title: Retrocochlear mass lesion in mid-frequency sudden deafness.
abstract: OBJECTIVE
  This study retrospectively reviewed all cases of mid-frequency sudden deafness to understand the clinical significance of this hallmark finding.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  From 1992 to 2006, a total of 556 patients with sudden deafness were experienced. Based on the audiographic configuration, these patients were classified into: flat-type group, 272 cases; high-frequency group, 146 cases; low-frequency group, 70 cases; mid-frequency group, 30 cases; and unclassified group, 38 cases. All patients underwent a battery of audiovestibular function testing.
  
  
  RESULTS
  Among 556 sudden deafness patients, 17 patients (3%) were proved to have a retrocochlear tumor, including mid-frequency group (10), high-frequency group (4), flat-type group (2), and low-frequency group (1). Thus, the mid-frequency group had significantly higher (33%) association with a retrocochlear tumor than other groups.
  
  
  CONCLUSIONS
  One-third of the patients with mid-frequency sudden deafness harbor a true retrocochlear mass lesion; hence, MR imaging is mandatory in such cases.
authors.affiliation: Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Yi-Tsen
authors.initials: YT
authors.lastname: Lin
authors.forename: Yi-Ho
authors.initials: YH
authors.lastname: Young
mesh_terms: D000293:Adolescent; D000328:Adult; D001301:Audiometry, Pure-Tone; D003390:Cranial Nerve Neoplasms / Q000150:complications* / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D003639:Hearing Loss, Sudden / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012720:Severity of Illness Index; D000160:Vestibulocochlear Nerve Diseases / Q000150:complications* / Q000175:diagnosis