The ocular vestibular-evoked myogenic potential to air-conducted sound; probable superior vestibular nerve origin.
OBJECTIVE
Intense air-conducted sound (ACS) elicits an ocular vestibular-evoked myogenic potential (oVEMP), and it has been suggested that it does so by stimulating saccular receptors and afferents in the inferior vestibular nerve and so activating a crossed sacculo-ocular pathway. Bone conducted vibration (BCV) also elicits an oVEMP probably by activating utricular receptors and a crossed utriculo-ocular pathway. Are there two separate pathways mediating oVEMPs for ACS and BCV? If saccular receptors and afferents are primarily responsible for the oVEMP to ACS, then the oVEMP to ACS should be normal in patients with reduced or absent utricular function--unilateral superior vestibular neuritis (SVN). If utricular receptors and afferents are primarily responsible for oVEMP n10, then oVEMP to ACS should be reduced or absent in SVN patients, and in these patients there should be a close relationship between the size of the oVEMP n10 to BCV and to ACS.


METHODS
The n10 component of the oVEMP to 500 Hz BCV and to 500 Hz ACS was recorded in 10 patients with unilateral SVN but who had saccular and inferior vestibular nerve function preserved, as shown by their normal cVEMP responses to ACS.


RESULTS
In SVN patients with normal saccular and inferior vestibular nerve function, the oVEMP n10 in response to ACS was reduced or absent. Across SVN patients there was a very close correspondence between the size of oVEMP n10 for ACS and for BCV.


CONCLUSIONS
The n10 component of the oVEMP to ACS is probably mediated predominantly by the superior vestibular nerve and so most likely by utricular receptors and afferents.


CONCLUSIONS
The n10 component of the oVEMP to either ACS or BCV probably indicates mainly superior vestibular nerve function.
Curthoys
Ian S
IS
Vestibular Research Laboratory, School of Psychology, The University of Sydney, NSW, Australia. Electronic address: ianc@psych.usyd.edu.au.
Iwasaki
Shinichi
S
Department of Otolaryngology, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
Chihara
Yasuhiro
Y
Department of Otolaryngology, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
Ushio
Munetaka
M
Department of Otolaryngology, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
McGarvie
Leigh A
LA
Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, NSW, Australia.
Burgess
Ann M
AM
Vestibular Research Laboratory, School of Psychology, The University of Sydney, NSW, Australia.
D000161:Acoustic Stimulation; D000328:Adult; D004576:Electromyography; D055724:Electrophysiological Phenomena; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008266:Macula Lutea / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009475:Neurons, Afferent / Q000502:physiology; D009801:Oculomotor Muscles / Q000294:innervation / Q000502:physiology; D012438:Saccades / Q000502:physiology; D012444:Saccule and Utricle / Q000502:physiology; D058585:Vestibular Evoked Myogenic Potentials / Q000502:physiology*; D014724:Vestibular Function Tests; D014725:Vestibular Nerve / Q000502:physiology*; D020338:Vestibular Neuronitis / Q000503:physiopathology*; D055815:Young Adult