A stroke is an immediate neurological failure of varying severity, which is usually caused by an acute circulatory disorder in the brain. The human brain has billions of nerve cells, which are interconnected. It houses “consciousness” and simultaneously 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.” In the process, different regions on the surface of the brain also have different control functions. Each region of the body, as well as each organ function, can be assigned a specific brain area. Short-term or long-term dysfunctions in the individual centers of the brain therefore also cause immediate disturbances in the associated regions of the body.
Symptoms of stroke
What is popularly called a stroke refers to a neurological dysfunction that occurs suddenly – like a blow. In common conception of a stroke, an abrupt onset of paralysis occurs on one side of the body. However, in addition to this phenomenon, called hemiparesis, numerous other neurological dysfunctions can be caused by a stroke. These include:
- Visual disturbances
- Loss of vision
- Dizziness
- Uncertainty when walking
- Speech disorders
- Emotional disturbances
- Clouding of consciousness
Causes of stroke
Thus, a stroke corresponds to an immediate dysfunction in the brain, which manifests itself as one of many symptoms in the “periphery”. These disturbances can have various causes:
- Acute circulatory disturbances (caused by vascular narrowing or – less frequently – hemorrhage).
- Injury (trauma)
- Inflammation
- Tumors
The most common cause of stroke is an acute disturbance of blood flow to the brain. Blood flow to the brain occurs through the two carotid arteries, which feed a branching network of vessels inside as well as outside the skull bone to supply organs with oxygen. The brain works metabolically and therefore reacts very sensitively to circulatory disturbances. Even a blood flow stoppage of a few seconds can cause disturbances of consciousness or neurological deficits. If a circulatory disturbance lasts for several minutes, the affected brain area is irreparably damaged. The result: permanent infarct scars in the brain and permanent restrictions in subordinate bodily functions in each case. Many stroke patients, for example, are therefore still paralyzed on one side even years after the attack.
Forms of stroke
A distinction is made between microvascular and macrovascular cerebral infarctions, depending on whether large vessels or small vascular branches are the cause of a circulatory disturbance. Whether a stroke is caused by a sudden lack of blood in an area of the brain or by hemorrhage following the rupture of a vessel (which ultimately also leads to a reduced supply to an area of the brain), is important for a correct diagnosis. Basically, about 85 percent of a stroke is caused by a sudden disturbance of blood flow in a vascular district of the brain as a result of a vascular occlusion. Vascular occlusion, in turn, can be caused by the following:
- Thrombosis: Formation of a blood clot as an exaggerated reaction of the coagulation system. Mostly in vessels which are already pre-damaged by vein calcification. Thrombosis often brings the barrel to overflow, as it finally completely closes an already severely constricted vessel.
- Embolism: embolism means entrainment by the bloodstream of a blood clot that has formed, for example, in the heart or on a wall of a larger vessel. If this blood clot reaches a smaller diameter vessel, it can result in acute occlusion.
- Hemodymic disruption: hemodynamic infarction mechanism is based on the same principle as the water supply to an apartment on a higher floor. If the pressure of the water in the pipes drops to a certain level, the water supply dries up first in the apartments, which are the highest. Since our head also has the highest position of all organs, a critical drop in blood pressure can lead to circulatory problems in the brain.For this to occur, however, there must also be a high-grade constriction, for example in the large arterial vessels of the neck. In some cases, however, fat particles after extensive injuries or air, which has penetrated into the vascular system, can also lead to embolic vessel occlusion.
- Inflammation: Occasionally, inflammation of the cerebral vessels also leads to sudden vascular occlusion, resulting in stroke.
Very many strokes are caused by years of progressive atherosclerosis, which for a long time does not cause any symptoms, but ultimately promotes strokes through one of the mechanisms outlined above. A major risk factor for this arteriosclerosis of the large as well as the small vessels of the brain is high blood pressure. Other risk factors for stroke include elevated blood lipids, smoking, diabetes, obesity, or birth control pills.
