Video Head Impulse Testing (vHIT) and the Assessment of Horizontal Semicircular Canal Function

Background:Vestibular function (specifically, horizontal semicircular canal function) can be assessed across a broad frequency range using several different techniques. The head impulse test is a qualitative test of horizontal semicircular canal function that can be completed at bedside. Recently, a new instrument (video head impulse test [vHIT]) has been developed to provide an objective assessment to the clinical test. Questions persist regarding how this test may be used in the overall vestibular test battery.Purpose:The purpose of this case report is to describe vestibular test results (vHIT, rotational testing, vestibular evoked myogenic potentials, and balance and gait performance) in an individual with a 100% unilateral caloric weakness who was asymptomatic for dizziness, vertigo or imbalance.Data Collection and/or Analysis:Comprehensive assessment was completed to evaluate vestibular function. Caloric irrigations, rotary chair testing, vHIT, and vestibular evoked myogenic potentials were completed.Results:A 100% left-sided unilateral caloric weakness was observed in an asymptomatic individual. vHIT produced normal gain with covert saccades.Conclusions:This case demonstrates the clinical usefulness of vHIT as a diagnostic tool and indicator of vestibular compensation and functional status.