Which arteries form the arterial circle of the brain. The circle of Willis is not closed

10.04.2020

Thanks to him, the correct distribution of blood flow occurs in case of dysfunction of the carotid arteries. Therefore, any pathology in its development can provoke the appearance of negative consequences. In order to identify them in a timely manner, it is necessary to know the structure and features of the circle of Willis.

What the circle of Willis consists of

First of all, you need to figure out what it is - the circle of Willis. This is an anastomosis of the arteries of the brain, which has the shape of an oval crown. This education was named after its discoverer, Thomas Willis.

The circle is formed by arteries such as:

Back connecting.
Posterior cerebral.
Anterior cerebral.
Internal sleepy.

This structure of the circle allows you to connect two systems: the spinal cord and the carotid.

The development of the circle of Willis more often occurs according to the classical version. In this case, the formation will be symmetrical about the vertical axis. Structural pathologies are common.

What functions is responsible for

The main task of this system is to ensure sufficient blood supply to certain areas of the brain. This is especially important in the case of impaired blood flow in the neck arteries. Obstruction of blood flow through the cervical arteries threatens oxygen starvation of the brain, which provokes various deviations... To prevent this from happening, the circle of Willis is provided.

The provision of the functionality of the circle is achieved due to the fact that the carotid arteries are connected not only with each other, but also with the vertebral arterial system. This scheme allows you to constantly supply the brain with nutrients.

According to statistics, the classic variant of the development of the circle of Willis is observed only in 50% of cases. For many people, its symmetry is broken.

Possible pathologies

Human anatomy provides for a complex structure of internal systems, which ensures the full functioning of the body. Unfortunately, often, due to certain reasons, developmental deviations are observed. This is the case with the Circle of Willis. Its normal structure is observed only in half of the people.

Most often, deviations from the classical version of development are manifested in the asymmetry of the outgoing branches or the absence of certain sections of the circle. There is often a difference in the diameters of the vertebral arteries in the posterior and anterior parts. Research has shown that breaking the symmetry of the circle is sometimes the cause of frequent migraine attacks.

Among the most significant pathologies:

Hypoplasia. It is a malformation in which the arteries have greatly reduced parameters. If there are no blood flow disturbances in other areas of the brain, then hypoplasia will be asymptomatic. Such a pathology can be detected during a comprehensive diagnosis of the state of the brain. It is clearly visible in the images obtained with magnetic resonance imaging.
Aneurysm. This is the protrusion of the artery wall outward. The deviation is asymptomatic until the aneurysm ruptures. This leads to cerebral hemorrhage. In this case, unbearable headaches, attacks of nausea and vomiting, acute reactions to bright light appear. If you do not take action in time, a person can fall into a coma and die.
Aplasia. This is a condition in which the circle of Willis is not closed due to the absence of a connecting artery. It can be observed as in anterior sectionand in the back. If the artery is still present, but extremely poorly developed, then an incomplete openness of the circle is diagnosed. Pathology in the anterior part of the circle is extremely rare, only in 4% of cases. Most often, the deviation is found behind. An open circle is examined using MRI. The reason for this phenomenon is a stop in development at the stage of fetal formation.
Carotid artery trifurcation. This is the splitting of the artery into three components. This deviation is observed in 28% of cases. It is not dangerous as long as there are no occlusive changes in the arteries. Distinguish between anterior and posterior trifurcation. This deviation is associated with a delay in the reduction of the connective arteries during embryonic development.

Pathologies that are extremely rare include Heibner's artery, splitting of the anterior communicating artery, plexus-like appearance of the basilar arteries, and some others.

What consequences can the wrong development of the circle of Willis have?

In the normal state, the Willis circle is closed. It acts as a backup system. If no deviations in the work of the cervical arteries are observed, then it is not activated. Therefore, even if there are deviations from normal development in it, they do not manifest themselves in any way.

When there is a problem with the supply of nutrients to the brain, the circle of Willis turns on. It helps pump blood from other departments. In this case, his pathology can have negative health consequences.

Congenital pathologies of the circle of Willis in certain situations lead to difficulty in cerebral circulation. It can manifest itself at an early age and grow over time.

Unlike the rest of the cerebral arteries, there is no pressure difference in the parts of the circle. This is due to the lack of pressure balancing of the brain tissue. This can lead to the following negative consequences:

Frequent dizziness.
Unpleasant sensations with a sharp change in the position of the head.
Severe headaches, which are not always possible to stop even with painkillers.
Migraine attacks, which are accompanied by photophobia, nausea, reaction to sounds.

One of the most dangerous pathologies is considered an aneurysm. It appears as a result of thinning and increasing elasticity of the artery wall. Moreover, this process is completely asymptomatic. Any impact on the head area leads to instant rupture of the aneurysm. If measures are not taken in a timely manner, the person will simply die.

How are deviations detected?

Most often, pathologies of the development of the circle of Willis are detected when comprehensive examination a patient who has complained about headache... First of all, in such a situation, experts check for the presence of circulatory disorders in the brain.

The most accurate modern diagnostic method is MRI. The examination is carried out on a special magnetic resonance imager. Its principle of action is based on fixing the reactions of body cells in response to exposure to a strong magnetic field.

Such an examination helps to get a complete picture of the structure of any internal organs, including vascular system... MRI is considered completely safe, as it is a non-invasive examination and does not involve the use of radiation.

Angiography

Angiography is considered one of the most popular methods for examining the vascular system. This technique involves the introduction of a special contrast agent into the patient's blood. After it is evenly distributed over all arteries, an X-ray is taken. All pathologies are clearly visible on it.

Such an examination can be carried out using a conventional radiograph or under the control of computed tomography. The contrast agent is completely harmless to humans. After a certain time, it is completely excreted from the body in a natural way.

To determine the exact location and condition of the arteries, they also use computed tomography... This examination is carried out using X-ray radiation. And although the dose of investment is extremely small, this diagnostic method cannot be called completely safe for health.

How is it treated

If during the examination, pathologies that are not life-threatening, for example, trifurcation, are identified, then no special treatment is required in this case. But it is worth remembering that the state of health can deteriorate sharply with the appearance of complications, for example, vascular thrombosis. Therefore, the patient is recommended measures aimed at preventing complications.

It is necessary to adhere to proper nutrition, exclude the use of excessively fatty foods, fried, smoked foods. Give up bad habits... Try to eat as many fresh vegetables and fruits as possible. Lead an active lifestyle, walk more in the fresh air. All this has a beneficial effect on the health of the cardiovascular system as a whole.

Operation

If an aneurysm is diagnosed, urgent surgery will be required. No other methods can cope with such a problem. The operation is performed under general anesthesia.

The surgeon makes a burr hole in the patient's skull. He then spreads the tissue apart to reach the damaged artery. Using special instruments, the doctor removes the aneurysm and ligates the vessel.

Then it only remains to restore meninges and suture. Most often, after such an operation, it is necessary drug treatment, which is aimed at preventing possible complications.

There is a variant of the operation in which the aneurysm is not removed, therefore, there is no rupture of the vessels. This procedure is performed under local anesthesia. The surgeon makes a small puncture in the vessel and inserts a special instrument into it. With its help, the specialist fills the aneurysm cavity with a certain material in the form of microscopic spirals.

These spirals contribute to the formation of a dense thrombus in the aneurysm cavity. Thus, pathology is completely excluded from the circulatory process.

During the operation, the surgeon must act very carefully, since the slightest inaccuracy will lead to rupture of the aneurysm and hemorrhage. Three months after such treatment, a control examination is mandatory.

The circle of Willis is a reserve blood supply to the brain. If a pathology is detected, it is necessary to undergo regular examinations in order to identify the likelihood of an aneurysm development.

Hello! I am 57 years old. The head often hurts, dizziness occurs with nausea. MRI showed a variant of the development of the circle of Willis in the form of a lack of blood flow in both posterior communicating arteries. Is such a pathology dangerous, what symptoms does it give, how does it manifest?

Valentina, I'm 33, and I have the same nonsense + another bouquet)))). Fun)))))

I'm 32 years. The MRI showed that my vascular system in the circle of Willis was impaired by 55%. Is it dangerous?

The circle of Willisiev and Zakharchenko - what functions? The first function is anastomosis, and what is the second? Urgently needed!

Try leeches. The result is fantastic, the pain is gone!

I had frequent headaches, after acupuncture together with hirudotherapy, everything went away. At least once a year should be treated. And what is the point of swallowing chemistry? And so we eat one chemistry from the store.

On MRI, a variant of the development of the circle of Willis was revealed in the form of a lack of blood flow in both posterior communicating arteries and anterior left-sided trifurcation. At first, I had an MRI of the brain, and the doctor, suspecting an aneurysm due to uncharacteristic intersections, suggested doing an MRI of the arteries. I didn't have any particular headaches, the defect was revealed by chance. The doctor said that the circle of Willis is like a backup blood supply system, which is used in case of failure of the main one. It turns out that I have no reserve.

At the age of 19, terrible migraines began, until they lost consciousness. Injected injections, drank pills, did not save for a long time. I got on the device magnetoturbotron (physiotherapy), it helps very well and for a long time. I take a course as a prophylaxis once a year. Pains are extremely rare in the off-season and are not so strong, one-day.

Diseases
Body parts

The subject index on common diseases of the cardiovascular system will help you with a quick search for the necessary material.

Select the body part you are interested in, the system will show the materials associated with it.

Use of site materials is possible only if there is an active link to the source.

Possible pathologies of the circle of Willis and their treatment

The human brain (GM) is a delicate structure that performs an enormous amount of work. A prerequisite for the functioning of any organ is normal blood circulation. The first person to describe the arterial blood circulation in the brain was Willis Thomas, an anatomist and neurologist from Great Britain. Since then, the vascular ring of the brain has been named after him.

The structure and function of the arterial circle of the brain

Decreased blood circulation in the brain is life-threatening. The human anatomy is such that the arterial ring (circle of Willis) located in the subarachnoid space at the base of the brain performs the function of compensating for insufficient blood flow.

The cerebral vessels are interconnected (anastomosed) based on the GM. The following vessels form the pool of the circle of Willis:

Anterior cerebral artery: the initial segment (a. Cerebri anterior).
Anterior communicating artery (a.communicans anterior).
Internal carotid artery: supracliniform segment (a. Carotis interna).
The back connecting artery (a.communicans posterior).
Posterior cerebral artery: the initial segment (a. Cerebri posterior).

In his work, Willis Thomas describes an anastomosis in the form of a heptagon - heptagon Willis. But after conducting research, M.A.Tikhomirov revealed that the shape of the ring is nine-sided. The connection between the GM vessels is centralized in the circle of Willis.

