[Experimental study of post-labyrinthectomy compensation by means of the torsion pendulum]

Recovery patterns after unilateral labyrinthectomy were studied using a torsion pendulum to produce angular accelerations in unanaesthetized, immovilized cats. The oculomotor activity before and during angular accelerations was recorded and cuantified in 10 post-labyrinthectomized cats during 26 days of recovery both with and without environmental fixation (eyes open or covered). The integrated nistagmus obtained with rotation in each direction was used as a measure of oculomotor activity, as well as an indicator of directional preponderance. It was found this indicator to be far more sensitive than the raw electronystagmic tracings to detect asymmetries in the oculomotor response. The integrated movement of the eyes without ambiental fixation (eyes covered) was consistently 40% of the pendulum's displacement; while having both eyes open, the ocular displacement was equal (100%) to that of the environment. These relations changed in a predictable and characteristic way after labyrinthectomy. Approximately between 5 and 12 days post-labyrinthectomy, the responses to stimulus in both directions become of very small magnitude, indicating a depression of the reflexes originating in the remaining normal labyrinth.