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Types of Stroke

Small Vessel Strokes

Small vessel disease is a common cause of cerebrovascular disease. It is responsible for ischemic and hemorrhagic strokes, cognitive decline, and asymptomatic disease. Lacunar stroke is the most common manifestation. Little is known about the causes of small vessel disease, but it is closely linked to hypertension (high blood pressure).

Hemorrhagic Stroke Ischemic Stroke
Intracranial Small Vessel Disease Lacunar Stroke
Subarachnoid Hemorrhage

TIA

Transient Ischemic AttackTIA is caused by a clot; the only difference between a stroke and TIA is that with TIA the blockage is transient. 

  • TIA symptoms occur rapidly and last a relatively short time.
  • Most TIAs last less than five minutes; the average is about a minute.
  • When a TIA is over, it usually causes no permanent injury to the brain.
  • A third of people who experience TIA go on to have a stroke within a year.

TIA Clinic – Now Available!
The CentraCare Neurosciences Transient Ischemic Attack (TIA) Clinic is an efficient service developed by the Stroke Team to treat patients who have had a recent TIA episode. Instead of having to make several visits to get work-up done, the TIA Clinic provides a one-stop service for TIA patients. We are dedicated to offering quality care to patients who are at risk for stroke, focusing on secondary prevention of stroke after a TIA.

Patients must be referred to the TIA clinic. If you are having stroke-like symptoms, call 911.

Risk Factors

  • Family history of stroke or TIA substantially increases risk.
  • People 55 years or older are at higher risk.
  • Males have a slightly higher risk of TIA than females but females are more likely to die from a stroke.
  • High blood pressure
  • Diabetes Mellitus
  • Tobacco smoking

Symptoms

Symptoms can vary widely from person to person. The most frequent symptoms include:
  • temporary loss of vision (amaurosis fugax)
  • difficulty speaking (aphasia)
  • weakness on one side of the body (hemiparesis)
  • and numbness or tingling (paresthesia), usually on one side of the body
  • impairment of consciousness is very uncommon
  • The symptoms of a TIA are short-lived and usually last a few seconds to a few minutes and most symptoms disappear within 60 minutes.

 

Large Vessel Strokes

A large vessel stroke is a medical emergency and can cause permanent neurological damage and death. Risk factors for LVS stroke include old age, high blood pressure, previous stroke or transient ischemic attack (TIA), diabetes, high cholesterol, tobacco smoking and atrial fibrillation. High blood pressure is the most important modifiable risk factor of stroke.

After the age of 55, stroke risk doubles for every decade a person is alive. Women suffer more strokes each year and more disability after stroke than men. Since women live longer than men, and stroke occurs more often at older ages, more women than men die from stroke each year. However, at younger ages, men have a stroke more often than women.

African Americans have twice the risk of stroke when compared to Caucasians. Hispanics and Asian/Pacific Islanders also have higher stroke risks.

Family history of stroke indicates the presence of a genetic predisposition. This risk is significant for first degree relatives only, particularly when the stroke occurs at a younger age, usually less than age 70. Thus, if the parent died from a stroke at age 90, the implication is longevity, not heightened stroke risk for the patient in the office.

A variety of structural vascular and heart conditions are associated with strokes, including patent foramen ovale, aortic stenosis, cardiomyopathy, previous heart attack with scarring of the heart muscles, fibromuscular dysplasia, and different forms of inflammatory blood vessel conditions called vasculitis among others.

Occurrence of a stroke or TIA is associated with a high risk of future stroke. Within 5 years, the risk of recurrence is 20-40 percent. TIAs are serious warning signs of an impending stroke. Up to 40 percent of people who experience a TIA are expected at some time later to have a stroke. Therefore, after a first CVA or TIA, the patients and their families must concentrate not just on rehabilitation and recovery, but must consider how medical treatments, surgery and lifestyle changes can help reduce the risk of recurrence.

Lifestyle Risk Factors

Smoking tobacco doubles the risk of stroke due to effects on atherosclerosis of the arteries and increased blood pressure.

