title: Is microvascular compression of the vestibulocochlear nerve a cause of unilateral hearing loss?
abstract: OBJECTIVE
  We sought to confirm earlier findings in the literature that microvascular compression of the vestibulocochlear nerve might cause unilateral sensorineural hearing loss. We measured the length and width of the internal auditory canal (IAC) to investigate a possible association between a narrow porus, the presence of an anterior inferior cerebellar artery (AICA) loop, and the development of a microvascular compression syndrome.
  
  
  METHODS
  We performed a prospective blinded analysis of 167 magnetic resonance imaging scans of the cerebellopontine angle. The presence of an AICA loop was scored. We analyzed these 167 patients for unilateral sensorineural hearing loss, which was defined as an interaural difference of 20 dB at 1 frequency or 10 dB at 2 or more frequencies. Furthermore, the width and length of the IAC on magnetic resonance imaging were measured.
  
  
  RESULTS
  An AICA loop was identified in 94% of the 167 patients. There were 196 type I loops, 106 type II loops, and 14 type III loops. Sixty-six patients had unexplained unilateral hearing loss. There was no association between type II and III vascular loops, the width of the IAC, and unilateral hearing loss (p > .05).
  
  
  CONCLUSIONS
  In this study we found no association between the depth of extension of the AICA loop into the IAC and the presence of unilateral hearing loss.
authors.affiliation: Department of Otorhinolaryngology, University Medical Center Utrecht, The Netherlands.
authors.forename: Femke
authors.initials: F
authors.lastname: van der Steenstraten
authors.forename: J Alexander
authors.initials: JA
authors.lastname: de Ru
authors.forename: Theo D
authors.initials: TD
authors.lastname: Witkamp
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001301:Audiometry, Pure-Tone; D002531:Cerebellum / Q000098:blood supply*; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D012189:Retrospective Studies; D000159:Vestibulocochlear Nerve / Q000098:blood supply*; D000160:Vestibulocochlear Nerve Diseases / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology