Arteriovenous malformation
The content of the article:
- Causes and risk factors
- Forms of the disease
- Symptoms
- Diagnostics
- Treatment
- Possible complications and consequences
- Forecast
- Prevention
Arteriovenous malformation is a cerebral vascular malformation. It is characterized by the formation in some parts of the brain or spinal cord of a vascular tangle, consisting of arteries and veins, connecting directly to each other, that is, without the participation of the capillary network.
The disease occurs with a frequency of 2 cases per 100,000 population, it is more susceptible to men. Most often it manifests itself clinically between the ages of 20 and 40, but sometimes it debuts after 50 years.
The main danger of arteriovenous malformation is the risk of intracranial hemorrhage, which can lead to death or lead to permanent disability.
Vascular ball in the brain with arteriovenous malformation
Causes and risk factors
Arteriovenous malformation is a congenital pathology that is not hereditary. Its main reason is negative factors affecting the process of laying and developing the vascular network (in the first trimester of pregnancy):
- intrauterine infections;
- some common diseases (bronchial asthma, chronic glomerulonephritis, diabetes mellitus);
- the use of drugs with a teratogenic effect;
- smoking, alcoholism, drug addiction;
- exposure to ionizing radiation;
- intoxication with salts of heavy metals.
Arteriovenous malformations can be found anywhere in the brain or spinal cord. Since there is no capillary network in such vascular formations, the discharge of blood occurs directly from the arteries into the veins. This leads to the fact that the pressure in the veins increases and their lumen expands. Arteries with this pathology have an underdeveloped muscle layer and thinned walls. All together increase the risk of arteriovenous malformation rupture with the occurrence of life-threatening bleeding.
Direct discharge of blood from arteries into veins bypassing capillaries entails disturbances in breathing and metabolic processes in the brain tissue in the area of localization of pathological vascular formation, which causes chronic local hypoxia.
Forms of the disease
Arteriovenous malformations are classified by size, location, and hemodynamic activity.
By localization:
- Superficial. The pathological process takes place in the cerebral cortex or in the layer of white matter located directly below it.
- Deep. The vascular conglomerate is located in the subcortical ganglia, in the area of the convolutions, in the trunk and (or) ventricles of the brain.
By coil diameter:
- scanty (less than 1 cm);
- small (from 1 to 2 cm);
- medium (from 2 to 4 cm);
- large (from 4 to 6 cm);
- giant (over 6 cm).
Arteriovenous malformations are active and inactive depending on the hemodynamic characteristics.
Arteriovenous malformation can be localized in any part of the body, but most often in the vessels of the neck and head
Active vascular lesions are easily detected by angiography. In turn, they are divided into fistula and mixed.
Inactive malformations include:
- some types of cavities;
- capillary malformations;
- venous malformations.
Symptoms
Arteriovenous malformation is often asymptomatic and is discovered by chance, during examination for another reason.
With a significant size of the pathological vascular formation, it exerts pressure on the brain tissue, which leads to the development of cerebral symptoms:
- bursting headache;
- nausea, vomiting;
- general weakness, decreased ability to work.
In some cases, in the clinical picture of arteriovenous malformation, focal symptoms associated with impaired blood supply to a certain part of the brain may appear.
When the malformation is located in the frontal lobe, the patient is characterized by:
- motor aphasia;
- decreased intelligence;
- proboscis reflex;
- unsure gait;
- convulsive seizures.
With cerebellar localization:
- muscle hypotension;
- horizontal coarse nystagmus;
- unsteadiness of gait;
- violation of coordination of movements.
With temporal localization:
- convulsive seizures;
- narrowing of the visual fields, up to complete loss;
- sensory aphasia.
When localized in the base of the brain:
- paralysis;
- visual impairment up to complete blindness in one or both eyes;
- strabismus;
- Difficulty moving the eyeballs.
Arteriovenous malformation in the spinal cord is manifested by paresis or paralysis of the limbs, impairment of all types of sensitivity in the limbs.
When a malformation ruptures, hemorrhage occurs in the tissues of the spinal cord or brain, which leads to their death.
Signs of ruptured malformation and cerebral hemorrhage:
- sudden sharp headache of high intensity;
- photophobia, visual impairment;
- violations of speech function;
- nausea, repeated vomiting that does not bring relief;
- paralysis;
- loss of consciousness;
- convulsive seizures.
Rupture of an arteriovenous malformation in the spinal cord leads to sudden paralysis of the limbs.
Diagnostics
Neurological examination reveals symptoms characteristic of spinal cord or brain damage, after which patients are referred for angiography and computed or magnetic resonance imaging.
Arteriovenous malformation detected by CT angiography
Treatment
The only method that allows to eliminate arteriovenous malformation and thereby prevent the development of complications is surgical intervention.
If the malformation is located outside a functionally significant area and its volume does not exceed 100 ml, it is removed using the classic open method. After craniotomy, the surgeon ligates the adductor and discharge vessels of the vascular ball, then selects it and removes it.
The classic way to remove arteriovenous malformation
When an arteriovenous malformation is located in the deep structures of the brain or functionally significant areas, it can be difficult to carry out its transcranial removal. In these cases, preference is given to the radiosurgical method. Its main disadvantages:
- a long period of time required for obliteration of the vessels of the malformation;
- low efficiency in the removal of vascular plexuses, the diameter of which exceeds 3 cm;
- the need to perform repeated irradiation sessions.
Another way to remove arteriovenous malformation is X-ray endovascular embolization of the feeding artery. This method can only be used if there is a blood vessel available for catheterization. Its disadvantages are the need for step-by-step treatment and low efficiency. As statistics show, X-ray endovascular embolization allows to achieve complete embolization of the malformation vessels only in 30-50% of cases.
Currently, most neurosurgeons prefer the combined removal of arteriovenous malformations. For example, if their size is significant, X-ray endovascular embolization is first used, and after a reduction in the size of the vascular conglomerate, its transcranial removal is performed.
Possible complications and consequences
The most dangerous complications of arteriovenous cerebral malformations:
- hemorrhage in the spinal cord or brain;
- the development of persistent neurological disorders (including paralysis);
- fatal outcome.
Forecast
The risk of rupture of arteriovenous malformation is 2–5%. If a hemorrhage has already taken place once, the risk of recurrence increases 3-4 times.
With intracranial hemorrhage associated with rupture of arteriovenous malformation, every tenth patient dies.
Prevention
Arteriovenous malformation is an abnormality of intrauterine vascular development, therefore, there are no preventive measures to purposefully prevent its development.
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Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