Impaired blood flow in the cervical vessels can lead to insufficient blood circulation to the brain. To prevent a situation of reduced blood flow, a "fallback" option is provided - a compensatory arterial circle. This is its function. Carotid arteries, connecting with each other, anastomose with vertebrates. It is thanks to this connection, in case of obstruction of the vessels of the brain, blood circulation is not disturbed and all tissues receive a sufficient amount of substances.

Pathologies and their symptoms

The correct development of the circle of Willis is evidenced by its symmetry on both sides. But this development is observed only in 50% of the population. Failure of vascular development is often observed - hypoplasia. There is a mismatch in the size of the arteries from different sides, the lack of symmetry in their discharge. If all the vessels are interconnected and symmetrically depart on both sides, then they say that the arterial circle is closed. This makes it possible to completely replenish the blood flow in case of pathology of other vessels.

The most gross anomaly in the structure of the ring is openness. It occurs when there is no connection of the main artery - with the vertebrates. There are two variants of pathology: the circle is completely open, if the connecting arteries are absent and not completely open, if there is a narrowing or hypoplasia of the connecting arteries.

A frequent localization of cerebral aneurysms is the circle of Willis. The danger lies in the fact that for a long time the aneurysm does not cause any symptoms. The patient's condition worsens when it breaks. If help is not provided in a timely manner, then the person falls into a coma.

The results of the study show that there is a connection between the asymmetric structure of the circle of Willis and the occurrence of migraines. Pathology is revealed by chance during magnetic resonance imaging. Under the condition of normal blood circulation in the brain, when the arterial circle does not fulfill its compensatory function, the symptoms do not appear.

Diagnostics and treatment

To study the state of blood vessels in medicine, the method of angiography is used. The most accessible diagnostic method is considered to be transcranial Doppler, which allows assessing blood flow in the cerebral arteries. This method has a large number of advantages, because it allows you to assess the state of the vascular lumen, the speed and direction of blood flow. To make a diagnosis, a comprehensive examination is used that evaluates all the criteria for the structure of the arteries and the characteristics of the blood supply in them.

The presence of an anomaly in the development of the arterial circle does not pose a danger to the quality of human life, provided that there are no circulatory disorders in the vessels of the brain; therefore, no treatment is prescribed. If the pathology manifests itself in the form of migraines, then the attending physician may prescribe you to take painkillers.

If an aneurysm is detected in the vessels of the circle of Willis, surgery is indicated. When a vessel ruptures, blood flows into the subarachnoid space. It is difficult to stop bleeding. An operation is required, as well as long-term rehabilitation.

An overview of all the options for the development of the circle of Willis, what this means in practice

From this article you will learn: what are the options for the development of the circle of Willis, what it is, which arteries are part of it. What diseases can be caused by congenital or acquired pathology of the Willis circle.

The circle of Willis (abbreviated VK) is a system of anastomoses (connections between vessels) blood vesselslocated at the base of the brain. It provides an important connection between the internal carotid artery systems and the vertebrobasilar basin.

The VC includes several arteries, which, connecting with each other, form a circle. In most cases, this circle is closed, but some people may have one of the vessels missing, which makes it open. These possible features VK structures are called variants. Some of these developmental options can lead to increased risk dangerous diseases the brain, such as an aneurysm or stroke.

Nevertheless, in most people, various variants of the structure of VC are physiological norms, that is, they do not cause any symptoms or consequences.

Since complications of improper development of the circle of Willis arise in the brain, neurosurgeons and neurologists are engaged in them.

The structure of the circle of Willis

The brain is, without exaggeration, the most important body in human body... Therefore, it is not surprising that its blood supply is one of the priority goals of the cardiovascular system. The brain receives blood from two sources - from the internal carotid artery system and from the vertebrobasilar basin.

To avoid catastrophic consequences when one of the large vessels is blocked, there are anastomoses between these two blood supply systems, forming a circle of Willis at the base of the brain.

The VC consists of three pairs of main arteries:

Anterior cerebral arteries (PMA) - depart from the internal carotid arteries.
Internal carotid arteries (ICA) - their terminal part is part of the IC, before the discharge of the middle cerebral arteries (MCA).
The posterior cerebral arteries (PCA) are the terminal branches of the basilar artery (BA), which is formed as a result of the fusion of the vertebral arteries (PA).

To complete the circle, there are also two connecting blood vessels:

Anterior communicating artery (PSA) - connects two PMA.
The posterior communicating arteries (PCA) are branches from the ICA that connect them to the PCA.

If the Willis circle is closed, the blood can, if necessary, pass through the anastomoses from one artery to another.

VK development options

A completely closed VC, in which there are no missing or underdeveloped (hypoplastic) components, is found in only 20–25% of people.

There are a huge number of possible options for the anatomical structure and development of the VC. The most common ones are:

hypoplasia of one or two PAD;
hypoplasia or absence of the PMA segment;
pSA hypoplasia;
absence of one of the ZSA.

B - hypolasia of the right posterior communicating artery

C - hypolasia of the left posterior communicating artery

D - bilateral hypoplasia of the posterior connecting arteries

E - the right posterior cerebral artery is absent or not developed

F - the left posterior cerebral artery is absent or not developed

G - hypoplasia of the left communicating artery and the right posterior cerebral artery is absent or not developed

H - hypoplasia of the right communicating artery and the left posterior cerebral artery is absent or not developed

I - hypoplasia of the anterior communicating artery

J - anterior communicating artery and hypolasia of the left posterior communicating artery

K - hypoplasia of the right anterior cerebral artery and hypoplasia of the right posterior communicating artery

What do different options for VK development mean in practice?

The asymmetry of the VC structure leads to a significant asymmetry of the blood flow and is an important factor in the development intracranial aneurysms and ischemic strokes. These disorders usually occur in elderly patients in whom an open VC limits the ability to compensate for acute changes in the arterial blood supply to the brain.

Before the development of these diseases or their complications, a person does not even know that he has abnormalities in the development of cerebral vessels.

VK vascular aneurysms

An aneurysm is a bulging of the vascular wall. Aneurysms of the vessels entering the VC are the most common cerebral aneurysms. Most often, they arise in the PSA, on the bifurcation (bifurcation) of the ICA and in the PCA, on the BA bifurcation.

Most cerebral aneurysms do not cause any symptoms until they rupture. However, with large protrusions, squeezing of the central tissues located nearby may occur. nervous system, which in some people leads to:

double vision;
dilated pupils;
the occurrence of pain behind the eyeballs;
headaches.

When an aneurysm of the vessels included in the VC ruptures, hemorrhage develops into the space around the brain (subarachnoid hemorrhage), the symptoms of which include:

Sudden onset of severe headache.
Nausea and vomiting.
Stiffness in the neck.
Temporary loss of vision or consciousness.

Ischemic stroke with different variants of the VC structure

Impaired blood flow through the arteries of the brain can contribute to the development of atherosclerotic lesions, which increases the risk of ischemic stroke. An open VC does not provide good collateral blood flow; therefore, the size of the stroke may increase.

Ischemic stroke symptoms:

Sudden numbness or weakness in the muscles of one side of the body.
Sudden deterioration in consciousness, speech disorder or speech understanding.
Sudden visual disturbances.
Sudden disturbances in walking, dizziness, loss of balance and coordination of movements.
Sudden onset of headache.

Diagnostics: identification of variants of the structure of the circle of Willis

For most people, an open VC does not manifest itself in any way. The development of the circle of Willis and its variants are most often detected by chance, when examining the vessels of the brain for other reasons.

If the patient has symptoms of an unruptured cerebral aneurysm, the following examinations are performed:

CT angiography is a non-invasive (that is, without penetration into the body) X-ray examination, during which the blood vessels are injected into the bloodstream to visualize the vessels of the brain contrast agentand then computed tomography is performed.
Magnetic resonance imaging is a non-invasive technique that uses a magnetic field and radio frequency waves to produce detailed images of the blood vessels in the brain.
A cerebral angiography is an invasive examination in which a special catheter is inserted into an artery in the brain. After that, contrast is injected through the catheter and an x-ray is taken.

Treatment options for the development of the circle of Willis

By themselves, the options for the development of VC are not a disease and do not need treatment. If their presence has led to the development of an aneurysm or ischemic stroke, these diseases are treated.

Why does it hurt

and how to cure

Circle of Willis - development, treatment, symptoms

Therefore, in most cases, the pathology of the development of the Willis circle does not require treatment. 3) The circle of Willis is not closed: the signal from the blood flow along the left and right PCMA is not determined. With the normal development of the circle of Willis, its right and left halves have a symmetrical structure. The circle of Willis connects each of the carotid arteries not only to each other, but also to the vertebral artery system.

The main function of the circle of Willis is to ensure a full blood supply to individual parts of the brain, in the event of a violation of blood flow in one of the cervical arteries caused by any reason. With hypoplasia of the vessels of the Willis circle, symptoms may be absent, naturally, provided there is normal blood flow in the basins of other cerebral arteries.

Circle of Willis diseases: treatment

With aneurysm of the vessels of the Willis circle, symptoms are usually absent until it ruptures. But in reality, treatment of the circle of Willis is not carried out. As we said above, there are various options for the development of the circle of Willis, and those that are considered the norm are not found in every person. In the presence of an aneurysm of one of the arteries of the Willis circle, the treatment is surgical and consists in bandaging the aneurysm.

The main function of the circle of Willis is to ensure the normal blood supply to certain parts of the brain in cases of blockage of the vessels feeding it. For many people, as soon as it becomes known that they may have a variant that does not correspond to the norm of development of the circle of Willis, it is difficult not to despair.

In the case of an aneurysm of the artery of the circle of Willis, therapy is indispensable. Named after the English physician Thomas Willis, the vessels that make up the circle of Willis normally form a closed system at the base of the brain. The only trick is that the Vilisian circle is functionally open in most healthy patients. The most constant in their structure and development are the arteries of the anterior section of the circle of Willis, while the vessels of the posterior section of it are highly variable.

The formation of islets with a diameter of 1-2 mm in the trunk of the anterior cerebral artery (more often on the left) is observed in 1.9% of cases. Of all the arteries that form the circle of Willis, the posterior communicating artery is characterized by the greatest variability in terms of development and severity. We also studied the smaller branches extending from the arteries of the anterior and posterior parts of the circle of Willis, supplying the subcortical ganglia with their branches.

In this case, the pathology is detected as an accidental diagnostic finding during magnetic resonance imaging. In the event of a rupture, blood from the damaged vessel begins to flow into the subarachnoid space. In cases where the aneurysm is opened, conservative treatment, is the same as with subarachnoid hemorrhage caused by any other cause.

