Stroke and Neurovascular Center

A stroke — also called a “cerebrovascular accident” or “brain attack” — is a sudden interruption in blood flow in the brain. It can be due to either a blockage or a rupture in a blood vessel in or leading to the brain. The interruption deprives brain tissue in and around the affected area of the essential oxygen and nutrients carried in the blood.

Within minutes of oxygen deprivation, the sensitive cells of the brain suffer permanent damage and die. This impairs the functions that the affected areas of the brain controls – for example walking, talking, and vital functions such as breathing. Unlike many other cells in the body, brain cells cannot be replaced.

Ischemic stroke occurs when there is blockage of an artery supplying the brain tissue while hemorrhagic stroke occurs when a weakened vessel ruptures causing leakage of blood into or around the brain itself. Transient ischemic attacks (TIAs) occur when there is a transient blockage of blood flow to the brain, resulting in transient stroke like symptoms.

Treatment for each type of stroke is significantly different. In fact, treating an ischemic stroke as though it were hemorrhagic or vice versa could have life-threatening consequences. Therefore, a reliable diagnosis is critical before beginning treatment.

Ischemic Strokes

About 80% of strokes are ischemic. They are caused by an obstruction of an artery supplying the brain, which prevents oxygenated blood from reaching parts of the brain that the artery feeds. Ischemic strokes are either thrombotic or embolic, depending on where the clot originated from.

Thrombotic Ischemic Stroke

Thrombotic stroke is caused by a thrombus (blood clot) that develops in an artery supplying blood to the brain. This usually occurs because of repeated buildup of fatty deposits, calcium and clotting factors such as fibrinogen, and cholesterol, in the blood. The body perceives the buildup as an injury to the vessel wall and responds the way it would to a small wound — it forms blood clots around the injured area. This progressive build-up of clot eventually blocks blood flow.

Large vessel thrombosis occurs in the brain’s larger arteries. The impact and damage tends to be magnified because all the smaller vessels that the artery feeds are deprived of blood. In most cases, large vessel thrombosis is caused by a combination of long-term plaque buildup (atherosclerosis) followed by rapid blood clot formation. High cholesterol is a common risk factor for this type of stroke.

Small vessel disease (lacunar infarction) occurs when blood flow is blocked to a very small artery. It has been linked to high blood pressure (hypertension) and is an indicator of atherosclerotic disease.

Thrombotic disease accounts for about 60 percent of acute ischemic strokes. Of these, approximately 70 percent are large vessel thrombosis.

Embolic Ischemic Stroke

An embolus is a blood clot that forms in one area of the body and travels through the bloodstream to another. In the case of embolic stroke, a clot usually forms in the heart or large arteries of the upper chest and neck. It then travels to the smaller vessels of the brain where it lodges and blocks blood flow.

Emboli can be fat globules, air bubbles or, most commonly, pieces of atherosclerotic plaque that have detached from an artery wall. Many emboli are caused by a cardiac condition called atrial fibrillation, which is an abnormal, rapid heartbeat in which the two small upper chambers of the heart (called the atria) quiver instead of beat. This quivering causes blood to pool and form clots that can travel to the brain and cause a stroke. Cardiac sources of embolism account for 80 percent of embolic ischemic strokes.

Ischemic Stroke Symptoms

The most common symptom of an ischemic stroke is sudden weakness of the face, arm or leg, most often on one side of the body.

Other warning signs may include:

• Sudden numbness of the face, arm, or leg, especially on one side of the body
• Sudden confusion, trouble speaking or understanding speech
• Sudden trouble seeing in one or both eyes
• Sudden trouble walking, dizziness, loss of balance or coordination
• Sudden severe headache with no known cause (most common with hemorrhagic stroke)

The symptoms depend on the side of the brain that’s affected, the part of the brain, and how severely the brain is injured. Stroke may be associated with a headache, or may be completely painless. Therefore, each person may have different warning signs.

Transient Ischemic Attack (TIA)

A Transient ischemic attack (TIA) or “mini-stroke” is caused by a brief disruption in blood flow to a part of the brain. The symptoms of a TIA resemble those of a stroke but they usually resolve within minutes or up to 24 hours and there is no damage to the brain.

