title: Radiographic diagnosis of trans-stapedial cerebrospinal fluid fistula.
abstract: OBJECTIVE
  To report the high-resolution computed tomography and magnetic resonance imaging (MRI) findings of a bulging oval window in children with recurrent meningitis and congenital cerebrospinal fluid fistula.
  
  
  METHODS
  Case series.
  
  
  METHODS
  Academic medical center children's hospital.
  
  
  METHODS
  A series of eight ears in four children with profound, bilateral sensorineural hearing loss and perilymphatic hydrops were evaluated. Two patients presented with recurrent meningitis. All children were assessed with high-resolution computed tomography, and two children also underwent MRI.
  
  
  RESULTS
  Seven of eight ears had a common cavity malformation. The vestibular compartment showed severe dysplasia (n = 5), moderate dysplasia (n = 1), or a single semicircular canal (n = 2). The lamina cribrosa was clearly absent in four of eight ears. Its presence was difficult to assess in ears with small internal auditory canals. A bulging oval window, present in six of eight ears, was defined as a fluid density on high-resolution computed tomography or a hyperintense mass demonstrated by T2-weighted MRI protruding from the vestibule into the middle ear cavity. When present, this herniation of a fluid-filled sac could be seen on both MRI and computed tomography. This imaging finding was surgically confirmed in two patients.
  
  
  CONCLUSIONS
  The bulging oval window, which represents a fluid-filled sac, can be identified by both high-resolution computed tomography and MRI. Communication between the middle ear and the subarachnoid space through the inner ear is an important etiology for recurrent meningitis in children with sensorineural hearing loss.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, UT Southwestern Medical Center at Dallas, Dallas, TX 75390-9035, USA.
authors.forename: Dale R
authors.initials: DR
authors.lastname: Ehmer
authors.forename: Timothy
authors.initials: T
authors.lastname: Booth
authors.forename: J Walter
authors.initials: JW
authors.lastname: Kutz
authors.forename: Peter S
authors.initials: PS
authors.lastname: Roland
mesh_terms: D002555:Cerebrospinal Fluid; D002648:Child; D002675:Child, Preschool; D005260:Female; D005402:Fistula / Q000000981:diagnostic imaging*; D006319:Hearing Loss, Sensorineural / Q000151:congenital / Q000000981:diagnostic imaging; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D010046:Oval Window, Ear / Q000002:abnormalities* / Q000000981:diagnostic imaging; D012665:Semicircular Canals / Q000002:abnormalities; D014057:Tomography, X-Ray Computed