Stroke is a major neurological problem in the United States, affecting millions of people and their families. Stroke is the fifth-leading cause of death and the primary cause of serious disability.1 About 800,000 people experience a new or recurrent stroke each year.1 The direct and indirect cost of stroke in the U.S. is estimated at $34 billion.1 This estimate includes acute care, acute rehabilitation and follow-up care needed to manage ongoing neurological deficits.
A stroke produces long-term physical, psychological, social and financial problems that can be devastating for patients and families. Healthcare providers as a team play an essential role from the ED to the rehabilitation department with rapid, appropriate intervention and rehabilitation for patients with stroke.
Rehabilitation helps those who have had a stroke relearn skills to become productive members of society, promotes quality of life and reduces further treatment costs. The neurological deficits that occur when a person has a stroke may cause permanent damage to areas in the brain. Patients may need to learn how to speak again and compensate for the many other deficits that can occur from a stroke. They may, for example, need to develop new skills, such as walking with a cane if one side of the body is affected.2
This module will discuss the pathophysiology of stroke, stroke treatment options and prevention strategies. This information will help healthcare professionals across disciplines be better prepared to provide standardized and evidence-based care for patients with stroke.
Previously called a “cerebrovascular accident” (also known as a “brain attack”), stroke occurs when a part of the brain dies because of a lack of oxygen or nutrients.3 Stroke may occur because of a blockage from a clot or blood leaking into the brain. Temporary stroke symptoms may be caused by a transient ischemic attack. A TIA occurs when a person temporarily loses neurological function but there is no acute infarction; many recover in just minutes or a few hours.4 (The public often calls this a ministroke.) A TIA is a warning sign that a major stroke may occur and should prompt a complete medical workup.
Permanent neurological impairment results from a “completed” stroke. A completed stroke may occur when atherosclerotic plaque becomes lodged in a cerebral artery, blocking arterial blood flow to oxygen-dependent brain cells and producing permanent neurological deficits. If the plaque continues to move through the artery, a TIA will occur because the surrounding tissue is able to recover, and the neurological deficit resolves.
Types of Stroke
Ischemic stroke accounts for 87% of all strokes, hemorrhagic stroke for 13%. Hemorrhagic strokes are caused by an intracerebral bleed or by a subarachnoid hemorrhage. An ischemic stroke occurs when an atherosclerotic plaque or a clot blocks blood vessels in the brain, depriving brain cells of essential nutrients, such as glucose and oxygen. When a cerebral artery cannot maintain blood supply to a specific area in the brain, tissue death occurs. Ischemic strokes are divided into the following categories:4
- An atherosclerotic cerebrovascular stroke occurs when arteries in the brain are occluded because of atherosclerosis.
- A lacunar stroke is caused by atherosclerotic plaques affecting the deep white matter of the brain.
- An embolic stroke is caused by a blood clot that travels from the systemic arteries to the arteries in the brain.
- A cardiogenic embolic stroke is caused by underlying cardiac disease, such as atrial fibrillation, that causes a plaque or clot to break off and travel to the brain.
Too much pressure on the cerebral arteries in the brain causes hemorrhagic strokes. The pressure weakens the integrity of the blood vessels, causing the cerebral arteries to rupture. There are two types of hemorrhagic strokes:3
- An intracerebral hemorrhage is caused by a ruptured blood vessel that causes bleeding within the brain itself.
- A subarachnoid hemorrhage is bleeding into the area between the arachnoid matter and the pia mater surrounding the brain as a result of an aneurysmal rupture.
Ischemic injury and infarction occurs when oxygen supply is altered as a result of an obstruction (a clot or plaque) within a cerebral blood vessel or due to a weakened vessel that ruptures and bleeds (hemorrhages) into the surrounding brain. Cerebral ischemia depletes the brain’s oxygen and glucose levels within two to four minutes.4 Brain anoxia causes unconsciousness within 10 seconds.4 In response to ischemia, the brain’s cellular metabolism tries to correct the problem by switching to an anaerobic metabolism without oxygen or nutrients to prevent further death of nerve cells. In addition to the lack of oxygen and glucose to the injured area, other changes occur that produce further damage to neurons, which contribute to metabolic and hemodynamic disturbances. If the brain’s own protective response cannot halt or minimize these changes, cells in the ischemic area suffer permanent damage.4,5
An area surrounding the ischemic tissue known as the penumbra contains neurons that continue to receive some blood flow. Cells in the penumbra can remain preserved for up to four hours. If treatment does not occur within this short time, cells in the penumbra begin to die, brain tissue survival becomes critical, and medical treatment must be initiated to prevent a completed stroke. Rapid response to a stroke is crucial and should involve the patient, EMS personnel, nurses, physicians and other healthcare professionals and the public, who can be educated to recognize symptoms of stroke.5