Ocular Vestibular Evoked Myogenic Potentials in Response to Bone-Conducted Vibration of the Midline Forehead at Fz : A New Indicator of Unilateral Otolithic Loss

• Published in: Audiology & neurotology Vol. 13; no. 6; pp. 396 - 404
• Main Authors: IWASAKI, S, SMULDERS, Y. E, BURGESS, A. M, MCGARVIE, L. A, MACDOUGALL, H. G, HALMAGYI, G. M, CURTHOYS, I. S
• Format: Journal Article
• Language: English
• Published: Basel Karger 2008
• Subjects: Adult; Biological and medical sciences; Bone Conduction; Electromyography - methods; Evoked Potentials; Female; Forehead - innervation; Forehead - physiology; Functional Laterality; Humans; Male; Medical sciences; Middle Aged; Nervous system (semeiology, syndromes); Nervous system as a whole; Neurology; Neuroma, Acoustic - physiopathology; Neuroma, Acoustic - surgery; Otolithic Membrane - physiopathology; Otorhinolaryngology. Stomatology; Reaction Time; Vestibular Diseases - diagnosis; Vestibular Diseases - physiopathology; Vestibular Nerve - physiology; Vestibular Nerve - surgery; Vibration; Clinical test; Nervous system diseases; Vibration; Internal ear disease; ENT; Utricular; Vestibular evoked potential; Indicator; Eye; Clinical vestibular test; Forehead; Asymmetry; Unilateral; ENT disease; Vestibular syndrome; Saccular afferents; Unilateral vestibular loss; Bone; Vestibular evoked myogenic potentials, asymmetry
• ISSN: 1420-3030; 1421-9700
• DOI: 10.1159/000148203

If a patient, who is lying supine and looking upward, is given bone-conducted vibration (BCV) of the forehead at the hairline in the midline (Fz) with a clinical reflex hammer or a powerful bone conduction vibrator, short-latency surface potentials called ocular vestibular evoked myogenic potentials (oVEMP) can be recorded from just beneath the eyes. The early negative (excitatory) component (n10) is approximately equal in amplitude for both eyes in healthy subjects, but in patients with unilateral vestibular loss, the n10 component is significantly asymmetrical under the 2 eyes - the n10 component is small or absent under the eye on the side contralateral to the prior unilateral vestibular nerve removal, but of normal amplitude under the eye on the side contralateral to the healthy ear. The n10 component of the oVEMP response to BCV at Fz stimuli reflects vestibular and probably mainly otolithic function via crossed otolithic-ocular pathways, and so n10 asymmetry is a new way of identifying the affected side in patients with unilateral otolithic loss.