Disorders of the blood supply
A number of disorders can interfere with blood supply to the brain—here we’ll look at a few key examples.
1) We'll start with stroke, the most common cause of death related to disruptions in cerebral blood flow:
2) Now, watch these videos about other conditions related to cerebral blood flow:
3) Finally, answer these questions to test your understanding:
1. In a thrombotic stroke (i.e., a stroke caused by a thrombus), a blood clot:
- A. forms in a distant site and then travels to the brain
- B. forms in a cerebral vein and blocks venous blood outflow from the brain
- C. forms locally in an artery in the brain or an artery that supplies the brain
- D. forms only in the blood supply to the peripheral nervous system
Show Answer
Correct answer: C
When a blood clot forms in same area where the blockage occurs, it is known as a thrombus. When a blood clot forms at a distant site and then travels to another part of the body or the brain to block a blood vessel, it is known as an embolus. A thrombotic stroke involves a blood clot that forms in the brain or in an artery that directly supplies the brain.
2. True or False: Most brain aneurysms never cause any symptoms.
- A. true
- B. false
Show Answer
Correct answer: A
While estimates vary, it is thought that brain aneurysms may occur in somewhere between 2 and 5% of the population. Most brain aneurysms, however, do not cause any symptoms, but larger aneurysms may cause symptoms by putting pressure on brain tissue and in a small percentage of cases, an aneurysm may rupture.
3. A person experiences a stroke that is caused by a blood clot blocking blood flow to parts of their occipital cortex. What type of stroke is this?
- A. hemorrhagic
- B. ischemic
Show Answer
Correct answer: B
Ischemic strokes occur when blood flow to a part of the brain is blocked or restricted. This is most commonly due to a blood clot blocking a blood vessel.
4. A patient presents with a sudden, severe “worst headache of their life.” Imaging confirms rupture of a saccular (berry) aneurysm in the Circle of Willis. Which type of brain hemorrhage most commonly results from this event?
- A. epidural hemorrhage
- B. subdural hemorrhage
- C. subarachnoid hemorrhage
- D. intraparenchymal hemorrhage
Show Answer
Correct answer: C
Subarachnoid hemorrhage can be caused by a variety of conditions, but the most common and severe cases typically result from the rupture of a brain aneurysm. Subarachnoid hemorrhage usually begins suddenly, with a severe headache that develops within seconds, sometimes referred to as a thunderclap headache.
5. Which of the following best describes the defining difference between a transient ischemic attack (TIA), also known as a "mini-stroke," and a stroke?
- A. a TIA causes mild symptoms, while a stroke causes more severe symptoms
- B. a TIA does not cause lasting damage to the brain, while a stroke does
- C. a TIA only affects small blood vessels, while a stroke affects larger vessels
- D. a TIA occurs in individuals under the age of 45 only
Show Answer
Correct answer: B
The defining difference between a TIA and an actual stroke is that TIAs do not result in a brain infarct, or death of brain tissue, while a true stroke does.
