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STRUCTURAL AND FUNCTIONAL BRAIN ALTERATIONS
AS TRIGGERS OF ISCHEMIC STROKE IN COVID-19 PATIENTS
Kazakov Bekzod Shodiyorovich
Bukhara State Medical Institute
Abstract.
Stroke remains one of the major causes of long-term disability
worldwide, significantly impairing motor abilities, sensory perception, and emotional-
cognitive functions. By the end of the acute phase, approximately 85% of stroke
survivors experience persistent motor dysfunction and speech disturbances such as
aphasia. In some individuals infected with COVID-19, the onset of acute ischemic
stroke may be linked to specific structural and functional alterations in the brain. This
article explores the possible mechanisms by which COVID-19-related neurological
changes contribute to stroke development.
Keywords:
COVID-19, ischemic stroke, brain function, neurological
complications, structural changes, neurovascular events.
Introduction.
Neurologists from the United States compared the risk of ischemic
stroke in patients with COVID-19 and the flu. It turned out that in the first case it is 7.6
times higher. Scientists also identified an excess of specific markers for the
development of cerebrovascular accident in the blood of those coronavirus patients
who eventually developed a stroke. (1) Russian experts believe that the study expands
understanding of the characteristics, mechanisms and short-term outcomes of acute
cerebral circulation in patients with COVID-19. This means that it can help doctors
prevent the development of such a pathology. (3,5,6)
Neurologists from the Clinical and Translational Neuroscience Division of the
Fail Family Brain and Consciousness Research Institute at Weil Cornell College of
Medicine and other American institutions have published an article assessing the risks
of ischemic stroke in patients with influenza and coronavirus. They studied data from
1,916 people with COVID-19 who received care in the emergency room or hospitalized
in two clinical hospitals in New York. Then doctors compared them with data from a
similar sample of patients with influenza.
Of all patients with coronavirus infection, 31 (1.6%) had an acute cerebrovascular
accident of the ischemic type (ischemic stroke). In the group of patients with influenza,
stroke was observed in only three patients out of 1486 (0.2%). After adjusting for age,
gender and race, the likelihood of ischemic stroke with coronavirus was 7.6 times
higher than with flu.
Neurologists from the Department of Clinical and Translational Neuroscience at
the Feil Family Brain and Mind Research Institute at Weil Cornell College of Medicine
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and other American institutions have published an article assessing the risks of
ischemic stroke in patients with influenza and coronavirus. They studied data from
1,916 people with COVID-19 who were receiving care in the emergency room or
hospitalized in two clinical hospitals in New York. Then doctors compared them with
data from a similar sample of patients with influenza. [4]
Of all patients with coronavirus infection, 31 (1.6%) had an acute cerebrovascular
accident of the ischemic type (ischemic stroke). In the group of patients with influenza,
stroke was observed in only three patients out of 1486 (0.2%). After adjusting for age,
gender and race, the likelihood of ischemic stroke with coronavirus was 7.6 times
higher than with flu. [1,3,8]
The complex biological nature of disorders leading to stroke is a consequence of
the interaction of many risk factors, including both non-modifiable (age, gender, race
and ethnicity, heredity, etc.) and modifiable factors (high blood pressure, diabetes ,
high cholesterol, atrial fibrillation, overweight, lifestyle). Modifiable risk factors are
responsible for no more than 60% of the general population risk of ischemic stroke.
[10]
The 2019-2020 coronavirus infection pandemic has demonstrated not only the
high aggressiveness of the new infectious agent, but also its ability to cause severe
cardiovascular complications. In recent decades, ischemic stroke has been one of the
leading causes of death in older age groups (Mozaffarian D., Benjamin E., Go A. et al.,
2016). A generalization of the first results of treatment of victims of coronavirus
infection showed that the development of IS in such patients is very likely. The high
mortality rate in elderly patients infected with COVID-19 is partly associated with the
development of fatal cardiovascular complications, the most severe of which is stroke
(7,14).
