I. Also called cerebrovascular accident or CVA
1. Occurs when blood vessels carrying O2 and nutrients to a specific part of the brain suddenly bursts (hemorrhagic) or becomes blocked (ischemic).
2. Because brain cells must have continuous supply of o2 & nutrients from blood to function when the supply is disrupted, a stroke results.
II. Strokes fall into several major categories depending on weather the disrupted blood supply is caused by a blocked blood vessel (ischemic) or a hemorrhage.
1. Because there are different types of strokes, each type has a different type of treatment.
III. Ischemic stroke results from a blocked blood vessel and includes both a thrombotic and embolic stroke.
A. Thrombotic stroke
- Most common type of stroke.
- a blood clot (thrombus) forms inside an artery in the brain, blocking blood flow.
- Sometimes clot occurs in one of the neck (carotid or vertebral) arteries that transport blood from heart to the brain.
- Blood clots form most often in arteries damaged by (atherosclerosis)
- a disease where rough, fatty deposits build up on walls of arteries and project into bloodstream. The deposits gradually narrow the passageway, causing the blood flow to slow down and sometimes completely occlude (block) the artery
B. Embolic stroke (cerebral embolism)
- Also caused by a clot but unlike cerebral thrombosis , clot originates somewhere other than the brain.
- Occurs when a pc. Of clot (embolus) breaks loose and carried by blood stream to the brain.
- Traveling through the arteries into the smaller vessels , the clot, reaches a point where it can’t go any further and plugs the vessel, cutting off the blood supply , the sudden blockage is called an embolism hence the name embolic stroke.
• Thrombotic and embolic strokes are the two types of cerebral infarction category strokes. In connection with these two types of strokes you hear the term cerebral infarction. An infarct is an area of necrosis, or tissue death, due to obstruction of blood vessels by a thrombus or embolus.
IV. Hemorrhagic stroke occurs when a blood vessel in or around the brain ruptures, spilling blood into the brain and/or surrounding the brain. Two main types of hemorrhagic stroke: subarachnoid hemorrhage & intracerebral hemorrhage ( referring to the parts of the brain affected by the bleeding.)
a) When this occurs, the cells nourished by the artery fail to get their normal supply of nutrients and stop functioning properly. The accumulated blood from the ruptured artery soon clots, displacing normal brain tissue and disrupting brain function.
A. Subarachnoid Hemorrhage
- The bleeding occurs in the space between the brain and the skull. In a subarachnoid hemorrhage, an artery on or near the surface of your brain bursts and spills into the space between the surface of your brain and your skull. This bleeding is often signaled by a sudden, severe headache. A subarachnoid hemorrhage is commonly caused by the rupture of an aneurysm, a small sack-shaped or