a 21-year-old woman presents with double vision that occurs only when she looks to her right side. the double vision began when she woke up in the morning. she had an episode of left leg numbness while at summer camp 6 years ago, but it resolved over 3 days and she never told anyone. also, 3 years ago she saw her private physician after a 7-day episode of right eye pain and visual blurring. he attributed her symptoms to an ocular migraine. there is no history of head trauma. she hasn't had any infections, fevers, or immunizations recently. she is awake, alert, and in no acute distress. positive findings include mild pallor and atrophy of the right optic disc. bedside visual fields and acuity are normal. testing external ocular motion in both eyes together reveals that there is no left eye movement beyond midline when attempting to look to her right, accompanied by right eye lateral nystagmus. when the left eye is tested with the right eye closed, eye movements are full. no other motor signs are found. no skin, sensory, or hearing findings are found. a magnetic resonance imaging scan (mri) of the head with gadolinium enhancement reveals a 2 x 3 cm lucency in the region of the right parietal white matter without swelling or enhancement. multiple sclerosis (ms) is suspected. question: given this history, how would this patient's condition best be subtyped?
