Successful treatment of acquired pendular elliptical nystagmus in multiple sclerosis with isoniazid and base-out prisms.

We treated 3 multiple sclerosis patients who had pendular nystagmus with isoniazid (800 to 1,000 mg/d). Isoniazid abolished the nystagmus and relieved oscillopsia in 2 patients but was ineffective in the 3rd in whom the nystagmus was damped with convergence and vision improved with converging (base-out) prisms.