Walsh & Hoyt: Ocular Motor Dysfunction and Multiple Sclerosis

MS causes a variety of ocular motor deficits; bilateral INO, cerebellar eye signs (including gaze-evoked nystagmus), and acquired pendular nystagmus are the most common. Pendular or elliptical nystagmus is a frequent disabling manifestation of the disease. Measurement of eye movements may help establish the diagnosis of MS during early stages of the disease. Saccadic abnormalities may be more readily detected when targets are presented randomly so that neither their time of onset nor their location can be predicted. Large saccades (20 or more) are more likely to show changes in velocity than are small saccades. Because normal subjects show differences in the peak velocity of abducting and adducting saccades, it is worth developing a normative database for each of these. With these provisos, most patients with MS show saccadic abnormalities that include prolonged latency, inaccuracy, and decreased velocity. In particular, minor slowing of adducting saccades may indicate an INO that may not be evident with clinical testing.