The fusion of the vertebral arteries into the main artery is common. Now everything is all right. Hello! I am 35 years old. 2 months ago, there was a sharp increase in pressure and with a partial loss of coordination.

The structure of the circle of Willis

BUT, incomprehensible sensations became in my head and ringing in my ears appeared. 4) is determined by a moderate expansion of the initial segments of the PMA, MCA. the signal from the blood flow through the cerebral arteries is symmetrical. While the aneurysm is opened, conservative treatment is performed.

Only the complex use of methods is permissible in making the final diagnosis, it is important both the anatomical structure and lumen of the vessel, and the characteristics of the blood flow.

The posterior connecting artery is, as it were, a link between the internal carotid and the main artery. Depending on the development of the anterior or posterior segment of this vessel, the posterior cerebral artery receives blood either from the internal carotid or from the main artery. We observed weak development of this vessel in 1.4% of cases on the right. In some cases (12.8%), an accessory anterior communicating artery is observed, which is usually located 0.5-1 cm in front of the main one.

Underdevelopment of this artery is observed equally often on the left and on the right (24%). Its diameter in these cases does not exceed 0.5-0.6 mm compared to 1-1.5 mm for a well-developed vessel. It should be borne in mind that the ligation of the common and internal carotid arteries is not the same in its effect on cerebral circulation.

The branches extending from the initial section of the posterior cerebral artery of both sides, up to 2 or 3 on each side, are less pronounced. Focal and diffuse changes in the brain matter were not revealed. On a series of MR angiograms performed in the TOF mode, the internal carotid, main, and intracranial segments of the vertebral arteries and their branches are visualized in the axial projection. Monitoring in dynamics is recommended against the background of treatment taking into account neurological changes in 1-2 months.

In the circle of Willis, two sections are distinguished: anterior and posterior. However, in reality, treatment of the circle of Willis is not carried out at all. Anterior cerebral artery (initial segment).

The circle of Willis: how it works, the norm and anomalies (open, decreased blood flow), diagnosis, treatment

The circle of Willis in the cerebral vascular system was described more than three hundred years ago by the English physician T. Willis. The structure of this arterial ring plays great importance in conditions of trouble, when certain parts of the nervous tissue experience insufficient arterial blood flow due to blockage or stenosis of the arteries. Normally, even with abnormally developed vessels of this circle, a person does not feel the existing features due to the full functioning of other arteries.

The norm for the structure of the circle of Willis is defined, but not everyone can boast of it. According to some reports, the classical arterial ring is developed only by half of people, other researchers call the figure in only 25% of people, and all the rest have some kind of anomalies of the branching of blood vessels. This, however, does not mean that those whose arterial circle is developed in a peculiar way will have any negative symptoms or disorders, but nevertheless, manifestations of impaired blood flow can periodically make themselves felt with migraines, vascular encephalopathy, or even manifest acute disorders of cerebral circulation.

There are a lot of options for the development of the circle of Willis. This can be tripling (trifurcation), aplasia, hypoplasia, complete absence of any arterial elements. Depending on the type of arterial branching, its clinical significance and prognosis are determined.

To determine the anatomy of the circle of Willis, non-invasive and invasive diagnostic procedures are used; they are carried out according to indications for specific complaints of the patient. In other situations, anomalies are discovered by chance during examination for another pathology.

The structure of the circle of Willis

The classic Willisian circle is formed by:

The initial sections of the anterior cerebral arteries (PMA);
Anterior communicating artery (PSA);
Posterior cerebral arteries (PCA);
Posterior communicating arteries (PCA);
The supra-wedge-shaped part of the internal carotid artery (ICA).

The listed vessels form a semblance of a heptagon. ICA bring blood to the brain from the common sleepyheads and, at the base of the brain, give off PMA, which communicate with each other through PSA. The posterior cerebral arteries start from the main one, which is formed by the union of two vertebrates. There is a connection between the ICA and the PCA - the posterior connecting vessels, depending on the diameter, receive nutrition either from the system of the internal carotid or from the basilar artery.

structure of the circle of Willis

Thus, a ring is formed that connects two arterial flows - from the basin of the internal carotid and basilar arteries, different parts of which can take over the function of providing nutrition to those parts of the brain that lack blood when other components of the brain network are blocked or narrowed.

The circle of Willis is located in the subarachnoid space of the base of the brain, surrounding with its constituent elements the visual chiasm and the formation of the midbrain, behind is the Varoliev bridge, on the surface of which the basilar artery is located.

The anterior cerebral and carotid arteries are characterized by the greatest constancy in the structure, the posterior cerebral and connecting branches are very variable in their anatomy and branching features. However, changes in the anterior part of the circle of Willis are of greater clinical significance due to more pronounced symptoms and a worse prognosis.

The anterior cerebral artery, as a rule, is well formed and normally its lumen reaches one and a half to two and a half millimeters. The PSA is the same size and about a centimeter long. The lumen of the left internal carotid artery is normally larger than the right one by 0.5-1 mm. The middle cerebral artery also has some asymmetry in size: it is thicker on the left than on the right.

Video: the structure of the circle of Willis

The role of the circle of Willis

The circle of Willis is a defense mechanism, compensation for impaired blood circulation, provided by nature to provide blood to the brain in case of damage to specific arteries. If obstruction, rupture, compression occurs, there is a congenital underdevelopment of the branches of the arterial bed, then the vessels of the opposite side will take over the function of blood supply, delivering blood through the collaterals - the connecting arteries.

Considering functional significance arterial network of the base of the brain, it becomes clear why these arteries are so important. It's not just about serious illnesses like a stroke or aneurysm. The circle of Willis helps to maximize the supply of blood to the brain in case of functional disorders (spasm), some variants of the structure of the arteries, when the vascular ring still remains closed, but the diameter of individual vessels does not allow to deliver the required amount of blood.

The role of the Willis circle increases dramatically with complete occlusion of any of the arteries. Then the prognosis, and the rate of increase in symptoms, and the volume of the focus of damage to the nervous tissue will depend on how this ring is formed and how much it is capable of redirecting blood to those parts of the brain that are not receiving enough nutrition. It is clear that a properly formed vascular system will cope with this task better than one where there are abnormalities in the development of blood vessels or even the complete absence of specific branches.

Variant anatomy of the arteries of the base of the brain

There are many types of structure of the Willis circle. They depend on how the process of vascular formation took place even in the prenatal period, and it is impossible to predict this process.

Among the most common anomalies of the arteries of the brain indicate: aplasia, hypoplasia of individual branches, trifurcation, fusion of two arteries into one trunk and some other types. Some people have a combination of different vascular anomalies.

The most common variant of the development of the circle of Willis is the posterior trifurcation of the ICA, which accounts for almost a fifth of all anomalies of the arterial ring. With this type of structure, three cerebral arteries begin at once from the ICA - the anterior, middle and posterior, and the PCA will be a continuation of the posterior connecting branch.

A similar structure is characteristic of the circulatory system of the fetal brain at 16 weeks of gestation, but later the size of the vessels changes, the posterior connective decreases, and the remaining branches increase significantly. If such a transformation of the vessels does not occur, then the child is subsequently born with posterior trifurcation.

Another common variant of the structure of the circle of Willis is aplasia of the PAD, which occurs under various unfavorable external conditions and genetic abnormalities during embryogenesis. In the absence of this artery, the Willis circle does not close on the side where it does not exist, that is, there is no relationship between the internal carotid artery system and the basilar basin.

The absence of PSA is also diagnosed, but much less often than the posterior one. With this type of structure of the arterial ring, there is no relationship between the branches of the carotid arteries, so it is impossible, if necessary, to "transfer" blood from the vessels of the left half to the right.

Aplasia of the anterior communicating artery does not give a chance to carry out blood flow in the affected part of the brain by delivering blood from the opposite vasculature, since the carotid arteries are disconnected. With an unformed PCA, there is no relationship between the anterior and posterior parts of the circle of Willis, and the anastomoses do not function. This type of branching of the arterial system seems to be unfavorable in terms of possible decompensation of blood flow disorders.

Rare forms of the structure of the circle of Willis include:

The median artery of the corpus callosum;
The union of the anterior cerebral arteries into one common trunk or their parietal course, when they are in close contact with each other;
Anterior trifurcation of the internal carotid artery (two anterior cerebral arteries depart from one carotid artery at once);
Split, double anterior communicating artery;
Bilateral absence of ARD;
Trifurcation of the carotid arteries on both sides.

Vascular branching anomalies and the openness of the Willis circle make it unable to perform the role of an anastomosis in critical situations - with hypertensive crisis, thrombus formation, spasm, atherosclerosis. In addition, some types of branching suggest large areas of necrosis of the nerve tissue in the event of circulatory failure. For example, anterior trifurcation means that most parts of the hemisphere receive blood from the branches of only one artery, so if it is damaged, the scale of necrosis or hemorrhage will be significant.

When the arteries of the base of the brain are developed classically, all the necessary connecting branches are present between them and the caliber of each vessel within the normal range, they say that the Willis circle is closed. This is the norm, saying that the anastomosis is consistent, and with pathology, the blood flow will be maximally compensated.

fully open VC

The unclosed circle of Willis is considered a serious anomaly that predisposes to various kinds of cerebrovascular accidents. The openness of the anterior part of the arterial ring, which occurs with aplasia of the PSA or anterior trifurcation of the carotid artery, and the openness of the Willis circle due to anomalies of the posterior part of the vascular bed - aplasia of the posterior connecting, basilar artery, posterior trifurcation of the ICA are distinguished.

If the connecting branches are completely absent, they speak of the complete openness of the circle of Willis, and when the arteries are preserved, but stenotic, hypoplastic, then the openness is considered incomplete.

Signs and diagnosis of circle of Willis anomalies

Clinical signs of vascular branching abnormalities in the circle of Willis occur when the blood flow through the collaterals becomes insufficient for various reasons. For example, fatty plaques formed in the arteries, a thrombus appeared or an embolus migrated from the left half of the heart, an aneurysm ruptured. Healthy man does not feel non-classical branching of blood vessels, since his brain does not feel the need for bypass blood flow paths.

development of stroke / disorders associated with insufficient blood supply to the brain area

The symptoms of obstructed blood flow can be very different. If we are not talking about a stroke, then patients complain of dizziness, headaches, decreased intellectual abilities, memory, attention. Psychological problems are also frequent - often abnormal branching of blood vessels is accompanied by neuroses, panic attacks, the emotional lability of its owners.

