Vestibular Testing and Assessment

Vestibular function tests are bedside and laboratory methods that probe the vestibular end organs and their reflexes to localise balance disorders. They range from positional manoeuvres and the bedside oculomotor examination to instrumented techniques such as caloric testing, videonystagmography, the video head impulse test, and vestibular evoked myogenic potentials.

Definition

Vestibular function tests are procedures that assess the integrity of the peripheral vestibular organs, the vestibular nerve, and central vestibular pathways by measuring reflex eye movements and otolith-driven responses to controlled stimulation.

Scope

This topic surveys how the vestibulo-ocular reflex and otolith function are measured, what the principal tests assess, and how bedside examination helps separate peripheral from central disease. It is descriptive and educational and does not specify how to evaluate or manage an individual patient.

Core questions

• Which reflex or organ does each vestibular test probe?
• How can bedside oculomotor signs distinguish peripheral from central causes of acute dizziness?
• What do high-acceleration head-impulse and otolith tests add to traditional caloric testing?

Key concepts

• Caloric irrigation test
• Videonystagmography (VNG) / electronystagmography (ENG)
• Video head impulse test (vHIT)
• Vestibular evoked myogenic potentials (VEMP)
• Dix-Hallpike and supine roll manoeuvres
• HINTS bedside oculomotor examination
• Rotary chair and dynamic posturography

Mechanisms

Most tests work by stimulating a vestibular organ and observing the eye movement it should drive through the vestibulo-ocular reflex. Caloric irrigation thermally stimulates the horizontal canal at low frequency, whereas the video head impulse test measures the reflex to brief high-acceleration head turns and can interrogate individual canals (Halmagyi et al., 2017). Vestibular evoked myogenic potentials assess otolith-driven reflexes in neck and eye muscles. At the bedside, the HINTS battery combines the head-impulse test, evaluation of nystagmus, and a test of ocular skew to infer whether an acute vestibular syndrome is peripheral or central (Kattah et al., 2009).

Clinical relevance

Vestibular testing supports the localisation of balance disorders and, in the acute setting, helps flag presentations that may be central rather than peripheral. The methods illustrate how specific reflexes are translated into measurable signals. This entry describes the tests for educational purposes and is not a protocol for examining or treating any individual.

History

Caloric testing introduced by Bárány in the early twentieth century made vestibular function clinically measurable and earned a place in the history of the field. The head-impulse test described by Halmagyi and Curthoys, its later video-based form, otolith-function testing through evoked myogenic potentials, and the HINTS bedside battery progressively broadened assessment beyond the single low-frequency caloric stimulus.

Key figures

• Michael Halmagyi
• Ian Curthoys
• David Newman-Toker
• Robert Bárány

Seminal works

• halmagyi-2017
• kattah-2009

Frequently asked questions

What does the caloric test measure?

The caloric test uses warm or cool irrigation of the ear canal to thermally stimulate the horizontal semicircular canal and evoke nystagmus, providing a low-frequency measure of that canal's function and a comparison between the two ears.

What is the HINTS examination?

HINTS is a three-part bedside oculomotor examination — head-impulse test, evaluation of nystagmus, and test of ocular skew — used in acute continuous dizziness to help distinguish a peripheral vestibular cause from a central one such as stroke.