title: Superior canal dehiscence reveals concomitant unilateral utricular loss (UUL).
abstract: CONCLUSIONS
  We report enhanced symmetrical cervical vestibular evoked myogenic potential (cVEMP) but asymmetrical ocular VEMP (oVEMP) responses in a patient with CT-verified bilateral superior semicircular canal dehiscence (SCD) but with acute vestibular syndrome. This implies that absence of unilateral utricular macula function alone is sufficient to cause symptoms of acute vertigo. Acute vertigo should not automatically be presumed to originate from semicircular canal dysfunction.
  
  
  OBJECTIVE
  To identify the cause of an acute vertigo attack in a patient with bilateral SCD.
  
  
  METHODS
  The functional state of all peripheral vestibular sense organs was tested using the video head impulse test (vHIT) for all semicircular canals and VEMPs to air-conducted sound (ACS) or bone-conducted vibration (BCV) to test all otolith organs. The cVEMP tested mainly saccular function and the oVEMP mainly utricular function.
  
  
  RESULTS
  All semicircular canals showed normal function. The cVEMPs showed enhanced, but symmetrical saccular function. In contrast, oVEMPs showed an enhanced but asymmetric n10 component - it was greatly reduced beneath the left eye, implying decreased function in the right utricular macula. That result was confirmed using very high frequency stimuli which are effective in SCD: 4000 Hz BCV stimuli showed that oVEMP n10 was present beneath the right eye but absent beneath the left eye.
authors.affiliation: MSA ENT Academy Center , Cassino (FR) , Italy.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Manzari
authors.forename: Ann M
authors.initials: AM
authors.lastname: Burgess
authors.forename: Hamish G
authors.initials: HG
authors.lastname: MacDougall
authors.forename: Ian S
authors.initials: IS
authors.lastname: Curthoys
mesh_terms: D008267:Acoustic Maculae / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D012665:Semicircular Canals / Q000502:physiology; D014717:Vertigo / Q000209:etiology* / Q000503:physiopathology; D058585:Vestibular Evoked Myogenic Potentials
keywords: Ocular vestibular evoked myogenic potential; VEMP; otolith; saccular; vestibular