Slow Horizontal, Vertical and Oblique Saccades in Spinocerebellar Ataxia Type I

This is a patient presenting with horizontal diplopia who was found to have divergence insufficiency, an esotropia greater at distance than near in the absence of abduction paresis. She also had very slow saccades, more so vertically than horizontally. This is particularly noticeable when asking her to perform oblique saccades. The initial portion of the saccade is mainly horizontal, and this is followed by a curved or L-shaped trajectory as the patient reaches the target horizontally first, but then must make it to the target vertically. She also had saccadic smooth pursuit as well as gaze evoked nystagmus. Given her slow saccades, the fast phases of the gaze evoked nystagmus looked particularly weak given slower than normal quick phases of nystagmus.