9th September 2020

A 22-year-old woman presents to the emergency department after suffering a unilateral throbbing headache

A 22-year-old woman presents to the emergency department after suffering a unilateral throbbing headache of subacute onset associated with nausea and vomiting. This was preceded by an episode of visual disturbance where she saw a bright shimmering pattern move across her visual field. On examination, she has a dilated pupil ipsilateral to the pain.

For the patient above, please select the SINGLE most likely underlying cause of their pupillary abnormality. Select ONE option from the list above.