mrcem2-1260

A 35-year-old woman presents to the Emergency Department with a brief history of headaches, which are more severe in the morning, and blurred vision and ringing in the ears. Her headache is worse than usual today, and she has vomited multiple times. She has no significant medical history but does take the combined oral contraceptive pill. On examination, you find her to be overweight, and her neurological system examination reveals a sixth cranial nerve palsy, but no other focal neurology and fundoscopy reveals bilateral papilloedema.

What is the SINGLE most likely diagnosis?