19th June 2023

A 72-year-old man presented with a 4-hour history of headache associated with weakness of the right arm

A 72-year-old man presented with a 4-hour history of headache associated with weakness of the right arm. He has a past medical history of arthritis, migraine, and type 2 diabetes. He takes metformin and co-codamol regularly. He is a smoker, lives with his partner and works part-time as a manager in an office. On examination, you notice power 3/5 of the right upper arm, but the rest of the neurological examination is normal.

Which one of the following is the most likely cause of his symptoms?