- Ischemic stroke is the most frequently occurring type of cerebrovascular accident, accounting for approximately 85% of all strokes.
- It results from occlusion of cerebral arteries due to thrombosis or embolism, leading to infarction of brain tissue.
- In contrast, hemorrhagic strokes are caused by rupture of blood vessels and are less common but often more severe.
- Transient ischemic attacks (TIAs) are brief episodes of neurological dysfunction without infarction, thus not classified as full strokes.
- Brainstem strokes are a subset of ischemic or hemorrhagic strokes but are less common overall.
- The high prevalence of ischemic strokes is related to widespread atherosclerosis and embolic sources in most populations.

Reference: Davidson’s Principles and Practice of Medicine, 23rd Edition, Chapter: Disorders of the Nervous System, Page 787.