Cerebral vascular disease: Pathology review

At the emergency department, 30-year-old Lydia presents with severe headache and confusion. Clinical examination reveals low grade fever and nuchal rigidity. Past medical history reveals she has polycystic kidney disease. Non-contrast CT reveals blood between the arachnoid and the pia mater. Lydia is treated supportively and sent home. Three days later she suddenly develops a severe headache, vomiting, and confusion.

Later that day, 70-year-old Amanda presents with left-sided weakness and numbness, with her foot and leg more affected than her arm. She can speak fluently and understands everything being said to her. Past medical history includes hypertension, hyperlipidemia, and a myocardial infarction last year.

Based on their presentation, the diagnosis is that both Lydia and Amanda had a cerebral vascular disease, most often referred to as a stroke. A stroke is when there’s a sudden focal neurological deficit due to a part of the brain losing its blood supply. Now, to safeguard the brain from hypoxia, the brain has a dual circulation called the circle of Willis, divided into an anterior and posterior circulation. The anterior circulation starts in the neck, where the common carotid artery splits into the external and internal branches. The internal carotid passes through the carotid canal of the temporal bone of the skull and into the cranial cavity. Once inside, the internal carotid artery gives off branches. First are the middl