Abstract
A simple technique is described for the determination of the visual vertical and horizontal. In order to determine the influence of exclusively vestibular factors on spatial orientation, patients were tested prior and in the days following unilateral therapeutic labyrinthectomy. Unilateral labyrinthectomy in patients operated upon for Menière's disease or cochleo-saccular degeneration introduces a marked deviation of the visual vertical and horizontal towards the operated side, which varies with the individual but is less pronounced in the group of patients operated upon for cochleosaccular degeneration. The origin, significance, and clinical applications of the phenomenon are discussed.