Although mild use of alcohol has been associated with lower risk of stroke, daily use of larger amounts of alcohol increases the risk for stroke. Alcohol tolerance is less in women and in people with less body weight.

Obesity also makes people more likely to have high cholesterol, high blood pressure and diabetes, all of which can increase the risk of stroke. Obstructive sleep apnea of the obese patient is associated with increased risk of stroke, but also headaches, memory problems and diminished attention.

Adopting healthy eating habits and increasing physical activity can help reduce stroke risk. Numerous studies have demonstrated that daily physical exercise, even walking for 30 minutes (at home on a treadmill in front of the TV), is associated with lesser risk of stroke, heart attack, but also of memory loss, and movement abnormalities from Parkinson’s disease.

General Risk Factors

The most important modifiable risk factors for stroke are high blood pressure and atrial fibrillation. Other modifiable risk factors include high blood cholesterol levels, diabetes, cigarette smoking (active and passive), heavy alcohol consumption and drug use, lack of physical activity, obesity, processed red meat consumption and unhealthy diet. The drugs most commonly associated with stroke are cocaine, amphetamines causing hemorrhagic stroke, but also over-the-counter cough and cold drugs containing sympathomimetics.

No high quality studies have shown the effectiveness of interventions aimed at weight reduction, promotion of regular exercise, reducing alcohol consumption or smoking cessation. Nonetheless, given the large body of circumstantial evidence, best medical management for stroke includes advice on diet, exercise, smoking and alcohol use. Medication or drug therapy is the most common method of stroke prevention; carotid endarterectomy can be a useful surgical method of preventing stroke.

Blood pressure

Hypertension (high blood pressure) accounts for 35-50 percent of stroke risk. Blood pressure reduction of 10 mmHg systolic or 5 mmHg diastolic reduces the risk of stroke by ~40 percent. Lowering blood pressure has been conclusively shown to prevent both ischemic and hemorrhagic strokes.

Atrial Fibrillation

Those with atrial fibrillation have a 5 percent a year risk of stroke, and this risk is higher in those with valvular atrial fibrillation. Depending on the stroke risk, anticoagulation with medications such as warfarin or aspirin is warranted for stroke prevention.

Blood Lipids

High cholesterol levels have been inconsistently associated with (ischemic) stroke. Statins have been shown to reduce the risk of stroke by about 15 percent. Since earlier meta-analyses of other lipid-lowering drugs did not show a decreased risk, statins might exert their effect through mechanisms other than their lipid-lowering effects.

Diabetes Mellitus

Diabetes mellitus increases the risk of stroke by 2 to 3 times. While intensive control of blood sugar has been shown to reduce microvascular complications such as nephropathy and retinopathy it has not been shown to reduce macrovascular complications such as stroke.

Anticoagulation Drugs

Oral anticoagulants such as warfarin have been the mainstay of stroke prevention for over 50 years. However, several studies have shown that aspirin and antiplatelet drugs are highly effective in secondary prevention after a stroke or transient ischemic attack. Low doses of aspirin (for example 75–150 mg) are as effective as high doses but have fewer side effects.

Low-dose aspirin is also effective for stroke prevention after sustaining a myocardial infarction. Except for in atrial fibrillation, oral anticoagulants are not advised for stroke prevention —any benefit is offset by bleeding risk.

In primary prevention however, antiplatelet drugs did not reduce the risk of ischemic stroke while increasing the risk of major bleeding. Further studies are needed to investigate a possible protective effect of aspirin against ischemic stroke in women.

Surgery

Carotid endarterectomy or carotid angioplasty can be used to remove atherosclerotic narrowing (stenosis) of the carotid artery. There is evidence supporting this procedure in selected cases. Endarterectomy for a significant stenosis has been shown to be useful in the prevention of further strokes in those who have already had one. Carotid artery stenting has shown to be equally useful. Patients are selected for surgery based on age, gender, degree of stenosis, time since symptoms and patients' preferences. Surgery is most efficient when not delayed too long — the risk of recurrent stroke in a patient who has a 50 percent or greater stenosis is up to 20 percent after 5 years, but endarterectomy reduces this risk to around 5 percent. The number of procedures needed to cure one patient was 5 for early surgery (within two weeks after the initial stroke), but 125 if delayed longer than 12 weeks.

