The vessels of the brain form a complex circulatory system, which must ensure constant delivery of nutrients and oxygen to nerve cells.
The circle of Willis is a closed complex of arteries that provides blood supply to the structures of the central nervous system due to the redistribution of blood.
Pathologies in its structure and function lead to various neurological disorders. We will talk further about what the Circle of Willis is and what it means if it is open.
About the Circle of Willis of the brain
The circle of Willis protects the brain from hypoxia when blood flow through the arteries is impaired. Redistribution of blood helps prevent the death of neurons due to thrombosis, compression or rupture of blood vessels.
A closed circle system with anastomoses ensures normal blood flow due to the blood that flows through the vessels of the opposite side. An anastomosis is a small artery that connects two areas of the nervous system with separate blood supplies.
Anatomical structure
The vessels of the circle are located under the arachnoid membrane in the area of the optic chiasm at the base of the brain. In most people, several vessels are involved in the formation of the arterial circle:
- anterior communicating artery;
- posterior communicating arteries;
- left and right anterior cerebral arteries;
- left and right posterior cerebral arteries;
- supracuneiform part of the internal carotid artery.
All arteries connect with each other, forming a vascular heptagon. Due to this, anastomoses are formed between the carotid and basilar arteries. This makes it possible to prevent ischemic brain damage due to unilateral disturbances of blood flow through the vessels.
Functions
The main function of the arterial circle is to ensure normal blood supply to the brain in case of pathology of individual vessels. This is achieved due to its closed structure and constant blood flow through several arteries.
Operating principle of TKDS
The essence of TCD is to visualize the veins and arteries located inside the skull, as well as the vessels of the cervical spine using color mapping of blood flow. The method allows you to determine the presence of vascular damage.
The technique used for diagnostics connects the obtained drawings and displays an overall picture, according to which a specialist can make an accurate analysis. Procedures can be carried out in two modes:
What pathologies are possible
The circle of Willis has a complex structure and consists of 10-12 arteries. Therefore, some people may have diseases associated with vascular damage. They are divided into two groups: congenital, which arose during intrauterine development of the fetus, and acquired, developing after birth. The most common pathologies are:
- Aneurysm is a local protrusion of the arterial wall outward. A person can go for a long time without any symptoms, which makes timely diagnosis difficult. If blood pressure increases, the aneurysm may rupture. In this case, an intracranial hematoma develops. The patient complains of headache, nausea, vomiting and dizziness. He experiences neurological disorders, including severe paralysis or death. Aneurysms can be located on any vessel;
- hypoplasia is characterized by underdevelopment of the artery with a decrease in its diameter and lumen. This leads to insufficient blood flow. If the circle is closed, then the disease is asymptomatic, since blood flows to the brain through other vessels;
- aplasia is complete underdevelopment of the artery. Can be observed in any vessel. Aplasia of the anterior or posterior communicating artery leads to the fact that the circle of Willis becomes open. This is fraught with the development of cerebral ischemia against the background of concomitant pathologies: atherosclerosis, aneurysms, thrombosis, etc.;
- trifurcation of the carotid artery with its splitting into three vessels. The condition is not manifested by any diseases, however, if the patency of the artery is impaired, cerebral ischemia is possible.
Is an open circle of Willis good or bad?
The structure of the arterial circle has many variations. Normally, it is closed, which helps protect nervous tissue from ischemia and damage.
In some people, the circle of Willis is not closed on the side of the anterior or posterior communicating artery. This condition is not always regarded by doctors as a pathology.
An open arterial circle is bad. In the absence of all anastomoses, a person has an increased risk of developing ischemia of nervous tissue against the background of atherosclerosis, thrombosis and arterial embolism.
However, the condition itself does not require treatment, since pathologies arise only against the background of concomitant diseases of the cardiovascular system.
Role of VC
The circle of Willis is a protective mechanism that compensates for disturbances in the blood flow system. This brain structure is formed by nature to avoid the irreversible consequences of minor nutritional deficiencies in the brain.
If one of the vessels is damaged, then the Ring of Willis takes over its functional responsibilities and supplies blood to all parts of the head, receiving it from the second functional artery.
Through connecting vessels the required volume of blood is delivered to all parts of the organ.
The role of the ring of Willis in the blood flow system is very important, and not only during periods of serious diseases such as arterial aneurysm or stroke, but even when vascular spasm occurs.
When one channel is occluded, the circle of Willis performs the function of pumping arterial blood.
The symptoms of occlusion and the development of pathology, its speed and the area of the focus of destruction, directly depend on the correct structure of the ring and how effectively it can redirect the blood flow to those organs that suffer from blood deficiency.
With the normal structure of the system, this circle copes with the task assigned to it.
With an abnormal physiological structure, when the vascular system is not correctly formed, or there are no branches at all, then the functionality of the VC is practically ineffective.
Clinical manifestations
Violations of the structure of the circle and its openness lead to disruption of the blood supply to the brain. Depending on where ischemia develops, a person may develop different symptoms. The first symptoms are often:
- dizziness that occurs during severe physical or emotional stress;
- severe headache that does not disappear when taking painkillers;
- migraine attacks with nausea, vomiting, and fear of loud sounds and lights.
As anemia progresses, neurological disorders occur. The patient may complain of impaired sensitivity on the skin, decreased muscle strength or complete absence of movements in the arm or leg, frequent dizziness, etc. Cognitive functions are also impaired: the ability to remember information decreases, the patient takes a long time to make decisions, forgets the way home, etc. With ischemia frontal cortex, speech is impaired. The patient cannot speak clearly or does not perceive the speech of other people.
