title: Ratio of Vestibular Endolymph in Patients with Isolated Lateral Semicircular Canal Dysplasia.
abstract: OBJECTIVE
  Isolated vestibular-lateral semicircular canal dysplasia (LSCCD) is one of the most common anomalies of the inner ear. However, endolymphatic size in LSCCD is unknown. We measured the size of the endolymph in the vestibule of patients with LSCCD and compared it with that measured in patients without LSCCD.
  
  
  METHODS
  We extracted 1102 magnetic resonance (MR) studies for the evaluation of endolymphatic hydrops (EH) from our database of radiology reports. Among these, we found 15 ears from 11 patients with LSCCD; 4 patients had bilateral abnormalities. Seven of the 15 ears demonstrated aplasia and 8 ears, hypoplasia of the lateral semicircular canal (LSCC). The control group consisted of 26 ears from 13 randomly selected patients without LSCCD. We measured the area of endolymph in the vestibule (ELA), total area of vestibular lymph fluid (TLA), and area of the central bony island (CBI) of the LSCC from axial MR images obtained after intratympanic or intravenous administration of gadolinium-based contrast material. The ratio of endolymphatic area to total lymphatic area (%EL) was defined as %EL = ELA/TLA × 100.We evaluated the correlation between %EL and the area of the CBI and compared age, %EL, degree of cochlear EH, hearing level, and presence of rotating vertigo among the 3 groups (aplasia, hypoplasia, control).
  
  
  RESULTS
  The mean %EL was 76.7% in the aplasia group, 50.0% in the hypoplasia group, and 27.8% in the control group (P < 0.001). There was a relatively strong linear correlation between the area of the CBI and %EL (r = -0.767). Patient age, mean hearing level, degree of cochlear EH, or presence of vertigo attacks did not differ significantly among the groups (P > 0.05).
  
  
  CONCLUSIONS
  The size of vestibular endolymph was larger in the groups with aplasia or hypoplasia than the control group. Thus, the current diagnostic cut-off value for significant vestibular EH (>50%) might not be appropriate for ears with LSCCD.
authors.affiliation: Department of Radiology, Nagoya University Graduate School of Medicine.
authors.forename: Shinji
authors.initials: S
authors.lastname: Naganawa
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kawai
authors.forename: Michihiko
authors.initials: M
authors.lastname: Sone
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Ikeda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D004710:Endolymph; D005260:Female; D005682:Gadolinium; D006801:Humans; D007089:Image Enhancement; D007759:Labyrinth Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012665:Semicircular Canals / Q000473:pathology*; D014722:Vestibule, Labyrinth / Q000473:pathology*; D055815:Young Adult
chemical_list: D003287:Contrast Media; D005682:Gadolinium