Etiology of transient cerebrovascular accidents
Transient disturbance of cerebral blood flow (TCI) is an acute disturbance of the blood circulation of the brain, which is accompanied by the appearance of focal, cerebral or mixed symptoms.
PNMK occurs in 30% of the population.
The main causative factors in the development of PNMK are: hypertension, symptomatic hypertension, atherosclerosis, vasculitis with autoimmune connective tissue lesions, heart defects, acute cardiac disorders (myocardial infarction, acute coronary syndrome, exertional angina), osteochondrosis of the cervical spine, vertebral artery syndrome .
The following forms of PNMK are distinguished: transient ischemic attacks (TIA) and hypertensive crises. PNMK of the TIA type is a short-term disturbance of blood flow and is not accompanied by pronounced destructive changes in brain tissue, but sometimes TIA can lead to the formation of cysts of small diameter.
Typically, TIA-type PNMK is reversible and this is due to the large compensatory capabilities of the brain, but it tends to form “silent” zones.
PNMK of the TIA type may also include diffuse atrophic changes in brain tissue, which can serve as a trigger in the development of ischemic stroke.
One of the causes of PNMC may be congenital vascular anomalies, for example, coarctation of the aorta, hypo- or aplasia of the arteries, pathological tortuosity of the choroid plexuses.
Severe spasm of the neck muscles, pathological compression from the outside by a growing tumor, enlarged lymph nodes can play an important role in the formation of PNMK.
Causes
Chronic cerebral circulatory failure is most often associated with atherosclerosis, hypertension, and heart disease accompanied by chronic circulatory failure. In addition, CNMK may be associated with vascular anomalies and diseases (vasculitis), venous anomalies, diabetes mellitus and various blood diseases, which result in chronic cerebral hypoxia.
Also, chronic cerebrovascular accident occurs as a consequence of acute cerebral circulatory disorders such as ischemic or hemorrhagic stroke.
An ischemic stroke occurs when a blood vessel that supplies blood to the brain is blocked by a blood clot. A clot can form in an artery that is already narrowed. Also, a clot can break off from the wall of a vessel somewhere in the body and travel through the bloodstream to the brain.
Ischemic strokes can also be caused by blood clots that form in the heart. These clots travel to the brain through the bloodstream and can become lodged in small arteries in the brain.
Certain medications and medical conditions can increase blood clotting and cause blood clot formation and increase the risk of ischemic stroke. A hemorrhagic stroke occurs when a blood vessel in a certain part of the brain becomes weak and ruptures, causing blood to leak into the brain and the blood damages brain cells. Some people have defects in the blood vessels in the brain that make a hemorrhagic stroke more likely.
Pathogenesis of transient cerebrovascular accidents
If the patency of the vessels of the brain or vessels of the neck is impaired, for example, with atherosclerosis, vasculitis, thrombosis, blood circulation in the brain tissue may become difficult.
This leads to ischemia of brain tissue and activation of metabolism with the production of under-oxidized products that trigger the destruction of phospholipids in cell membranes.
The result of such exposure is the death of brain cells with the development of atrophic diffuse foci, which leads to dysfunction of the nervous system and is manifested by various symptoms.
Diagnostics
The diagnosis of chronic cerebrovascular accident is made based on a combination of examination data, symptoms, neurological signs, results of brain neuroimaging (MRI, or MSCT), and angiography of cerebral vessels.
The doctor may detect the presence of certain neurological, motor, and sensory deficits, such as changes in vision or visual fields, abnormal reflexes, abnormal eye movements, muscle weakness, decreased sensation, and other changes. In addition, certain tests help determine the presence of intellectual-mnestic disorders.
Laboratory research methods are prescribed for the diagnosis of somatic diseases.
Clinic of transient cerebrovascular accidents
Transient disorders of cerebral circulation, the symptoms of which can be divided into focal, cerebral or mixed.
Focal symptoms: loss of sensitivity, hypoesthesia or hyperesthesia of the skin of the face, limbs or torso.
Impaired motor activity with the development of paresis of the central type, which involves the muscles of the hands and feet.
Muscle hypotonia and decreased muscle strength are characteristic of TIA-type PMI. These processes can lead to the development of partial epileptic seizures.
Pathological reflexes may appear.
Visual impairment of the optic-pyramidal syndrome type appears with the development of monocular blindness on the side of the vessel occlusion.
