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Tests Used in Stroke Diagnosis

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Updated May 28, 2014

Nurse overlooking woman in CT-scanner
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Stroke Diagnosis is relatively straight forward, but it requires the rapid combination of medical personnel, technology, and at times, a little bit of luck so that all the testing can be done on time and appropriate treatment can be offered. Below you will find the main tests used by doctors during stroke diagnosis.

The Neurological Examination

This test is performed by a physician in order to uncover deficiencies 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

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 also can reveal ischemic strokes but only 6-12 hours after their onset.

CT Scan Basics

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 in someone whose CT scan does not show clear blood. 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.

What is Cerebral Spinal Fluid?

Lumbar Puncture Basics

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. Its images of the brain are also superior in quality by comparison with CT images. Because of this, MRI is the test of preference in the diagnosis of stroke. A special type of MRI called magnetic resonance angiography, or MRA, lets doctors precisely visualize narrowing or blockage of blood vessels in the brain.

MRI Basics

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 faster blood flow than normal areas. This information can be used by doctors to follow the progress of occluded 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 contraction of the wall 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. In a person who has a partial or a total obstruction in one of these blood vessels, or in any other blood vessel inside the brain, little or no dye can be seen flowing through 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 of 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

Cerebral Angiography Basics

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

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 stops beating rhythmically and it is said to be suffering from arrhythmia, or irregular heart beats.

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.

Electrocardiogram Basics

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. It also is used to look for abnormalities in heart function which 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.

Echocardiogram Basics

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 which 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.

Leg Ultrasound Basics

Blood Tests

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

Source

Bradley G Walter, Daroff B Robert, Fenichel M Gerald, Jancovic, Joseph Neurology in clinical practice, principles of diagnosis and management. Philadelphia Elsevier, 2004.

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