The patient is a 27-year-old graduate student who was admitt…
The patient is a 27-year-old graduate student who was admitted to an acute care facility with a chief complaint of double vision for 2 weeks. She reported that both lower extremities (LEs) seemed weaker recently. Four months earlier, she had noticed persistent tingling of her fingers on the left hand and some numbness on the left side of her face. Neurological examination showed a scotoma in the upper field of the left eye, weakness of the left medial rectus muscle, horizontal nystagmus on left lateral gaze, and mild weakness of the left central facial muscles. All other muscles had normal strength. The deep tendon reflexes were normal on the right and brisk on the left, and there was a left extensor plantar response. The sensory system was unremarkable. She ambulates with a wide base of support and mild trunk ataxia. What is this patient’s most likely diagnosis?