CausesGenesis of a stroke

A vascular occlusion can lead to the brain tissue being undersupplied, so that it dies. The causes of vascular occlusion are arteriosclerotic changes in the vessel walls (vascular calcification), the displacement of the vessel lumen due to a blood clot (= thrombus) or the occlusion of a vessel due to a displaced thrombus (= embolus). Furthermore, bleeding from a cerebral artery can cause tissue damage.

More rarely, venous thrombosis (= blood clot) of the intracranial veins or hypoxaemia (= too low oxygen content in the blood) are the cause of brain substance damage. A stroke is caused by a circulatory disorder in the brain. This means that there is either a reduced blood flow in a certain area of the brain or a haemorrhage.

The reduced blood flow leads to so-called cerebral ischemia, i.e. the undersupply of oxygen to brain tissue. This in turn leads to the death of the cells that need the oxygen to survive. Bleeding, on the other hand, leads to increased mechanical pressure on the cells, which eventually causes them to die as well.

At approx. 80%, the reduced blood flow is the significantly more frequent cause of all strokes. It is promoted by various factors.

Blood flow (usually subarachnoid bleeding) is promoted by aneurysms, for example.

Arteriosclerosis
Cardiac arrhythmia and
Vascular Inflammation

In about 80% of the cases of illness, a stroke is based on the undersupply of blood to brain tissue (ischemia). The vessels supplying the blood are either constricted or completely blocked.

Most frequently, the arteria carotis interna, usually at the junction of its parent vessel (arteria carotis communis) with the arteria carotis interna and externa, is affected by constriction or occlusion. Two thirds of strokes caused by ischemia are caused by vascular wall changes at the base of an arteriosclerosis: a thrombosis or embolism, in which a blood clot usually separates from the carotid bifurcation, is the cause of the narrowing of a vessel and the resulting undersupply of a certain area of the brain. One third is caused by blood clots that form in the heart and from there enter the vascular system of the brain as an embolus.

With a frequency of 15%, circulatory disorders of the brain are caused by a bleeding, during which blood flows into brain tissue. In most cases, the artery walls are brittle due to long-standing high blood pressure and the pre-existence of arteriosclerosis. Other causes of bleeding are vascular malformations or sagging vessels whose walls can quickly tear (aneurysms).

A cerebral hemorrhage leads to severe headaches, nausea, vomiting and disturbances of consciousness. The neurological deficits occur within minutes to hours. Imaging diagnostics are necessary: A computed tomography (CT) examination can show a bleeding.

The subarachnoid space is located under one leaf of the meninges, which is formed by three leaves in total. The subarachnoid space is located between the leaf that is firmly attached to the brain, the so-called pia mater, and the arachnoidea. It is filled with liquor and vessels run through it.

Often, the affected patients have a vascular sacculation at the base of the skull and this sacculation suddenly tears, so that blood can enter the liquor. The symptoms of SAH are as follows: By means of a CT or a spinal tap (= lumbar puncture) a subarachnoid hemorrhage can be diagnosed.

Severe, shooting headache
Neck stiffness (= meningismus) un
Disturbance of consciousness.

Thromboses are a rare cause of a stroke. They occur in patients who have a coagulation disorder with a tendency to form thromboses and are not common at 1%. Here too, headache is an early symptom of vascular occlusion, followed by neurological dysfunction, small seizures are also possible.