Patients can experience any of the following symptoms:

• Loss of vision
• Dizziness
• Imbalance
• Confusion
• Weakness or loss of sensation on one side of the body
• Difficulty speaking or understanding
• Generalized weakness

A TIA is usually a warning sign of an impending stroke and should be considered an emergency. It is vital to present to the nearest primary stroke center for urgent evaluation and treatment in order to prevent a stroke from occurring.

Hemorrhagic Strokes

Hemorrhagic stroke occurs when a vessel in the brain suddenly ruptures causing blood to leak directly into brain tissue and/or into the clear cerebrospinal fluid that surrounds the brain as well as in its central cavities (ventricles). The rupture can be caused by the force of high blood pressure. It can also originate from a weak spot in a blood vessel wall, such as a cerebral aneurysm, or other blood vessel malformations in or around the brain.

Damage can be caused in two ways. As in the case of ischemic stroke, oxygen- and nutrient-rich blood is prevented from reaching the brain cells beyond the point of rupture. In addition, extravasated blood can irritate and harm the brain cells in the areas where it accumulates.

It is the location of the hemorrhage, rather than the amount of blood, that tends to be the bigger factor in influencing the severity of the stroke. For example, tiny bleeds in the brainstem can be quite lethal whereas the same-sized bleed in the frontal lobe may not even result in symptoms.

There are different types of hemorrhagic strokes. They are differentiated by where the ruptured artery is located and where the bleed occurs.

Intracerebral Hemorrhage (ICH)

Also called intraparenchymal hemorrhage or intracranial hematoma, this type of stroke is caused by the sudden rupture of an artery or blood vessel within the brain. The blood that leaks into the brain results in a sudden increase in pressure that can damage the surrounding brain cells. If the amount of blood increases rapidly, the sudden and extreme buildup in pressure can lead to unconsciousness or death.

Approximately 10 percent of all strokes are intracerebral hemorrhages. They occur most commonly in the basal ganglia where the vessels can be particularly delicate. High blood pressure (hypertension) is the most common cause of this type of stroke. Less common causes include trauma, infections, tumors, blood clotting deficiencies, and abnormalities in cerebral blood vessels.

Blood Vessel Abnormalities

Blood vessel abnormalities in the brain include arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs). AVMs and AVFs are abnormal connections between cerebral arteries (which carry blood to the brain) and veins (which take blood away from the brain). AVMs appear to be acquired prior to birth (congenital) and tend to form near the back of the brain. Although AVFs can be congenital, they are more often caused by trauma that damages an artery and a vein that are adjacent in the brain.

These blood vessel abnormalities can cause a host of problems but most commonly they exert pressure against the adjacent parts of the brain and cause neurological problems such as seizures, paralysis or loss of speech. They can also bleed (hemorrhage) into surrounding tissues. 2 to 4 percent of all strokes are due to hemorrhage from a cerebral arteriovenous abnormality.

Subarachnoid Hemorrhage (SAH)

Subarachnoid hemorrhage occurs when bleeding from a damaged vessel causes blood to accumulate in the subarachnoid space between the brain and the skull. This blood presses on the surface of the brain and can irritate, damage or destroy surrounding brain cells.

When blood enters the subarachnoid space, it mixes with the cerebrospinal fluid (CSF) that cushions the brain and spinal cord. This blood can block CSF circulation and lead to fluid buildup, increasing pressure on the brain. The open spaces in the brain (ventricles) may enlarge and result in a condition called hydrocephalus. This can make a patient lethargic, confused or incontinent.

The blood also can also irritate and lead to narrowing of the blood vessels. This condition, referred to as vasospasm, can impede blood flow to the brain and result in an ischemic stroke. Vasospasm typically develops five to eight days after the initial hemorrhage.

After trauma, the most common cause of a subarachnoid hemorrhage is a ruptured cerebral aneurysm. SAH also can occur when blood leaks from abnormal blood vessel connections (AVMs and AVFs) near the surface of the brain.

Cerebral Aneurysm

A cerebral aneurysm is a weak and bulging area in the wall of an artery very that is akin to a thin balloon or weak spot in an inner tube. Aneurysms form when there is wear and tear in the arteries, injury, infection, or an inherited tendency to form them.