An analysis of the few available publications that mention the problem of
COVID-associated ischemic stroke can show not only the significance of the problem,
but also reveal the mechanisms of acute cerebral ischemia. Prevention of acute
cerebrovascular accidents (ACVI) in those infected with COVID-19 seems to be one
of the important clinical tasks that need to be addressed in conditions of high workload
in specialized hospitals and a shortage of specialists.
According to the data of the first publications, which analyzed the neurological
complications of coronavirus infection, acute cerebrovascular accidents (ACVI) were
found in 6% of patients. The first generalizations of clinical observations show that
syndromes of thrombotic occlusion of large arteries prevail in the structure of
pathogenetic subtypes of ischemic stroke (IS). In addition, a high incidence of impaired
consciousness (more than 15% according to Mao L. 2020) may indicate the possibility
of diffuse brain damage of the type of acute (toxic, hypoxemic, ischemic)
encephalopathy. [12]
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To clarify the pathogenesis of acute cerebral ischemia, it is now customary to
distinguish pathogenetic subtypes of IS in accordance with the TOAST etiological
classification. According to this classification, about 80% of all AIs are distributed
between the main subtypes - atherothrombotic (atherosclerotic disease of large
arteries), cardioembolic (the main cause is atrial fibrillation), lacunar (microangiopathy
is a disease of small arteries). Formally, CVA against the background of coronavirus
infection can be classified as “other established causes”. However, there are several
important arguments against this formal allocation. These arguments call for a more
detailed analysis of the causes and mechanisms of COVID-associated ischemic stroke.
[11] The first argument is based on the assumption that this form of stroke is not
associated with atherosclerosis, and therefore has an original pathogenesis and a
completely different etiology. [6,8] The second argument is based on facts indicating
the participation of an active inflammatory process in the pathogenesis of COVID-
associated ischemic stroke. Finally, the third argument comes from the established
practice of treating such patients. In contrast to standard methods of treatment based
on the use of antiplatelet and lipid-lowering therapy to prevent atherothrombosis,
anticoagulants show better results in patients with coronavirus infection (does not
comply with current clinical guidelines) [4].
Analysis of clinical data shows that patients suffer a stroke in the acute period of
coronavirus infection against a background of hyperthermia and often pneumonia.
Stroke is characterized by a large-focal lesion in the carotid vascular system, more like
a syndrome of thrombotic occlusion of a large artery. A significant difference between
COVID-dependent atherothrombotic IS is the absence of a connection between a
thrombus and an atherosclerotic plaque and the presence of signs of inflammation of
the vascular wall. D.McNamara (2020) draws attention to the inflammation and edema
of the arteries of the vascular basin in which cerebral infarction develops, which can
be regarded as acute vasculitis. Inflammation and edema of the vascular wall directly
or indirectly associated with exposure to a virus or an autoimmune reaction is possible,
but not an obligatory sign of the development and generalization of the infectious
process. Moreover, neurological syndrome associated with inflammation of large
arteries is more rare than a regularity.
Analysis of the first data containing a comparison of the clinical picture of stroke
and the results of laboratory tests can, to some extent, explain the fact and frequency
of the development of large artery disease syndrome. L. Mao et al. (2020) present an
analysis of laboratory data from 124 patients who were hospitalized with coronavirus
infection. The average age of the patients was 54 years, the severe course of the disease
was noted in 59%. Cerebrovascular syndromes were detected in 6% of patients, all in
the group with severe course.
Determination of predictors and biomarkers of an aggressive course of the disease
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is an important scientific and practical task, the solution of which will allow avoiding
such severe complications as stroke. However, the possibility of such hyperreactivity
suggests the use of active immunosuppression when signs of vasculitis appear.
The hypercoagulable status of patients with coronavirus infection is another
important factor in changing the stable course of diseases associated with
atherosclerosis.
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