Stroke Cerebrovascular disease

Ischemic stroke

Makes up about 87% of strokes

Transient ischemic (silent strokes) are less severe, and only last for 24 hours, with symptoms such as visual abnormalities, like sudden vision loss. This does not result into permanent brain damage, but does higher your risk of future strokes.

Is caused by a blockage of blood supply to part of the brain, 2 kinds of ischemic strokes:

• Thrombotic stroke – caused by a blood clot forming in a blood vessel leading to the brain, disrupting the blood flow to part of the brain.
• Embolic stroke – caused when a blood vessel supplying the brain is blocked by an embolus, from elsewhere in the body. These strokes are caused typically from blood clots.

Haemorrhagic stroke

Caused by blood vessels that break and leak blood into the brain.

There are 2 types of this stroke:

• Intracerebral haemorrhage – The most common form of stroke. Caused when a blood vessel ruptures in the brain, and leaks blood into surrounding tissues. High blood pressure is the primary cause.
• This type of stroke has a sudden onset of symptoms – loss of consciousness, nausea and vomiting, numbness of the face, severe headache, with no known cause.
• Subarachnoid haemorrhage – Caused by an aneurysm, which is a bulge in a blood vessel that bursts into a large artery near the delicate membrane surrounding the brain. The blood fills the area around the brain where the cerebrospinal fluid is that protects the brain and becomes contaminated. There are no warning signs, but symptoms may be a severe headache. This is caused by the blood that irritates the vessels and become narrow in size and begin to spasm, making it more difficult to supply the brain with blood to survive.

Silent stroke

Lack symptoms and can go unnoticed, they cause lesions on the brain which can be detected via an MRI. This is associated with age-dependant memory loss and reduced brain volume. This stroke is 5 times more common than symptomatic strokes. Can be from a minor haemorrhage resulting in lesions in the brains white matter.

• Sudden onset of numbness or weakness of face or limbs, usually only on one side of the body
• Sudden confusion or difficulty speaking or understanding
• Sudden loss of vision
• Sudden severe headache with no known cause
• Sudden trouble walking, feeling dizzy, or loss of balance and coordination
• An ambulance or doctor must be called immediately after these symptoms have occurred, even if you are unsure of it being a stroke

The following may become impaired after a stroke, cognitive abilities, perception, coordination, speech and balance. Paralysis could also be possible.

The right side of the brain, controls the left side of the body, a stroke on the right side of the brain, could cause paralysis on the left side of the body.

A stroke in the cerebellum may cause problems with balance and coordination, and in the brainstem it may cause damage such as breathing, heart rate and death.

The most common complications of a stroke are:

• Aphasia – Patients have an impaired ability to speak, understand spoken or written language. This is due to stroke induced damage to the brain, where speech and language is processed. These patients may be helped by doing speech and language therapy
• Pain – They may experience pain immediately after a stroke and even up to weeks or months later. They experience local or mechanical pain that are in the joints, this due to damage caused in the tissues and muscles. Others experience pain chronic central pain due to damage caused in the brain. Central pain occurs when the damaged brain does not relay pain messages to the body properly, and then registers the slightest touch as painful.
• Pseudobulbar affect– This is when damage is caused to the brainstem and cerebral cortex, which causes uncontrollable episodes of laughing or crying, disrupting social interaction.
• Vascular dementia – Stroke victims may develop problems with their cognitive and mental abilities. This is loss of intellectual ability due to tissue damage from reduced blood flow to the brain. A stroke doubles the risk of dementia. Symptoms of vascular dementia are, memory loss, confusion, and decreased attention span.
• Paralysis and Spasticity– Some patients experience complete paralysis, where they cannot voluntarily move muscles. Some experience tightening or stiffness of muscles that impair movement of the arms or legs, this is called spasticity. This is caused from messages that are not properly conveyed from the brain to the muscles. The damaged brain sends signals to muscles to contract for long periods of time, and cause painful muscle spasms similar to severe cramping.

