The stroke is described as “ischemic” in 85 percent of instances, meaning that a blood vessel in the brain becomes clogged. often due to a clot, which blocks the supply of oxygen and causes lesions in the area not irrigated.
Stroke is mainly the result of atherosclerosis, a pathology that consists of the formation, in the wall of the arteries, of atherosclerotic plaques (a deposit of cholesterol, limestone, and cells, which is surrounded by a fibrous cap ). These plaques grow, thickening the walls of the arteries.
In most cases, they remain stable, non-symptomatic. But it happens that the fibrous cap becomes fragile, and ends up breaking: the release of its contents into the circulation then causes the formation of the clot. If this clot blocks a cerebral artery, it’s a stroke.
The remaining 15% of accidents are “hemorrhagic”, and result from the rupture of a cerebral artery.
What are the symptoms of a stroke?
The symptoms of a stroke differ depending on which part of the brain is affected:
paralysis or numbness of part of the face (deviation of the mouth, etc.);
speech problems, inability to speak or find words;
loss of strength or motor skills in a limb (arm, leg) or part of the body;
severe headaches with vomiting and dizziness;
disturbances in the sensations of touch or sight.
What are the exams performed?
The diagnosis of stroke can be confirmed by imaging. Two techniques are used: the scanner makes it possible to define the type of CVA in question (ischemic or hemorrhagic). It can be supplemented by a magnetic resonance imaging (MRI) examination in the event of a small stroke.
What treatment for stroke?
Treatment for stroke differs depending on the type. In the case of an ischemic stroke, the goal is to unclog the cerebral vessel as quickly as possible in order to limit the lesions, and therefore the sequelae. The first technique is thrombolysis, that is to say the injection of a product intended to dissolve the clot. Thrombolysis is effective only in the first 4-5 hours after the start of the stroke.
There is a second, more recent therapeutic response: thrombectomy. It consists of removing the clot that obstructs the artery mechanically using a catheter inserted into the femoral artery. However, this technique is reserved for easily accessible clots, obstructing a large artery, or those that respond less well to thrombolysis.
In the event of a hemorrhagic stroke, treatment is surgical in order to restore normal blood flow.
It is then a question of fighting against the risk factors of relapse. These include diabetes and arterial hypertension (which have deleterious effects on the condition of the vessels), cardiac arrhythmias (which promote the formation of clots), smoking, hypercholesterolemia, and ‘obesity. Anticoagulant treatment may be prescribed to thin the blood and limit recurrences.
Promising avenues of research
As we have seen in the causes of stroke, clots that block the vessels most often derive from the formation of atherosclerotic plaque. This is why researchers want to be able to detect and predict which are the most threatening atherosclerotic plaques. To this end, they wish to set up biological markers capable of discriminating threatening plaques from “stable” plaques, without risk of stalling. Several trials are in progress.
The treatments for an ischemic vascular accident call on so-called “anti-thrombotic” molecules that will degrade the clot blocking the vessel. However, these treatments are not without side effects and are only fully effective shortly after the accident. One of the avenues of research is to improve treatments with a view to limiting these harmful effects and to one day be able to use them in wider therapeutic windows.
Another track is to protect the neurons threatened by the accident. Researchers want to develop molecules with the ability to counter the mechanisms involved in cell death to block the onset of brain damage.
Rehabilitation after a stroke involves stimulating neurons to form new networks that can compensate for deficiencies. Researchers want to develop treatments that accelerate the creation of these neural networks for better recovery.
Finally, cell therapy is also a treatment of the future. The idea is to inject immature stem cells into injured brain areas, which, once in place, would turn into adult neurons and replace the lost neurons. This method has demonstrated very interesting potential, but many investigations are still needed to prove its long-term safety.