Intracranial atherosclerosis: diagnosis, clinical manifestations, therapy

Blood supply to the brain is one of the invisible functions of our body. Strong emotions, physical activity or prolonged mental work cause a feeling of a rush of blood. But when we brush our teeth or make a cup of tea, it seems that nothing happens. However, at the biological level, any, even the most primitive activity is a continuous process of saturation of brain structures with blood. The quality of our life directly depends on the safety of the vascular system. The brain: your own doctor In the blood supply system of the brain, there are two groups of arteries: extracranial (located between the head and heart) and intracranial (vessels of the cranial cavity and bone canals). The brain has protection from mechanical damage to blood vessels - the so-called arterial circle or circle of Willis. This is a closed system of arteries at the base of the brain that provides normal blood supply when one or more arteries are blocked. If nature were not so prudent, boxers would end their careers after the first knockout. In everyday life, it is not only mechanical injuries that pose a danger. Pathologies are associated with blockage or narrowing, changes in the structure of blood vessels and the tone of their walls. In illness, blood flow to the brain deteriorates. Disturbances in natural blood flow cause atherosclerosis, stroke, aneurysm, etc. Chronic pathologies lead to irreversible changes. At an early stage, the disease is often asymptomatic. Cannot be ignored: ringing in the ears or head, heaviness in the head, dizziness, blurred vision, fainting, loss of coordination, spontaneous weakness or numbness of the limbs. If these disorders occur, you should immediately consult a doctor. Smoking harms blood vessels Using ultrasound, the diagnostician determines: - The condition of the walls of the arteries - Altered course of the arteries - The presence of narrowing (stenosis), lack of lumen (occlusion) of the arteries - Disturbances in blood flow through the arteries - The presence of formations inside the arteries (for example, atherosclerotic plaques) The study is performed in lying on your back (sometimes with a cushion under your shoulder blades). The specialist examines the brachiocephalic trunk, subclavian arteries, vertebral arteries, carotid arteries, cerebral arteries (only with a joint examination of the extracranial and intracranial sections; the intracranial section is not examined separately from the extracranial). On the day of your doctor’s appointment, you must stop using substances that affect vascular tone: nicotine, tea, coffee, energy drinks. As with other vascular diseases, the best method of prevention is a healthy lifestyle: giving up bad habits, controlling nutrition and moderate physical activity. You must bring the results of previous studies (if available) with you to your appointment. Ultrasound at OLMED MC is the key to effective treatment without the risk of complications and premature relapses!

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Intracranial atherosclerosis: diagnosis, clinical manifestations, therapy

Atherosclerosis of intracranial arteries is a significant factor in the development of acute cerebrovascular accident. The article discusses pathophysiological aspects, clinical manifestations, methods of diagnosis, treatment and prevention of atherosclerosis of intracranial arteries. It is noted that further progress in the study of this problem is associated with new techniques for visualizing vessels and atherosclerotic plaque and the search for individual approaches to treatment, including determining indications for endovascular interventions.

Rice. 1. Computed tomographic angiography of intracranial arteries: occlusion of the right vertebral artery at the intracranial level (MIP and 3D images)

Rice. 2. Magnetic resonance angiography and magnetic resonance imaging of the brain in T2 mode (magnetic resonance imaging with a magnetic field strength of 3T)

Table. Advantages and disadvantages of imaging methods for intracranial atherosclerosis

Introduction

Atherosclerosis of intracranial arteries is one of the most common causes of stroke worldwide. According to epidemiological studies, the development of acute cerebrovascular accident due to this pathology depends on race. In Caucasians, symptomatic intracranial atherosclerosis (that is, arterial damage causing transient ischemic attack or stroke) occurs in 10% of cases, while in representatives of the Black and Asian races this figure reaches 30 and 50%, respectively [1–6]. This difference is due to genetic predisposition to the development of the disease, as well as differences in lifestyle and typical risk factors [2]. The incidence of asymptomatic atherosclerosis reaches 54% of cases in Asians and 12% among representatives of other races [2, 7–9].

