Abstract
In the initial assessment of the patient with acute vertigo or dizziness, both structured history-taking and a targeted bedside neuro-otological examination are essential for distinguishing potentially life-threatening central vestibular causes from those of benign, self-limited peripheral labyrinthine origin and thus for deciding on further diagnostic testing. In this article, the key elements of the vestibular and ocular motor examination, which should be obtained at the bedside in these acutely dizzy patients, will be discussed. Specifically, this will include the following five domains: ocular stability for (I) nystagmus and for (II) eye position (skew deviation), (III) the head-impulse test (HIT), (IV) postural stability, and (V) ocular motor deficits of saccades, smooth pursuit eye movements, and optokinetic nystagmus. We will also discuss the diagnostic accuracy of specific combinations of these bedside tests (i.e. HIT, testing for nystagmus and vertical divergence, referred to as the H.I.N.T.S. three-step examination), emphasizing that the targeted neuro-otological bedside examination is more sensitive for identifying central causes in acute prolonged vertigo and dizziness than early MRI of the brain.
Highlights
Acute vertigo or dizziness is one of the most frequent single causes for patients to present to the emergency department (ED), representing between 2.1% and 4.4% of all consultations[1,2,3,4] and causing annual costs of about 9 billion dollars.[5,6]
Its aim is to provide tools to the clinician that facilitates the distinction between acute central and peripheral vestibular causes and non-vestibular causes of vertigo and dizziness at the bedside. This is especially true for acute prolonged vertigo or dizziness in association with nausea/vomiting, gait imbalance, motion intolerance, and nystagmus Here the distinction between dangerous, potentially life-threatening central causes such as vertebrobasilar stroke on the one hand and benign, self
When evaluating such spontaneous jerk nystagmus, several elements should be assessed, including the main beating direction of the nystagmus, the effect of fixation and its suppression and its modulation depending on eye position
Summary
Damage to the peripheral or central structures of the vestibular or ocular motor system may result in eye drift (“slow phase”), usually interrupted by compensatory saccadic eye movements (“fast phase”), bringing the eyes back to the desired position When evaluating such spontaneous jerk nystagmus (i.e. nystagmus elicited while looking straight-ahead), several elements should be assessed, including the main beating direction of the nystagmus (horizontal vs vertical vs torsional vs diagonal), the effect of fixation and its suppression (typically a peripheral-type nystagmus can be suppressed or diminished on fixation— is increased on fixation suppression—while lacking visual fixation suppression favors a central cause) and its modulation depending on eye position (i.e. whether it follows Alexander’s law—see further below). A three-step bedside testing battery called H.I.N.T.S. includes the head impulse test, testing for GEN and skew deviation (see Table 1 for details) This has been shown to distinguish peripheral from central causes with high sensitivity and specificity in patients with acute prolonged vertigo or dizziness accompanied by either spontaneous or GEN.[18,19] Adding a fourth sign (ipsilateral new-onset hearing loss) increases the sensitivity of H.I.N.T.S. Additional testing of the saccade and smooth pursuit systems (see below) increases the sensitivity for detecting a central origin
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