There are two types of aneurysm:

• Saccular Aneurysm – This is the most common type. It has a neck and stem and is known as a “berry” aneurysm because of its shape.
• Fusiform Aneurysm – These are dilatations in the walls of a vessel and are commonly located at the base of the brain in the Circle of Willis. This is an area where significant blood pressure changes occur and where a lot of vessels branch off. These factors weaken the walls of blood vessels in this area.

Although it is not possible to predict whether an aneurysm will rupture, an aneurysm is more likely to do so when it has a diameter of 7 millimeters or more. Unruptured brain aneurysms can be medically treated to prevent a possible rupture.

Sudden & Severe Symptoms

Symptoms of a hemorrhagic stroke appear without warning. The sudden increase in blood volume within the rigid skull (cranium) creates intense intracranial pressure that cannot be released. This, in turn, may trigger a severe (“thunderclap”) headache, neck pain, double vision, nausea or vomiting, loss of consciousness or even death.

About 17 percent of strokes are hemorrhagic. The average age at which people suffer hemorrhagic stroke tends to be lower than for ischemic stroke. This is because many of the risk factors are related to unhealthy behaviors, such as smoking or drug use, rather than the effects of aging on the body.The fatality rate for hemorrhagic strokes is higher than for ischemic strokes and overall prognosis is poorer

Many of the risk factors for stroke are preventable or controllable.

Studies show that a healthy lifestyle and diet along with preventive medical care where appropriate can significantly reduce the risk of suffering a stroke. By modifying certain behaviors and getting treatment for risky medical conditions, we can prevent or control many of the conditions that commonly lead to stroke.

According to current estimates, more than 80 percent of strokes could be eliminated if people recognize and reduce their risks!

Common Risk Factors for Stroke Include:

Manageable or Preventable Risk Factors:

• Diet & Nutrition
• Physical Inactivity
• Smoking
• Substance/Alcohol Abuse
• Certain medical conditions, including:
  • Cerebral aneurysms (unruptured)
  • Cholesterol level (high levels of “bad” cholesterol and/or low levels of “good” cholesterol)
  • Diabetes
  • Hardening of the arteries (atherosclerosis/arteriosclerosis)
  • Heart (cardiovascular) disease
  • High blood pressure (hypertension)
  • Obesity
  • Transient ischemic attacks (TIAs)
  • Abnormal blood vessel connections (arteriovenous malformations and arteriovenous fistulas)

Unalterable Risk Factors:

• Age
• Ethnicity
• Heredity/family history of stroke
• Gender

It is difficult to say which risk factor increases stroke risk more because many of them are interconnected. For example, overeating and a sedentary lifestyle can lead to harmful medical conditions such as hypertension, high levels of bad cholesterol and obesity – all of which are linked to stroke.

Many of the risk factors for stroke are also major risk factors for heart attack. There is a direct correlation between cardiovascular disease and cerebrovascular disease.

Behavioral Factors

Diet and Nutrition: A high level of “bad” cholesterol in the bloodstream is a major risk factor for stroke. The primary way that cholesterol enters our bodies is through fats in the food we consume, which is why a sensible, balanced diet is so important. Studies also link high levels of sodium (salt) in the diet, which increases blood pressure, to an increased risk of stroke.

Physical Activity: Regular physical activity helps control many of the risk factors associated with stroke. By improving blood circulation, exercise enhances the body’s ability to use oxygen, which in turn helps to reduce blood pressure. Regular physical activity has been shown to increase “good” cholesterol levels, decrease triglyceride (fat) levels, and help manage body weight.

Smoking: Smoking is a risk factor for all types of stroke. A study published in the May 2003 issue of Stroke, a journal of the American Heart Association, shows that the risk of stroke increases incrementally depending on how many cigarettes a day you smoke. Nicotine, the addictive element in cigarettes, raises blood pressure and increases the risk of developing hypertension. Cigarette smoke contains more than 4,000 chemicals, including 43 known to cause cancer. It thickens the blood, making it more likely to clot. Even environmental tobacco smoke (ETS), or second hand smoke, has been linked to increased risk of stroke because it contains the same harmful chemicals that smokers inhale. ETS includes mainstream smoke (smoke that is drawn through the mouthpiece of a cigarette and exhaled into the air by the smoker) and sidestream smoke (comes from the burning tobacco in cigarettes).

