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Disease of the Day: Stroke

Category

This is a Circulatory System Disease

Synonym Name

Stroke

Overview

 
A stroke occurs when the blood supply to part of your brain is interrupted or severely reduced, depriving brain tissue of oxygen and food. Within minutes, brain cells begin to die. A stroke is a medical emergency. Prompt treatment is crucial. Early action can minimize brain damage and potential complications. The good news is that strokes can be treated and prevented, and many fewer Americans die of stroke now than even 15 years ago.

Risks

Other risk factors may include:
 
  • Personal or family history of stroke, heart attack or transient ischemic attack
  • Being age 55 or older
  • Race — African-Americans have higher risk of stroke than do people of other races
  • Gender — Men have a higher risk of stroke than women: Women are usually older when they have strokes, and they are more likely to die of strokes than are men. Also, they may have some risk from some birth control pills or hormone therapies that include estrogen, as well as from pregnancy and childbirth
Many factors can increase your risk of a stroke. Some factors can also increase your chances of having a heart attack. Stroke risk factors include:
 
  • Being overweight or obese
  • Physical inactivity
  • Heavy or binge drinking
  • Use of illicit drugs such as cocaine and methamphetamines
  • High blood pressure — risk of stroke begins to increase at blood pressure readings higher than 120/80 millimeters of mercury (mm Hg): Your doctor will help you decide on a target blood pressure based on your age, whether you have diabetes and other factors
  • Cigarette smoking or exposure to secondhand smoke
  • High cholesterol — a total cholesterol level above 200 milligrams per deciliter (5: 2 millimoles per liter)
  • Diabetes
  • Obstructive sleep apnea — a sleep disorder in which the oxygen level intermittently drops during the night
  • Cardiovascular disease, including heart failure, heart defects, heart infection or abnormal heart rhythm
  • Personal or family history of stroke, heart attack or transient ischemic attack
  • Being age 55 or older
  • Race — African-Americans have higher risk of stroke than do people of other races
  • Gender — Men have a higher risk of stroke than women: Women are usually older when they have strokes, and they are more likely to die of strokes than are men. Also, they may have some risk from some birth control pills or hormone therapies that include estrogen, as well as from pregnancy and childbirth
Potentially treatable risk factors
 
  • High blood pressure — risk of stroke begins to increase at blood pressure readings higher than 120/80 millimeters of mercury (mm Hg): Your doctor will help you decide on a target blood pressure based on your age, whether you have diabetes and other factors
  • Cigarette smoking or exposure to secondhand smoke
  • High cholesterol — a total cholesterol level above 200 milligrams per deciliter (5: 2 millimoles per liter)
  • Diabetes
  • Obstructive sleep apnea — a sleep disorder in which the oxygen level intermittently drops during the night
  • Cardiovascular disease, including heart failure, heart defects, heart infection or abnormal heart rhythm

Causes

 
  • A stroke occurs when the blood supply to your brain is interrupted or reduced: This deprives your brain of oxygen and nutrients, which can cause your brain cells to die. A stroke may be caused by a blocked artery (ischemic stroke) or a leaking or burst blood vessel (hemorrhagic stroke). Some people may experience a temporary disruption of blood flow through their brain (transient ischemic attack)
  • Like an ischemic stroke, a TIA occurs when a clot or debris blocks blood flow to part of your brain: A TIA doesn't leave lasting symptoms because the blockage is temporary
  • Seek emergency care even if your symptoms seem to clear up: If you've had a TIA, it means there's likely a partially blocked or narrowed artery leading to your brain, putting you at a greater risk of a full-blown stroke that could cause permanent damage later. It's not possible to tell if you're having a stroke or a TIA based only on your symptoms. Up to half of people whose symptoms appear to go away actually have had a stroke causing brain damage
Ischemic stroke
 
About 85 percent of strokes are ischemic strokes. Ischemic strokes occur when the arteries to your brain become narrowed or blocked, causing severely reduced blood flow (ischemia). The most common ischemic strokes include:
 
