Stroke: definition and causes

Stroke is an immediate neurological deficiency of varying severity, most often caused by an acute circulatory disorder in the brain. The human brain has billions of nerve cells that are interconnected. It houses the "consciousness" and at the same time controls all bodily functions as well as sensory perceptions.

Control center brain

Like the processor of a PC, the brain constantly exchanges information with the "executive organs". Different regions on the surface of the brain also have different control functions. Each region of the body and each organ function can be assigned to a specific brain area. Short-term or long-lasting dysfunctions in the individual centers of the brain therefore also cause immediate disturbances in the associated body regions.

Symptoms of a stroke

What is popularly referred to as stroke means a sudden - like a blow - occurring neurological dysfunction. In common perception of a stroke, a sudden onset of paralysis occurs on one side of the body. In addition to this phenomenon called hemiparesis, many other neurological dysfunctions can be caused by a stroke. This includes:

  • blurred vision
  • vision loss
  • dizziness
  • Uncertainty while walking
  • speech disorders
  • numbness
  • Lose consciousness

Causes of a stroke

A stroke thus corresponds to an immediate dysfunction in the brain, which manifests itself as one of many symptoms in the "periphery". These disorders can have different causes:

  • Acute circulatory disorders (due to vascular or - less - hemorrhage)
  • Injury (trauma)
  • inflammation
  • tumors

The most common cause of stroke is an acute circulatory disorder of the brain. The circulation of the brain takes place via the two carotid arteries, which feed a branched network of vessels inside and outside the cranial bone, in order to supply organs with oxygen. The brain works metabolically intensive and therefore reacts very sensitively to circulatory disorders. Already a stop of blood circulation of a few seconds can cause disturbances of the consciousness or neurological failures.

If a circulatory disturbance persists for several minutes, the affected brain area is irreparably damaged. Result: permanent infarct scars in the brain and permanent restrictions in each subordinate body function. Many stroke patients are paralyzed, for example, even years after the attack on one side.

Forms of a stroke

A distinction is made between microvascular and macrovascular brain infarcts, depending on whether large vessels or small vessel branches are the cause of a circulatory disorder. Whether a stroke was caused by a sudden empty blood in a brain area or a hemorrhage after the rupture of a vessel (which ultimately also leads to a shortage of a brain area), is important for a correct diagnosis.

Basically, about 85 percent of a stroke is caused by a sudden circulatory disturbance in a vascular area of ​​the brain as a result of vascular occlusion. A vascular occlusion may in turn have the following causes:

  • Thrombosis: formation of a blood clot as an excessive reaction of the coagulation system. Mostly in vessels already damaged by vascular calcification. Thrombosis often brings the cask to overflow, as it completely closes a already heavily constricted vessel completely.
  • Embolism: Embolism means the carry-over of a blood clot that has formed, for example, in the heart or on the wall of a larger vessel, through the bloodstream. If this blood clot reaches a smaller diameter vessel, it can result in an acute occlusion.
  • Hemodymic disorder: Hemodynamic infarction mechanism is based on the same principle as the water supply of an apartment on a higher floor. If the pressure of the water in the pipes falls to a certain level, the water supply will dry up first in the apartments which are the highest. Since our head also has the highest position of all organs, a critical fall in blood pressure can lead to circulatory disorders in the brain. In addition, however, a high-grade constriction, for example on the large arterial neck vessels, must exist for this purpose. In some cases, however, fat particles can also lead to embolic vessel occlusions after extensive injury or air that has entered the vascular system.
  • Inflammation: Occasionally, inflammation of the cerebral vessels also leads to sudden vascular occlusion, leading to stroke.

Many strokes are caused by years of progressive vascular calcification, which causes no discomfort for a long time, but ultimately favors strokes via one of the mechanisms outlined above. The main risk factor for atherosclerosis of the large and small cerebral vessels is hypertension.

Other risk factors for stroke include elevated blood lipid levels, smoking, diabetes, obesity, or birth control pills.

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