Third nerve palsy

A 79-year-old Caucasian man presented with a four-day history of left retrobulbar pain and a left-sided headache which he described as 10/10 in severity and throbbing in quality. One day later, he developed diplopia and left upper lid ptosis. His past medical history was significant for stage III colorectal adenocarcinoma, for which he had a colorectal resection and received chemotherapy and radiation therapy. He had prior coronary artery disease treated with coronary artery bypass. His medications included aspirin, clopidogrel, metoprolol, ramipril, niacin, and donepezil. He smoked cigarettes in the distant past but denied any alcohol or illicit drug use. There was no temporal artery tenderness or nodularity. Best-corrected visual acuity was 20/25+1 in the right eye (OD) and 20/30−1 in the left eye (OS). Extraocular motility was full OD, but revealed a 25-prism-diopter left exotropia (XT) in primary gaze with −4 limitation of adduction, −3 underaction of supraduction and infraduction, but full abduction OS (see Fig. 10.1). There was intorsion in downgaze suggesting an intact fourth nerve. There was no trigeminal or facial nerve dysfunction. Confrontation visual field testing was full in both eyes (OU). Automated Humphrey visual fields (24-2) showed non-specific scatter OD and left superior lid artifact from the left ptosis. There was no variability or fatigue, Cogan’s lid twitch sign, or enhancement of ptosis. Pupils were both reactive and measured 3 mm in the dark and 1 mm in the light OU with no relative afferent pupillary defect (RAPD) or anisocoria. Slit lamp exam was significant for corneal arcus OU, and 2+ nuclear sclerotic cataracts OU consistent with 20/30 vision OU. Fundus examination was within normal limits OU.