title: Acute hyperfibrinogenemia impairs cochlear blood flow and hearing function in guinea pigs in vivo.
abstract: OBJECTIVE
  Impairment of microcirculation is a possible cause of sudden sensorineural hearing loss (SSNHL). Fibrinogen is known as a risk factor for both microvascular dysfunction and SSNHL. Therefore, the aim of this study was to investigate the effect of elevated serum levels of fibrinogen on cochlear blood flow and hearing function in vivo.
  
  
  METHODS
  One group of guinea pigs received two consecutive injections of 100 mg fibrinogen while a control group received equimolar doses of albumin. Measurements of cochlear microcirculation by intravital microscopy and of hearing thresholds by auditory brainstem response (ABR) recordings were carried out before, after first and after second injection.
  
  
  METHODS
  Ten healthy guinea pigs were randomly assigned to a treatment group or a control group of five animals each.
  
  
  RESULTS
  Serum fibrinogen levels were elevated after the first and second injections of fibrinogen compared to basal values and control group respectively. Increasing levels of fibrinogen were paralleled by decreasing cochlear blood flow as well as increasing hearing thresholds. Hearing threshold correlated negatively with cochlear blood flow.
  
  
  CONCLUSIONS
  The effect of microcirculatory impairment on hearing function could be explained by a malfunction of the cochlear amplifier. Further investigation is needed to quantify cochlear potentials under elevated serum fibrinogen levels.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, University of Göttingen Hospital, Robert-Koch-Strasse 40, Göttingen, Germany.
authors.forename: Fritz
authors.initials: F
authors.lastname: Ihler
authors.forename: Sebastian
authors.initials: S
authors.lastname: Strieth
authors.forename: Nicos
authors.initials: N
authors.lastname: Pieri
authors.forename: Peter
authors.initials: P
authors.lastname: Göhring
authors.forename: Martin
authors.initials: M
authors.lastname: Canis
mesh_terms: D000818:Animals; D001309:Auditory Threshold; D003051:Cochlea / Q000098:blood supply*; D005260:Female; D005340:Fibrinogen / Q000378:metabolism*; D006168:Guinea Pigs; D006309:Hearing; D006319:Hearing Loss, Sensorineural / Q000209:etiology; D003639:Hearing Loss, Sudden / Q000209:etiology; D008833:Microcirculation
chemical_list: D005340:Fibrinogen