Substance Abuse: The use of certain illegal or controlled substances has been shown to increase the risk of stroke, particularly hemorrhagic stroke. Cocaine (“crack” in its smoked form) causes a severe elevation of blood pressure that can rupture a blood vessel leading to or inside of the brain. Smoked amphetamines — such as crystal meth and ice — as well as any illicit drug injected into the bloodstream can also produce stroke.

Among adolescents and young adults, an increasing percentage of strokes occur in relation to drug use.

Alcohol Consumption: Heavy and regular use of alcohol can dramatically increase blood pressure. Studies suggest that heavy alcohol use, defined as two drinks or more a day, may increase the risk of suffering a subarachnoid hemorrhage (SAH) more than tenfold.

Medical Conditions & General Health

Obesity: Obesity increases the chances of developing hypertension, high blood cholesterol, and diabetes, all of which are significant factors in stroke. Some research suggests that even modest weight gain (20-40 pounds) over ideal body weight doubles the chances of suffering a stroke.

Cholesterol Levels: Although it gets a lot of bad press, the waxy, fatty substance called cholesterol is necessary for healthy cell membranes, among other things. We manufacture cholesterol naturally in our liver and we consume it through our diet.

There are different types of cholesterol. HDL (high-density lipoprotein) is considered “good” cholesterol while LDL (low-density lipoprotein) is considered “bad”. Good cholesterol (HDL) carries bad cholesterol (LDL) away from the arteries. Bad cholesterol (LDL) can combine with other substances in the blood to form plaque, which can stick to the artery walls and potentially lead to clot formation and ischemic stroke.

Some people are genetically predisposed to bad-cholesterol build up. Their liver produces too much LDL. But in most cases, bad behaviors, such as smoking and lack of physical activity causes increased LDL. Diets high in saturated, polyunsaturated and/or hydrogenated fats (trans fatty acids) and/or low in monosaturated fats, appear to elevate bad cholesterol without affecting good cholesterol. Lifestyle modification can help maintain cholesterol levels within the normal range (less than 200 mg/dL). When that is not enough, physicians also can prescribe appropriate medications to control cholesterol levels.

Cholesterol Medications: The most prominent cholesterol drugs are in the statin family. They work by interfering with the cholesterol-producing mechanisms of the liver and by increasing the capacity of the liver to remove cholesterol from circulating blood (by producing more HDL). They include lovastatin (Mevacor®), fluvastatin (Lescol®), pravastatin (Pravachol®), simvastatin (Zocor®), atorvastatin (Lipitor®) and rosuvastatin (Crestor®).

Other Drug Treatments Include:

• Nicotinic Acid (Niacin) lowers LDL levels and raises HDL , must be given in large doses and can potentially be toxic.
• Questran (cholestyramine) and Colestid (colestipol) increase HDL levels and therefore the liver’s uptake of cholesterol from the bloodstream.
• Fibric Acid derivatives, such as Lopid (gemfibrozil) and Tricor (fenofibrate), which can also increase HDL levels.
• Aspirin can thin the blood and reduce the possibility of clot formation.

Diabetes: People with diabetes are 2 to 4 times more likely to suffer strokes. Diabetes impedes the body’s ability to produce or properly use insulin, a hormone that allows our cells to absorb glucose (blood sugar). Glucose, the body’s main source of fuel, is created naturally during the digestive process. The pancreas is supposed to produce the right amount of insulin automatically to allow our bodies to use the glucose. In diabetics, the pancreas produces little or no insulin, so glucose builds up to high levels in the blood.

The disease falls into two main categories: type 1, which usually occurs during childhood or adolescence; and type 2, the most common form that generally occurs after age 45. There is also gestational diabetes, which can occur during pregnancy.