As a rule, severe asymptomatic atherosclerosis of the intracranial arteries is combined with other vascular risk factors, which usually serve as the basis for examining such patients. Damage to the intracranial arteries is associated with a high incidence of recurrent acute cerebrovascular accidents - according to the WASID study, up to 19% over the next two years [10]. The incidence of recurrent stroke is also influenced by morphological characteristics, in particular stenosis > 70%, female gender and time since the previous ischemic episode (less than 17 days).

Pathophysiological aspects of atherosclerosis of intracranial arteries

The immediate causes of stroke in atherosclerosis of intracranial arteries include:

• hypoperfusion of brain tissue with infarction in areas of adjacent blood supply, associated with decompensation of the processes of autoregulation of cerebral blood flow, especially in conditions of impaired systemic hemodynamics;
• arterio-arterial embolism, the consequence of which, as a rule, is a wedge-shaped infarction;
• the presence of an atherosclerotic plaque at the mouth of a small perforating artery, which leads to the formation of small infarctions.

The high frequency of recurrent infarctions, as a rule, is caused precisely by a violation of the autoregulation of cerebral blood flow in conditions of severe stenosis [11]. Knowing the mechanism of development of the first stroke, it is possible to predict the mechanism of recurrent stroke: for example, in patients with small infarctions due to occlusion of a small artery, a recurrent stroke, as a rule, develops of a different type and is localized distal to the affected artery [12]. Most often, atherosclerotic lesions are localized in the middle cerebral artery (up to 27% [13]) and the internal carotid artery (petrosal, cavernous and supraclinoid parts), less often in the basilar artery and the intracranial segment of the vertebral artery [10, 14].

It is believed that even substenotic lesions of the arteries can cause acute cerebrovascular accidents by analogy with atherosclerotic changes in the coronary arteries, which can cause myocardial infarction against the background of relatively mild stenosis. This threat is associated with inflammatory processes that occur during the onset, progression and damage of plaque and lead to rupture of the plaque cap and the formation of thrombosis and infarction.

Diagnostics

To diagnose atherosclerosis of intracranial arteries, ultrasound methods (transcranial Dopplerography), magnetic resonance (MR), computed tomography (CT) (Fig. 1 and 2) and digital subtraction angiography (table) are used. The latter method is considered the gold standard for diagnosis [15], as it allows one to accurately determine the degree of arterial stenosis. However, digital subtraction angiography is an invasive intervention that involves the introduction of a contrast agent. In addition, the method is associated with the development of transient and persistent neurological deficits, the frequency of which can reach 1.8 and 0.6%, respectively [16].

There is no clear evidence regarding the accuracy of safer and more accessible non-invasive methods. Thus, with MR angiography, visualization of the lumen of a vessel depends on the blood flow in it, while the true severity of vessel damage can be distorted in the case of critical stenosis with very low blood flow (it may look like an occlusion) and in high-degree stenoses with high blood flow velocity.

It is believed that transcranial Doppler ultrasonography and MR angiography can be used as screening to exclude lesions of intracranial arteries, but they are not reliable enough to confirm the presence of stenosis and determine its severity [17]. At the same time, transcranial Doppler sonography provides additional information with which one can assess blood flow through collateral vessels and determine cerebrovascular reactivity.

CT angiography is superior to MR angiography in terms of diagnostic accuracy [18, 19] and has the highest sensitivity and specificity for detecting stenosis after direct angiography, >50% [20]. In addition, CT or MR angiography can be supplemented with methods for assessing cerebral blood flow - perfusion computed tomography or magnetic resonance imaging. As a rule, the latter are included in the standard research protocol and make it possible to identify areas of hypoperfusion that arise in conditions of long-term stenosis and do not manifest themselves clinically.

