A 70-year-old man is brought to the Emergency Department with a history of confusion, irritability and partial loss of consciousness for the past 3 hours. He apparently fell down the basement stairs 1 week ago, struck his head and was unconscious for about 10 minutes. He is now stuporous and his level of consciousness is decreasing. Which one of the following is considered to be the most likely cause of his deterioration?
Transient ischemic attack.