How Stroke Is Diagnosed

Stroke diagnosis requires a careful and fast medical examination, often with the aid of medical technology. If you ever have a stroke evaluation, your examination will include a neurological examination, computed tomography (CT) scans, and other imaging tests.

At-Home Stroke Assessment

If you suspect someone is having a stroke, a simple three-step test known as the Cincinnati Pre-Hospital Stroke Scale (CPSS) can help in the determination.

If the person can do all of the following, it is unlikely they are having a stroke:

1. "Show me your teeth": Known as the smile test, this is used to check for one-sided facial weakness, a classic stroke symptom. 
2. "Close your eyes and raise your arms": Used to check for arm weakness, stroke patients usually cannot raise both arms to the same height.  
3. "Repeat after me": Used to check for slurred speech, the person is asked to say a simple sentence, such as “You can’t teach an old dog new tricks.” 

A 2018 study published in the Journal of Emergencies, Trauma, and Shock found CPSS is 81% accurate in determining whether someone is having a stroke.

Labs and Tests

If your healthcare provider suspects a stroke, the first test is a neurological exam to uncover whether there is a problem in brain function that might confirm a person is actually having a stroke.

Each part of the neurological exam tests a different area of the brain, including:

• Awareness and consciousness
• Speech, language, and memory function
• Vision and eye movements
• Sensation and movement in the face, arms, and legs
• Reflexes
• Walking and sense of balance

Electrocardiogram

This test, also known as an EKG or ECG, helps healthcare providers identify problems with the electrical conduction of the heart. Normally, the heart beats in a regular, rhythmic pattern that promotes smooth blood flow toward the brain and other organs. But when the heart has a defect in electrical conduction, it may beat with an irregular rhythm. This is called an arrhythmia, or an irregular heartbeat.

Blood Tests

For the most part, blood tests help healthcare providers look for diseases known to increase the risk of stroke, including:

• High cholesterol
• Diabetes
• Blood clotting disorders

Imaging

There are several imaging tests that are used for diagnosing and determining the extent of a stroke.

Computed Tomography (CT)

This test is performed in the emergency room to detect a hemorrhagic stroke. CT scans are good tests for this purpose not only because they easily detect bleeding inside the brain, but because they can be performed quickly.

CT scans can also reveal ischemic strokes, but not until six to 12 hours after stroke onset.

Magnetic Resonance Imaging (MRI)

This is one of the most helpful tests in the diagnosis of stroke because it can detect strokes within minutes of their onset. MRI images of the brain are also superior in quality to CT images. A special type of MRI called magnetic resonance angiography, or MRA, lets healthcare providers visualize narrowing or blockage of blood vessels in the brain.

Transthoracic Echocardiogram (TTE)

This test, also known as an "echo," uses sound waves to look for blood clots or other sources of emboli inside the heart, as well as abnormalities in heart function that can lead to blood clot formation inside the heart chambers.

TTEs are also used to investigate if blood clots from the legs can travel through the heart and reach the brain.

Transcranial Doppler (TCD)

This test uses sound waves to measure blood flow through the major blood vessels in the brain. Narrow areas inside of a blood vessel demonstrate a different rate of blood flow than normal areas. This information can be used by healthcare providers to follow the progress of partially blocked blood vessels.

Another important use for the TCD is the assessment of blood flow through blood vessels in the area of a hemorrhagic stroke, as these blood vessels have a propensity to undergo vasospasm—a dangerous and sudden narrowing of a blood vessel that can block blood flow.

Cerebral Angiography

Stroke doctors use this test to visualize blood vessels in the neck and brain. A special dye, which can be seen using X-rays, is injected into the carotid arteries, which bring blood to the brain. If a person has a partial or total obstruction in one of these blood vessels, the pattern of dye will reflect it.

A common cause of stroke is narrowing of a carotid artery, carotid stenosis, which is usually the result of cholesterol deposits along the walls of these blood vessels. This condition can also be diagnosed by a test called a carotid duplex, by which sound waves are used to evaluate blood flow through these blood vessels.

Depending on the degree of narrowing and the symptoms, surgery might be needed to remove the plaque from the affected artery.

