Clinical reasoning: a 64-year-old man with painful, unilateral external ophthalmoplegia.

M. Tariq Bhatti, MD SECTION 1 A 64-year-old man was referred for evaluation of double vision in March 2009. Four months prior, he experienced daily pain in the region of the right forehead and right eye. Two months later, he noticed constant binocular, vertical double vision. Evaluation by an outside ophthalmologist resulted in the diagnosis of a right 4th cranial nerve (CN) palsy, a normal cranial and orbital MRI study with contrast, and an unremarkable laboratory evaluation. One month later, his right eye began “turning in,” and within a few days he was unable to abduct the eye. Several weeks later, the right eyelid began to droop and progressively worsened over the next several days to complete closure of the eye. His past medical history was notable for arterial hypertension, depression, rheumatoid arthritis, gastroesophageal reflux disease, nephrolithiasis, squamous cell carcinoma of the forehead, and a precancerous melanoma of the left ear. When he was seen in the neuro-ophthalmology clinic, visual acuity was 20/20 in each eye. Color vision was intact in each eye. The right pupil was 2 mm larger than the left and was nonreactive to light or near effort. There was no relative afferent pupillary defect (RAPD). Dilated fundus examination was normal in each eye. Eye movements of the right eye were limited in all directions and there was complete right upper eyelid ptosis (figure 1). Corneal sensation of the right eye was absent and there was numbness over the right forehead. The remainder of the cranial nerve examination was normal.