Unilateral internuclear ophthalmoplegia and recovery with thiamine in Wernicke syndrome.

Internuclear ophthalmoplegia is usually caused by multiple sclerosis, tumors, or vascular lesions of the brain stem. We report a patient with Wernicke syndrome who presented with a right-sided internuclear ophthalmoplegia. He recovered completely with intravenous thiamine (vitamin B1). There were no lesions in the magnetic resonance image (MRI) of the brain, suggesting a derangement at the cellular level as the cause.