5.1.2 Ischemic stroke: risk factors and classification

What are the cervical and intracerebral arteries?

4 large arteries that go to the brain.

How do the 4 arteries form a connection to each other?

Through the circle of willis.

What is the purpose of the connection between the 4 arteries via the circle of willis?

The blood can reach the brain though different routes when one is blocked by a blockage.

In what 2 arteries does the common carotid artery split?

• Internal carotid artery: goes in the direction of the brain

• External carotid artery: goes in the direction of the outer part of the skull

What is the function of the carotid arteries and the distillary system?

• Carotid arteries: the anterior blood supply

• Distillary system: the posterior blood supply

Where do the carotid arteries and the distillary system meet?

In the communicating arteries.

Name the blood circulations of the 4 large arteries.

• Basilar artery: brainstem, cerebellum

• Posterior artery: occipital lobes

• Middle artery: very large part of brain, its more lateral

• Anterior artery: more in the middle and anterior part

What is the TOAST criteria and what is it based on?

It is a classification for ischemic strokes, based the different causes.

What are different causes of an ischemic stroke, that the TOAST criteria is based on?

• Large artery atherosclerosis (embolus or thrombosis) ;

• Cardio-embolism;

• Small vessel occlusion (lacunar infarction);

• Other cause;

• Undetermined (cryptogenic stroke).

What is the first step of large artery atherosclerosis?

A normal artery wall with 3 layers: intima, media, adventia.

What is the second step of large artery atherosclerosis?

High blood pressure can irritate the endothelial cells. This will result in adhesion molecules that catch monocytes. Moreover, the LDL cholesterol particles can enter the intima. The LDL particles will then turn into macrophages and transform to foam cells.

What is the third step of large artery atherosclerosis?

If the second step keeps taking place, apoptotic bodies and cholesterol crystal will start to form in the intima when the foam cells start to disintegrate. De smooth musclles will integrate the intima and form a now layer: the fibric cap. Lastly, blood cells can come: vasa vasorum.

What is the fourth step of large artery atherosclerosis?

If the process keeps continuing, a lipid core will form, where things such as cholesterol and foam cells will get stuck. This bubble can pop (rupture fibrous cap), wherefore the contents will enter the bloodstream. On the place where the pop happened, thrombosis formation will take place, which leads to ischemic stroke.

What happens to the blood vessel as a result of the plaque?

The blood vessel has become smaller, wherefore the blood can reach the brain more poorly through this vessel.

What are 2 therapeutic options for atherosclerosis>

• Carotid endarterectomy;

• Stenting.

What is a carotid endarterectomy?

Plaques removal following a longitudinal incision of the vessel. And then there is

arteriotomy repair with the use of a patch

What is stenting?

Following engagement of the common carotid artery (CCA) with a guiding catheter or long sheath, the lesion in the internal carotid artery (ICA) is passed with a wire or with the filter emboli protection device (A). Subsequently, a self- expanding stent is deployed, usually covering the carotid bifurcation (B and C). Thereafter, a balloon post-dilatation is performed to achieve good stent expansion (D). Then the lumen get wider and the blood flow is not reduced anymore.

What are high risk sources of a cardio-embolism?

Atrial fibrillation (most knew one), recent myocardial infarction, mechanical valve, rhematic mitral valve stenosis, endocarditits, tumor (myxoma), thrombus

What is atrial fibrillation?

A rhythm disorder of the hearth.

What can happen as a result of atrial fibrillation?

Blood cloths can easily start to form, because the blood stays remains in the heart for short period of time. These blood cloths go towards the brain.

What is recent myocardial infarction?

The walls of the heart have abnormalities, wherefore a part cannot move anymore. Therefore, the blood, again, remains still at some moments and clot formation can take place easily.

Name 3 causes that involve problems with the valves of the heart.

• Mechanical valve;

• Rheumatic mitral valve stenosis;

• Endocarditis.

Where do small vessel disease refer to?

To a group of pathological processes with various etiologies that affect the small arteries, arterioles, venules, and capillaries of the brain.

What are 4 consequences of small vessel disease that are located in subcortical structures?

• Microbleed;

• Macrohemorrhages;

• White matter lesions;

• Lacunar infarcts.

In what does a lacunar infarct play a role?

• Stroke;

• Dementia;

• Aging.

Which organs can a lacunar infarct also affect?

• Kidneys;

• Retina.

What are 3 types of small vessel disease?

• Arteriolosclerosis = hardening and loss of elasticity of small arteries

• Arteriosclerosis= hardening and loss of elasticity of medium and large arteries

• Atherosclerosis = hardening of an artery due to an atheromatous plaque

What is arteriolosclerosis most often associated with?

Higher age, hypertension, diabetes mellitus

What are 2 types of arteriolosclerosis?

• Hyaline arteriolosclerosis (lipohyalinosis);

• Hyperplastic arteriolosclerosis.
  

How does hyaline arteriolosclerosis develop?

During hypertension there can be a leak in the internal lamina, whereby substances enter the wall of the arteriole: accumulation of proteins. Here hyaline arteriolosclerosis develops.

What is the effect of hyaline arteriolosclerosis?

Less blood can go through the arteriole. This wall will then start to harden and if this process proceeds, there is hyperplastic arteriolsclerosis.

What happens if occlusion occurs?

Infarction

Why do arterioles lead to small infarctions?

Because the arterioles are small and thus have a small flow territory.

Why can a small infarction still have a large effect?

It can have a greater effect if it takes place in a important arteriole.

What are 4 types other causes for an ischemic stroke?

• Arterial dissection';

• Vasculitis;

• Hematological disease;

• Hemodynamic.

How many of all strokes are caused by cervical artery dissection?

2% in general and in patients <50 years: 10-25% of all strokes.

What can cause a arterial dissection?

Can result from trauma (for example car accident), but also spontaneous.

What happens during an arterial dissection?

The intima separates itself from the media and a thrombus will develop. The intima will disappear and the thrombus will go into the blood and move towards the brain.

What are 2 examples of hematological disease?

• Thrombocytosis;

• Clotting disease (lupus disease, diffuse intravascular coagulation).

What is a hemodynamic stroke?

A type of ischaemic stroke that is caused by hypoperfusion rather than by embolism or local vasculopathy.

What are causes of a hemodynamic stroke?

Heart failure, hypotension, severe stenosis or obstruction of carotid and/or vertebral arteries and combination.

What are watershed infarctions?

Infarctions that occur at the border zones between major cerebral arterial territories as a result of hypoperfusion.

When is the cause of an ischemic stroke undetermined?

• Two or more causes identified

• No cause identified

• Incomplete evaluation