Migraine is considered a characteristic manifestation of the non-classical development of the circle of Willis. Many observations have been devoted to the question of the relationship between the structure of the arteries of the brain and migraine, which indicate that most patients with migraine have some anomalies. Especially often with migraine, abnormalities in the structure of the posterior arterial system are diagnosed. When the circle of Willis is open, hypoplasia or aplasia of the posterior connective arteries, posterior trifurcation, those parts of the brain that are responsible for vision do not receive blood, therefore, an intense headache is preceded by a visual aura in the form of flashes, zigzags, etc.

A decrease in blood flow through the vessels of the arterial ring of the brain can provoke periodic headaches and disorders similar to discirculatory encephalopathy - apathy or irritability, decreased performance, fatigue, etc. Usually, such a conclusion can be found in the results of MR angiography and it speaks of hypoplasia of those or other vessels.

With aplasia of the arterial trunks, when some vessels are absent at all, the study fixes the absence of blood flow. For example, aplasia of the posterior communicating arteries will be accompanied by a lack of blood flow through them, respectively. Such aplasia can also be asymptomatic, but when a sufficient amount of blood passes through the main arteries. With atherosclerosis or arterial spasm, signs of insufficient blood supply to the brain will not keep you waiting.

% of distribution of cases of aneurysms in the arteries of the brain

If, against the background of the abnormal structure of the arteries of the base of the brain, acute disorder circulation, then the clinic will have obvious symptoms of stroke - paresis and paralysis, speech disorders, pathological reflexes, impaired consciousness up to coma.

Separately, it is worth mentioning aneurysms - dilations of the vessels of the brain. According to statistics, it is in the arteries of the Willis circle that the largest number is found. Aneurysm of the arteries in this area is fraught with rupture and massive subarachnoid hemorrhage with a stroke, coma and gross neurological manifestations.

Aneurysm is an independent pathology, and not a variant of individual vascular branching, but it is much more likely to accompany non-classical types of the Willis circle.

The diagnosis of one or another anomaly in the development of the circle of Willis can be established only with the involvement of modern instrumental methods survey. Opportunities in diagnostics gave specialists a chance to analyze the nature of the prevalence of variants in the structure of cerebral vessels and their varieties, but more recently, conclusions could be drawn mainly from the results of autopsies of deceased patients.

The development of ultrasound Doppler and magnetic resonance imaging techniques made it possible to make the study of the nature of the structure of the circle of Willis an accessible and safe measure. The main methods for diagnosing variants of the vascular system of the brain include:

X-ray contrast angiography is one of the most informative methods, but it has contraindications associated with the need for contrasting (pathology of the liver, kidneys, allergy to contrast, etc.);
Transcranial Doppler - the procedure is safe, affordable, requires devices with a Doppler probe, which are available in many medical institutions;
MR-angiography - performed on a magnetic tomograph, has contraindications, a significant drawback is its high cost.

The circle of Willis in the diagnostic image

Selective angiography of cerebral vessels refers to invasive procedures when femoral artery a catheter is inserted, advancing to the area of \u200b\u200binterest of the cerebral arteries. When the desired area is reached, a contrast agent is applied. The method is used most often during surgical treatment (stenting, angioplasty).

Instead of selective angiography, CT angiography can be used, when a contrast agent is injected intravenously, and then images of the head are taken in different projections and sections. Subsequently, you can recreate a three-dimensional image of the vascular structures of the brain.

Transcranial Doppler ultrasonography allows you to determine the nature of blood flow in the vessels of the brain (reduced, absent), but it does not provide enough data on the anatomical structure of the arteries. An important advantage is the almost complete absence of contraindications and cheapness.

MR angiography is one of the most expensive, but at the same time, quite informative method for diagnosing the structure of the circle of Willis. It is performed in a magnetic tomograph and the contraindications to it are the same as for a conventional MRI (high degree of obesity, claustrophobia, the presence of metal implants in the body that conduct a magnetic field).

The MRI picture shows the structure of the vessels of the Willis circle, the presence or absence of connections between them, aplasia or hypoplasia of the arteries. When assessing the result, the specialist can determine the diameter of each artery and the features of its branching.

Video: an example of an MRI brain angiography

(The circle of Willis is closed; the convoluted S-shaped course of the intracranial section of the left vertebral artery is determined; C-shaped course of the main artery; otherwise, in the segments of the ICA and paired arteries of the ring of the base of the brain data for the presence of hemodynamically significant stenoses, pathological tortuosities were not obtained).

As you can see, each of the methods has both advantages and disadvantages, therefore, they are combined to obtain accurate conclusions regarding the arteries of the brain. A complex approach allows you to determine the anatomy of the vessels, and the nature and direction of blood flow through them, which is very important in assessing the degree of risk of vascular accidents and possible prognosis.

Many people who have found any variant of the structure of the circle of Willis are immediately interested in methods of treatment. Since deviations in the branching of blood vessels are not considered an independent disease, treatment as such is not required. Moreover, in the absence of a clinic of insufficient blood flow, it does not make sense.

In cases where there are specific complaints (migraines, decreased mental capacity, etc.), you need to seek help from a neurologist who will prescribe vascular drugs (nootropil, fezam, actovegin), drugs to improve metabolism in the brain (mildronate, vitamins of the group C), if necessary - sedatives, tranquilizers, antidepressants, in case of migraine - analgesics, anti-inflammatory, specific anti-migraine drugs (ketorol, ibuprofen, paracetamol, ascofen, drugs of the triptan group).

Surgical treatment is indicated for severe impairment of blood circulation with progression of vascular encephalopathy, diagnosed aneurysm, and sometimes after a stroke. It consists in stenting, clipping or cutting off the aneurysm from the bloodstream, balloon angioplasty with narrowing of the arteries.

What diseases can be caused by congenital or acquired pathology of the Willis circle.

The circle of Willis (abbreviated VC) is a system of anastomoses (connections between vessels) of blood vessels located at the base of the brain. It provides an important connection between the internal carotid artery systems and the vertebrobasilar basin.

The VC includes several arteries, which, connecting with each other, form a circle. In most cases, this circle is closed, but some people may be missing one of the vessels, which is why it becomes open. These possible structural features of the VC are called its variants. Some of these developmental options can lead to an increased risk of dangerous brain diseases such as aneurysm or stroke.

Nevertheless, in most people, various variants of the structure of VC are physiological norms, that is, they do not cause any symptoms or consequences.

Since complications of improper development of the circle of Willis arise in the brain, neurosurgeons and neurologists are engaged in them.

The structure of the circle of Willis

The brain is without exaggeration the most important organ in the human body. Therefore, it is not surprising that its blood supply is one of the priority goals of the cardiovascular system. The brain receives blood from two sources - from the internal carotid artery system and from the vertebrobasilar basin.

To avoid catastrophic consequences when one of the large vessels is blocked, there are anastomoses between these two blood supply systems, forming a circle of Willis at the base of the brain.

The VC consists of three pairs of main arteries:

Anterior cerebral arteries (PMA) - depart from the internal carotid arteries.
Internal carotid arteries (ICA) - their terminal part is part of the IC, before the discharge of the middle cerebral arteries (MCA).
The posterior cerebral arteries (PCA) are the terminal branches of the basilar artery (BA), which is formed as a result of the fusion of the vertebral arteries (PA).

To complete the circle, there are also two connecting blood vessels:

Anterior communicating artery (PSA) - connects two PMA.
The posterior communicating arteries (PCA) are branches from the ICA that connect them to the PCA.

If the Willis circle is closed, the blood can, if necessary, pass through the anastomoses from one artery to another.

VK development options

A completely closed VC, in which there are no missing or underdeveloped (hypoplastic) components, is found in only 20–25% of people.

There are a huge number of possible options for the anatomical structure and development of the VC. The most common ones are:

hypoplasia of one or two PAD;
hypoplasia or absence of the PMA segment;
pSA hypoplasia;
absence of one of the ZSA.

B - hypolasia of the right posterior communicating artery

C - hypolasia of the left posterior communicating artery

D - bilateral hypoplasia of the posterior connecting arteries

E - the right posterior cerebral artery is absent or not developed

F - the left posterior cerebral artery is absent or not developed

G - hypoplasia of the left communicating artery and the right posterior cerebral artery is absent or not developed

H - hypoplasia of the right communicating artery and the left posterior cerebral artery is absent or not developed

I - hypoplasia of the anterior communicating artery

J - anterior communicating artery and hypolasia of the left posterior communicating artery

K - hypoplasia of the right anterior cerebral artery and hypoplasia of the right posterior communicating artery

What do different options for VK development mean in practice?

The asymmetry of the VC structure leads to a significant asymmetry of the blood flow and is an important factor in the development of intracranial aneurysms and ischemic strokes. These disorders usually occur in elderly patients in whom an open VC limits the ability to compensate for acute changes in the arterial blood supply to the brain.

Before the development of these diseases or their complications, a person does not even know that he has abnormalities in the development of cerebral vessels.

VK vascular aneurysms

Most cerebral aneurysms do not cause any symptoms until they rupture. However, with a large protrusion, squeezing of the tissues of the central nervous system located nearby may occur, which in some people leads to:

double vision;
dilated pupils;
the occurrence of pain behind the eyeballs;
headaches.

When an aneurysm of the vessels included in the VC ruptures, hemorrhage develops into the space around the brain (subarachnoid hemorrhage), the symptoms of which include:

Sudden onset of severe headache.
Nausea and vomiting.
Stiffness in the neck.
Temporary loss of vision or consciousness.

Ischemic stroke with different variants of the VC structure

Ischemic stroke symptoms:

Sudden numbness or weakness in the muscles of one side of the body.
Sudden deterioration in consciousness, speech disorder or speech understanding.
Sudden visual disturbances.
Sudden disturbances in walking, dizziness, loss of balance and coordination of movements.
Sudden onset of headache.

Diagnostics: identification of variants of the structure of the circle of Willis

If the patient has symptoms of an unruptured cerebral aneurysm, the following examinations are performed:

CT angiography is a non-invasive (that is, no penetration into the body) X-ray examination, during which a contrast agent is injected into the bloodstream to visualize the vessels of the brain, and then a computed tomography is performed.
Magnetic resonance imaging is a non-invasive technique that uses a magnetic field and radio frequency waves to produce detailed images of the blood vessels in the brain.
A cerebral angiography is an invasive examination in which a special catheter is inserted into an artery in the brain. After that, contrast is injected through the catheter and an x-ray is taken.

