A 50-year-old White male with a history of multiple sclerosis presented to the emergency department with fatigue, lightheadedness, and dizziness, exacerbated with sitting upright and worsening over the prior one to two days. He stated his last flare was approximately two years prior, and presented with aphasia as his primary symptom. On physical exam, the patient had non-fatigable horizontal bidirectional nystagmus with no other abnormalities noted. Non-contrast computed tomography of the head showed an indeterminate 13- millimeter low density in the left frontal lobe ().