AUTHOR=Starkov Dmitrii , Vermorken Bernd , Van Dooren T. S. , Van Stiphout Lisa , Janssen Miranda , Pleshkov Maksim , Guinand Nils , Pérez Fornos Angelica , Van Rompaey Vincent , Kingma Herman , Van de Berg Raymond 

TITLE=The Effect of Different Head Movement Paradigms on Vestibulo-Ocular Reflex Gain and Saccadic Eye Responses in the Suppression Head Impulse Test in Healthy Adult Volunteers

JOURNAL=Frontiers in Neurology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2021.729081

DOI=10.3389/fneur.2021.729081

ISSN=1664-2295

ABSTRACT=<p><bold>Objective:</bold> This study aimed to identify differences in vestibulo-ocular reflex gain (VOR gain) and saccadic response in the suppression head impulse paradigm (SHIMP) between predictable and less predictable head movements, in a group of healthy subjects. It was hypothesized that higher prediction could lead to a lower VOR gain, a shorter saccadic latency, and higher grouping of saccades.</p><p><bold>Methods:</bold> Sixty-two healthy subjects were tested using the video head impulse test and SHIMPs in four conditions: active and passive head movements for both inward and outward directions. VOR gain, latency of the first saccade, and the level of saccade grouping (PR-score) were compared among conditions. Inward and active head movements were considered to be more predictable than outward and passive head movements.</p><p><bold>Results:</bold> After validation, results of 57 tested subjects were analyzed. Mean VOR gain was significantly lower for inward passive compared with outward passive head impulses (<italic>p</italic> &lt; 0.001), and it was higher for active compared with passive head impulses (both inward and outward) (<italic>p</italic> ≤ 0.024). Mean latency of the first saccade was significantly shorter for inward active compared with inward passive (<italic>p</italic> ≤ 0.001) and for inward passive compared with outward passive head impulses (<italic>p</italic> = 0.012). Mean PR-score was only significantly higher in active outward than in active inward head impulses (<italic>p</italic> = 0.004).</p><p><bold>Conclusion:</bold> For SHIMP, a higher predictability in head movements lowered gain only in passive impulses and shortened latencies of compensatory saccades overall. For active impulses, gain calculation was affected by short-latency compensatory saccades, hindering reliable comparison with gains of passive impulses. Predictability did not substantially influence grouping of compensatory saccades.</p>