Treatment options for the development of the circle of Willis

Funny and serious

A variant of the development of the circle of Willis in the form of the absence of a signal from the blood flow along the right posterior communicating artery. A variant of the development of the circle of Willis. Narrowing of the lumen of the left vertebral artery. Focal and diffuse changes in the brain matter were not revealed. The circle of Willis connects each of the carotid arteries not only to each other, but also to the vertebral artery system.

With the normal development of the circle of Willis, its right and left halves have a symmetrical structure. The main function of the circle of Willis is to ensure a full blood supply to individual parts of the brain, in the event of a violation of blood flow in one of the cervical arteries caused by any reason. Normal development of the circle of Willis occurs in no more than 50% of people. The most common pathology of this arterial system is various types of hypoplasia of the connecting arteries.

In this case, the pathology is detected as an accidental diagnostic finding during magnetic resonance imaging. With aneurysm of the vessels of the Willis circle, symptoms are usually absent until it ruptures. But in reality, treatment of the circle of Willis is not carried out. As we said above, there are various options for the development of the circle of Willis, and those that are considered the norm are not found in every person.

Circle of Willis functions

In the presence of an aneurysm of one of the arteries of the Willis circle, the treatment is surgical and consists in bandaging the aneurysm. In cases where an aneurysm is opened, conservative treatment is carried out, the same as for subarachnoid hemorrhage caused by any other cause.

Hello! I am 21 years old have been worried about severe headaches for about a year every day, I did an MRI of the head, brain and neck, there are no pathologies except osteochondrosis. Hello! I am 49 years old, and I understand that all the sores I have are of age (that's what they tell me in hospitals).

I was very tired of living in this state. Incomplete Wilisian circle. Decreased C2 blood flow along the wing, ICA segments on both sides. How serious it is and whether hospitalization is necessary. They live in the village. With these analyzes, your sister needs to contact a neurologist who will determine how serious everything is and what treatment is required. It also hurts in the back of the head sometimes. Heroin, for example, was originally marketed as a cure for baby cough... And cocaine was recommended by doctors as anesthesia and as a means of increasing endurance.

In the stomach of one patient suffering from this mania, 2500 foreign objects were found. Even if a person's heart does not beat, he can still live for a long period of time, which was demonstrated to us by the Norwegian fisherman Jan Revsdal.

The pains are periodic. 4 times the vessels in the eye burst, the eye was bloody and at the same time there were severe headaches. She underwent examination, no abnormalities in the eye were found. CONCLUSION: MRA picture of decreased blood flow and narrowing of the diameter along the orbital arteries.

The neuropathologist prescribed instenon tablets for 1 month, and for headaches, diclofenac should be drunk for 3 days. I didn’t make an appointment to come again. Good afternoon, In February of this year, not sharp, aching constant pains began in the occiput and temple on the left side of the head.

A variant of the development of the circle of Willis. Infiltrative changes in the mucous membrane of the left maxillary sinus

On a series of T1 and T2 weighted MRI tomograms, sub- and supratentorial structures are visualized in three projections. The lateral ventricles of the brain are of normal size and configuration. Subarachnoid convexital spaces are locally unevenly expanded, mainly in the region of the frontal and parietal lobes. The median structures are not displaced.

MR picture of arachnoid changes of liquor-cystic nature. Monitoring in dynamics is recommended against the background of treatment taking into account neurological changes in 1-2 months. MRI Study: “MRI picture of structural, degenerative changes in the area of \u200b\u200bbasal structures and midbrain, caused by deposits of manganese-containing pigments.

What do manganese pigments mean and where can they come from at all? On a series of MR angiograms, performed in the TOF mode, the internal carotid, main, and intracranial segments of the vertebral arteries and their branches are visualized in the axial projection.

Small asymmetry of blood flow along the vertebral arteries (D absence of the A1 section of the right anterior cerebral artery anterior trifurcation Shoot Twelve permalink

What is the circle of Willis - functions, anatomy and structural anomalies

1. What is the function 2. Anatomical data 3. Variants of formation 4. Causes of structural anomalies 5. Treatment and prevention

The brain provides all the most important physiological functions and human mental activity. Neurons in the brain require a significant supply of nutrients and oxygen, which are sourced from blood. If blood flow is disturbed, some of the nerve cells can die, which is fraught with serious consequences. Therefore, nature has invented a mechanism for compensating for the lack of blood in one of the two vascular regions of the brain. This is the circle of Willis, connecting the carotid and vertebral basins.

What is this anatomical formation? Why are the anomalies of its development dangerous? How do they change the blood supply to the brain? The answers to these questions are of interest to patients, since many of them have vascular problems.

What is the function

The scheme of cerebral blood supply is reduced to a developed vascular network, originating from two main sources. These are the carotid and vertebral basins. It is the arteries of the Willis circle that ensure their connection and mutual compensation in case of blood flow disturbances in one of them.

Also, due to this anatomical formation, circulatory disorders in one pool on a certain half of the brain are eliminated due to the overflow of blood from the other half. Therefore, the clinic of insufficient blood supply to the brain may be absent.

Anatomical data

The common carotid artery is divided into internal and external branches. The right and left internal carotid arteries must provide blood supply to their half of the brain. They create the anterior cerebral arteries in both hemispheres, between which there is a connecting vascular bridge. This is how the anterior portion of the arterial circle is formed.

The two vertebral arteries merge into a single basilar vessel. Then this cerebral artery is divided into two posterior cerebral arteries, which are part of the posterior semi-oval of the arterial vascular ring.

The sleepy and vertebral pools are connected with the help of the posterior connecting branches.

Thus, the normal anatomy of the arterial ring involves the participation in its formation of the following arteries originating from different basins:

anterior and posterior cerebral:
internal sleepy;
front and back connecting.

The ring of arteries occupies the base of the brain, being in front of the pons of varoli, along which the main artery passes. There is a cross inside the ring optic nerves, structure of the midbrain.

The classic arterial circle as described in anatomical atlases, according to medical statistics only 35-45% of people have it. What does this mean for the rest of the population? It is obvious that even the abnormal structure of the circle of Willis does not always lead to brain disasters. But a person with the peculiarities of its structure may complain of recurrent headaches, often of a migraine nature, dizziness.

Noise in the head, memory impairment, attention and a decrease in the emotional background may also disturb. Sometimes the abnormal arrangement of blood vessels manifests itself suddenly as ischemic or hemorrhagic cerebral stroke. The protective role of the vascular ring is evident under the following pathological circumstances:

organic (stroke, aneurysm, atherosclerosis);
functional (vascular spasms, dystonia, hypertensive crisis).

Vascular collaterals save from brain catastrophe, even if the vessels are underdeveloped or have a small lumen. The main thing is that the circle is closed.

Formation options

The development of the circle of Willis assumes various variants of the branching of its constituent parts. A great variability in structure is inherent in the posterior parts of the ring, mainly containing blood from the vertebral basin. But the decrease in blood flow here is not so dangerous to life and health.

Circulatory disorders in the anterior parts of the circle, which are associated with the carotid pool, can be fatal. Poor blood flow is accompanied by a pronounced clinic, the prognosis of complete recovery is often dubious. In the presence of an abnormal structure and topography of the vascular circle, arterial-venous malformations and aneurysms are very often formed.

The variant of the development of the circle of Willis determines clinical manifestations and the prognosis of the disease. Its anatomy is established using various diagnostic methods, the choice of which depends on the patient's complaints and condition.

The arterial circle has a lot of development options.

Aplasia (absence) of individual arteries. Most often, the posterior connecting vessel is absent. In this case, an open circle of Willis is formed. People with this abnormality are at greatest risk of vascular disease. An open arterial circle will not be able to protect the brain tissue in case of circulatory problems, since there will be no connection between the front and back of the ring. The vascular circle may not be closed due to the absence of the anterior connecting branch. This can cause significant health damage.
Hypoplasia (underdevelopment) of blood vessels. It occurs in any part of the vascular system, which can mean a high probability of poor blood supply in a certain part of the brain.
Trifurcation (the arterial trunk forms three, not two branches). Most often it concerns the internal carotid artery. In the event of a deficit, the area of \u200b\u200bnecrosis will be larger.
Merging of two vessels into one. This threatens the development of ischemia.

Causes of structural anomalies

Vascular anomalies are formed during intrauterine development of the fetus with violations of embryogenesis. This can be caused by adverse external influences, diseases of the expectant mother, or genetic factors.

If there are no connecting branches at all, experts say that the circle of Willis is completely open. If the vessels are formed, but their diameter is less than the anatomical norm, or they are underdeveloped, it is considered that the circle is not completely open.

Most often found following reasons openness:

Anterior part of the ring - absence of the anterior communicating artery, trifurcation of the anterior cerebral artery.
The posterior part is the absence of the posterior connecting artery, the basilar artery, the posterior trifurcation of the internal carotid artery.

Anomalies in the structure of the arterial system of the Willis circle are felt only if necessary in bypass blood flow paths. This can be with the formation of an atherosclerotic plaque, a blood clot, severe spasm, rupture of a vessel.

Treatment and prevention

Often, patients learn about the presence of abnormalities in the structure of the vascular system of the brain only after an examination, to which they were sent by specialists in connection with health problems. They wonder how to treat vascular anomalies? First of all, it is necessary to prevent decompensation in the circulatory system, to strive to maintain the level of blood flow at the physiological level, and not to cause overload of blood vessels.

To do this, you need to carry out the following preventive measures:

blood clotting control;
measuring cholesterol levels;
normalization of blood pressure;
timely treatment of cardiovascular diseases and vegetative dystonia.

In the presence of migraine attacks, especially with visual impairments, it is mandatory to consult a doctor to clarify the diagnosis. Of the examinations, the most informative are magnetic resonance angiography, transcranial dopplerography.

If abnormalities in the structure of the arteries are found, it is necessary to regularly undergo dispensary examinations, visiting a therapist, neurologist, cardiologist. It is necessary to provide a course of vascular drugs (inside, intravenous drip), including Cavinton, Pentoxifylline. It is considered mandatory to take nootropics that improve the metabolism and blood supply to the nervous tissue (Nootropil, Fezam, Vinpotropil).

It is also important to take antioxidant (Mexidol, Cytoflavin) and metabolic (Actovegin) drugs in courses several times a year. To maintain the functionality of brain neurons and immune defense need B vitamins.

Patients with deviations in the structure of vascular collaterals should avoid nervous and physical overstrain, increase stress resistance, eat right, and maintain a positive emotional tone.

With a deficiency of blood flow caused by an anomaly in the structure, thrombosis or stenosis of a particular vessel, it is the circle of Willis system that saves neurons from death, redirecting the flow of blood and compensating for its deficiency. If you carry out timely diagnostics and have data on the structure of the vascular system of the brain, you can conduct a course preventive therapy... This will give a good prognosis for life and health, despite the peculiarities of the structure of the anastomoses.