Diabetes can seriously harm blood vessels throughout the body, including those in the brain. High blood glucose levels can harden the arteries (atherosclerosis), thicken capillary walls, and make blood stickier — all significant risk factors for ischemic stroke. It can also cause small vessels to leak, reducing blood flow to the body tissue.

If blood sugar levels are high at the time of a stroke, brain damage can be more severe and extensive. This occurs because the body breaks down glucose differently when the brain is deprived of oxygen. The products of this breakdown are in and around the area of dead tissue (infarction) and are, themselves, toxic to the brain tissue. If blood circulation is restored to the area, these products will break down even further and result in an increase in the size of the infarction.

Treating diabetes can delay or prevent the onset of complications that increase the risk of stroke. Healthy eating, physical activity, and insulin via injection or an insulin pump are the basic therapies for type 1 diabetes.

Healthy eating, physical activity, and blood glucose testing are the basic management tools for type 2 diabetes. In addition, many people with type 2 diabetes require oral medication, insulin injection, or both to control their blood glucose levels.

Hardening of the Arteries (Atherosclerosis/Arteriosclerosis): Atherosclerosis and arteriosclerosis involve the buildup of deposits on the insides of the artery walls, which causes thickening and hardening (sclerosis) of the arteries. In atherosclerosis, the deposits consist of fatty substances. In arteriosclerosis, the deposits are composed largely of calcium.

The narrowing of the artery caused by the buildup of hardened plaque is called “stenosis.” The narrowing is measured as a percentage of the artery diameter that is blocked. For example, 70 percent stenosis means the artery is 70 percent blocked.

Atherosclerosis typically occurs in the carotid artery leading to the brain, resulting in a condition called carotid stenosis. This is a leading cause of ischemic stroke. Early warning signs of carotid stenosis include carotid bruits, which can be detected by a primary care physician during a physical exam. Carotid bruits are the noise made by the blood flowing past the blockage. The disturbed flow creates turbulence that can be heard by the physician listening to the artery with a stethoscope.

These narrowed vessels can be treated by “best medical management” or through surgical/endovascular procedure. Medical management would involve lifestyle modifications (diet, exercise, smoking cessation, etc) and medications including cholesterol medication and an antithrombotic agent. Procedures such as carotid endarterectomy or carotid stenting can also be done in appropriate patients to reduce the risk of stroke.

Heart Disease (Cardiovascular Disease): One in five Americans has some form of treatable cardiovascular disease, such as heart valve disorders, heart muscle disease (cardiomyopathy), coronary artery disease, and hearth rhythm disorders(arrhythmias) in which the heart does not beat normally. People with coronary heart disease or heart failure have a higher risk of stroke than those with hearts that work normally. Certain types of congenital heart defects also raise the risk of stroke.

Atrial fibrillation, an arrhythmia that some patients describe as a “fluttering” in their chest, is a common risk factor for ischemic stroke and is most common in the elderly. The heart’s upper chambers quiver instead of beat, which allows blood to pool and lead to clot formation. The clot can then break away, enter the bloodstream, lodge in an artery leading to or inside the brain, and result in an ischemic stroke.

Treating Atrial Fibrillation

Medications are used to slow down the rapid heart rate seen in atrial fibrillation. These may include drugs such as amiodarone, beta blockers, calcium antagonists, digoxin, disopyramide, flecainide, procainamide, propafenone, quinidine and sotalol.

Electrical cardioversion may be used to restore normal heart rhythm with an electric shock. Radiofrequency ablation may also be used to restore normal heart rhythm. This involves inserting a thin, flexible catheter into an artery and threading it to the heart muscle where a burst of radiofrequency energy is delivered through it to destroy tissue that triggers abnormal electrical signals or to block abnormal electrical pathways. Surgery (rarely used) also can be used to disrupt electrical pathways that generate atrial fibrillation. An atrial pacemaker can be implanted under the skin of the chest to regulate the heart rhythm.

High Blood Pressure (Hypertension): High blood pressure (generally considered over 120/80 mm Hg) is the most common and most serious of all the modifiable risk factors for stroke. People with uncontrolled high blood pressure are seven times more likely to have a stroke than those with controlled blood pressure.

