At least half of all people with multiple sclerosis (MS) are expected to have nystagmus at some point during the course of their illness. Nystagmus results from demyelination that involves the brainstem or cerebellar eye movement pathways. While it may be asymptomatic, it often causes blurred vision or oscillopsia. The extent of the visual disturbance is directly related to the velocity of the slow phase of the nystagmus.
In MS patients with chronic nystagmus, the most common form is an acquired pendular nystagmus (APN), which is almost always accompanied by optic atrophy, and often by internuclear ophthalmoplegia (INO).
Numerous treatment trials have demonstrated the efficacy of pharmacologic treatment of chronic symptomatic nystagmus. Treatment should be considered in individuals in whom blurred vision or oscillopsia is severe enough to warrant the potential risk of medication side effects. As a general rule, drugs used to treat nystagmus are titrated slowly upwards from a low dose to either efficacy or tolerance.
The two most effective medications for APN in MS are....