To be beneficial, the complication rate of the surgery should be kept below 4 percent. Even then, for 100 surgeries, 5 patients will benefit by avoiding stroke, 3 will develop stroke despite surgery, 3 will develop stroke or die due to the surgery itself, and 89 will remain stroke-free but would also have done so without intervention.

 

Ischemic Strokes Etiology

Thrombotic Stroke

In thrombotic stroke a thrombus or blood clot usually forms around atherosclerotic plaques. Since blockage of the artery is gradual, onset of symptomatic thrombotic strokes is slower. A thrombus itself (even if non-occluding) can lead to an embolic stroke if the thrombus breaks off, at which point it is called an embolus.

Two types of thrombosis can cause stroke: Large vessel disease involves the common and internal carotids, vertebral, and the Circle of Willis. Diseases that may form thrombi in the large vessels include: atherosclerosis, vasoconstriction (tightening of the artery), aortic, carotid or vertebral artery dissection, various inflammatory diseases of the blood vessel wall (Takayasu arteritis, giant cell arteritis, vasculitis), noninflammatory vasculopathy, Moyamoya disease and fibromuscular dysplasia.

Small vessel disease involves the smaller arteries inside the brain: branches of the Circle of Willis, middle cerebral artery, stem, and arteries arising from the distal vertebral and basilar artery. Diseases that may form thrombi in the small vessels include: lipohyalinosis (build-up of fatty hyaline matter in the blood vessel as a result of high blood pressure and aging) and fibrinoid degeneration (stroke involving these vessels are known as lacunar infarcts) and microatheroma (small atherosclerotic plaques).

Sickle-cell anemia, which can cause blood cells to clump up and block blood vessels, can also lead to stroke.

Embolic Stroke

An embolic stroke refers to the blockage of an artery by an arterial embolus, a travelling particle or debris in the arterial bloodstream originating from elsewhere. An embolus is most frequently a thrombus, but it can also be a number of other substances including fat, air, cancer cells or clumps of bacteria (usually from infectious endocarditis).

Emboli most commonly arise from the heart (especially in atrial fibrillation) but may originate from elsewhere in the arterial tree. In paradoxical embolism, a deep vein thrombosis embolisms through an atrial or ventricular septal defect in the heart into the brain.

Cardiac causes can be distinguished between high and low-risk:

High risk: atrial fibrillation and paroxysmal atrial fibrillation, rheumatic disease of the mitral or aortic valve disease, artificial heart valves, known cardiac thrombus of the atrium or ventricle, sick sinus syndrome, sustained atrial flutter, recent myocardial infarction, chronic myocardial infarction together with ejection fraction <28 percent, symptomatic congestive heart failure with ejection fraction <30 percent, dilated cardiomyopathy, Libman-Sacks endocarditis, Marantic endocarditis, infective endocarditis, papillary fibroelastoma, left atrial myxoma and coronary artery bypass graft (CABG) surgery.

Low risk/potential: calcification of the annulus (ring) of the mitral valve, patent foramen ovale (PFO), atrial septal aneurysm, atrial septal aneurysm with patent foramen ovale, left ventricular aneurysm without thrombus, isolated left atrial "smoke" on echocardiography (no mitral stenosis or atrial fibrillation), complex atheroma in the ascending aorta or proximal arch.

Systemic Hypoperfusion

Systemic hypoperfusion is the reduction of blood flow to all parts of the body. It is most commonly due to heart failure from cardiac arrest or arrhythmias, or from reduced cardiac output as a result of myocardial infarction, pulmonary embolism, pericardial effusion, or bleeding. Hypoxemia (low blood oxygen content) may precipitate the hypoperfusion.

Cerebral venous sinus thrombosis leads to stroke due to locally increased venous pressure, which exceeds the pressure generated by the arteries. Infarcts are more likely to undergo hemorrhagic transformation (leaking of blood into the damaged area) than other types of ischemic stroke. 

 

 

 

 

 

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