Stroke - Diagnosis 

Diagnosing stroke 

Brain imaging is often used to identify which part of the brain has been affected by stroke and how severe it is 

Strokes are usually diagnosed by studying images of the brain (brain imaging) and carrying out physical tests.

Your doctor may check for the causes of your stroke by taking blood tests to determine your cholesterol and blood sugar levels, checking your pulse for an irregular heartbeat and taking a blood pressure measurement.

Even if the physical symptoms of a stroke are obvious, brain imaging should also be carried out to determine:

  • if the stroke has been caused by a blocked artery or burst blood vessel
  • which part of the brain has been affected
  • how severe the stroke is
  • the risk of a transient ischaemic attack (TIA)

Different treatment is required for each type of stroke so a rapid diagnosis will make treatment more straightforward.

CT and MRI scans

Two common methods used for brain imaging are a computer tomography (CT) scan and a magnetic resonance imaging (MRI) scan.

A CT scan is like an X-ray, but uses multiple images to build up a more detailed, three-dimensional (3D) picture of your brain. An MRI scan uses a strong magnetic field and radio waves to produce a detailed picture of the inside of your body.

The type of scan you may have in hospital depends on your symptoms. If it is suspected you had a major stroke, a CT scan is sufficient to identify whether the stroke is due to bleeding or clotting. It's quicker than an MRI scan and improves the chances of rapidly delivering treatments such as clot-busting drugs (thrombolysis) that might be used in appropriate cases, but are time-limited and require the results of the scan before the treatment can be given safely.

For people with more complex symptoms, where the extent or location of the damage is unknown, and in patients who have recovered from a transient ischaemic attack, an MRI scan is more appropriate. This will provide greater detail of brain tissue, allowing smaller, or more unusually located strokes to be identified.

All patients with suspected stroke should receive a brain scan within 24 hours. Some patients should be scanned within the hour, especially those who:

  • might benefit from clot-busting drugs (thrombolysis) such as alteplase or early anticoagulant treatment
  • are already on anticoagulant treatments
  • have a lower level of consciousness

After the injection of a dye into an arm vein, both CT and MRI can be used to take pictures of the blood vessels in the brain, as well as the blood vessels in the neck that take blood to the brain from the heart. This is known as CT or MR angiography and is often done immediately after taking pictures of the brain itself.

Read more information at The Royal College of Radiologists.

Swallow tests

A swallow test is essential for anybody who has had a stroke.

Swallowing problems affect over a third of people after a stroke. When a person cannot swallow properly, there is a risk that food and drink may get into the windpipe and then into the lungs (called aspiration), which can lead to chest infections and pneumonia.

The test is simple. The person is given a few teaspoons of water to drink. If they can swallow this without choking and coughing they will be asked to swallow half a glass of water.

If they have any difficulty swallowing, they will be referred to the speech and language therapist for a more detailed assessment. They will usually be kept ‘nil by mouth’ until they have seen the therapist and may therefore need to have fluids or food given directly into an arm vein (intravenous drip) or through the nose using a nasogastric tube.

Heart and blood vessel tests 

Further tests on the heart and blood vessels might be carried out later to confirm what caused the stroke. These may include:

Ultrasound (carotid ultrasonography)

An ultrasound scan uses high frequency sound waves to produce an image of the inside of your body. Your doctor may use a wand-like probe (transducer) to send high-frequency sound waves into your neck. These pass through the tissue creating images on a screen that will show if there is any narrowing or clotting in the arteries leading to your brain.

This type of ultrasound scan is sometimes known as a doppler scan or a duplex scan. Where carotid ultrasonography is needed, it should happen within 48 hours.

Catheter angiography (arteriography)

Dye is injected into your carotid or vertebral artery via a tube called a catheter. This gives a more detailed view of your arteries than can be obtained using ultrasound, CT angiography or MR angiography.

Echocardiogram

In some cases an echocardiogram may be used to produce images of your heart using an ultrasound probe placed on your chest (transthoracic echocardiogram). In addition, transoesophageal echocardiography (TOE) may also be used. This involves an ultrasonic probe which is passed down the foodpipe (oesophagus), usually under sedation. Because it's directly behind the heart, it produces a clear image of blood clots and other abnormalities that may not get picked up by the transthoracic echocardiogram.

Read more about hospital tests at The Stroke Association.

Page last reviewed: 29/08/2012

Next review due: 29/08/2014

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