Unilateral examination of utricle and saccule function

Area of Science:

• Neuroscience
• Otolaryngology
• Vestibular System

Background:

• Comprehensive unilateral examination of labyrinth function is crucial for diagnosing vestibular disorders.
• Existing tests like the head-thrust and caloric tests assess semicircular canal function, but dedicated unilateral saccular and utricular tests are recent advancements.

Observation:

• Vestibular evoked myogenic potentials (VEMP) are increasingly validated as a direct, saccule-mediated response, supported by animal studies delineating neuronal pathways.
• The unilateral centrifugation paradigm, using a rotary chair, effectively stimulates the utricle and measures utriculo-ocular response (UOR) or subjective visual vertical (SVV).
• Estimating SVV during standard yaw-axis rotation is also proving sufficient for localizing peripheral otolith dysfunction and can be integrated into routine clinical practice.

Findings:

• The study presents findings from two patients, demonstrating for the first time an isolated unilateral utricular dysfunction.
• These cases illustrate the efficacy of differential testing in identifying specific otolith impairments.

Implications:

• These advanced unilateral vestibular tests, including VEMP and modified centrifugation/SVV testing, enhance the diagnostic capabilities for peripheral vestibular disorders.
• The ability to detect isolated unilateral utricular dysfunction opens new avenues for targeted treatment and understanding of balance disorders.