title: Delayed vestibular evoked responses to the eyes and neck in a patient with an isolated brainstem lesion.
abstract: OBJECTIVE
  Two recently described tests of the vestibular system, vestibular evoked myogenic potentials (VEMPs) and ocular vestibular evoked myogenic potentials (OVEMPs), test the descending and ascending vestibular brainstem pathways, respectively. We describe a case of a patient in whom these investigations localised the lesion and suggested its nature.
  
  
  METHODS
  VEMPs (to clicks and short duration galvanic stimulation) and OVEMPs (to clicks) were recorded.
  
  
  RESULTS
  Click- and galvanic-evoked VEMPs were delayed on the left side (by approximately 5-6 ms), and click-evoked OVEMPs were similarly delayed (by approximately 4 ms) following left-sided stimulation. Repeat testing 21 months later showed partial resolution.
  
  
  CONCLUSIONS
  The observed delays in evoked potentials suggested a demyelinating lesion. Furthermore, the similarity in delayed responses to neck and extraocular muscles was suggestive of a lesion at the root entry zone of the vestibulocochlear nerve.
  
  
  CONCLUSIONS
  VEMPs and OVEMPS may thus provide information about the location and nature of lesions affecting central vestibular pathways.
authors.affiliation: UNSW Clinical School and Prince of Wales Medical Research Institute, Institute of Neurological Sciences, High Street, Randwick, Sydney, NSW 2031, Australia.
authors.forename: Sally M
authors.initials: SM
authors.lastname: Rosengren
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Nogajski
authors.forename: Phillip D
authors.initials: PD
authors.lastname: Cremer
authors.forename: James G
authors.initials: JG
authors.lastname: Colebatch
mesh_terms: D001933:Brain Stem / Q000503:physiopathology*; D003711:Demyelinating Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D004558:Electric Stimulation; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009334:Neck Muscles / Q000503:physiopathology*; D009801:Oculomotor Muscles / Q000503:physiopathology*; D011930:Reaction Time; D014722:Vestibule, Labyrinth / Q000503:physiopathology*; D000159:Vestibulocochlear Nerve / Q000503:physiopathology