title: Clinical characteristics of patients with narrow bony cochlear nerve canal: is the bilateral case just a duplicate of the unilateral case?
abstract: OBJECTIVE
  To evaluate whether there is a genetic contribution to the development of narrow bony cochlear nerve canal and analyze the differences between unilateral and bilateral narrow bony cochlear nerve canal.
  
  
  METHODS
  Retrospective review.
  
  
  METHODS
  Patients diagnosed with unilateral (n=44) or bilateral (n=13) sensorineural hearing loss with narrow bony cochlear nerve canals from October 2004 to July 2011 were evaluated. The segregation ratio of hearing loss among siblings of probands was calculated. The differences in segregation ratio and other clinical characteristics were also compared.
  
  
  RESULTS
  The segregation ratio of hearing loss in siblings of patients with unilateral narrow bony cochlear nerve canal was close to zero, whereas the ratio in siblings of patients with bilateral canals was 20%. Internal auditory canal narrowing was significantly more frequently combined in unilateral than bilateral narrow bony cochlear nerve canal cases. Cochlear nerve deficiency based on magnetic resonance imaging was found in 63.6% of bilateral narrow bony cochlear nerve canal cases. Milder hearing loss was exclusively detected in bilateral cases.
  
  
  CONCLUSIONS
  Narrow bony cochlear nerve canal is not likely to have a simple Mendelian inheritance pattern, especially in unilateral cases. The contribution of a Mendelian genetic etiology to bilateral narrow bony cochlear nerve canals remains elusive. More frequent coexistence of internal auditory canal narrowing among unilateral narrow bony cochlear nerve canal cases suggests that bilateral narrow bony cochlear nerve canals are not just a duplicate of the unilateral narrow bony cochlear nerve canal.
authors: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea.
authors: Sung-Woo
authors: SW
authors: Cho
authors: Seong Il
authors: SI
authors: Kang
authors: Sung Joon
authors: SJ
authors: Park
authors: Ah Reum
authors: AR
authors: Kim
authors: Ja Won
authors: JW
authors: Koo
authors: Chong Sun
authors: CS
authors: Kim
authors: Jun Ho
authors: JH
authors: Lee
authors: Sun O
authors: SO
authors: Chang
authors: Seung-Ha
authors: SH
authors: Oh
authors: Byung Yoon
authors: BY
authors: Choi
mesh_terms: D000293:Adolescent; D000328:Adult; D001299:Audiometry; D002648:Child; D002675:Child, Preschool; D003051:Cochlea / Q000000981:diagnostic imaging*; D003056:Cochlear Nerve / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D013701:Temporal Bone / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Bony cochlear nerve canal; bilateral; internal auditory canal; narrowing; recurrence risk; unilateral