Seesaw Nystagmus

A 52-year-old man presented to the emergency department with a 1-year history of headache and reduced visual acuity. Physical examination showed seesaw nystagmus; a video is available at NEJM.org. A 52-year-old man presented to the emergency department with a 1-year history of generalized headache, diminished vision, and abnormal eye movements. Examination of the fundus revealed disk pallor. His pupillary reflexes were normal, but there was reduced visual acuity (20/120) in both eyes and bitemporal hemianopia. Ocular examination revealed rhythmic, torsional, and vertical movement in which the eye rotating inward moved up as the other eye moved down, a finding known as seesaw nystagmus (see video). The movement increased in amplitude during downward gaze. Magnetic resonance imaging of the brain revealed a giant pituitary adenoma measuring 48 mm in diameter . . .