When the heart beats and pumps blood into the arteries, it creates pressure in them and causes them to stretch. The degree of stretch depends on the health of the vessels (the more muscular and elastic, the more they can stretch) and how much pressure the blood exerts.

High blood pressure puts excess stress on the heart (which has to pump harder) and damages blood vessels. If there is a weak spot in a blood vessel wall in the brain, high blood pressure could eventually cause it to rupture.

High blood pressure can be cause by other conditions including kidney disease, pregnancy, hormonal disorders, or certain medications. The most common causes of hypertension appear to be family history, diet (high salt intake or obesity), or habits such as smoking and excessive alcohol intake.

Hypertension is often called the “silent killer”. It is not uncommon to have high blood pressure and not know it because symptoms are not always present. Thus it is very important for health care professionals to routinely check blood pressure. This condition can be managed through lifestyle changes (diet and exercise) and medications, of which there are many different types.

Transient Ischemic Attack (TIA): TIAs are “warning strokes” that produce stroke-like symptoms but no lasting damage. Recognizing and treating TIAs can reduce the risk of a major stroke.

Abnormal Blood Vessel Connections: Abnormalities within cerebral arteries and veins include arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs). AVMs and AVFs are abnormal connections between cerebral arteries (which carry blood to the brain) and veins (which take blood away from the brain).

AVMs are masses of arteries and veins without intervening capillaries. Arteries decrease in size the farther they are from the heart. Ultimately they become so small that they are called capillaries. Capillaries are large enough to allow only one or two red blood cells to flow through them at a time. The decrease in the size of arteries from the heart to the capillaries is accompanied by a large decrease in the pressure within them at these locations. Veins form where capillaries join together and they transport blood back to the heart under low pressure.

In AVMs, because there are no capillaries, high-pressure arterial blood empties directly into veins, which have thin walls capable of containing only low pressure. The stress of the pressure can cause a vein to rupture, resulting in hemorrhage. The other clinically significant consequence of arterial blood flowing directly into veins without intervening capillaries is that the tissues through which the blood flows cannot adequately extract oxygen and nutrients necessary for their functioning and survival. This can result in seizure or stroke.

Although AVFs can be congenital, more often they are caused by a trauma that damages an artery and vein that are adjacent in the brain. These blood vessel abnormalities can cause a host of neurological problems including seizures and bleeding (hemorrhage) into surrounding tissues. Two to four percent of all strokes are related to hemorrhage from cerebral arteriovenous abnormalities.

There are three general forms of treatment for AVMs/AVFs:

• Surgery: This is the longest-standing treatment for AVMs. It involves entering the skull and tying off or clipping the arterial vessels that feed the malformation, eliminating the draining veins, and removing or obliterating the nest (nidus) of the AVM.
• Endovascular Embolization: This involves closing off the vessels of the AVM or AVF by injecting an agent– such as a special glue, tiny coil, or balloon– into them to block blood flow through the abnormal connection. Embolization is often used before surgery to minimize blood loss, making the operation safer and shorter. It can also be performed before radiosurgery to make the AVM smaller and increase the chance that radiosurgery will be successful. In some cases, endovascular embolization alone can permanently cure an AVM.
• Radiosurgery: Despite its name, radiosurgery does not require any surgical instruments to be placed within the head. This procedure tightly focuses beams of radiation from outside the skull onto the abnormal vessels in order to injure and clog the AVM. The vessels gradually close off and are replaced with scar tissue. The results of radiosurgery can take from weeks to years to become fully effective. A danger of radiosurgery is damage to normal brain or spinal cord tissue around the AVM. Therefore, the procedure is usually reserved for AVMs that are relatively small (less than 3 cm in diameter), are situated so deep beneath important brain tissue that the surgical approach is hazardous, or involve so many vessels that embolization is not feasible.

Cerebral Aneurysm (Unruptured): A brain aneurysm is a weak bulging spot on the wall of a brain artery very much like a thin balloon or weak spot on an inner tube. Aneurysms form from wear and tear on the arteries, and sometimes from injury, infection or an inherited tendency. The primary problem a cerebral aneurysm poses is rupture and hemorrhagic stroke. Patients often experience no symptoms before a rupture occurs. In these cases, the aneurysm may be discovered incidentally, perhaps during an angiogram for carotid artery disease.

