Age-related Refixating Saccades in the Three-Dimensional Video-Head-Impulse Test: Source and Dissociation From Unilateral Vestibular Failure

Objective: To examine “refixating saccades” in the three-dimensional video-head impulse test (vHIT) depending on the age and compare them to refixating saccades in pathological vHIT. Design: Retrospective database study. Setting: County hospital, specialized vertigo center. Patients: Eight hundred ninety-nine patients without a peripheral vestibular hypofunction were tested with the three-dimensional vHIT and compared with 135 patients with unilateral vestibular hypofunction (UVF). Main Outcome Measures: Occurrence and peak velocity of refixating saccades (covert and overt) during the video-head-impulse test (vHIT) in three age groups (0–30, 30–60, and 60–100 yr) and in UVF. Results: Overt saccade frequency of refixating saccades increased with increasing age, especially in the horizontal and posterior vHIT. Saccades were mostly directed opposite to the head movement. The aging effect was not explained by the VOR-gain decrease. Refixating saccades in normal vHIT were less frequent and slower than in UVF. Conclusion: We conclude that refixating saccades increase with higher age and could be differentiated from those in UVF by frequency and peak velocity. Saccades are not caused by a deficient VOR but might be caused by a deficient suppression of saccades to novel targets.

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