Figure 6.

Results from video head impulse test (VHIT) performed on a 9-year-old child referred for an acute episode of vertigo lasting for several days (same formats as Figures 3 and 5, with analysis of the upper part of Figure 4). Partial vestibular loss in the right lateral and posterior canals is indicated by abnormally low gains in the corresponding (pink shaded) arms of the canalograms while gain is normal in the other four canals (green shaded arms of the canalogram). The dots appearing in the gray shaded slices of the canalograms indicate as a gain value the efficiency of the first corrective saccade to shift gaze back to the target. (A) Lower left, for a right lateral head impulse, the peak of the left eye movement trace (blue) is at a lower velocity relative to the head movement trace (green)—this corresponds to a reduction in gain. The corrective saccade starts at about 150 ms. Upper right, overlays of traces from all right lateral head impulses performed. (B) Summary table of results. The gain values for the pathological measures show low variability similar to the measures in normal subjects (figures adapted from Synapsys^® vHIT Ulmer data processing program screenshots).