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Catch up saccades or gain of the video head impulse test: which has the higher significance?
18 April 2018 (online)
The main question for the analysis of the video head impulse test is, which parameter is more important for the interpretation: the appearance of saccades or the gain. In three common neurootological diseases a comparison was done, which parameter reflects better the pathology.
A total of 240 patients were included: 90 neuropathia vestibularis (VN), 100 Menière's disease (MM), 50 vestibular migraine (VM). The proof of catch up saccades or a diminution of the the gain under 85% or a side difference of > 10% was considered as pathological.
In 68, 4% the appearance of saccades and gain corresponded, in 31, 6% not. The results varied for the different pathologies. In NV the lesioned side was reflected in 78% by saccades, but in only 53% by a lowered gain. For MM the relation was 42% for the saccades and 40% for a diminution of gain. In all VM patients no saccades became visible, but in 26% a diminished gain.
The appearance of saccades corresponded in 2/3 of the cases to a diminished gain, in 1/3 not. So the appearance of catch up saccades was the parameter with the best significance, mainly in NV and VM. The causes for the lower significance of gain could have methodological, but also physiological reasons.