduct (EVA), and to identify risk factors for fluctuating hearing loss (HL) and vertigo/dizziness in EVA patients.
  
  
  METHODS
  In this nationwide survey in Japan, a first survey sheet was mailed to 662 board-certified otolaryngology departments to identify the ones treating EVA patients. A second survey sheet, which contained solicited clinical information and the results of the hearing tests, was mailed to all facilities that reported treating EVA cases. We analyzed clinical information, including age at the time of the most recent evaluation, gender, EVA side, age at onset, initial symptoms, precipitating factors, and etiology from survey responses, and assessed 4-frequency (500, 1000, 2000, and 4000Hz) pure-tone average (PTA) from accompanying pure-tone audiometry data. A multivariate logistic regression analysis was utilized to identify the possible risk factors for fluctuating HL and vertigo/dizziness.
  
  
  RESULTS
  In total, 513 hospitals (response rate, 77.5%) responded to the first survey, and 113 reported treating patients with EVA. Seventy-nine out of the 113 hospitals (response rate 69.9%) responded to the second survey, and the data of 380 EVA patients were registered and analyzed. Of the 380 patients, 221 (58.2%) were female, suggesting female preponderance. The patient age ranged from 0 to 73 years (mean, 16.7 years; median, 13 years; interquartile range, 6-24 years). EVA was bilateral in 91.1% of the patients (346/380). The most prevalent initial symptom was HL (341/380), followed by vertigo/dizziness/imbalance (34/380). Sudden HL occurred secondary to head trauma in 5.3% of the patients and upper respiratory infection in 5.0%. Pure-tone audiometry showed profound HL (PTA >91dB) in 316 (52.0%) of the 608 ears in the 304 patients tested, and asymmetric HL, defined as >10dB, in 147 (48.4%) of the 304 patients. The mean PTA was 83.7dB (median, 91.3dB; interquartile range, 71.3-103.8dB), and the severity in PTA did not correlate with age. Multivariate logistic regression identified age ≥10 years (compared to age of 0-9 years), bilateral HL (compared to unilateral HL/normal hearing), a history of head trauma, and Pendred syndrome (compared to the other EVA-associated disorders) as significant risk factors for fluctuating HL and/or vertigo/dizziness.
  
  
  CONCLUSIONS
  The present nationwide survey of 380 EVA patients provided a more precise description of the clinical features, including risk factors for fluctuating HL and vertigo/dizziness.
authors.affiliation: Department of Hearing Implant Sciences, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan; Department of Otolaryngology, Tokyo Medical and Dental University School of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan. Electronic address: noguchi.oto@gmail.com.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Noguchi
authors.affiliation: Department of Otolaryngology Head and Neck Surgery, Graduate School of Medicine, University of Hokkaido, Kita 15, Nishi 7, Kita-ku, Sapporo, Hokkaido 060-8683, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fukuda
authors.affiliation: Department of Otolaryngology, School of Medicine, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Fukushima
authors.affiliation: Department of Otolaryngology, Takanoko Hospital, Takanoko-Cho 525-1, Matsuyama City, Ehime 790-0925, Japan.
authors.forename: Kiyofumi
authors.initials: K
authors.lastname: Gyo
authors.affiliation: Department of Otolaryngology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Hara
authors.affiliation: Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan; Ichinomiya Medical Treatment & Habilitation Center, 1679-2 Tomida, Ichinomiya, Aichi 496-0018, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakashima
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Keio University, School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Ogawa
authors.affiliation: Department of Otolaryngology, Kitasato University, School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 228-8555, Japan.
authors.forename: Makito
authors.initials: M
authors.lastname: Okamoto
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Iwate Medical University, 19-1 Uchimaru, Morioka, Iwate 020-8505, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sato
authors.affiliation: Department of Otolaryngology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Usami
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamasoba
authors.affiliation: Department of Health Promotion, National Institute of Public Health, 2-3-6 Minami, Wako, Saitama 351-0197, Japan.
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Yokoyama
authors.affiliation: Department of Otolaryngology, Tokyo Medical and Dental University School of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Kitamura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D002648:Child; D002675:Child, Preschool; D006259:Craniocerebral Trauma / Q000453:epidemiology; D004244:Dizziness / Q000453:epidemiology*; D005260:Female; D006044:Goiter, Nodular / Q000453:epidemiology; D006312:Hearing Loss, Bilateral / Q000453:epidemiology / Q000503:physiopathology; D006319:Hearing Loss, Sensorineural / Q000453:epidemiology* / Q000503:physiopathology; D003639:Hearing Loss, Sudden / Q000453:epidemiology* / Q000503:physiopathology; D046088:Hearing Loss, Unilateral / Q000453:epidemiology / Q000503:physiopathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012307:Risk Factors; D014717:Vertigo / Q000453:epidemiology*; D014723:Vestibular Aqueduct / Q000002:abnormalities* / Q000503:physiopathology; D055815:Young Adult
keywords: Enlarged; Fluctuation; Hearing loss; Large; Risk factor; Vertigo; Vestibular aqueduct