Comments (0)

Write a comment

Would you like to move on to the next article "Cisterns of the brain: varieties, localization and functions"?

Copying of materials is possible only with an active link to the source.

Circle of willis

However, a fully closed and normally developed circle of Willis occurs only in 25-50% of cases. The revealed structural features of the arterial and venous circles of the base of the brain with different forms of the skull may be important in the theory of etiopathogenesis of cerebrovascular diseases. In the circle of Willis, anterior and posterior sections are distinguished. Therefore, in most cases, the pathology of the development of the Willis circle does not require treatment.

Named after the English physician Thomas Willis, the vessels that make up the circle of Willis normally form a closed system at the base of the brain. Transcranial Doppler ultrasonography evaluates blood flow in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery.

The only trick is that the Vilisian circle is functionally open in most healthy patients. With the normal development of the circle of Willis, its right and left halves have a symmetrical structure. The main function of the circle of Willis is to ensure a full blood supply to individual parts of the brain, in the event of a violation of blood flow in one of the cervical arteries caused by any reason.

Normal development of the circle of Willis occurs in no more than 50% of people. The most common pathology of this arterial system is various types of hypoplasia of the connective arteries.

With aneurysm of the vessels of the Willis circle, symptoms are usually absent until it ruptures. But in reality, treatment of the circle of Willis is not carried out. As we said above, there are various options for the development of the circle of Willis, and those that are considered the norm are not found in every person. I made an MRI and here is the diagnosis: an MRI picture of a variant of the development of the circle of Willis. Asymmetry of PA lumens (D\u003e S). There is no neurologist yet, the therapist said that he needed to see a specialist.

Incomplete Wilisian circle. Decreased C2 blood flow along the wing, ICA segments on both sides. The correct development of the circle of Willis is evidenced by its symmetry on both sides. There are two variants of pathology: the circle is completely open if the connecting arteries are absent and not completely open, if there is a narrowing or hypoplasia of the connecting arteries. A frequent localization of cerebral aneurysms is the circle of Willis. The danger lies in the fact that for a long time the aneurysm does not cause any symptoms.

The results of the study show that there is a connection between the asymmetric structure of the circle of Willis and the occurrence of migraine. Under the condition of normal blood circulation in the brain, when the arterial circle does not fulfill its compensatory function, the symptoms do not appear. If an aneurysm is detected in the vessels of the circle of Willis, surgery is indicated. When a vessel ruptures, blood flows into the subarachnoid space.

Circle of Willis diseases: treatment

Key words: circle of Willis, large venous circle of the base of the brain, skull shape. Output. The study showed that the most common in brachycephalics is the closed circle of Willis (83.4%), and there is a large venous circle at the base of the brain (47.6% of cases).

The most valuable and informative method for studying the blood flow of the brain is cerebral angiography. This study allows you to see all circulatory system, but has its own contraindications and difficulties.

With the help of TOF angiography, it is possible to assess the anatomical structure of blood vessels; thrombi can give a signal and cannot be detected on an angiogram. Color Doppler mapping also allows you to determine the direction of blood flow, but this method does not allow visualizing the anatomical structure of blood vessels.

With hypoplasia of the vessels of the Willis circle, symptoms may be absent, naturally, provided there is normal blood flow in the basins of other cerebral arteries. In this case, the pathology is detected as an accidental diagnostic finding during magnetic resonance imaging.

In cases where an aneurysm is opened, conservative treatment is carried out, the same as for subarachnoid hemorrhage caused by any other cause. Hello! I am 21 years old and have had severe headaches for about a year every day, I did an MRI of the head of the brain and neck, there are no pathologies except osteochondrosis. Hello! I am 49 years old, and I understand that all the sores I have are of age (that's what they tell me in hospitals).

Possible pathologies of the circle of Willis and their treatment

I was very tired of living in this state. How serious it is and whether hospitalization is needed. They live in the village. With these analyzes, your sister needs to contact a neurologist who will determine how serious everything is and what treatment is required. The neuropathologist in our small town doesn't say anything specifically. I can't work normally and just live …………… .. It also hurts in the back of my head sometimes. Smiling just twice a day can lower blood pressure and reduce the risk of heart attacks and strokes.

The person taking antidepressants will, in most cases, be depressed again. Heroin, for example, was originally marketed as a cough medicine. And cocaine was recommended by doctors as anesthesia and as a means of increasing endurance. Significant changes as a result this study not found. In this case, it is not recommended to postpone the start of treatment, since with earlier treatment, the patient's condition will normalize faster.

If all the vessels are interconnected and symmetrically depart on both sides, then they say that the arterial circle is closed. The circle of Willis connects each of the carotid arteries not only to each other, but also to the vertebral artery system.

Also

August 22, 2016
Comments disabled
Alexandra Volska

What is the circle of Willis

The vascular system of the brain has a complex structure. One of its most important components is the circle of Willis. It is a complex of arteries located at the base of the brain.

What the circle of Willis consists of

The circle is formed by arteries such as:

Back connecting.
Posterior cerebral.
Anterior cerebral.
Internal sleepy.

This structure of the circle allows you to connect two systems: the spinal cord and the carotid.

What functions is responsible for

The main task of this system is to ensure sufficient blood supply to certain areas of the brain. This is especially important in the case of impaired blood flow in the arteries of the neck. Obstruction of blood flow through the cervical arteries threatens oxygen starvation of the brain, which provokes various deviations. To prevent this from happening, the circle of Willis is provided.

According to statistics, the classic variant of the development of the circle of Willis is observed only in 50% of cases. For many people, its symmetry is broken.

Possible pathologies

Among the most significant pathologies:

Hypoplasia. It is a malformation in which the arteries have greatly reduced parameters. If there are no blood flow disturbances in other areas of the brain, then hypoplasia will be asymptomatic. Such a pathology can be detected during a comprehensive diagnosis of the state of the brain. It is clearly visible in the images obtained with magnetic resonance imaging.
Aneurysm. This is the protrusion of the artery wall outward. The deviation is asymptomatic until the aneurysm ruptures. This leads to cerebral hemorrhage. In this case, unbearable headaches, attacks of nausea and vomiting, acute reactions to bright light appear. If you do not take action in time, a person can fall into a coma and die.
Aplasia. This is a condition in which the Willis circle is not closed due to the absence of a connecting artery. It can be observed both in the anterior and posterior regions. If the artery is still present, but extremely poorly developed, then an incomplete openness of the circle is diagnosed. Pathology in the anterior part of the circle is extremely rare, only in 4% of cases. Most often, the deviation is found behind. An open circle is examined using MRI. The reason for this phenomenon is a stop in development at the stage of fetal formation.
Carotid artery trifurcation. This is the splitting of the artery into three components. This deviation is observed in 28% of cases. It is not dangerous as long as there are no occlusive changes in the arteries. Distinguish between anterior and posterior trifurcation. This deviation is associated with a delay in the reduction of the connective arteries during embryonic development.

Pathologies that are extremely rare include Heibner's artery, splitting of the anterior communicating artery, plexus-like appearance of the basilar arteries, and some others.

What consequences can the wrong development of the circle of Willis have?

Congenital pathologies of the circle of Willis in certain situations lead to difficulty in cerebral circulation. It can manifest itself at an early age and grow over time.

Unlike the rest of the cerebral arteries, there is no pressure difference in the parts of the circle. This is due to the lack of pressure balancing of the brain tissue. This can lead to the following negative consequences:

Frequent dizziness.
Unpleasant sensations with a sharp change in the position of the head.
Severe headaches, which are not always possible to stop even with painkillers.
Migraine attacks, which are accompanied by photophobia, nausea, reaction to sounds.

How are deviations detected?

Most often, the pathologies of the development of the circle of Willis are revealed during a comprehensive examination of a patient who has complained of headache. First of all, in such a situation, experts check for the presence of circulatory disorders in the brain.

Such an examination helps to get a complete picture of the structure of any internal organs, including the vascular system. MRI is considered completely safe, as it is a non-invasive examination and does not involve the use of radiation.

Angiography

Computed tomography is also used to determine the exact location and condition of the arteries. This examination is carried out using X-ray radiation. And although the dose of investment is extremely small, this diagnostic method cannot be called completely safe for health.

How is it treated

It is necessary to adhere to proper nutrition, exclude the use of excessively fatty foods, fried, smoked foods. To refuse from bad habits. Try to eat as many fresh vegetables and fruits as possible. Lead an active lifestyle, walk more in the fresh air. All this has a beneficial effect on the health of the cardiovascular system as a whole.

Operation

If an aneurysm is diagnosed, urgent surgery will be required. No other methods can cope with such a problem. The operation is performed under general anesthesia.

The surgeon makes a burr hole in the patient's skull. He then spreads the tissue apart to reach the damaged artery. Using special instruments, the doctor removes the aneurysm and ligates the vessel.

Then all that remains is to restore the meninges and suture. Most often, after such an operation, medical treatment is needed, which is aimed at preventing possible complications.

These spirals contribute to the formation of a dense thrombus in the aneurysm cavity. Thus, pathology is completely excluded from the circulatory process.

Valentina, I'm 33, and I have the same nonsense + another bouquet)))). Fun)))))

I'm 32 years. The MRI showed that my vascular system in the circle of Willis was impaired by 55%. Is it dangerous?

The circle of Willisiev and Zakharchenko - what functions? The first function is anastomosis, and what is the second? Urgently needed!

Try leeches. The result is fantastic, the pain is gone!

Diseases
Body parts

The subject index on common diseases of the cardiovascular system will help you with a quick search for the necessary material.

Select the body part you are interested in, the system will show the materials associated with it.

Use of site materials is possible only if there is an active link to the source.

The brain is an extremely important organ for human life. One of the most important factors determining its correct operation is a full blood supply to the tissues of the hemispheres, which is responsible for the most complex configuration of the vascular system in the hemispheres.

In this article, we will talk about the meaning and role of the circle of Willis, which is the most important integral part of the vascular system of the brain, consider the options for its structure and dominant pathologies that affect the functioning of the hemispheres, methods of diagnosis, the specifics and methodology of treating deviations from the norm in the VC design.

The role of the circle of Willis

A circle or a peculiar ring of vessels, localized at the base of the skull, was discovered by the scientist Thomas Willis about three hundred years ago. It bears the name corresponding to the name of the discoverer. A circle of vessels is a chain of anamostoses, which form a closed polygon, visually similar to a circle or an oval, which gave it such an extraordinary name.