• Age – each year over 65 stroke rate doubles, in men and woman
• Gender – Higher in men than woman, but more woman die of strokes each year
• Race and Ethnicity– The rates vary between different races. Higher in African Americans than in white people. The rates have increased in Japanese and Chinese populations
• Genetics and hereditary factors – a family history is a strong predictor for stroke risk in the future

• High blood pressure– The strongest risk factor for cardiovascular disease. Strokes caused by people with high blood pressure, can be prevented by lowering the blood pressure. Men with high blood pressure in there middle ages are at high risk of having a stroke for their lifetime. Blood pressure is measured as systolic (pressure when blood is expelled out of the heart, when contracting), and diastolic (pressure between contractions). People with a healthy blood pressure are at lower risk for strokes than people with a high blood pressure, are at risk for heart attacks, heart failure, stroke and kidney disease. High blood pressure contributes to atherosclerosis and blood clot formation.
• Elevated Homocysteine- It’s an amino acid derivative that can damage blood vessels. High levels, are associated with higher stroke risks and recurrence. Disrupts endothelial tissues and stops the growth of new endothelial cells, and then contributes to atherosclerotic plaque formation. High levels of Homocysteine disrupt the function of brain cells and their survival.
• C- reactive protein – It’s a protein in the blood that works with the level of systemic inflammation. This blood test can be done to see the severity and incidence of strokes. This protein is produced in the liver and its growth rate is regulated by pro-inflammatory proteins, this becomes elevated in people with inflammation, infection and tissue damage.
• Excess Fibrinogen – It’s a component in blood that helps with clotting/coagulation. High levels of this protein is associated with cerebrovascular disease.
• High LDL Cholesterol – Found all over the body, important for cellular function. Cholesterol is carried to and from cells by lipoproteins. LDL “bad cholesterol” contributes to the build-up of plaque in arterial walls. High level of HDL “good cholesterol” help to reduce the risk of stroke or cerebrovascular disease.
• Insulin resistance/Glucose tolerance – Its characterised by reduced sensitivity to the hormone insulin, and regulates blood sugar levels. Insulin signals cells to take up glucose from the blood. People with diabetes have abnormal sugar levels in the blood. Insulin resistance occurs when the levels are normal but the ability to regulate blood sugar is impaired, thus high blood sugar levels.
• Sleep apnea – Is people who suffer from periodic breathing lapses during sleep. This is when the upper airway collapses for intermittent periods. Which makes the person gasp, or choke during night-time breathing. This also deprives them of oxygen during sleep, and is also associated with inflammation, endothelial dysfunction, and oxidative stress. This Highers the risk of blood clots to form, and then causes a stroke.

Diagnosis:

• Ischemic stokes are time dependant, cell death cascades to greater areas of the brain until the blood flow is restored
• Haemorrhagic stroke is also time dependant. Blood continues to leak from the original rupture site, and the area of the brain that is damaged by the hematoma increases

Treatment:

Seeing what type of stroke someone has had is very important, as Ischemic stroke medication would not work with haemorrhagic strokes and the other way around.

• Brain imaging can detect strokes and determine the nature of them:
• Computerized tomography angiography (CTA) – Looks for aneurisms, arterial and venous malformations, narrowing arteries in the neck and brain.
• Computerized tomography (CT) – Medical imaging tool used to identify cerebral haemorrhaging
• Magnetic resonance imaging (MRI) – Aids in the diagnosis of strokes
• Magnetic resonance angiography (MRA) – Uses a magnetic field, radio waves and a dye injected into veins that evaluate arteries in the neck and brain.
• Emergency treatment of ischemic stroke– Treatment is critical within the 4.5 hours onset of symptoms, this may dramatically help to reduce brain damage caused by blood clots during a stroke.
• Intravenous injection of tissue plasminogen activator (t PA) – It’s an enzyme that converts plasminogen to plasmin – enzyme that breaks down clots. It decreases the ischemic injury and helps salvage brain tissue.
• There is a risk of bleeding specially with people taking warfarin, high risk of brain haemorrhage
• Aspirin and antiplatelet agents– It’s an important treatment for Ischemic stokes, aspirin given to these patients within 48 hours of this type of stroke onset reduces the death rate over time.
• Surgical procedures – Emergency procedures must be done as soon as possible. When there is a weakness in a blood vessel a surgeon can clip the aneurism and stop the bleeding. Balloon angioplasty can be used when there is a closure in an artery to improve the blood flow.
• Secondary ischemic stroke prevention – Patients may be prescribed anti-platelet therapy, which includes low-dose aspirin or anticoagulant such as warfarin for long term use.
• Emergency treatment of haemorrhagic stroke– This focuses on controlling bleeding and reducing the pressure in the brain. Surgical procedure is used to drain the blood that collects outside the blood vessels during a haemorrhage. Warfarin is given to prevent blood clots, and Vitamin K is used to counteract the effects of the warfarin.
• Secondary haemorrhagic stroke prevention – Medication is prescribed to control blood pressure. Prescription medications for lowering blood pressure includes diuretics, calcium channel blockers, beta blockers, ACE inhibitors. 

