HEALTH TOPICS 
Stroke Overview
What Is It?
A stroke is a brain injury that occurs because the brain's blood supply is interrupted.
The brain's blood supply can be disrupted for different reasons. Doctors generally classify strokes into three categories, depending on the cause:
To continue reading this article, you must log in.
Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.
- Research health conditions
- Check your symptoms
- Prepare for a doctor's visit or test
- Find the best treatments and procedures for you
- Explore options for better nutrition and exercise