LAUSR

Missed vestibular deficiency in children bares the risk of delayed postural, motor, and cognitive development [1, 2]. Conversely, of the 5–25% of children experiencing dizziness or vertigo per year [3], many will have migraine-equivalents [4] or somatoform disorders [5], where it is important to reassure children and parents about the normal peripheral-vestibular function. This requires a good history and an easy vestibular function test [6]. Whereas in adults, clinical [7] and now also video-based head impulses [8, 9] are widely used to assess vestibulo-ocular reflex (VOR) function, and there has long been no quantitative bedside test of vestibular function in children [10]. In addition, the stationary tests available (calorics and rotational chair testing) may induce unpleasant vertigo and nausea [10, 11] and are, therefore, not always tolerated by children [11]. Here, we determined feasibility and normative data for video head impulses in children. We first performed the standard clinical horizontal head impulses (in analogy to adults [7]) and then video head impulses (EyeSeeCam system, in analogy to Bartl et al. [9] but with monocular recording of the left eye and without an additional camera on a bite bar) on 44 healthy children aged 4–18 years (mean ± SD 10.1 ± 3.6 years, 23 girls). All children and their parents/legal guardians gave their informed consent to the study, which was approved by the ethics committee of the Medical Faculty of Ludwig-Maximilians-University Munich and in accordance with the declaration of Helsinki. Children were divided into three age groups (4–7 years, early childhood, 8–11 years, middle childhood and 12–18 years, late childhood). The lower age limit was chosen according to preliminary experience: not all children under four have a long-enough attention span for fixation calibration. Video head impulse data were analyzed offline using the custom MATLAB software (Mathworks, Natick, USA). Head impulse start was when head velocity exceeded 20 /s, end when it crossed zero again. The VOR gain was determined as the ratio of the median of eye and head velocity in a window between 55 and 65 ms after head movement start. Outliers were defined as outside mean ± 2SD of their age group. Refixation saccades and covert anti-compensatory quick eye movements (CAQEM) were analyzed in analogy to Heuberger et al. [12]. A peripheral-vestibular deficit was defined as a gain below 2SD of the mean of the respective age group in the presence of re-fixation saccades. The tests took less than 10 min and were well tolerated: no child reported any discomfort. Clinical head impulses were normal in all subjects. Figure 1a, panels a–c, shows eye and head velocity traces during video head impulse testing to the left and right sides in exemplary children Klaus Jahn and Erich Schneider authors contributed equally to the work.