ABSTRACT
This chapter addresses the three-dimensional characteristics of upward drift in cerebellar downbeat nystagmus. The slow phases during downbeat nystagmus in eight patients with cerebellar atrophy show a consistent three-dimensional pattern with the ocular rotation axis close to eye-fixed and, hence, violations of Listing’s law. The three-dimensional characterization of vertical slow phases produced by vestibular stimulation in cerebellar patients may be helpful to infer the role of the cerebellum in three-dimensional eye movement control. The panels on the left show the front, in the middle the side, and on the right the top view of eye rotation vector trajectories in the head-fixed Cartesian coordinate system defined by torsional, horizontal, and vertical base vectors. The clinical interest in movement of the eyes about all three axes of rotation is related to the question, do specific lesions of the ocular motor system produce specific deficits of three-dimensional eye movement trajectories.
