9.9 Cerebrovascular Accident
A cerebrovascular accident (CVA), commonly referred to as a stroke, is a sudden interruption of blood flow to the brain that requires immediate emergency care. A spectrum of neurological deficits and potential complications can occur as a result of a CVA. Each year in the United States, there are more than 800,000 strokes. Stroke is a leading cause of death or serious long-term disability. Nearly three quarters of all strokes occur in people over the age of 65.
Diagnosing and treating a stroke is often referred to as “time is brain.” With timely treatment, it is possible to save brain cells and greatly reduce the damage or death that can occur due to a stroke. Brain cells die because they stop getting the oxygen and nutrients needed to function, or they are damaged by sudden bleeding in or around the brain. Knowing the signs of stroke and calling 911 immediately can help save someone’s life.[1]
Pathophysiology
There are two types of strokes called ischemic and hemorrhagic. An acute ischemic stroke is caused by a blockage or occlusion of a cerebral or carotid artery. This can be caused by plaque that has built up within the vessel, resulting in a thrombus or a blood clot that has traveled from another area of the body and lodged in the blood vessel, referred to as an embolism. An ischemic stroke is further categorized depending on the cause. CVAs caused by a thrombus are referred to as a thrombotic stroke, and CVAs caused by an embolism are called an embolic stroke. Thrombotic strokes account for more than half of all strokes and commonly occur because of atherosclerosis. An embolic stroke is caused by a thrombus or a group of thrombi that break away from one area of the body and travel through the arterial system via the carotid artery or through the arteries at the base of the skull. The most common source of the emboli is the heart. For example, emboli occur frequently in clients with atrial fibrillation, where tiny clots form within the atria of the heart and then break away and move into the brain’s circulation.
The second type of CVA is a hemorrhagic stroke. With this type of stroke, the stability of a blood vessel in the brain is compromised, leading to rupture and bleeding. The blood accumulates into the brain tissue or subarachnoid space. As the blood presses against the tissue in the brain, it can increase intracranial pressure.[2]
Several factors can lead to a hemorrhagic stroke. Sustained elevated blood pressure can cause changes within the arterial wall, making it susceptible to rupture. If this occurs it can cause an intracerebral hemorrhage, leading to bleeding, which causes edema irritation and displacement of the brain tissue. A subarachnoid hemorrhage is more common and refers to bleeding in the space between the brain and the surrounding membrane (subarachnoid space). This bleeding is usually triggered by a ruptured aneurysm or arteriovenous malformation. An aneurysm is an abnormal bulging or balloon