Multiple sclerosis Quiz: Ace Your Exams

A 37-year-old woman presents to the ophthalmologist for evaluation of vision changes in the left eye. The patient was painting in her art studio two days ago when she noticed that red hues appeared “washed out” or lighter in her left eye. As the day progressed, she developed blurry vision in the left eye. She has no refractive error in either eye and does not wear corrective lenses. Past medical history is notable for vitamin D deficiency for which she takes a daily supplement. Temperature is 37.0°C (98.6°F), pulse is 80/min, respirations are 12/min, and blood pressure is 120/72 mmHg. Visual acuity is 20/20 in the right eye and 20/50 in the left eye. Examination reveals failure of both pupils to constrict when the light is shown in the left eye. There is no conjunctival erythema. Fundoscopic evaluation reveals subtle disc edema and pallor of the left optic nerve. The right optic nerve appears normal. The remainder of the cranial nerve examination is unremarkable. The patient has normal strength and reflexes bilaterally in the upper and lower extremities. Which of the following additional findings is most likely to be present?