How is a stroke diagnosed?

It’s critical to diagnose a stroke in progress because the treatment for stroke depends on the type, the source of the stroke (usually related to risk factors), and in some cases, the location of the injury to the brain.

Other conditions with similar symptoms to stroke and transient ischemic attack (TIA, or “warning stroke” or “mini-stroke) will need to be ruled out to diagnose stroke. Some of these include seizures, fainting, migraine, heart problems or other general medical conditions.

The type of stroke also must be determined. Treatment for stroke is different if it’s an ischemic (blockage) stroke or a hemorrhagic (bleeding) stroke.

Ischemic strokes, caused by a blocked artery in the brain, may be treated with a clot-busting drug, called tPA (tissue plasminogen activator). Therefore, it’s important to receive a correct diagnosis before treatment begins. To receive a clot-busting drug treatment such as tPA, a medical doctor must diagnose your stroke as an ischemic stroke and treat you within three hours of the onset of symptoms.  If more than three hours passes, tPA can’t be given.

A ruptured blood vessel causes a hemorrhagic stroke.

Timing is very important!  Time lost is brain lost.

In the emergency room, your doctor or stroke emergency team may:

- Ask you when the symptoms of the stroke started. 

- Ask you about your medical history.

- Conduct a physical and neurological examination.

- Have certain laboratory (blood) tests done.

- Do a CT (computed tomography) scan of the brain or MRI (magnetic resonance imaging) brain scan.  This determines what kind of stroke a person has had.

- Study the results of other diagnostic tests that might be needed.

A stroke, is a sudden onset of neurological deficit caused by injury to the brain due to either, not enough blood supply to part of the brain due to blockage of an artery (ischemic stroke), or because of rupture of an artery of the brain due to high blood pressure, aneurysms, or arteriorvenous malformations (hemorrhagic stroke). Ischemic strokes are more common (85 percent) than hemorrhagic strokes (15 percent). 

A person with sudden neurological deficits (weakness on one side of the body, dizziness, double vision, blindness, and headache) should seek immediate medical attention in order to make the proper diagnosis and emergent treatment.

The first study required in the diagnosis of stroke is a CT scan of the head to make the differentiation of ischemic or hemorrhagic strokes. Treatment can be started after a CT scan is performed, but other tests may be necessary to look for the cause of the stroke in order to prevent another one from happening. Some patients may need an MRI of the brain and an MRA of the brain and neck (to look at the arteries). Some patients may need a CT Angiography or femoral cerebral angiography (navigating a catheter from the femoral artery to the arteries of the neck); to look at the arteries of the head and neck in a more detailed way.

A number of tests may be done if a stroke is suspected:

• Your health care provider will check for changes in how your body is working. For example, your provider will check your ability to move your arms and legs. Your health care provider also can check brain functions such as your ability to read or to describe a picture.

• CT (computed tomography) and MRI (magnetic resonance imaging) tests use special scans to provide images of the brain.

• An ECG (electrocardiogram) provides information on heart rate and rhythm.

• An ultrasound examination can show problems in the carotid arteries, which carry blood from the heart to the brain.

• In a cerebral arteriogram, a small tube is inserted into an artery and positioned in the neck. The health care provider injects dye into the artery. Then the provider takes X rays to look for narrowed or blocked arteries.

Emergency personnel, physicians, and other members of the stroke care team will perform and order the following tests to determine as quickly as possible if you are having a stroke, and if you are, the type of stroke (ischemic - caused by a blockage, or hemorrhagic - caused by bleeding), and the location of the problem:

• You will be asked to describe your symptoms and provide a medical history, family history of illnesses, and a list of any medications that you take.
• Your doctor will examine you by listening to your heart and checking your pulse, lungs, blood pressure, muscles, nerves, sensation, coordination, reflexes, memory, speech, and thinking.
• Blood tests will be done to provide more information but also rule out other possible causes of the stroke. 
• Most hospitals will give you a computed tomography (CT) or magnetic resonance imaging (MRI) test to determine if the stroke was caused by a blockage in the artery or by bleeding.
• To see how blood is flowing through the carotid artery in the neck, your doctor may also order a carotid ultrasound/Doppler scan, and magnetic resonance angiogram (MRA), CT angiogram, or carotid angiogram.
• Sometimes stroke can be related to a heart problem, so your doctor may also request an echocardiogram to find out for sure.
• If the stroke is caused by the blockage or narrowing of the arteries to the brain, your doctor may also look at arteries in other parts of the body for signs of coronary artery disease or peripheral artery disease. If arteries are narrowed or blocked in one part of the body, chances are good that plaque (a fatty substance) is building up in other parts of the body, too, putting you at risk for other problems, such as a heart attack.

