During ischemic stroke, blood supply to part of the brain is decreased, leading to dysfunction of the brain tissue in that area. There are four reasons why this might happen:
- Thrombosis (obstruction of a blood vessel by a blood clot forming locally)
- Embolism (obstruction due to an embolus from elsewhere in the body),
- Systemic hypoperfusion (general decrease in blood supply, e.g., in shock)
- Cerebral venous sinus thrombosis.