Vestibular-evoked myogenic potentials

Abstract

Purpose of review:This article reviews the literature on vestibularevoked myogenic potential testing, a short latency electromyogram evoked by high acoustic stimuli and recorded via surface electrodes over the sternocleidomastoid muscle. Applications and refinements of this technique are described for different pathologies and in adults and children. Recent findings: Various techniques for electrode placement have been described to elicit a vestibular-evoked myogenic potential response, which has been clinically investigated in normal individuals, under pathological conditions, and in adult and pediatric patients. As vestibular-evoked myogenic potential amplitude is linearly related to the level of background activity of the sternocleidomastoid muscle, maintaining steady contraction of the muscle can be challenging in some patients. Summary: Vestibular-evoked myogenic potential testing may provide additional information about the vestibular system and allow site of lesion testing (e.g. saccule and inferior vestibular nerve) in patients of all ages. Its role has yet to be defined in the diagnosis and treatment of common vestibular disorders, including Meniere's disease, vestibular neuronitis, labyrinthitis, and other diseases. Further research is needed to support its clinical usefulness in patients with balance disorders, to optimize patient selection, and to establish its cost effectiveness.

Visuospatial cognition in acute unilateral peripheral vestibulopathy

“…The caloric irrigation test was performed with the patient in the supine position and 30 0 head elevation using closed-loop water irrigators at 30°C and 44°C (irrigation time 30 s, intervals 5 min) and was characterized by induced nystagmus (SLMED, Seoul, Korea) ( 21 ), especially the slow-phase velocity to estimate unilateral weakness using Jongkees formula ( 22 ). For cervical VEMPs ( 23 ), active electrodes were placed over the middle or upper portion of the sternocleidomastoid muscle; for ocular VEMPs ( 24 ), electrodes were placed on the infraorbital margin 1 cm below the center of the contralateral lower eyelid. The VEMP results can be easily interpreted based on the asymmetry ratio (AR) of the amplitude, computed as the difference in amplitudes between the ears divided by the sum of the amplitudes in both ears ( 25 ).…”

Vestibular function testing

“…It appears to be a sensitive screening test for superior semicircular canal dehiscence, a condition in which a dehiscent superior canal causes the symptoms of sudden vertigo and nystagmus on exposure to loud noise or pressure. The role of this test has yet to be defined in the diagnosis and treatment of common vestibular disorders, including Ménière's disease, vestibular neuronitis, labyrinthitis and other diseases [12][13][14][15]. Further research is needed to support its clinical usefulness in patients with balance disorders, to optimise patient selection and to establish its cost effectiveness.…”

Evaluación electrofisiológica del sistema auditivo y vestibular

“…Los VEMPs corresponden a un examen electrofisiológico no invasivo que evalúa la función otolí-tica (utrículo y sáculo) por medio de reflejos vestíbulo-espinales (cVEMP, sáculo) y vestíbulo-ocular (oVEMP, utrículo) (37) . Estas respuestas se obtienen promediando la respuesta miogénica de latencia corta evocada por pulsos breves de sonido intensos (conducida por aire en el caso de los cVEMP), o por vibración (conducida por hueso, en el caso de los oVEMP).…”