Ideally, the ring has a closed cycle, which directly determines the full circulation of blood and its supply to its intended purposes. VK plays a significant role in the blood supply to the brain, as it acts as a kind of natural defense mechanism that compensates for the full supply of blood to tissues in case of problems with certain arteries that make up the ring. In simple wordsif one of the highways of the circle has undergone obstruction or stenosis due to unfavorable factors or congenital pathologies, the reverse side will take over the functions of the affected area, supplying blood to the segments of the brain suffering from blood deficiency along bypass channels.

Despite the invaluable value of the ring of vascular highways for the brain, according to the data of scientists and luminaries of medicine, not every person can become proud of the full-fledged design of the circle of Willis.

According to some statistics, no more than fifty percent of people in the world have a closed configuration of VC, while some sources indicate a percentage of no more than twenty. Based on this information, a large proportion of the world's population has a peculiar structure of the circle of Willis, not even suspecting the presence of such a deviation from the standard in the structure of cerebral vessels.

Deviations from the standard are often determined during head examinations in case of complications with vascular health or other situational instrumental studies of the hemispheres. The verdict of doctors about the presence of a specific morphology of the Willis circle in a patient makes a person look for an answer to the question of what the “variant of VC development” means and what is the threat of such a constitution of vascular ramifications. To understand what types of vascular pathways at the base of the brain can cause health problems, it is necessary to delve into the anatomical features of the VC configuration in an ideal configuration from the beginning. Let us consider in detail what the crown of Willis is in the optimal relationship of the vessels.

VK structure

Ideally, in order to perform their compensatory functions, the VC vessels should anastomose or connect at the original fragment of the brain, forming a closed circuit, resembling a ring in shape.

The following blood channels are included in the Crown of Willis complex:

The original segments of the frontal and dorsal cerebral arteries.
Two connecting lines.
Supraclinoid part of the carotid artery.

The physiological relationship between the described channels is centralized in the area of \u200b\u200bthe base of the brain through the closed configuration of the Willis basin. The development of the vessels of the Willis circle, when they are combined, authorizes the hemispheres to receive blood simultaneously from the following primary sources: the internal carotid and vertebrobasilar lines. Accordingly, if one of the central highways supplying the brain has undergone deformations or disturbances, the second, with the correct development of VC, will be able to compensate for the functionality of the affected channel.

Signs of violations and methodology for diagnosing VC anomalies

Since the VC performs mainly a backup mission, minor errors in the design may not bother a person with negative symptoms until the moment when activation of his compensatory functions is required.

The need to include the elements of the circle of Willis in the work is formed under circumstances when the failure of blood flow along the annular pathways develops for various reasons. Symptoms of an abnormal development of VC can be triggered by pinching of the vascular bed, appear against the background of the formation of blood clots or in the arteries that saturate the brain, with aneurysms or their rupture. Such precedents provoke the need to include “workarounds” for the supply of blood to deficient areas of the brain.

Symptoms of insufficient blood supply to the hemispheres can be varied. The most popular signs of a non-classical variant of the development of the circle of Willis are systematic manifestations of migraine, dizziness, deterioration of the competencies of the thinking class, memory and attentiveness. The pathological structure of VK can also be expressed by neurological problems in the form of panic attacks, emotional instability or a tendency to neuroses.

In situations where the abnormal configuration of the circle of Willis has caused serious blood flow disturbances, the pathology can be expressed by symptoms of a stroke with possible paralysis, paresis, impaired consciousness, fainting and other symptoms characteristic of this disease.

Enlargements of cerebral vessels are most often formed in the segments of the highways of the Willis ring against the background of its modification of the nonclassical type. In such situations, precedents of hemorrhage in the subarachnoid area of \u200b\u200bthe brain are possible when the integrity of the aneurysm is damaged, which in medicine is referred to as hemorrhagic strokes, with its dangerous consequences. In such cases, the disease manifests itself with signs characteristic of strokes, serious neurological disorders with the possible falling of a person into a coma and death.

Determine the incorrect structure of the VC allows modern hardware techniques that allow us to study the structure and structure of the vascular highways of the brain.

The main diagnostic procedures include the following studies:

or computed tomography. Both methods are non-contact and provide informative data on the state of cerebral vascular ramifications. The first method is considered the safest for health, however, it belongs to expensive diagnostics, CT is more affordable financially, while it is performed through X-ray irradiation, which can be called a "conditionally safe" process for health.
Angiography is a methodology that allows you to obtain information about the state of the bloodstream after direct injection of a contrast substance into the vessel. Angiography refers to invasive diagnostics, therefore it may have contraindications or lead to certain complications. Such a study is less modern than previous methodologies, while authorizing the assessment of the condition and passability of highways.
Doppler examination of the hemispheres is carried out by passing ultrasonic waves through the human brain, which is an absolutely safe process for health. This method has many advantages, since it allows not only to reveal the abnormal configuration of blood vessels, but also to determine the presence of pathological deformations of the channels, their localization, to assess the speed and direction of blood flow.

It is important to understand that the doctor's verdict “non-traditional variant of VC development” is not a reason for panic and start treatment. Certain inconsistencies with the norms in the construction of the vascular ring do not require mandatory therapy, treatment is prescribed only in those situations when the incorrect configuration of the highways is unsafe for health, provokes a deterioration in the blood supply to the brain.

Only a qualified specialist decides on the need for treatment and its specificity and only on the basis of the results of hardware diagnostics. To concretize the diagnosis, you may need several ways to diagnose the problem.

VK development options

Having analyzed and studied the functional significance of the VC for a person, the originality of its structure and ways of identifying the problem, one can proceed to solving the question of what is the “variant of the development of the circle of Willis”.

It is possible to obtain a subjective picture of the developmental variant of the circle of Willis by means of angiography, MRI or CT. The image obtained by hardware methods allows you to visually examine and analyze the configuration of vascular branches, to identify deviations, if any.

The most common in medical practice are the following non-traditional VC formations:

Underdevelopment of arteries connecting type... Such a pathology may not exhibit itself with any negative symptomatology throughout life, if there are no additional difficulties with the functioning of other arterial channels.
Discrepancy in the parameters of symmetrical vessels or their asymmetry about the axis. This design of the VC branching does not threaten health, since the ring has a closed shape, which allows it to fulfill its responsibilities for the blood supply to the brain. This variant of the development of the ring can serve as an explanation for the systematic migraines in humans.
Disruption of the ring sequence is the most difficult variant of the abnormal development of VC. At the same time, the lack of continuity can be either partial, due to stenosis or underdevelopment of anamostoses, and one hundred percent, characterized by the absence of connecting type lines. The lack of blood flow in the circle of Willis is a critical precedent for the patient.
Aneurysm of any of the VC vessels. It is characterized by protrusion or thinning of the channel shell, which can lead to deformation and rupture of the vessel, followed by hemorrhage into the brain zones. The most dangerous condition for the patient's life, requiring urgent medical attention.

Let's consider the features of various modifications of the vascular ring from the point of view of medical practice, their impact on human life.

What do the various variants of the VC structure imply in practice?

For most people, the non-standard formation of VC acts as a physiological standard and may not bother a person throughout the entire life path. Health problems, due to the pathological structure of the ring, manifest themselves in situations when, against the background of unfavorable factors, the channels of the ring formation undergo deformations, which is reflected by a deterioration in blood flow.

Previously, such precedents arose mainly in old age, as a consequence of the aging process of the body, which was expressed in parallel with a decrease in the elasticity and tone of blood vessels. At the present time, the development of the circle of Willis in the form of a decrease in blood flow is characteristic of people of the younger generation as a result of negative provocateurs of a social or subjective nature.

Nonspecific versions of the VC design can act as provocateurs of the progression of life-threatening problems in the head, when compensatory capabilities in the vascular lines of the hemispheres decrease against the background of critical changes in blood circulation.

Among the most popular pathologies that are life-threatening and often found in medical practice, medicine distinguishes:

Aneurysms.

VK vascular aneurysms

Aneurysm in medicine is called the deformation of the vessel, accompanied by protrusion of the shell against the background of thinning of its surface cover. Vessels of the VC ring are considered the most susceptible to the appearance of aneurysms with non-standard variants of its design. With a small scale of formation, the patient may not feel any negative symptoms, however, the enlargement of the protrusion can provoke infringement of the tissues of the central nervous system, which will be expressed by the following symptoms:

Deterioration of vision.
The occurrence of intense headaches, turning into regular migraines.

If you do not ask for help in time medical institution and not to identify the problem at this stage, further aneurysm rupture may follow, which is a direct threat to the patient's life. The following symptoms will indicate a ruptured aneurysm:

Intense, stabbing head pain.
Nausea with bouts of vomiting.
Short-term loss of consciousness or vision.

Ischemic stroke as a consequence of the non-standard structure of the VC

Often, the presence of breaks in the VC or the asymmetric structure of its structure is a provocateur of the progression of ischemic stroke. In the presence of additional negative factors, collateral blood flow deteriorates, and VC cannot provide adequate compensatory blood supply to the hemispheres. As a result, certain parts of the brain begin to experience a deficiency of blood, and with it oxygen and useful components, as a result of which tissue death begins in the hemispheres.

The most common symptoms of a precedent are the following:

Sudden numbness in half of the body or weakness in the muscles.
Rapid degradation of consciousness, distortion of speech.
Loss of motor coordination.
Rapid growth.

Such symptomatology is a harbinger of a stroke, requires urgent hospitalization of the sick person in a medical facility.

Specificity and need for treatment of different types of VC configuration

The non-standard development of the circle of Willis revealed as a result of a situational examination of the body often does not require urgent hospitalization of the patient or targeted therapy. If a person is not worried about negative manifestations, then doctors will recommend him exclusively preventive measures that are aimed at reducing the risk of thrombosis and vascular atherosclerosis. The prevention of these diseases often consists in the elimination of negative factors of a social and subjective nature, which include rejection of addictions, rationalization of nutrition, maintaining an active life, avoiding stressful situations. In addition, after detecting a non-standard formation of the Ring of Willis, the patient should be more careful about his health, regularly undergo medical examinations in order not to miss possible development complications and urgently take measures to eliminate them.

Treatment is provided only in cases where the state of the VC vessels is critical for the patient's life, mainly with aneurysms. With an existing aneurysm, the patient will have to undergo surgery: surgery to remove the formation, which is carried out by craniotomy, or the installation of a special spiral into the damaged vessel under local anesthesia, if the aneurysm has not reached critical dimensions in terms of its parameters. IN postoperative period the patient is assigned complex therapywhich aims to eliminate inflammatory processes, restoration of blood microcirculation and prevention of complications.

