Miriam S Welgampola1. 1. Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, NSW, Australia. miriam@icn.usyd.edu.au
Abstract
PURPOSE OF REVIEW: To outline clinically applicable and evolving evoked potential techniques in neuro-otology. RECENT FINDINGS: Vestibular evoked potentials can be recorded from the averaged electromyogram of actively contracting sternocleidomastoid muscles (cervical vestibular evoked myogenic potentials) using air-conducted sound, bone-conducted vibration or direct current stimulation of the mastoid. Typical cervical vestibular evoked myogenic potential changes in common peripheral and central vestibulopathies are now known. A sound or vibration evoked vestibulo-ocular response has recently been recorded from averaged extra-ocular muscle electromyograms using surface recordings beneath the eye (ocular vestibular evoked myogenic potentials). Both techniques enable assessment of otolith function, and are sensitive screening tests for the superior canal dehiscence syndrome presenting with sound and pressure sensitivity. Vestibular evoked potentials recorded from human masseter muscles and from scalp electrodes are new techniques whose characteristics are still being explored. SUMMARY: Vestibular evoked potentials to nonphysiological stimuli can be recorded from cervical and extra-ocular muscles. They enable assessment of otolith organs, complement conventional tests of semicircular canal function and can be easily established in a neurology or otology practice.
PURPOSE OF REVIEW: To outline clinically applicable and evolving evoked potential techniques in neuro-otology. RECENT FINDINGS: Vestibular evoked potentials can be recorded from the averaged electromyogram of actively contracting sternocleidomastoid muscles (cervical vestibular evoked myogenic potentials) using air-conducted sound, bone-conducted vibration or direct current stimulation of the mastoid. Typical cervical vestibular evoked myogenic potential changes in common peripheral and central vestibulopathies are now known. A sound or vibration evoked vestibulo-ocular response has recently been recorded from averaged extra-ocular muscle electromyograms using surface recordings beneath the eye (ocular vestibular evoked myogenic potentials). Both techniques enable assessment of otolith function, and are sensitive screening tests for the superior canal dehiscence syndrome presenting with sound and pressure sensitivity. Vestibular evoked potentials recorded from human masseter muscles and from scalp electrodes are new techniques whose characteristics are still being explored. SUMMARY: Vestibular evoked potentials to nonphysiological stimuli can be recorded from cervical and extra-ocular muscles. They enable assessment of otolith organs, complement conventional tests of semicircular canal function and can be easily established in a neurology or otology practice.