Everyone has heard of stroke, but many people are not familiar with its symptoms or causes. A stroke occurs either when a blood vessel in the brain bursts, allowing blood to pool in the brain, or when the blood flow to part of the brain is blocked. Either way, affected parts of the brain become damaged or die. An ischemic stroke is the most common type of stroke. It occurs when a blood clot or fatty plaque lodges in a blood vessel within the brain, blocking blood flow. Because brain cells begin to die within minutes of the interruption of blood flow, it’s crucial for an ischemic stroke to be diagnosed and treated as quickly as possible.
In the United States, about 795,000 Americans experience some form of stroke each year, and most of those—about 87%—are ischemic strokes. Strokes are more common among adults aged 65 and older; the risk of stroke increases with age.
People who have one stroke are at higher risk of more strokes in the future; about one-quarter of all strokes occur in people who have had one previously. Some people will recover fully from an ischemic stroke. Others will experience disability afterward, and still others will die from the event. Stroke is the fifth-leading cause of death in the U.S., and a leading cause of disability.
What is an ischemic stroke?
An ischemic stroke is a life-threatening emergency condition. It arises when blood flow to the brain is blocked by a blood clot or a piece of fatty plaque that has broken off from the inside of a blood vessel. When blood can’t reach brain tissue, the tissue is at risk of being damaged or dying. This is why an ischemic stroke may cause brain damage, disability, or death.
In a healthy person, blood flows freely throughout the body, delivering oxygen to different body parts, including the brain. When a clot or piece of plaque disrupts the flow of blood to the brain, function is impaired. The symptoms this can cause depend on the area of the brain starved of blood. Sometimes, the disruption of blood flow can result in difficulty with speech, face or muscle weakness, or loss of coordination. Other times, it may cause cognitive problems. It’s important for ischemic stroke to be diagnosed and treated quickly to unblock blood flow before permanent damage can occur.
What causes an ischemic stroke?
An ischemic stroke occurs when blood flow to the brain becomes blocked by a blood clot or a piece of fatty plaque. Some blood clots travel to the brain from the heart. In other circumstances, blood clots or pieces of fatty plaque may travel to the brain from a distant artery. It’s also possible for a piece of fatty plaque to originate in a brain artery, blocking the flow of blood.
In rare instances, clotting disorders or estrogen-containing oral contraceptives may cause blood clots to form, which may increase the risk of clots reaching the brain.
What are the symptoms of an ischemic stroke?
Those experiencing an ischemic stroke may have the following symptoms:
- Drooping muscles on one side of the face
- Numbness on one side of the face or in one arm or leg
- Weakness or paralysis in one arm, leg, or side of the body
- Loss of sensation or abnormal sensations on one side of the body
- Dizziness, balance problems
- Slurred speech
- Difficulty speaking and/or understanding speech
- Vision loss and/or double vision in one or both eyes
- Severe headache
- Memory problems
- Nausea or vomiting
What are the risk factors for an ischemic stroke?
People with the following health conditions may be at increased risk of ischemic stroke:
- High blood pressure
- Atrial fibrillation
- Heart-valve disease
- High cholesterol levels
- Narrowing of the carotid artery in the neck
- Insulin resistance
- Sleep apnea
- Heart attack
- Having had recent heart surgery
- An infection of the valves of the heart
- A blood clotting disorder
- A personal or family history of stroke
Additionally, these lifestyle habits may increase the risk of ischemic stroke:
- Excessive alcohol intake
- Physical inactivity
- Eating a high-calorie diet that’s high in saturated fats and/or trans fats
- Using cocaine or amphetamines
How is an ischemic stroke diagnosed?
A stroke is a life-threatening emergency that is typically diagnosed in the emergency department. If you or a loved one is experiencing stroke symptoms, call 911 immediately.
Doctors can make a diagnosis after learning about your medical history, performing a neurological exam, and running diagnostic tests. Because time is of the essence for stroke treatment, it’s important for the diagnosis to be made quickly.