• Have to look at the known risk factors, high blood pressure, elevated cholesterol, insulin resistance and dietary and lifestyle habits. Blood clots can be treated by using anticoagulants, and antiplatelet medications.
• Medications reduce the ischemic risk but increase the haemorrhagic stroke risk. As this focuses on reducing blood pressure, and not avoiding blood clotting.

• Warfarin – Anticoagulant that reduces blood clotting by helping against the effects of Vitamin K. Warfarin requires constant monitoring as it may cause excessive bleeding.
• Dabigatran – Is a thrombin inhibitor
• Rivaroxaban – Inhibits an enzyme involved in coagulation, these have only recently been approved for human use.
• These have benefits over warfarin, as they both inhibit clotting that don’t depend on vitamin K, they are also less sensitive to fluctuations of dietary vitamin K intake. People who take these meds, do not need monitoring like when taking warfarin.

Pradaxa vs Warfarin

Advantage;

• Rapid onset of action
• Predictable, consistent effect
• No need for blood test monitoring
• No need to maintain low vitamin K levels – promotes arterial calcification
• Preliminary and safety advantages

Disadvantage;

• No antidote for reversal of over anticoagulation effect
• No long term safety data on Pradaxa
• More expensive than warfarin

• Anti-platelet medications – Cell fragments in blood that help with clot formation. Anti-platelet drugs make these fragments less sticky and less likely to clot.
• Left arterial appendage occlusion – For patients who cannot take anti-coagulants, or blood thinners. This will stop clot formation and decrease the risk of a stroke. This is a muscle pouch that is like a reservoir for one of the heart chambers. When there is arrhythmia, there is a chance of blood clotting.

These are preventative measures to reduce inflammation, maintaining healthy body weight, reducing cholesterol, suppressing homocysteine and fibrinogen levels, lower blood pressure.

• Mediterranean diet– rich in fruits and vegetables, whole grains, fish and low in red meat and sweets. Which leads to less age-related diseases, including stroke. Decreases the levels of ischemic strokes irrespective of cholesterol levels, age and gender. Decreased risk of stroke, heart attack, vascular death. Because of this diet being low in red meat and rich in fruit and vegetables it controls homocysteine levels in people who are prone to high levels.
• Olive leaf and Olive oil – Has anti-high blood pressure and anti-atherosclerotic effects. The leaves of the olive tree have active compounds which reduce blood pressure. These are referred to as healthy heart compounds.
• Nattokinase – It’s extracted from fermented soybeans, and helps to reduce blood pressure in people who are hypertensive. It breaks down the protein fibrinogen that contributes to blood clotting and viscosity.
• L-Carnitine, Acetyl-L-carnitine, and propionyl-L-carnitine– L-carnitine has a protective effect against thrombosis in ischemic stroke.
• Vinpocetine – It’s an extract from the leaves of the periwinkle plant, which has both neuroprotective and cerebral blood-flow-enhancing properties. Neuroprotective effects are due to its manner of blocking sodium channels and calcium channels in the brain, preventing death of brain tissue.
• Vitamin D – regulates blood pressure by changing the calcium phosphate metabolism, and controls the endocrine glands, which improve the endothelial function.
• Vitamin B6, B12, and Folic Acid– Helps to lower the homocysteine levels which decreases the risk of strokes by 12%.
• Omega-3 fatty acids– Found in sources such as cold water fish and flaxseed oil. It helps to regulate blood pressure, reduce platelet aggregation, inflammation, LDL-cholesterol and other atherosclerosis risk factors. It enhances dilation of arteries which improves blood flow through the body, and prevent abnormal heart rhythms.
• Garlic – Can lower blood pressure in hypertensive people. It lowers systolic and diastolic blood pressure.
• DHEA – Steroid hormone derived from cholesterol, and improves arterial dilation and protects against endothelial dysfunction, and lower the risk of a stroke.
• Vitamin C – It’s a water soluble antioxidant and improves endothelial function. It also lowers blood pressure and heart rate. It also helps to enhance antihypertensive effects of some blood pressure medications.
• Flavonoids – Antioxidants found in fruit, vegetables, red wine, tea. There is also a reduced risk of ischemic stroke in woman. Citrus fruits can reduce overall stroke risk.
• Rutin – Found naturally in buckwheat and some fruits like apples. It also helps with the blood clot formation.