  • Thrombotic stroke: A thrombotic stroke occurs when a blood clot (thrombus) forms in one of the arteries that supply blood to your brain. A clot often may be caused by fatty deposits (plaque) that build up in arteries and cause reduced blood flow (atherosclerosis) or other artery conditions
  • Embolic stroke: An embolic stroke occurs when a blood clot or other debris forms away from your brain — commonly in your heart — and is swept through your bloodstream to lodge in narrower brain arteries. This type of blood clot is called an embolus
Hemorrhagic stroke
 
Hemorrhagic stroke occurs when a blood vessel in your brain leaks or ruptures. Brain hemorrhages can result from many conditions that affect your blood vessels, including uncontrolled high blood pressure (hypertension) and weak spots in your blood vessel walls (aneurysms). A less common cause of hemorrhage is the rupture of an arteriovenous malformation (AVM) — an abnormal tangle of thin-walled blood vessels, present at birth. The types of hemorrhagic stroke include:
 
  • Intracerebral hemorrhage: In an intracerebral hemorrhage, a blood vessel in the brain bursts and spills into the surrounding brain tissue, damaging brain cells. Brain cells beyond the leak are deprived of blood and damaged. High blood pressure, trauma, vascular malformations, use of blood-thinning medications and other conditions may cause intracerebral hemorrhage
  • Subarachnoid hemorrhage: In a subarachnoid hemorrhage, an artery on or near the surface of your brain bursts and spills into the space between the surface of your brain and your skull. This bleeding is often signaled by a sudden, severe headache. A subarachnoid hemorrhage is commonly caused by the rupture of an aneurysm, a small sack-shaped or berry-shaped outpouching on an artery in the brain. After the hemorrhage, the blood vessels in your brain may widen and narrow erratically (vasospasm), causing brain cell damage by further limiting blood flow to parts of your brain
Transient ischemic attack (TIA
 
  • A transient ischemic attack (TIA) — also called a ministroke — is a brief episode of symptoms similar to those you'd have in a stroke: A transient ischemic attack is caused by a temporary decrease in blood supply to part of your brain. TIAs often last less than five minutes

Symptoms

Watch for these signs and symptoms if you think you or someone else may be having a stroke. Note when your signs and symptoms begin, because the length of time they have been present may guide your treatment decisions:
 
  • Trouble with walking:  You may stumble or experience sudden dizziness, loss of balance or loss of coordination
  • Trouble with speaking and understanding:  You may experience confusion. You may slur your words or have difficulty understanding speech
  • Paralysis or numbness of the face, arm or leg:  You may develop sudden numbness, weakness or paralysis in your face, arm or leg, especially on one side of your body. Try to raise both your arms over your head at the same time. If one arm begins to fall, you may be having a stroke. Similarly, one side of your mouth may droop when you try to smile
  • Trouble with seeing in one or both eyes:  You may suddenly have blurred or blackened vision in one or both eyes, or you may see double
  • Headache:  A sudden, severe headache, which may be accompanied by vomiting, dizziness or altered consciousness, may indicate you're having a stroke

Tests

To determine the most appropriate treatment for your stroke, your emergency team needs to evaluate the type of stroke you're having and the areas of your brain affected by the stroke. They also need to rule out other possible causes of your symptoms, such as a brain tumor or a drug reaction. Your doctor may use several tests to determine your risk of stroke, including:
 
