Clinical testing of otolith function: perceptual thresholds and myogenic potentials

Area of Science:

• Neuroscience
• Otolith Function Assessment
• Vestibular System Research

Background:

• Cervical and ocular vestibular-evoked myogenic potential (cVEMP/oVEMP) tests are standard clinical tools for assessing otolith function.
• Current VEMP testing methods exhibit considerable inter-individual variability and utilize non-physiological stimuli, questioning their efficacy.
• Alternative methods for evaluating otolith function are needed to overcome the limitations of VEMP testing.

Purpose of the Study:

• To compare linear motion perceptual threshold testing with cVEMP and oVEMP for measuring saccular and utricular function, respectively.
• To investigate the association between perceptual thresholds, VEMP responses, and Dizziness Handicap Inventory (DHI) scores.
• To determine if horizontal perceptual thresholds and oVEMPs reflect the same physiological construct of utricular function.

Main Methods:

• Utilized a multi-axis motion platform to measure horizontal (inter-aural, naso-occipital) and vertical motion perceptual thresholds.
• Compared perceptual thresholds with vibration-evoked oVEMPs (utricular function) and sound-evoked cVEMPs (saccular function).
• Enrolled 33 patients with bilateral vestibulopathy and 42 controls to capture a range of otolith function variability.

Main Results:

• Abnormal oVEMP amplitudes correlated with significantly higher (poorer) perceptual thresholds along the inter-aural and naso-occipital axes.
• No significant associations were found between vertical perceptual thresholds and cVEMP amplitudes.
• Both oVEMP amplitudes and naso-occipital perceptual thresholds showed significant associations with DHI scores.

Conclusions:

• Horizontal perceptual thresholds and oVEMPs may assess the same underlying physiological aspect of utricular function.
• Linear motion perceptual threshold testing, especially for horizontal motion, shows promise as a clinical measure of otolith function.
• Findings suggest potential improvements in dizziness assessment by incorporating perceptual threshold testing alongside or as an alternative to VEMPs.