The classical approach to diagnosis, aimed only at establishing the degree of narrowing of the artery, has a number of disadvantages - in particular, it is impossible to establish the histological structure and, therefore, the degree of “instability” of the atherosclerotic plaque, as well as to differentiate atherosclerotic stenosis from narrowing of the artery lumen caused by other reasons.

Currently, new imaging technologies, such as high-resolution magnetic resonance imaging and intravascular ultrasound, are of particular importance - techniques that make it possible to study the atherosclerotic plaque itself. This is especially important in the early stages of the atherosclerotic process, when the lumen of the vessel has not yet narrowed due to remodeling. Thus, magnetic resonance imaging, performed on a device with a magnetic field strength of 3T, makes it possible to directly visualize a thrombus, hemorrhage into a plaque and determine the composition of the plaque, that is, assess the activity of the plaque [21].

Intravascular ultrasound also makes it possible to detect hemorrhage in the plaque, determine its composition and extent. This may influence the determination of risk and therefore the choice of treatment.

Thus, new research methods are especially important when examining patients with stroke and non-stenotic damage to intracranial arteries, when the cause of the infarction may be plaque damage not detected using classical imaging methods [22].

Clinical manifestations

The most serious clinical manifestations of atherosclerosis of intracranial arteries include transient ischemic attack and ischemic stroke, the symptoms of which correspond to the location of the lesion. Stenosis of the middle cerebral artery is usually characterized by lacunar infarctions and ischemia in the area of ​​adjacent blood supply. Stenosis of the internal carotid artery is accompanied by the development of more extensive lesions and involvement of gray matter. The neurological deficit in this case turns out to be more pronounced than with stenosis of the middle cerebral artery [23].

In addition to motor and sensory disturbances, in cases of damage to the gray matter, thalamus or caudate nucleus, patients may experience cognitive impairment. Cognitive impairment may also develop in the absence of infarcts due to decreased cerebral perfusion and associated changes in the white matter of the brain. Finally, an asymptomatic course of the atherosclerotic process is possible. Clinical symptoms are observed in the presence of a number of factors, among which it is necessary to note the degree of stenosis and the structure of collateral vessels [24]. Symptoms are usually accompanied by damage to the middle cerebral artery, basilar artery and intracranial part of the vertebral artery, while changes in the anterior and posterior cerebral arteries are most often asymptomatic [25].

Atherosclerosis of intracranial arteries can progress, stabilize, or regress [26]. It is generally accepted that asymptomatic patients have a more favorable outcome. Thus, when analyzing data from the TOSS-2 study, progression of the lesion was observed in 13% of cases in patients with symptomatic atherosclerosis and only in 6% of cases with asymptomatic stenosis [27]. In a study of 102 patients with significant middle cerebral artery stenosis or occlusion, the risk of stroke in symptomatic patients was 12.5% ​​per year and only 2.8% per year in asymptomatic patients [28]. Asymptomatic middle cerebral artery plaque can predict a relatively favorable outcome: such plaques are often calcified and, therefore, do not have a high risk of embolism [29].

A number of studies have identified differences between the location of stenosis and the course of the disease [30]. Obviously, the prognosis of the disease with occlusion of the basilar artery is worse than with occlusion of the internal carotid or middle cerebral artery [31].

Prevention and treatment

The main goal of treatment in patients with symptomatic atherosclerosis of intracranial arteries is to prevent recurrent acute cerebrovascular accident. To this end, the following activities are carried out:

• blood pressure control (systolic blood pressure ≥ 140 mm Hg significantly increases the risk of stroke in the corresponding arterial basin);
• elimination of dyslipidemia (total cholesterol ≤ 5.1 mmol/l and low-density lipoprotein ≤ 1.8 mmol/l);
• aggressive correction of other risk factors (normalization of body weight, increased physical activity, smoking cessation, maintenance of normoglycemia) in accordance with recommendations for secondary prevention of stroke [32];
• antithrombotic therapy.