Cerebral angiography can also help healthcare providers diagnose the following common conditions known to be associated with hemorrhagic stroke:

• Aneurysms
• Arteriovenous malformations

After a stroke is diagnosed, sometimes a new battery of tests needs to be performed in order to find out the cause of the stroke.

Leg Ultrasound

Healthcare providers usually perform this test on stroke patients diagnosed with a patent foramen ovale (PFO). The test uses sound waves to look for blood clots in the deep veins of the legs, which are also known as deep venous thrombosis (DVT).

DVTs can cause strokes by making a long journey that ends up in the brain. First, a small fragment of a DVT breaks off and travels to the heart via the venous circulation. Once in the heart, the blood clot crosses from the right side to the left side of the heart via the PFO, where it is propelled out via the aorta and carotids towards the brain, where it can cause a stroke.

Differential Diagnoses

In working to reach a diagnosis, a healthcare provider will also consider these other potential diagnoses, which present similarly to stroke (though they are unrelated).

Neuropathy 

Neuropathy, a disease of the nerves, may at times be confused with stroke. The symptoms of this common condition, like the symptoms of stroke, are bothersome and often unsettling. However, symptoms of neuropathy arise gradually, predominantly involve pain, and typically involve both sides of the body. In contrast, sensory stroke symptoms affect one side of the body and are characterized by abrupt onset, numbness, and loss of sensation.

Dementia 

There are several types of dementia. What they have in common is that they are characterized by gradually progressive cognitive and behavioral deficits.

Generally, cognitive and behavioral problems caused by a stroke are more abrupt. However, repeated strokes can sometimes produce symptoms that appear to resemble progressive dementia, making the distinction confusing.

Vascular dementia is a dementia caused by recurrent strokes and can be easily confused with other types of dementia, such as Alzheimer's disease.

Parkinson's Disease 

Parkinson's disease symptoms primarily include movement abnormalities, such as tremors and stiffness. Generally, the symptoms of Parkinson’s disease are gradual and affect both sides of the body, in contrast to the one-sided and sudden symptoms of stroke.

Migraine Headaches 

Migraine headaches are headaches that are characterized by more than just a feeling of head pain. They typically involve dizziness, photophobia (sensitivity to light), and phonophobia (sensitivity to noise). However, sometimes migraines also cause symptoms such as visual changes or weakness, with or without accompanying painful headaches. These episodes, often referred to as migraine with aura, are typically quite alarming.

Migraine headaches associated with neurological deficits almost always improve. However, it is not possible to know for certain whether neurological symptoms associated with migraines are the sign of an impending stroke. There is a slightly increased risk of stroke among people who experience these types of migraines. So if you have been diagnosed with migraines with aura, it is advisable to be under the care of a healthcare provider.

Myasthenia Gravis 

Myasthenia gravis is an uncommon condition that is characterized by droopy eyelids at the onset. As the condition progresses, it causes generalized weakness and can affect respiratory muscles.

As a neuromuscular disorder, myasthenia gravis affects the communication between the nerves and the muscles they are meant to control, in contrast to a stroke, which is a brain injury caused by a vascular interruption. Myasthenia gravis is also typically equal on both sides of the body, and its symptoms can be treated with medication.

Multiple Sclerosis 

Multiple sclerosis (MS) is a relatively common disease that affects the brain, the spine, and the optic nerves of the eyes. MS, like stroke, usually produces symptoms that typically include weakness, vision changes, and sensory deficits, however, they do not occur as suddenly as a stroke.

Another difference between MS symptoms and stroke symptoms is that those related to stroke correspond with regions of the brain that are supplied by the same blood vessels, while symptoms of MS do not follow this vascular distribution.

MS is a lifelong illness characterized by exacerbations and remissions.

TIA

Another type of stroke-like episode called a transient ischemic attack (TIA) is a temporary vascular interruption in the brain that resolves before causing permanent damage.

If you experience stroke symptoms that get better on their own, then that could be a TIA. But a TIA is not something to gloss over. Most people who experience a TIA go on to have a stroke if they don't start taking medication to prevent one—and no one can predict whether a TIA means that a stroke will happen within an hour or within a few months.