Doctors may rely on your relative for details about your medical history if you are experiencing confusion or having difficulty speaking. You or your loved one should discuss any history of high blood pressure, high cholesterol, diabetes, or a previous stroke. Lifestyle habits, including smoking and alcohol intake, should also be disclosed.
In the emergency room, a dedicated stroke team will perform a rapid neurological assessment of your speech, facial muscles, strength and sensation in your arms and legs, and coordination and balance to see if you are having a stroke.
A diagnosis may be obtained from these diagnostic tests:
- An imaging test, such as a CT scan or MRI, to rule out other conditions, including hemorrhagic stroke, and diagnose the problem
- A blood sugar test, because low blood sugar levels may cause symptoms that are similar to a stroke
- CT angiography, which shows images of the blood vessels in the brain, which can be used to pinpoint the location of a blockage
- CT perfusion, to determine how much brain tissue is permanently damaged and how much can be saved
How is an ischemic stroke treated?
One or more of the following treatments will be administered as quickly as possible to restore blood flow to the brain:
- Tissue plasminogen activator (tPA) drugs, such as alteplase or tenecteplase, which are given intravenously within 3 hours (and for some patients up to 4.5 hours) of stroke onset to break apart a clot that is blocking blood flow within the brain. This is sometimes called thrombolytic therapy. Research has shown that the earlier a patient receives tPA, the more likely they are to have better outcomes.
- Thrombectomy, a surgical catheter-based procedure during which a blood clot that is blocking blood flow within a large artery in the brain is removed. Similar to tPA, the earlier a blocked artery is opened, the better the chances are of recovery.
As you recover from a stroke, medications may be prescribed to lower the risk of another one. The type of medication prescribed varies, based on the type of stroke you had. Possibilities include:
- Cholesterol-lowering drugs
- Medication to decrease blood pressure
- Antiplatelet therapy
- Anticoagulant medications
Lifestyle changes may also be recommended, including:
- Quitting smoking
- Consuming less alcohol
- Following a low-sodium Mediterranean diet
- Getting regular physical activity
- Losing weight and/or maintaining a healthy weight
To reduce the risk of additional strokes, doctors may recommend:
- Carotid endarterectomy, a surgical procedure during which some of the fatty plaque from the interior of the carotid artery will be removed.
- Stenting, a minimally invasive procedure during which a catheter is used to insert a mesh-wire, tube-shaped stent that helps to hold the carotid artery open, preventing future blockages.
What is the outlook for people who have experienced ischemic stroke?
People who seek immediate treatment in an emergency department for stroke symptoms are more likely to have better outcomes than those who avoid or delay treatment. Many people experience some degree of disability after an ischemic stroke, including muscle weakness, lack of coordination, difficulty with speech or swallowing, or cognitive symptoms. These symptoms can improve with aggressive physical, occupational, and speech therapies. The window for meaningful recovery is about six months but can be longer for some patients.
What makes Yale unique in its treatment of ischemic stroke?
“The Comprehensive Stroke Center at Yale provides expertise in the management of both ischemic and hemorrhagic strokes,” says Yale Medicine stroke specialist Hardik Amin, MD. “We have a stroke team ready 24-7 that can perform state-of-the-art imaging in the emergency room and provide rapid medical and surgical treatments to maximize the chance of recovery.”
Our team of highly experienced stroke neurologists and neurosurgeons, dedicated trainees, specialized nurse practitioners, and nurse navigators provide comprehensive care for stroke patients from the moment they arrive at the emergency room, through their hospital stay, and when they are seen in our follow up clinics, he adds.
“By pairing a thoughtful, individualized approach with state-of-the-art imaging and diagnostic testing, we work to understand the cause of each patient’s stroke and how to lower the risk of future events. Our physical, occupational, and speech therapists provide detailed patient evaluations to set patients on a path to reaching their full rehabilitation potential,” he says. “We also participate in national clinical trials to help further our understanding of stroke causes and treatments.”