How Stroke Is Diagnosed

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Nurse overlooking woman in CT-scanner
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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 would include a neurological examination, computed tomography (CT) scans, and other imaging tests.

At-Home Testing

If you suspect someone is having a stroke, a simple three-step test known as the Cincinnati Pre-Hospital Stroke Scale (CPSS) can help predict stroke. If the person can do all of the following, it is unlikely they are having a stroke. However, if someone is not able to do any one of the items, the probability of stroke is 72 percent.

  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, 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 percent accurate in determining whether someone is having a stroke.

Labs and Tests

If your doctor suspects a stroke, the first test is a neurological exam to uncover whether there is a problem in brain function which might confirm the suspicion that 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 doctors identify problems with the electrical conduction of the heart. Normally, the heart beats in a regular, rhythmic pattern which promotes smooth blood flow towards 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.

Some arrhythmias, such as atrial fibrillation, cause the formation of blood clots inside the heart chambers. These blood clots sometimes migrate to the brain and cause a stroke.

Lumbar Puncture

Also known as a spinal tap, this test is sometimes performed in the emergency room when there is a strong suspicion for a hemorrhagic stroke.

The test involves the introduction of a needle into an area within the lower part of the spinal column where it is safe to collect cerebrospinal fluid (CSF). When there is bleeding in the brain, blood can be seen in the CSF.

Blood Tests

Your doctor may also perform bloodwork, but for the most part, blood tests help doctors 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 stroke and determining the extent of the stroke.

Computed Tomography Scan

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

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

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.

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 doctors visualize narrowing or blockage of blood vessels in 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 doctors 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 which can block blood flow.

Cerebral Angiography

Stroke doctors use this test to visualize blood vessels in the neck and brain. During this test, 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 a total obstruction in one of these blood vessels, the pattern of dye can help diagnose an abnormal blood vessel.

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 on the symptoms felt by a person, surgery might be needed to remove the plaque from the affected artery.

Carotid Stenosis Treatments

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

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

Doctors usually perform this test on stroke patients diagnosed with a patent foramen ovale. The test uses sound waves to look for blood clots in the deep veins of the legs, which are also known as deep venous thromboses or DVTs.

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

There are several conditionals that may present similarly to stroke but are not. Some other diseases include:

Neuropathy 

Neuropathy is a disease of the nerves. Neuropathy is the condition most frequently confused with stroke because it is fairly common. The symptoms of neuropathy, 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, while 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 not as gradual, but, instead, are more abrupt. However, repeated strokes can sometimes produce symptoms that appear to resemble progressive dementia, making the distinction confusing. Vascular dementia is 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. Migraines typically involve dizziness, photophobia (distress in response to light), and phonophobia (distress in response 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 complicated migraine, 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 complicated migraines, is advisable to be under the care of a physician.

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. Myasthenia gravis is a neuromuscular disorder, as it 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 sudden symptoms that typically include weakness, vision changes, and sensory deficits. The biggest difference between MS symptoms and stroke symptoms is that the symptoms of stroke correspond with regions of the brain that are supplied by the same blood vessels, while symptoms of MS do not follow this characteristic vascular distribution of stroke. MS is a lifelong illness characterized by exacerbations and remissions. There are a number of effective medications that can reduce the severity, the frequency, and the lasting impact of multiple sclerosis exacerbations.

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 a reason to breath a sigh of relief and forget about your symptoms. 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.

A Word From Verywell

A stroke is a serious medical condition that can lead to disability and death. If you suspect a stroke, get emergency treatment right away. Strokes are treatable, and if caught early enough, serious damage can be prevented.

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