Let's sum up

The verdict of doctors that the vascular lines of the circle of Willis have a non-standard structure is not always a reason for panic. More than half of the world's population has such a "pathological" design of the VC vessels, however, they live a long life without feeling negative manifestations at the physiological level.

Such a verdict should become a certain incentive for a person to change his life activity in the correct and correct direction, an attentive attitude to his health, regular preventive visits to doctors and the implementation of their recommendations.

Circle of willis- This is the arterial circle of the brain, located at the base of the brain, and provides compensation for insufficient blood supply due to overflows from other vascular pools. The circle is named after the English physician Thomas Willis. Normally, the vessels that make up the ["classic"] circle of Willis form a closed system at the base of the brain. The following arteries are involved in the formation of the circle of Willis - numbering according to the figure (see the first figure and the photograph of the macro-preparation):

(9) the initial segment of the anterior cerebral artery (A-1);
(10) the anterior communicating artery;
(12) supraclinoid segment of the internal carotid artery;
(3) the posterior communicating artery;
(16) the initial segment of the posterior cerebral artery (P-1).

[! the source of further information and photographs of macro-preparations (except for aneurysms) is article "Variants of non-classical structure of the cerebral arterial circle", author N.А. Trushel, Belarusian State Medical University (article published in the journal "Medical Journal" No. 1, 2011) ... this article can be downloaded from the link at the end of this message]

"Non-classical" variants of the structure of the circle of Willismeet according to various authors from 25 to 75% of cases. According to scientists, such options are reflected in its full function, which plays big role in the regulation of blood flow in the brain. Among them, there are the most dangerous (anterior or posterior trifurcation of the internal carotid artery), which affect the distribution of blood in the brain and are permissible until the occurrence of occlusive changes that require good collateral circulation. With anterior trifurcation, the internal carotid artery delivers 50% of the blood to the brain, and the opposite, as a result of hypoplasia of the proximal segment of the anterior cerebral artery (A1), delivers 30% of the blood. The internal carotid artery on the side of its posterior trifurcation delivers about 50% of the blood to the brain, the opposite internal carotid artery 40% of the blood, and the basilar artery only 10% of the blood. According to most scientists, variants of the non-classical structure of the circle of Willis can be the cause of aneurysms, both in the anterior and posterior parts of it (for example, look at the photo below):

With posterior trifurcation, the anterior, middle and posterior cerebral arteries depart from the internal carotid artery, and the latter departs through the large posterior communicating artery. The proximal segment of the posterior cerebral artery, adjacent to the basilar artery (P1), is usually hypoplastic, however, in rare cases, the diameter of P1 is equal to the diameter of the enlarged posterior communicating artery (Figure 1). In the first case, blood enters the posterior cerebral artery mainly from the internal carotid artery, and in the second - from both sources: the internal carotid and basilar arteries, which is confirmed in the works of individual authors.

Posterior trifurcation of both internal carotid arteries, in which there are large posterior communicating arteries, is found normally in the first half of the prenatal period, which is of great functional importance. In the postnatal period of ontogenesis, the posterior communicating arteries become thinner, while the other vessels of the circle of Willis increase in size. Probably, the delay in the reduction of the posterior communicating arteries in the embryonic period leads to the preservation of the posterior trifurcation of the internal carotid artery in an adult, which explains the high frequency of its occurrence. According to some authors, an increase in the diameter of the posterior communicating artery in some cases is likely to occur in cerebrovascular pathology, as a result of the adaptation of the vessels to new conditions.

The second most common is aplasia of one or both posterior communicating arteries. Unilateral aplasia of the posterior communicating artery is more common (Figure 2) than bilateral (Figure 3). The frequent absence of the posterior communicating arteries can be explained by the arrest in development, which is consistent with the literature data.

The absence of the posterior communicating arteries is observed 6 times more often than the anterior communicating artery. With aplasia of the anterior and posterior connecting arteries, there is a complete disconnection of the carotid artery systems with each other or disconnection of the blood circulation of the anterior and posterior parts of the brain, which is most unfavorable in terms of collateral support when compensating for hemodynamic disorders.

Other variants of the nonclassical structure of the cerebral arterial circle are found much less frequently. These include: the median artery of the corpus callosum (Figure 4), single-barreled type of the anterior cerebral artery (Figure 5), parietal contact of the anterior cerebral arteries (Figure 6), anterior trifurcation of the internal carotid artery (Figure 7), splitting of the anterior communicating artery, the presence of several anterior communicating arteries, absence of the anterior communicating artery.

The vascular system of the brain has a complex structure. One of its most important components is the circle of Willis. It is a complex of arteries located at the base of the brain.

What the circle of Willis consists of

First of all, you need to figure out what it is - the circle of Willis. This is an anastomosis of the arteries of the brain, which has the shape of an oval crown. This formation was named after its discoverer, Thomas Willis.

The circle is formed by arteries such as:

Back connecting.
Posterior cerebral.
Anterior cerebral.
Internal sleepy.

This structure of the circle allows you to connect two systems: the spinal cord and the carotid.

What functions is responsible for

According to statistics, the classic variant of the development of the circle of Willis is observed only in 50% of cases. For many people, its symmetry is broken.

Possible pathologies

Among the most significant pathologies:

Hypoplasia. It is a malformation in which the arteries have greatly reduced parameters. If there are no blood flow disturbances in other areas of the brain, then hypoplasia will be asymptomatic. Such a pathology can be detected during a comprehensive diagnosis of the state of the brain. It is clearly visible in the images obtained with magnetic resonance imaging.
Aneurysm. This is the protrusion of the artery wall outward. The deviation is asymptomatic until the aneurysm ruptures. This leads to cerebral hemorrhage. In this case, unbearable headaches, attacks of nausea and vomiting, acute reactions to bright light appear. If you do not take action in time, a person can fall into a coma and die.
Aplasia. This is a condition in which the Willis circle is not closed due to the absence of a connecting artery. It can be observed both in the anterior and posterior regions. If the artery is still present, but extremely poorly developed, then an incomplete openness of the circle is diagnosed. Pathology in the anterior part of the circle is extremely rare, only in 4% of cases. Most often, the deviation is found behind. An open circle is examined using MRI. The reason for this phenomenon is a stop in development at the stage of fetal formation.
Carotid artery trifurcation. This is the splitting of the artery into three components. This deviation is observed in 28% of cases. It is not dangerous as long as there are no occlusive changes in the arteries. Distinguish between anterior and posterior trifurcation. This deviation is associated with a delay in the reduction of the connective arteries during embryonic development.

Pathologies that are extremely rare include Heibner's artery, splitting of the anterior communicating artery, plexus-like appearance of the basilar arteries, and some others.

What consequences can the wrong development of the circle of Willis have?

Congenital pathologies of the circle of Willis in certain situations lead to difficulty in cerebral circulation. It can manifest itself at an early age and grow over time.

Frequent dizziness.
Unpleasant sensations with a sharp change in the position of the head.
Severe headaches, which are not always possible to stop even with painkillers.
Migraine attacks, which are accompanied by photophobia, nausea, reaction to sounds.

How are deviations detected?

MRI

Angiography

CT scan

How is it treated

It is necessary to adhere to proper nutrition, exclude the use of excessively fatty foods, fried, smoked foods. To refuse from bad habits... Try to eat as many fresh vegetables and fruits as possible. Lead an active lifestyle, walk more in the fresh air. All this has a beneficial effect on the health of the cardiovascular system as a whole.

Operation

If an aneurysm is diagnosed, urgent surgery will be required. No other methods can cope with such a problem. The operation is performed under general anesthesia.

The surgeon makes a burr hole in the patient's skull. He then spreads the tissue apart to reach the damaged artery. Using special instruments, the doctor removes the aneurysm and ligates the vessel.

Then all that remains is to restore the meninges and suture. Most often, after such an operation, medical treatment is needed, which is aimed at preventing possible complications.

These spirals contribute to the formation of a dense thrombus in the aneurysm cavity. Thus, pathology is completely excluded from the circulatory process.

What the circle of Willis consists of

What functions is responsible for

Possible pathologies

What consequences can the wrong development of the circle of Willis have?

How are deviations detected?

Angiography

How is it treated

Operation

Possible pathologies of the circle of Willis and their treatment

The structure and function of the arterial circle of the brain

Pathologies and their symptoms

Diagnostics and treatment

An overview of all the options for the development of the circle of Willis, what this means in practice

The structure of the circle of Willis

VK development options

What do different options for VK development mean in practice?

VK vascular aneurysms

Ischemic stroke with different variants of the VC structure

Diagnostics: identification of variants of the structure of the circle of Willis

Treatment options for the development of the circle of Willis

Why does it hurt

and how to cure

Circle of Willis - development, treatment, symptoms

Circle of Willis diseases: treatment

The structure of the circle of Willis

The circle of Willis: how it works, the norm and anomalies (open, decreased blood flow), diagnosis, treatment

The structure of the circle of Willis

Video: the structure of the circle of Willis

The role of the circle of Willis

Variant anatomy of the arteries of the base of the brain

Signs and diagnosis of circle of Willis anomalies

Video: an example of an MRI brain angiography

The structure of the circle of Willis

VK development options

What do different options for VK development mean in practice?

VK vascular aneurysms

Ischemic stroke with different variants of the VC structure

Diagnostics: identification of variants of the structure of the circle of Willis

Treatment options for the development of the circle of Willis

Funny and serious

Circle of Willis functions

A variant of the development of the circle of Willis. Infiltrative changes in the mucous membrane of the left maxillary sinus

What is the circle of Willis - functions, anatomy and structural anomalies

What is the function

Anatomical data

Formation options

Causes of structural anomalies

Treatment and prevention

Comments (0)

Write a comment

Circle of willis

Circle of Willis diseases: treatment

Possible pathologies of the circle of Willis and their treatment

Also

Post navigation

Recent Entries

Archives

Categories

What is the circle of Willis

What the circle of Willis consists of

What functions is responsible for

Possible pathologies

What consequences can the wrong development of the circle of Willis have?

How are deviations detected?

Angiography

How is it treated

Operation

The role of the circle of Willis

VK structure

Signs of violations and methodology for diagnosing VC anomalies

VK development options

What do the various variants of the VC structure imply in practice?

VK vascular aneurysms

Ischemic stroke as a consequence of the non-standard structure of the VC

Specificity and need for treatment of different types of VC configuration

Let's sum up

What the circle of Willis consists of

What functions is responsible for

Possible pathologies

What consequences can the wrong development of the circle of Willis have?