An 82-year-old man with arterial hypertension and hyperlipidemia was referred for evaluation of headaches and horizontal diplopia.

Our patient had a history of horizontal nonpositional headaches and sudden onset of binocular diplopia. He had a more pronounced horizontal separation of the images when looking at a distance. There was no associated scalp or occipital tenderness, eyelid ptosis, or history of thyroid disease. There was no diurnal variation of the diplopia and no fatigability. There was no history of diabetes, sore shoulders or hips, anorexia, weight loss, fever, or jaw claudication. On examination, he had impaired abduction (lateral rectus muscle) of the right eye and nasal deviation (esotropia) of the right eye in center gaze. There was no proptosis, chemosis, or lid swelling. He had no evidence of eyelid ptosis, papilledema, or a Horner syndrome. The remainder of his neurologic examination was unremarkable.