Question

Vignette #1: A 77-year-old woman was cooking in the kitchen when she collapsed onto the floor. Her daughter called an ambulance and the woman was taken to the emergency room. She had suffered a stroke, and slowly regained consciousness over the next two days. However, when she woke up, she had the following signs and symptoms:- loss of sight (although pupils were reactive to light
)- partial amnesia (loss of memory) - inability to create and store new long-term memories.

Vignette #2: A 61-year-old business executive with a long history of high blood pressure collapsed while jogging over the lunch hour. His jogging mate quickly contacted a police officer who helped carry the man to a hospital just down the road. At the hospital, an MRI was performed that revealed a blockage of a major cerebral artery and ischemic changes to the portion of the brain supplied by that artery. With quick medical attention, the man was stabilized, and he slowly improved over the next three weeks. The following signs and symptoms did persist, however:- weakness of the facial and upper extremity muscles on the left side - loss of sensory discrimination when objects are placed into the left hand - significant mood and character changes.

1. Based upon the patient's symptoms in Vignette #1, which cerebral artery was blocked? Your explanation should include which area(s) of the brain is/are affected as indicated by the reported symptoms, and how that leads to your identification of the blocked blood vessel. (Be Specific)

2. Which artery was blocked in Vignette #2? Your explanation should include which area(s) of the brain is/are affected as indicated by the reported symptoms, and how that leads to your identification of the blocked blood vessel. (Be Specific)

3. Take a moment to consider the “Circle of Willis”. Assuming both patients have a fully connected Circle of Willis, would you predict that blood flow to the affected areas would be maintained despite the blockage? Why or why not?

4. Propose a possible treatment for the patient in this case study. How does this treatment improve conditions for the patient? Are these improvements seen at the cellular, tissue, organ or systemic level?

Answer 1

1. The occipital lobe of the cerebrum is concerned with vision while the temporal lobe is responsible for memory. Since these two functions seem to be affected, the artery carrying blood to these areas of the brain must be blocked.

The internal carotid arteries supply blood to most of the anterior portion of the cerebrum. The occipital lobe is provided oxygenated blood by the posterior cerebral artery. The temporal lobe receives oxygen-rich blood by the internal carotid system and the vertebrobasilar artery. The middle cerebral artery branches into the temporopolar artery, anterior temporal artery, middle temporal artery, and posterior temporal artery.

Most probably, the internal carotid artery is blocked in the patient.

2. The limbic system of the brain mainly controls emotions, memory, and stimulation. It is located on both sides of the thalamus, just beneath the medial temporal lobe of the cerebrum, in the forebrain. the cerebellum of the brain controls muscle coordination but the muscles of the face are controlled by a collection of neurons in the brain stem. The right half of the brain controls the left facial muscles and the left side controls the right muscles.   

The paired arteries responsible for blood supply to the brain are the vertebral arteries and the internal carotid arteries. From the circle of Willis in the cranial vault, arise most of the blood vessels which supply to the cerebrum.

The posterior cerebral arteries supply both the medial and the lateral part of the posterior cerebrum and the brain stem. The blockage must be in this artery.

3. The Circle of Willis is formed by the terminal branches of the vertebral and interior carotid arteries. There are three main pairs of the Circle of Willis. They are - [a] anterior cerebral arteries, [b] internal carotid arteries, and [c] posterior cerebral arteries. To complete the circle, two connecting blood vessels are also present- [d] anterior communicating artery, and [e] posterior communicating artery. The circle of Willis allows blood to flow across the midline of the brain if an artery on one side is occluded.

4. Treatment for blockage in an artery is usually medication. Blood thinners such as clopidogrel and aspirin help to dissolve the blood clots. If surgery is possible, neurosurgeons can perform invasive surgery to remove the clot. After the surgery, medications such as stattins will help to prevent the build up of cholesterol plaques in the artery.