August 12 Highlights

Abstract

Murofushi et al. studied the site of lesions in “vestibular neuritis” using galvanic vestibular evoked myogenic potentials. Among the 11 patients diagnosed with vestibular neuritis, eight showed a neuritis pattern whereas three showed a labyrinthitis pattern. see page 417 Commentary by Michael Halmagyi and James Colebatch It is over a decade since Neurology published the first report of a short latency vestibulo-collic reflex we called the vestibular evoked myogenic potential (VEMP), recordable from anterior neck muscles, specifically the sternomastoid, in response to loud clicks.1 Since then, the VEMP has been studied in vestibular laboratories worldwide and has been shown to have application in the assessment of a range of vestibular disorders, including superior semicircular canal dehiscence, Meniere disease, multiple sclerosis, brainstem infarction, vestibular neuritis, and vestibular schwannomas.2 The definition of this vestibulo-collic reflex pathway has allowed the development of other novel methods of vestibular activation such as head tapping, mastoid bone vibration, and the technique used in this article, short duration galvanic (DC) currents. A galvanic current applied to the mastoid directly activates vestibular nerve endings. Murofushi and coworkers have produced much of the new clinical work in the last 5 years on VEMP. They previously reported that galvanic VEMP can separate vestibular nerve (retro- labyrinthine) lesions from vestibular end-organ (labyrinthine) lesions. They now turn their attention to defining the level of the pathology in vestibular neuritis. Sudden, isolated, total or subtotal, unilateral loss of vestibular function can occur during viral infections such as mumps and herpes zoster and perhaps herpes simplex. As a result, this form of unilateral loss of vestibular function has, like sudden unilateral loss of facial nerve function, …