Statistics and detection of asymptomatic strokes

Acute stroke is one of the most frequent causes of mortality and disease incidence in the world today. More than 400 000 stroke cases are registered annually on the territory of the Russian Federation. 35% of those lead to a lethal outcome. In other words, every fifteen minutes someone in Russia suffers a stroke.

100-120 strokes per day are recorded in large cities of the country. At the same time, 70-80% of patients who have suffered a stroke become disabled, and 20-30% of this number requires constant care and support.

Today, the understanding of ischemic stroke as an emergency medical condition is constantly developing. The effectiveness of acute stroke treatment in specialized wards - the so-called "stroke blocks” has already been proven. The use of thrombolytic treatment provides additional therapeutic possibilities. Unfortunately, this method of therapy is not really widely available yet.

Stroke is defined as a spontaneous neurological deficiency caused by hemorrhage or ischemia in the central nervous system. About 75% of all acute disorders of cerebral circulation account for the proportion of ischemic stroke due to local occlusion of the vessel. This dysfunction causes the delivery of glucose and oxygen to the brain to cease, which leads to the occurrence of subsequent disturbances of metabolic processes in the affected area.

Lethality of patients suffering from a stroke depends to a large extent on the conditions of treatment in an acute period. The early mortality (30 days) after ischemic stroke is 35%. In hospitals, this indicator is 24%, and on condition of home treatment - 43%. About 50% of patients die within a year after a stroke.

To date, the number of deaths due to stroke is second, after acute heart disease. By the way, the mortality rate is much higher in males than that of female half of the population. At the beginning of the 21st century, there was a trend in Russia to reduce annual mortality due to a stroke, but in Western Europe and the United States it is more significant. Positive dynamics is associated with a decrease in the consumption of foods containing large amounts of cholesterol, and active hypertension treatment.

The consequences and clinical characteristics of ischemic stroke directly depend on the location and magnitude of the infarction. The latter are caused by a complex of interdependent, but also mutually compensating factors. These include:

• Specific area of injury;
• Mechanisms of acute ischemia development (embolism, thrombosis, cerebrovascular insufficiency);
• Individual anatomical features of the patient;
• The degree of disorganization of autoregulation, which largely determines the level of perfusion pressure in the affected territory;
• Potential opportunities for inclusion of collateral circulation.

Today it is basically impossible to predict the extent to which the level of collateral circulation and the presence of anastomoses will be reflected in the overall clinical picture. There may be very heterogeneous variants. For example, stenoses of the internal carotid artery are sharply expressed, but with the full preservation of the Willis circle function they might have no symptoms. The embolism of the distal posterior cerebral artery in a region with a relatively small network of anastomoses can lead to the formation of sufficiently extensive infarctions accompanied by a persistent neurologic deficiency.

Asymptomatic stroke

The ever-increasing availability and ubiquitous distribution of MRIs made it possible not only to study brain pathologies after the appearance of clinical symptoms, but also to identify pathological foci that had not yet manifested themselves. According to various authors, the frequency of random detection of brain pathologies varies from 1.1% to 1.7%. A study was conducted by the Dutch scientists on a large population that showed how often various pathological foci can be detected in the brain of people who are perfectly healthy externally.

Neuroimaging study was carried out among Rotterdam Study participants. Rotterdam Study is a major population-based cohort study, started in 1990 by the Erasmus MC University Medical Center. Citizens of the Rotterdam suburbs over the age of 55 years old who voluntarily underwent a regular examination at the center participated in the research. The advent of MRI made tomography of the brain mandatory for all participants, and since 2006, the age of the patient has been reduced in the study to 45 years.

2 000 people took part in the study from 01.08.2005 to 01.02.2007, whose average age was 63.5 years. Women were slightly prevailing men - 52.4%. 7.2% of the patients were diagnosed with an asymptomatic stroke. In addition, aneurysms (1.8%) and benign tumors (1.6%) were frequently detected. Microadenomas of the pituitary gland were found in 6 participants (0.3%), schwannoma of the pre-collateral nerve cochlear was detected in two participants.

Only two of all the participants in the study who had pathological changes in the brain complained of hearing loss. Everyone else didn’t have any complaints. The random findings that occur during MRI of the brain - asymptomatic pathological changes in blood vessels in particular - were found relatively frequently in the general population. The data obtained during the study should be used in the course of educational work and taken into account when conducting preventative examinations of patients in the older age group.

Apparently, two biomarkers that are widely known as prognostic factors of the cardiovascular system pathologies can indicate an increased risk of a silent (asymptomatic) stroke. This is reported in the famous Stroke magazine by the authors from The Methodist Hospital.

Doctors determined that elevated levels of troponins T and NT-prоBNP have a direct relationship with an increase in the frequency of brain tissue damage by 3 and 3.5 times, respectively. These findings were made on the basis of an analysis of the results of a massive study "Atherosclerotic Risks in Society".

Another article based on the findings from this study was already published in Stroke magazine earlier. It has showed that a relationship exists between the levels of these substances in the blood and the stroke that occurs with the unfolded clinical picture. Now the director of the Center for Cardiovascular Disease Prevention in The Methodist Hospital, Christina Bellantine, and co-authors studied these biomarkers in the asymptomatic course of a stroke.

Both studies show that these biomarkers can effectively identify people who have a high risk of suffering a silent stroke, even in the event of a lesion occurring. The authors believe that this will help doctors to win valuable time.

To study subclinical pathologies of the brain, the authors collected data from 1,100 patients who agreed to undergo 2 MRI scans and donate blood at 11-year intervals. The aim of the study was to identify mild cerebral infarctions and white matter pathologies caused by chronic inflammation.

See also similar articles on the subject:

• Climax and stroke
• Drugs for stroke treatment
• Pseudostroke

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