Vestibular Thresholds: A Review of Advances and Challenges in Clinical Applications

Abstract

Vestibular disorders pose a substantial burden on the healthcare system due to a high prevalence and the severity of symptoms. Currently, a large portion of patients experiencing vestibular symptoms receive an ambiguous diagnosis or one that is based solely on history, unconfirmed by any objective measures. As patients primarily experience perceptual symptoms (e.g., dizziness), recent studies have investigated the use of vestibular perceptual thresholds, a quantitative measure of vestibular perception, in clinical populations. This review provides an overview of vestibular perceptual thresholds and the current literature assessing use in clinical populations as a potential diagnostic tool. Patients with peripheral and central vestibular pathologies, including bilateral vestibulopathy and vestibular migraine, show characteristic changes in vestibular thresholds. Vestibular perceptual thresholds have also been found to detect subtle, sub-clinical declines in vestibular function in asymptomatic older adults, suggesting a potential use of vestibular thresholds to augment or complement existing diagnostic methods in multiple populations. Vestibular thresholds are a reliable, sensitive, and specific assay of vestibular precision, however, continued research is needed to better understand the possible applications and limitations, especially with regard to the diagnosis of vestibular disorders.

Keywords: psychophysics; self-motion perception; vestibular disorders; vestibular system; vestibular thresholds.

Figure 1

Primary rotations of the head. (A) Movement is described in a head-fixed coordinate system. The x-axis is naso-occipital, y-axis is inter-aural, and the z-axis is head-vertical. (B) Roll rotation about the x-axis stimulating the vertical SCCs. (C) Pitch rotation about the y-axis stimulating primarily the vertical SCCs. (D) Yaw rotation about the z-axis stimulating the horizontal SCCs.

Figure 2

Primary head translations. (A) Positive x-translation, along the naso-occipital axis, stimulating predominantly the utricle with saccular contributions. (B) Positive y-translation, along the inter-aural axis, stimulating the utricles. (C) Positive z-translation, along the head-vertical axis, stimulating the saccules.

Figure 3

Head tilts from upright with respect to gravity. (A) Roll tilt about an earth-vertical axis, which stimulates both the vertical SCCs and the utricle. (B) Pitch-tilt about an earth-vertical axis, which stimulates both the vertical SCCs and the otoliths.