  • Physical examination: Your doctor will ask you or a family member what symptoms you've been having, when they started and what you were doing when they began. Your doctor then will evaluate whether these symptoms are still present. Your doctor will want to know what medications you take and whether you have experienced any head injuries. You'll be asked about your personal and family history of heart disease, transient ischemic attack or stroke. Your doctor will check your blood pressure and use a stethoscope to listen to your heart and to listen for a whooshing sound (bruit) over your neck (carotid) arteries, which may indicate atherosclerosis. Your doctor may also use an ophthalmoscope to check for signs of tiny cholesterol crystals or clots in the blood vessels at the back of your eyes
  • Blood tests:  You may have several blood tests, which tell your care team how fast your blood clots, whether your blood sugar is abnormally high or low, whether critical blood chemicals are out of balance, or whether you may have an infection. Care providers will manage your blood's clotting time and levels of sugar and key chemicals as part of your stroke care
  • Computerized tomography (CT) scan:  A CT scan uses a series of X-rays to create a detailed image of your brain. A CT scan can show a hemorrhage, tumors, strokes and other conditions. Doctors may inject a dye into your bloodstream to view your blood vessels in your neck and brain in greater detail (computerized tomography angiography)
  • Magnetic resonance imaging (MRI):  An MRI uses powerful radio waves and magnets to create a detailed view of your brain. An MRI can detect brain tissue damaged by an ischemic stroke and brain hemorrhages. Your doctor may inject a dye into a blood vessel to view the arteries and veins and highlight blood flow (magnetic resonance angiography, or magnetic resonance venography)
  • Carotid ultrasound:  In this test, sound waves create detailed images of the inside of the carotid arteries in your neck. This test shows buildup of fatty deposits (plaques) and blood flow in your carotid arteries
  • Cerebral angiogram:  In this test, your doctor inserts a thin, flexible tube (catheter) through a small incision, usually in your groin, and guides it through your major arteries and into your carotid or vertebral artery. Then your doctor injects a dye into your blood vessels to make them visible under X-ray imaging. This procedure gives a detailed view of arteries in your brain and neck
  • Echocardiogram: An echocardiogram uses sound waves to create detailed images of your heart. An echocardiogram can find a source of clots in your heart that may have traveled from your heart to your brain and caused your stroke. You may have a transesophageal echocardiogram. In this test, your doctor inserts a flexible tube with a small device (transducer) attached into your throat and down into the tube that connects the back of your mouth to your stomach (esophagus). Because your esophagus is directly behind your heart, a transesophageal echocardiogram can create clear, detailed ultrasound images of your heart and any blood clots

Treatments

Ischemic stroke
 
  • To treat an ischemic stroke, doctors must quickly restore blood flow to your brain
Emergency treatment with medications. Therapy with clot-busting drugs must start within 4.5 hours if they are given into the vein — and the sooner, the better. Quick treatment not only improves your chances of survival but also may reduce complications. You may be given:
 
  • Aspirin:  Aspirin is an immediate treatment given in the emergency room to reduce the likelihood of having another stroke. Aspirin prevents blood clots from forming
  • Intravenous injection of tissue plasminogen activator (TPA): Some people can benefit from an injection of a recombinant tissue plasminogen activator (TPA), also called alteplase. An injection of TPA is usually given through a vein in the arm. This potent clot-busting drug needs to be given within 4.5 hours after stroke symptoms begin if it's given in the vein. TPA restores blood flow by dissolving the blood clot causing your stroke, and it may help people who have had strokes recover more fully. Your doctor will consider certain risks, such as potential bleeding in the brain, to determine if TPA is appropriate for you
Emergency procedures. Doctors sometimes treat ischemic strokes with procedures that must be performed as soon as possible, depending on features of the blood clot:
 
  • Medications delivered directly to the brain:  Doctors may insert a long, thin tube (catheter) through an artery in your groin and thread it to your brain, and then release TPA directly into the area where the stroke is occurring. The time window for this treatment is somewhat longer than for intravenous TPA but is still limited
  • Mechanical clot removal:  Doctors may use a catheter to maneuver a tiny device into your brain to physically break up or grab and remove the clot
Other procedures. To decrease your risk of having another stroke or transient ischemic attack, your doctor may recommend a procedure to open up an artery that's moderately to severely narrowed by fatty deposits (plaques). Doctors sometimes recommend the following procedures to prevent a stroke. Options will vary depending on your situation, and may include:
 
