Tests

Test samples


Following a stroke or TIA (Transient Ischaemic Attack), some or all of the following investigations may be done depending on the circumstances and suspected nature of each individual case. Here is some information about these tests. Your doctor will be able to give you more information should you need it.

Brain scans

The diagnosis of a stroke is often made on the history and examination findings and brain scans may be normal even though the patient has had a stroke. Scans, however, usually provide very useful information about the type and site of a stroke and help with the management of the stroke and the prevention of future strokes.

Scans can also show up other abnormalities of the brain. There are broadly two types of brain scans and the one chosen depends on the clinical features on examination.

Computerised Tomography (CT Scanning)

Magnetic Resonance Imaging (MRI Scan)

 

Duplex ultrasound scan of the cartoid arteries

This is a method of scanning the carotid arteries, the main arteries in the side of the neck which carry blood to the brain. It is a painless procedure using ultrasound waves. It is done following a TIA or stroke .

It detects furring and narrowing of the carotid arteries and helps estimate the patients risk of a further stroke. It also helps select patients for a procedure called carotid endarterectomy where a severely narrowed carotid artery is operated upon to remove the plaque which has caused the narrowing.

This test is only done in patients with certain kinds of strokes if the disorder is believed to be in the carotid arteries.

 

Electrocardiograms (ECG)

This is a recording of the electrical activity of the heart using electrodes placed on the chest and limbs. It gives doctors useful information about the rate and rhythm of the heart and can help with the detection of heart attacks and other abnormalities.

Sometimes, continuous monitoring of the heart for 24 hours or more using a small, portable monitor called a Holter monitor is used to detect disturbances of the normal rhythm of the heart if that is suspected to be the underlying cause of the stroke.

 

Echocardiograms

Echocardiography is a form of scanning of the heart using ultrasound waves. It gives useful information about the structure and function of the heart. Defects in the heart are sometimes responsible for causing strokes.

Information about the working of heart valves, the size and movements of various walls and chambers of the heart, the presence of clots in the heart and holes in the heart can help with finding the underlying cause of the stroke. The test is painless and takes about 30 minutes to do.

There is another form of echocardiography is called trans- oesophageal echocardiography (TOE) where the ultrasound probe is passed into the gullet (food pipe) in the form of a flexible scope.

This enables a clearer view of certain parts of the heart and is only used in very few instances. This is done under sedation and with an anaesthetic throat spray.

Blood tests

Several blood tests are done after a stroke OR TIA. The exact tests done will depend on the type of the stroke and other clinical circumstances. These tests include:

Full blood count - This is a routine test to determine the haemoglobin, number of red blood cells, white blood cells, and platelets in the blood. It can diagnose anaemia, polycythaemia (excess of haemoglobin and red cells) and infections (too many white cells).

Markers of inflammation - C reactive protein (CRP), erythrocyte sedimentation rate (ESR) and plasma viscosity (PV) are measured to look for signs of inflammation such as that caused by infections or other underlying conditions that may have caused the stroke.

Blood glucose - this enables the diagnosis of diabetes to be made. Patients with strokes, who are not known diabetics, can have elevated blood sugars which may be the result of new onset diabetes. The blood sugar, if very high, has to be controlled as part of stroke treatment. It is also important to make sure that the glucose level is not too low.

Blood lipid tests - Cholesterol, total lipids, HDL, and LDL. Elevated cholesterol (particularly "bad" cholesterol, or LDL) is a risk factor for heart disease and stroke. Drugs called statins are used to lower the cholesterol after a stroke.

Clotting tests - Include the PT (Prothrombin time), APTT (Activated partial thromboplastin time) and INR (International normalised ratio). These tests measure how quickly the blood clots. An abnormality suggests a tendency to bleed. They are rarely abnormal in stroke patients. The INR test is most useful for people on warfarin to regulate the dose of warfarin and ensure that the blood is thinned down to the right extent.

Kidney, electrolyte and liver function tests - the function of the kidneys and liver are routinely assessed by these test. Electrolytes such as sodium, potassium and calcium are routinely measures as disorders of these electrolytes are very common and can be dangerous if not treated.

Other blood tests are sometimes done in young patients or patients with unusual forms of stroke; these include tests of abnormal blood clotting tendency and tests for autoimmune disease.