Preference is given to monotherapy with antiplatelet agents. At the same time, there is evidence that dual antiplatelet therapy has a greater effect in preventing recurrent stroke in the early stages after the first vascular episode. In the SAMMPRIS study, patients treated with aspirin and clopidogrel for 90 days followed by aspirin alone plus intensive risk factor management had a 5.8% rate of recurrent stroke in the first 30 days [33].

Based on the results of the largest studies, aspirin monotherapy at a dose of 325 mg/day in combination with intensive correction of risk factors can be recommended for patients with moderate stenosis (

For many years, attempts have been made to surgically treat atherosclerotic stenosis of intracranial arteries and its consequences. The earliest and most studied operation is the application of extra-intracranial anastomosis, but the results of those performed in the 1980s. and in 2011, studies did not confirm its effectiveness and currently this operation is not widespread [35].

Today, such methods of surgical treatment of intracranial atherosclerosis are used as endovascular interventions using balloon angioplasty, balloon angioplasty with stenting and with the installation of self-expanding stents. The latter are characterized by a high rate of technical success and relative ease of installation, since they do not require the use of a balloon and can be delivered to difficult-to-pass areas of the arterial bed. However, in the large randomized SAMMPRIS trial, endovascular intervention was found to be less safe and effective than medical treatment [33]. As a result, no endovascular technique has been approved as the preferred intervention. Possible indications for endovascular surgery in 70–99% of patients with atherosclerosis may be symptoms due to disturbances in systemic hemodynamics, as well as poor development of collaterals and recurrent acute cerebrovascular accidents, despite aggressive drug treatment and correction of risk factors [35].

In patients with asymptomatic atherosclerosis of intracranial arteries, it is advisable to carry out primary prevention of cerebral ischemia, taking into account the identified risk factors. Taking into account the possibility of progression of atherosclerotic lesions, it is advisable to monitor the condition of the arteries at intervals of about two years [36].

The development of stenosis of intracranial arteries is accompanied by a violation of the autoregulation of cerebral blood flow and the formation of zones with reduced perfusion, so it is appropriate for such patients to be prescribed drugs that have a neurotrophic, metabolic and antihypoxic effect. An example is Actovegin, a comprehensively studied drug with a pleiotropic effect and a favorable safety profile.

A number of foreign randomized placebo-controlled studies have shown the effectiveness of Actovegin in elderly patients with signs of mild and moderate dementia of various origins, including vascular [37]. Its use was accompanied by improvements in behavioral characteristics and neuropsychological test results. Extensive experience of Russian researchers confirms the effectiveness of the drug in patients with chronic cerebral ischemia accompanied by cognitive disorders [38]. Actovegin had a positive effect not only on memory and attention indicators, but also improved the psycho-emotional status of patients - reduced the severity of depressive and asthenic symptoms, improved sleep and general well-being [39, 40].

The proven endothelial protective effect of Actovegin and the positive effect on microcirculation likely provide additional therapeutic benefits in patients with cognitive disorders resulting from chronic cerebral ischemia, accompanied by tissue hypoxia, micro- and macrovascular damage [41].

Thus, the inclusion of Actovegin in the treatment regimen for patients with intracranial atherosclerosis, along with measures to prevent vascular events, can help level out the manifestations of cerebral circulatory failure and improve the well-being of such patients.

Conclusion

Atherosclerosis of intracranial arteries is a significant factor in the development of acute cerebrovascular accident, requiring a special approach to diagnosis and treatment. Further progress in studying the problem of diagnosis and treatment of atherosclerosis of intracranial arteries is associated with new techniques for visualizing vessels and atherosclerotic plaque and the search for individual approaches to treatment, including determining indications for endovascular interventions.