  • Carotid endarterectomy: In a carotid endarterectomy, a surgeon removes plaques from arteries that run along each side of your neck to your brain (carotid arteries). In this procedure, your surgeon makes an incision along the front of your neck, opens your carotid artery and removes plaques that block the carotid artery. Your surgeon then repairs the artery with stitches or a patch made from a vein or artificial material (graft). The procedure may reduce your risk of ischemic stroke. However, a carotid endarterectomy also involves risks, especially for people with heart disease or other medical conditions
  • Angioplasty and stents:  In an angioplasty, a surgeon inserts a catheter with a mesh tube (stent) and balloon on the tip into an artery in your groin and guides the catheter to the blocked carotid artery in your neck. Your surgeon inflates the balloon in the narrowed artery and inserts a mesh tube (stent) into the opening to keep your artery from narrowing after the procedure
Hemorrhagic stroke
 
  • Emergency treatment of hemorrhagic stroke focuses on controlling your bleeding and reducing pressure in your brain: Surgery also may be performed to help reduce future risk
Emergency measures
 
  • If you take warfarin (Coumadin) or anti-platelet drugs such as clopidogrel (Plavix) to prevent blood clots, you may be given drugs or transfusions of blood products to counteract the blood thinners' effects: You may also be given drugs to lower pressure in your brain (intracranial pressure), lower your blood pressure, prevent vasospasm or prevent seizures. Once the bleeding in your brain stops, treatment usually involves bed rest and supportive medical care while your body absorbs the blood. Healing is similar to what happens while a bad bruise goes away. If the area of bleeding is large, your doctor may perform surgery to remove the blood and relieve pressure on your brain
Surgical blood vessel repair. Surgery may be used to repair blood vessel abnormalities associated with hemorrhagic strokes. Your doctor may recommend one of these procedures after a stroke or if an aneurysm or arteriovenous malformation (AVM) or other type of vascular malformation caused your hemorrhagic stroke:
 
  • Surgical clipping:  A surgeon places a tiny clamp at the base of the aneurysm, to stop blood flow to it. This clamp can keep the aneurysm from bursting, or it can prevent re-bleeding of an aneurysm that has recently hemorrhaged
  • Coiling (endovascular embolization):  In this procedure, a surgeon inserts a catheter into an artery in your groin and guides it to your brain using X-ray imaging. Your surgeon then guides tiny detachable coils into the aneurysm (aneurysm coiling). The coils fill the aneurysm, which blocks blood flow into the aneurysm and causes the blood to clot
  • Surgical AVM removal:  Surgeons may remove a smaller AVM if it's located in an accessible area of your brain, to eliminate the risk of rupture and lower the risk of hemorrhagic stroke. However, it's not always possible to remove an AVM if it's large or located deep within your brain
Stroke recovery and rehabilitation
 
  • Following emergency treatment, stroke care focuses on helping you regain your strength, recover as much function as possible and return to independent living: The impact of your stroke depends on the area of the brain involved and the amount of tissue damaged. If your stroke affected the right side of your brain, your movement and sensation on the left side of your body may be affected. If your stroke damaged the brain tissue on the left side of your brain, your movement and sensation on the right side of your body may be affected. Brain damage to the left side of your brain may cause speech and language disorders. In addition, if you've had a stroke, you may have problems with breathing, swallowing, balancing and vision. Most stroke survivors receive treatment in a rehabilitation program. Your doctor will recommend the most rigorous therapy program you can handle based on your age, overall health and your degree of disability from your stroke. Your doctor will take into consideration your lifestyle, interests and priorities, and the availability of family members or other caregivers. Your rehabilitation program may begin before you leave the hospital. It may continue in a rehabilitation unit of the same hospital, another rehabilitation unit or skilled nursing facility, an outpatient unit, or your home. Every person's stroke recovery is different. Depending on your condition, your treatment team may include: Doctor trained in brain conditions (neurologist) Rehabilitation doctor (physiatrist) Nurse Dietitian Physical therapist Occupational therapist Recreational therapist Speech therapist Social worker Case manager Psychologist or psychiatrist Chaplain