Journal of Neuro-Ophthalmology, December 2001, Volume 21, Issue 4

Vertical Saccades in Superior Oblique Palsy and Browns Syndrome

OBJECTIVE: To compare saccadic dynamics in superior oblique palsy and Brown's syndrome. METHODS: Vertical saccades in adduction and in abduction were studied in two subjects with superior oblique palsy and one with Brown's syndrome. Using large numbers of centrifugal saccades over a wide range of amplitudes, we measured peak velocity, duration, and the peak velocity/mean velocity ratio (PV/MV) as a function of saccadic amplitude. We compared vertical saccades in 30 degrees of abduction with those in 30 degrees of adduction. RESULTS: Superior oblique palsy caused a 15-18% reduction in peak velocities in adduction compared with abduction. Saccadic duration was also increased in adduction, with the result that there was no net change in the PV/MV ratio. In the patient with Brown's syndrome, velocities and durations of upward saccades were similar in abduction and adduction, but the PV/MV ratio was significantly elevated in adduction. We also observed an unusual high-speed lateral 'snap' of about 5 degrees that frequently interrupted vertical saccades in the midline but not elsewhere. CONCLUSION: Both paresis and restriction of the superior oblique alter vertical saccades. The effects of restriction on saccadic dynamics are distinct from the effects of paresis.