Our ultrasound doctors

• Garayeva Anna Evgenievna

  Head of Ultrasound Diagnostics Department

• Lyzhin Dmitry Vyacheslavovich

• Pechenkina Natalya Vladimirovna

  Ultrasound diagnostic doctor

• Kravchenko Nikolay Alekseevich

  Ultrasound diagnostics doctor of the first category, author of 15 scientific papers

• Naronov Alexey Yurievich

  Ultrasound diagnostic doctor

• Maklakova Daria Ivanovna

  Ultrasound diagnostic doctor

1.What is included in the concept of “intracranial pathology”?

Intracranial pathology is a general term that covers the entire spectrum of disorders with intracranial localization.

Intracranial diseases may not manifest significant symptoms. In some cases, on the contrary, they are very painful for the patient. Due to the fact that we are talking about a pathology directly related to the brain, intracranial disorders are often life-threatening and require emergency assistance.

The consequences of intracranial pathology can be: persistent functional failure, mental disorders, organic disorders, including disability. Treatment tactics for intracranial pathology are often developed with the participation of doctors of several specialties. Targeted drug therapy and surgical procedures in close proximity to the brain can have unwanted side effects and risks, so the treatment plan is often approved by a medical council.

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Conducting research

No special preparation is required. Before the study, it is recommended to refrain from smoking, as nicotine affects vascular hemodynamics.

The study is carried out in a lying position. During functional tests, the doctor may press the vessels in the neck, ask you to turn your head, and perform breathing movements, for example, inhale and hold your breath.

There are no contraindications to triplex scanning of the extra- and intracranial sections of the brachiocephalic arteries. The method is safe and suitable for pregnant women and patients with severe concomitant pathologies.

The study is performed by doctors from the ultrasound diagnostics department who have the highest medical category and academic degrees. The department uses modern diagnostic equipment, including Accuvix A30 ultrasound scanners manufactured by Samsung Medison, South Korea and HIVision Prerius - Hitachi, Japan.

At the Clinical Hospital on Yauza, they will quickly and accurately determine pathological changes in the extracranial (neck) and intracranial (head) sections of the brachiocephalic arteries, changes in the blood supply to the brain, and clarify its cause; will provide treating physicians with irreplaceable information for making the correct diagnosis and prescribing effective treatment.

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Method capabilities

• Study of the anatomy of the brachiocephalic arteries, identification of their congenital (developmental anomalies) and acquired pathology
• Assessment of blood flow in the brachiocephalic arteries, cerebral blood flow and its components for the differential diagnosis of various diseases
• Diagnosis of organic and functional pathology of the arteries of the head and neck, accurate assessment of vascular patency, identification of the presence of stenoses, tortuosities, kinks, atherosclerotic plaques, thrombosis and occlusions.

Indications for the study of brachiocephalic arteries are:

• Anomalies and variants of development of the brachiocephalic arteries
• The presence of occlusion, thrombosis, stenosis, kinks, pathological tortuosity of the arteries
• Aneurysms and vascular malformations, vascular ruptures and aneurysms
• Syncope
• Acute stroke and post-stroke conditions, acute and chronic cerebral ischemia
• Diseases and pathological conditions that can lead to cerebrovascular accidents: Atherosclerosis
• Arterial hypertension
• Arterial hypotension
• Anomalies, lesions and diseases of the heart and disruption of its activity
• Infectious and allergic vasculitis
• Toxic lesions of cerebral vessels
• Traumatic lesions of cerebral vessels
• Angiopathy of various origins
• Detection of vertebral dyscirculation and extravasal compression in spinal pathology, tumors, etc.

A triplex scan of the brachiocephalic arteries is necessary for the following symptoms:

• changes in visual acuity and/or flashing “spots” before the eyes,
• poor coordination, such as unsteady gait
• dizziness and noise in the ears and head,
• headache,
• decreased memory, ability to concentrate,
• recurrent motor and/or sensory disturbances,
• fainting, syncope.

This method is effective in diagnosing the causes of headaches, dizziness, fainting and other symptoms and conditions.