Image of the Week: Headache, retro-orbital pain, and diplopia

A 25-year-old man presents to the emergency department with headache, retro-orbital pain, and diplopia when gazing to the right. He had visited an urgent care clinic with right ear pain 2 weeks earlier and had received a short course of antibiotics. After some initial improvement, he became increasingly unwell before presenting today. Otoscopy reveals purulent discharge in the right ear canal, and a CT scan demonstrates the findings seen here. Which organism is most commonly responsible for this patient’s likely diagnosis? Learn more about this case, take the quiz, and join the conversation on Figure 1.