But sometimes, as an aneurysm grows, it compresses surrounding nerves and brain tissue, causing functional problems. In about 40 percent of cases, people with unruptured aneurysms experience some or all of the following symptoms:

• Peripheral vision deficits
• Thinking or processing problems
• Speech complications
• Perceptual problems
• Sudden changes in behavior
• Loss of balance and coordination
• Decreased concentration
• Short-term memory difficulty
• Fatigue

Regardless of their size or whether they are producing symptoms, all aneurysms need prompt evaluation by a vascular neurologist. Appropriate treatment depends on the size and location of the aneurysm and the patient’s medical history. The risk of rupture increases with the size of the aneurysm and time. Evidence suggests that the risk of rupture for most unrepaired small aneurysms (less than 7 millimeters in size) is small. However, within the smaller sizes, some characteristics such as the shape of the aneurysm, location of the aneurysm and previous personal or family history of rupture can make the aneurysm a higher risk.

The most common treatment for both unruptured and ruptured aneurysms is coil embolization. A neurointerventional surgeon advances a small catheter through endovascular approach inside the aneurysm. The entry of a catheter in the blood vessel is either through the main blood vessel of the leg or the arm. This minimally invasive method allows the surgeon to approach the aneurysm from inside the blood vessels. Coils or glue-like material (Onyx) are then deposited within the aneurysm to seal the aneurysm. If the coils are used, they are usually made of complex metallic coats largely consisting of platinum that is inert and MRI friendly.

A more traditional way for treating aneurysm is an open surgical approach where the surgeon opens the cranium by drilling through the bone and blocks the blood flow into the aneurysm by applying a metal clip to its base (neck) where it connects to the blood vessel. This redirects the blood flow along its proper route.

Age

People of all ages can have a stroke, but the older the person the higher the risk. In fact, the risk of stroke more than doubles for each decade of life after age 55. As people age, they tend to develop many risk factors for stroke. For example, their arteries tend to harden and become less elastic, making them prone to rupture or blockage.

Although stroke often is considered a disease of the elderly, about 25 percent occur in people younger than 65 years. In fact, every year, five out of every 200,000 children have a stroke. It can even happen in utero.

The causes of stroke in children tend to be quite different from the usual ones in adults. Children haven’t had the time to develop hardening of the arteries (atherosclerosis) or other long-term effects of hypertension, high cholesterol, diabetes, and smoking that are among the most common stroke risk factors in adults. Causes can vary according to a child’s age and can include:

• Brain infections acquired in the uterus or during or after birth
• Premature birth (for example, inadequately developed blood clotting mechanisms and immature, fragile blood vessels)
• Birth defects of the heart or brain
• Blood clotting disorders
• Severe infections
• Metabolic disorders

Gender

Men have a higher risk for stroke (1.25 times that of women), but more women die from stroke. Women account for three out of every five stroke deaths. This may be due in part to the fact that men do not live as long as women so they are usually younger when they have their strokes and are better able to survive the insult.

Nearly one in five women over 45 will have a stroke by age 85. Among women worldwide, stroke is the number 2 cause of death and number 1 cause of disability.

Ethnicity & Heredity

Stroke is more common in people whose close relatives have suffered stroke. This appears to indicate certain genetic “predispositions” within families that put them at greater risk for stroke.

African-Americans have a higher risk of death from stroke than do Caucasians. This is partly because African-Americans have a higher incidence of many of the risk factors for stroke. For example, high blood pressure tends to occur earlier in African-Americans and be more severe. Sickle cell disease (sickle cell anemia) — a genetic disorder primarily affecting African-Americans — is a risk factor for stroke because “sickled” red blood cells are less able to carry oxygen to the body’s tissues and organs. They also tend to stick to blood vessel walls, which can block arteries to the brain.

African-Americans, along with Hispanics, American Indians and Asians, appear to be at higher risk for developing type 2 diabetes.

For Pacific Asians and South Asians, the general tendency of developing intracranial (inside the brain) plaque build up is much higher than the Caucasian population as opposed to the carotid disease in the neck.