General cerebral symptoms: nausea, vomiting, hiccups. Tinnitus, dizziness, imbalance, horizontal nystagmus, abnormal head position, photopsia, visual field defects, these symptoms may indicate a cerebrovascular accident.
Disorders of the bulbar part of the brain may occur: dysphonia, dysphagia, dysarthria.
Sudden attacks of muscle hypotension and immobility may occur with preserved consciousness.
Hypertensive crises are the result of a sharp increase in blood pressure, and are accompanied by vegetative symptoms.
Causes of NMC
There are many risk factors that may lead to the development of cerebrovascular accident:
- hereditary predisposition,
- congenital or acquired thinness and fragility of blood vessels,
- atherosclerosis, thrombophelitis,
- excessively thick blood
- hypertension,
- heart defects,
- heart rhythm disturbances and other cardiovascular diseases,
- scoliosis, osteochondrosis, compression of the spinal and carotid arteries,
- TBI and spinal injuries,
- diabetes,
- obesity,
- individual reaction to hormonal contraceptives,
- exhaustion of the body,
- combination of nicotine and alcohol,
- sudden stress on the body (mental, physical, sudden temperature changes, etc.).
With age (after 60 years), the risk of developing cerebral circulation disorders increases significantly.
Diagnosis of transient cerebrovascular accidents
The diagnosis is made on the basis of the patient’s complaints, medical history and illness, the presence of concomitant pathologies, clinical examination, laboratory and functional research methods.
The diagnosis of PNMK is made when stenosis of intracranial arteries is excluded; for this purpose, ultrasound scanning of vessels, MR angiography, and contrast angiography are used.
A coagulogram is examined, and a CT and MRI of the brain is also performed.
The diagnosis of PNMK should exclude subarachnoid hemorrhage. The diagnosis of PNMK can be made as a concomitant pathology.
Etiological factors
The cause of the development of insufficiency, which is especially common in elderly and senile patients, is small-focal or diffuse damage to brain tissue. It develops against the background of long-standing problems with cerebral circulation, since during ischemia the central nervous system does not receive enough oxygen and glucose.
The most common causes of chronic ischemia:
atherosclerotic changes (in particular, cholesterol plaques);- hypertonic disease;
- VSD (vegetative-vascular dystonia);
- chronic heart failure;
- arrhythmias (including paroxysmal);
- diabetes;
- systemic vasculitis;
- blood diseases (with an increase in its viscosity);
- vascular lesions due to chronic infections (tuberculosis, syphilis).
One of the etiological factors is considered to be anomalies in the development of the aortic arch and vessels of the neck and shoulder girdle. They may not make themselves felt until atherosclerosis and hypertension develop. Certain importance is attached to compression (squeezing) of blood vessels by bone structures (with spinal curvatures and osteochondrosis) or tumors.
Blood circulation may also be impaired due to deposits of a specific protein-polysaccharide complex, amyloid, on the vascular walls. Amyloidosis leads to dystrophic changes in blood vessels.
In older people, low blood pressure is often one of the risk factors for CNMC. It does not exclude arteriosclerosis, i.e. damage to the small arteries of the brain.
Treatment and prevention of transient cerebrovascular accidents
A transient disorder of cerebral circulation, treatment of which begins immediately after diagnosis.
Treatment of PNMK may include: drug therapy, the prescription of antiplatelet agents and anticoagulants after studying blood tests, plasmapheresis and, of course, physical therapy.
Physiotherapy as a treatment method for PMN has been used for many years and is highly effective.
Prevention comes down to quitting smoking, controlling blood pressure levels, correcting cholesterol and lipids in the blood, correcting blood glucose levels, and regular physical activity.
Symptoms
Symptoms of a cerebrovascular accident depend on the degree of damage to brain cells and the location of the area of the brain with impaired blood flow. In acute cerebrovascular accidents (hemorrhagic or ischemic stroke), movement disorders such as hemiplegia or hemiparesis develop.
In chronic cerebral circulatory disorders (also called discirculatory encephalopathy), symptoms develop gradually and are manifested by symptoms such as memory impairment, dizziness, headaches. At first, the patient does not have any impairment of intellectual abilities. But as there is a chronic lack of oxygen in the brain tissue, memory impairment begins to progress, personality disorders arise, and intelligence decreases significantly. Subsequently, the patient develops severe intellectual-mnestic and cognitive impairments and dementia develops; extrapyramidal disorders and cerebellar ataxia may also develop.
