Neurology Online // Stroke - Diagnostics, Diagnosis, Diagnosing the Disease

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Stroke. Diagnostics

Diagnostics for a stroke using CT and MRT

Whether a stroke has actually occurred and how great an area of the brain is affected and what caused such an event, needs clarification in a hospital. To this end the patient who has a suspected stroke undergoes a neurological examination in the first instance. The neurologist establishes the symptoms by examining, among other things, the patient's reflexes, coordination, memory, speech and orientation. In order to specify immediate therapeutic procedures, the exact cause of the stroke has to be established, i.e. whether a blood clot or a haemorrhage has been the trigger. This is done with the help of two special methods of examination, so-called imaging procedures - computed tomography and nuclear spin tomography.

Computer tomography

In nearly all cases the doctor will be able to differentiate between a circulatory disorder and a cerebral haemorrhage using this examination.

A computed tomography (CT) of the head provides specially processed X-ray images of the brain, the bones and the blood vessels. In nearly all cases the doctor will be able to differentiate between a circulatory disorder and a cerebral haemorrhage using this examination. The latter is usually immediately identifiable while a blood flow disruption on the other hand is often only visible after a few hours or even days. All depending on which part of the brain is affected and how large an area it is, it is sometimes not possible to identify with certainty a cerebral infarction using computed tomography. Special reconstruction of the images and after an X-ray contrast medium has been administered it is often possible to find evidence of a vascular occlusion.

Nuclear spin tomography

Nuclear spin tomography provides more exact images than computer tomography.

Another option for brain imaging with a vascular status is nuclear spin tomography (Magnetic Resonance Tomography, MRT). The tomograms (images in sections) are produced by a strong magnetic field and provide more exact images than computed tomography thus allowing even the smallest changes to be detected. Special weighted images often provide evidence of the extent of tissue which is still recoverable.

Ultrasound examinations if a stroke is suspected

In the case of an ultrasound the blood vessels in the head and neck are examined.

Further examinations involve ultrasound tests (Doppler sonogram) of the blood vessels in the neck and head. In this way the doctor determines whether and how badly the vessels are blocked through arterial calcification or whether the flow of blood to the brain is normal. An ultrasound of the heart (echocardiography) reveals changes in the heart which may cause blood clots to form.

Angiography when a stroke is suspected

In the case of an angiography ("angio" = vessel and "graphy" = process of producing an image) the blood vessels are made visible with X-ray contrast medium. This process can either depict all the vascular systems in all parts of the body as a survey or and/or only blood vessels in certain areas such as the brain. This provides the doctor with information on what has caused the haemorrhage, provides information on the extent of narrowing or occlusion of the blood vessels or whether vessels are already damaged. If the blood vessels are depicted using computed tomography or magnetic resonance tomography, then this is called a CT angiography or a magnetic resonance angiography (MRA).

Examinations of the heart if a stroke is suspected

So that other possible causes of a stroke can be identified, an in-depth examination of the heart is carried out. Using an electrocardiogram (ECG) and a long-term electrocardiogram, it is possible to diagnose dysrhythmias; echocardiography (heart ultrasound) provides information about the possible formation of a blood clot in the heart as the cause of the stroke.

Laboratory tests for a suspected stroke

The blood is tested for different criteria in the laboratory.

For the above-mentioned diagnostic procedures the patient has more blood taken for testing in the laboratory. These tests include blood counts (concentration of red and white blood cells), signs of inflammation, electrolyte and sugar (glucose) as well as liver and kidney values. Special attention is paid to platelets (thrombocytes), as they play an important role in coagulation. If this process is abnormal, then platelet aggregation occurs more easily to form clots, which are dangerous as these can block a vessel. Laboratory controls help in the identification of risk factors such as disorders in fat metabolism.