Figure 13.

Examples of head impulse test (HIT) results. (3) Acute Wernicke’s encephalopathy. (A) Binocular search-coil recording of head (green) and eye (left: red, right: blue) velocity demonstrating severe loss of horizontal canal (HC) function with slow, overt saccades, but preservation of vertical canal function during individual canal plane HIT. Increased posterior canal function with anticompensatory saccades might be related to the presence of spontaneous upbeat nystagmus. Hexagonal bars depict gains from each canal. (B) Monocular, right eye (blue) video HIT recording of another patient, again demonstrating severe loss of HC function with preservation of vertical canal function. Reproduced from the study by Akdal et al. (93), used with permission from Elsevier.