Abstract
The video head impulse test (VHIT) is widely used to identify semicircular canal function impairments in adults. But classical VHIT testing systems attach goggles tightly to the head, which is not tolerated by infants. Remote video detection of head and eye movements resolves this issue and, here, we report VHIT protocols and normative values for children. Vestibulo-ocular reflex (VOR) gain was measured for all canals of 303 healthy subjects, including 274 children (aged 2.6 months–15 years) and 26 adults (aged 16–67). We used the Synapsys® (Marseilles, France) VHIT Ulmer system whose remote camera measures head and eye movements. HITs were performed at high velocities. Testing typically lasts 5–10 min. In infants as young as 3 months old, VHIT yielded good inter-measure replicability. VOR gain increases rapidly until about the age of 6 years (with variation among canals), then progresses more slowly to reach adult values by the age of 16. Values are more variable among very young children and for the vertical canals, but showed no difference for right versus left head rotations. Normative values of VOR gain are presented to help detect vestibular impairment in patients. VHIT testing prior to cochlear implants could help prevent total vestibular loss and the resulting grave impairments of motor and cognitive development in patients with residual unilateral vestibular function.
Highlights
An important function of the vestibular system is to stabilize gaze during head movements
This study showed that video head impulse test (VHIT) provides reliable data as long as certain parameters are respected
Performing the VHIT for vertical canals is more challenging with very young children
Summary
An important function of the vestibular system is to stabilize gaze during head movements. Semicircular canal function can be evaluated by measuring the vestibulo-ocular reflex (VOR) to head rotation. The VOR stabilizes gaze by synchronously rotating the eyes in the opposite direction of head movement. Severe vestibular canal function loss is characterized by visual observation by VOR Gain Evolution in Childhood the clinician of a corrective saccade sometimes occurring after onset of the head impulse [ referred to as “overt saccades” [1, 3]]. Note that direct observation of the patient’s eye movements can only diagnose severe loss of canal function—quantitative VOR gain measurements are not possible and corrective saccades cannot always be detected, if they occur early during the head movement
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