Diagnostic measures
Detection of an open arterial circle requires instrumental studies: angiography, Dopplerography, computed tomography or magnetic resonance imaging.
These methods allow you to visually assess the condition of the arterial vessels and identify their pathological changes. Only the attending physician should interpret the examination results.
Angiography
“Gold standard” for examination of cerebral vessels. Angiography allows you to assess the condition of blood vessels, detect aneurysms, narrowings and complete blockage of the lumen. The principle of the method is similar to radiographic studies. Radiocontrast agents are used only to identify blood vessels on images.
They are inserted through a small catheter into the artery. Contrast agents circulate along with the blood and are clearly visible on the resulting images. They are excreted from the body in the urine, without having a negative effect on internal organs. Modern angiography allows you to obtain a three-dimensional image of the arteries of the circle of Willis.
Dopplerography
The method is carried out simultaneously with ultrasound examination of cerebral vessels. Dopplerography allows you to evaluate the structure of the vessels of the circle of Willis and identify their anomalies. In this case, the doctor can examine the speed of blood flow.
Treatment approaches
If the arterial circle is not closed, special treatment is not required. Without accompanying changes in the blood vessels, people do not experience any symptoms of disease. Therapy should be aimed at preventing arterial pathologies and eliminating them.
For this, patients are prescribed a number of medications, and are also advised to adhere to a diet and change their lifestyle.
Non-drug approaches
All patients should adhere to medical recommendations regarding lifestyle:
- exercise regularly. To prevent vascular diseases, aerobic exercise is recommended: walking, jogging, cycling and swimming. Classes should be ongoing and suitable for the person’s level of physical fitness;
- eliminate bad habits: smoking and drinking alcohol;
- Avoid fatty, salty, fried and spicy foods in your diet. They contribute to the development of atherosclerosis and hypertension. Both conditions are often complicated by thrombosis, aneurysms and their rupture;
- It is recommended to eat more vegetables, fruits, berries, nuts and lean meats. They are rich in beneficial amino acids, vitamins, microelements and biologically active substances that have a positive effect on the condition of the cardiovascular system;
- Limiting salt intake to 5 g per day. If the patient has severe arterial hypertension, then the volume of consumption is reduced to 1 g;
- avoid stressful situations at work and in your personal life.
These recommendations reduce the risk of developing heart and vascular diseases by preventing pathological changes in the arterial circle of the brain.
Medicines
Medications are recommended for people with vascular pathology of the circle of Willis and accompanying changes in the arteries. Medicines of the following pharmacological groups can be used:
- drugs that improve cerebral circulation (Cerebrolysin, Cavinton, etc.). They normalize vascular tone and increase the intensity of blood flow in the arteries of the brain. This avoids ischemia and neurological disorders;
- nootropics – Phenotropil, Glycine, Nootropil, etc. They enhance metabolic processes in neurons and reduce their sensitivity to damaging factors. Requires long-term use over several months to obtain a therapeutic effect;
- antioxidants (Dihydroquercetin, Mexidol) protect nerve cells from damage, including toxic substances. The effect is achieved by blocking free forms of oxygen, which negatively affect the structures of neurons;
- antispasmodics (Drotaverine, Papaverine and their analogues) are prescribed for spastic changes in blood vessels. Allows you to dilate arteries and restore normal blood supply to the brain. They have only a symptomatic effect and do not affect the underlying disease;
- B vitamins, which stimulate the restoration of nerve tissue and neuron membranes. Used in courses in the form of intramuscular injections;
- To eliminate pain, non-steroidal anti-inflammatory drugs (Diclofenac, Nise, etc.) are prescribed. They are highly effective for any form of headache, except migraine.
All medications are prescribed only by a doctor. Medicines have contraindications, failure to comply with which may cause progression of the underlying disease or lead to the development of side effects.
Surgical treatment
In case of multiple blood flow disorders, the patient is prescribed surgical interventions. They may be associated with the creation of a shunt or mechanical expansion of the lumen of the arteries. A shunt is a bypass for blood flow, which is placed around a narrowed area, an area of hypo- or aplasia. Mechanical expansion of the vessel is carried out using a stent or ballooning.
What are the dangers of improper development?
Congenital abnormalities can gradually create obstruction of the blood supply or signs of decompensation when excessive stress is placed on the arteries.
The consequences can be completely catastrophic - the development of an aneurysm, hemorrhagic or ischemic strokes.
Even young people can experience periodic migraine attacks.
In the older age category, aneurysms caused by acquired pathologies (atherosclerosis, vasculitis infections, syphilis) more often occur.
An aneurysm is a protrusion on the wall of an artery; the development of pathology occurs without visible symptoms. Most often localized inside the circle of Willis (in the ACA or PCA, at the bifurcation of the ICA and BA) against the background of the asymmetric structure of the arterial ring.
When an aneurysm forms, there is a danger of rupture of the vessel and, as a result, hemorrhage in the brain.
Clinical syndromes caused by arterial ring aneurysms:
- pseudotumor - nerve tissue and brain matter are compressed;
- hemorrhagic extracerebral basal - after rupture of a vessel with subarachnoid hemorrhage;
- discirculatory - with slow growth or with the development of a dissecting form of aneurysm.
Anomalies in branching options and deformation of the shape (broken circle) weaken or lead to loss of compensation in complex cases (hypertensive crisis, thrombophlebitis, spasm, etc.).
