The concept of “disorders of brain function”

Fifty-four-year-old Fred is complaining of a headache that started about 2 weeks ago. For the past 2 days, the headache has increased in severity, and he is photophobic and has uncial rigidity and projectile vomiting. CT scan results show an arteriovenous malformation in the basal artery and a small hemorrhagic bleed in the middle meningeal artery. How is the concept of “disorders of brain function” related to Fred’s presenting symptoms? What aspects of cerebral circulation would come into play in Fred’s case?