Physical examination and tests: Risk factors of stroke are evaluated, including high blood pressure, high cholesterol levels, diabetes, medications, elevated levels of homocysteine, and obesity. Stroke symptoms are documented after the occurrence, often using scoring systems such as the National Institutes of Health Stroke Scale, the Cincinnati Stroke Scale, and the Los Angeles Prehospital Stroke Screen. These tests ask medical history questions and measure left and right paralysis (loss of muscle control and movement). The latter is used by emergency medical technicians (EMTs) to determine whether a patient needs transport to a stroke center (a hospital specializing in stroke).

Carotid ultrasonography: This procedure evaluates blood flow using a wand-like device (transducer) that sends high-frequency sound waves into the neck. Narrowing or clotting in the carotid arteries can be determined.

Arteriography: Arteriography views arteries in the brain not normally able to be seen in X-rays. During this procedure, a thin, flexible tube (catheter) is inserted through a small incision, usually in the groin area. The catheter is manipulated through the major arteries and into the carotid or vertebral artery. A dye is then injected through the catheter to provide X-ray images of the arteries.

Magnetic resonance imaging (MRI): An MRI uses a strong magnetic field to generate a three-dimensional view of the brain. This test is sensitive for detecting an area of brain tissue damaged by an ischemic stroke. Magnetic resonance angiography (MRA) uses this magnetic field and a dye injected into the veins to evaluate arteries in the neck and brain.

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Tests in the emergency room

The first test after a stroke is typically a CT scan, a series of X-rays that can show whether there is bleeding in the brain. This test will show whether the stroke is ischemic or hemorrhagic. You may also have an MRI to find out the amount of damage to the brain and help predict recovery.

Other initial tests recommended for ischemic stroke include:

• Electrocardiogram (ECG, EKG) to check for heart problems.
• Liver and kidney function.
• Prothrombin time (a test that measures how long it takes your blood to clot).

Blood tests to help your doctor make choices about your treatment and to check for conditions that may cause symptoms similar to a stroke. Tests may include:

• Complete blood count (CBC).
• Blood sugar.
• Electrolytes.
• Liver and kidney function.
• Prothrombin time (a test that measures how long it takes your blood to clot).

Tests you may have later

If it seems that you may have a narrowing of a carotid artery, your doctor may want you to have:

• Carotid ultrasound/Doppler scan to evaluate blood flow through the artery.
• Magnetic resonance angiogram (MRA).
• CT angiogram.
• Carotid angiogram.

If your doctor believes that the stroke may have been caused by a problem with your heart, an echocardiogram or Holter monitoring or telemetry test may be done.

Guidelines recommend that risk factors for heart disease also be assessed after a stroke to prevent disability or death from a future heart problem. This is because many people who have had a stroke also have coronary artery disease.

A doctor diagnosing a stroke searches for anatomical and biological aberrations -- the underlying pathology -- in order to determine exactly what type of stroke has occurred and what caused it. Pathology is the medical version of a set of fingerprints left at a crime scene: it helps to identify the culprit.

When someone with symptoms of stroke arrives at the emergency room, the first challenge is to swiftly determine whether the stroke is ischemic or hemorrhagic -- that is, whether the stroke is caused by a blood clot blocking an artery (ischemic) or by blood leaking out of a blood vessel (hemorrhagic). The treatment will depend on this question. To make this determination, doctors will ask about your symptoms, perform a physical examination, and order blood, urine, and imaging (such as head CT scan) tests all within minutes of your arrival. Next, the doctors must find out precisely what pathological process in the affected artery might have caused a blockage (leading to ischemia) or a blood vessel rupture (leading to hemorrhage). Ischemic stroke and transient ischemic attacks (TIAs) -- brain attacks that resolves within 24 hours (or ministrokes) -- have five subtypes, based on four distinct pathologies. Hemorrhagic strokes also have subcategories defined first by location (either intracerebral or intracranial hemorrhage), and then by pathological subtype.

There isn't an easy way to diagnose a stroke, but, in this video, Robin Miller, MD, tells us about a bedside device that works like an EKG for strokes. It's less expensive than an MRI or CT Scan and it's accurate.