Arteriovenous malformation is a congenital abnormal violation of the mutual arrangement of blood vessels with pathognomonic localization in the cerebral hemispheres, but it is also found in other anatomical regions, characterized by a tendency to develop complications in the form of damage to the integrity of the vascular wall.
The result of the formation of such balls of dilated vessels, in which the veins and arteries are not delimited by capillaries, arterial blood enters the veins and there is no return transport of carbon dioxide, which provokes the development of acidotic and hypoxic complications.
The degree of indices of hemodynamic disturbances in the presence of arteriovenous malformation directly depends on the metric parameters of abnormally located vessels, which can be observed in wide ranges.
Causes of arteriovenous malformation
A lot of randomized studies have been devoted to the research of the etiopathogenesis of the development of arteriovenous malformation and, unfortunately, there is still no reliable information confirming the role of this or that factor in its development.
It is an undeniable fact that arteriovenous malformation occurs in humans even in the period of intrauterine development and belongs to the category of congenital anomalies of embryogenesis.
Joint scientific research conducted by geneticists and embryologists ended with the discovery that the maximum possibility of malformation development is observed in the first weeks of embryonic development, namely, until the sixth week. After the seventh week and until the end of the second trimester of pregnancy, the development of the most arteriovenous malformation of one or another localization is noted.
In connection with the rapid development of radiation diagnostic techniques, the detection of arteriovenous malformation of some pathomorphological variants becomes possible in the early stages of development. However, due to the lack of reliable data on the origin of the pathology, it is still impossible to develop methods for primary prevention.
Thus, the maximum pathogenetic role of the development of arteriovenous malformation of any localization remains behind the factors of an embryonic nature.
According to the world statistics of the incidence of arteriovenous malformation, there are data and the secondary development of this anomaly arising as a result of the negative effect of ionizing radiation, transferred inflammatory processes of the brain. In addition, at risk for the development of arteriovenous malformation are persons suffering from a sickle-cell form of anemia.
Also, many specialists note the correlation between the development of arteriovenous malformation and the sex of the patient (men suffer more from this pathology).
Symptoms of arteriovenous malformation
Depending on the patient's clinical manifestations, arteriovenous malformation has several variants of the course. Thus, with hemorrhagic flow type, which is observed in 70% of cases, the patient has a tendency to increase blood pressure figures and preferential localization in the projection of the posterior cranial fossa. For arteriovenous malformation of this type, the development of a large-size malformation node is not typical.
Hemorrhagic variant of the course of arteriovenous malformation often causes disability of the patient and is characterized by a high risk of hemorrhage development.
In 50% of cases of hemorrhagic type of arteriovenous malformation, the pathognomonic clinical picture of subarachnoid hemorrhage develops. The complicated course of hemorrhagic type of arteriovenous malformation consists in the formation of intracerebral, subdural and mixed localization of hematomas, as well as ventricular gemotamponade.
Torpid flow of arteriovenous malformation is observed in the formation of large-sized nodes localized in the cerebral cortex and blood supply to it by branches of the middle cerebral artery.
With regard to the clinical symptom complex in the torpid current of arteriovenous malformation, the first place is occupied by increased convulsive readiness, cluster headache , progressive focal neurological symptoms, which is also the case with tumor lesion of the brain.
It should be taken into account that the arteriovenous malformation of the lungs, for example, is not always characterized by the development of the classical variant of the course in the form of progressive respiratory disorders, cyanotic changes in the skin and thickening of the nail phalanges. In some situations, a person may even have a prolonged asymptomatic period. At a late stage of development, arteriovenous malformation with localization in the lungs is accompanied by the development of manifestations of severe respiratory and heart failure .
The most pathognomonic clinical manifestation of arteriovenous malformation of the lungs is progressive dyspnea. With a complicated course of arteriovenous malformation of this localization, the patient may experience episodes of hemoptysis.
Auscultatory signs of arteriovenous malformations of the lungs are the appearance of noise in the projection of the localization of the malformation node, which increases at the moment of maximum inspiration in the patient's position "lying on the right side."
Arteriovenous malformation of the spinal cord is most often not accompanied by the development of specific pathognomonic symptoms that distinguish it from other diseases accompanied by damage to the structures of the spinal cord. The first clinical manifestations in this situation are violations of various types of sensitivity of different depths, as well as motor activity.
Arteriovenous malformation of the brain
In view of the wider use of the latest methods of radiation diagnosis of brain structures, the verification of arteriovenous malformation significantly increased, even though the clinical symptoms did not manifest this pathology.
At the same time, in some patients, on the contrary, there is a rapid development of symptoms, the specificity of which directly depends on the localization of malformation in a particular structure of the brain.
The general cerebral manifestations resulting from the increase in intracranial pressure include: pain syndrome in the region of the head of a bursting nature, accompanied by vomiting, which brings relief, weakness, and inability to perform even minimal physical activity. Specific neurological manifestations of arteriovenous malformation, localized in the frontal lobes, is the reduction of the intellectual and mnestic possibilities, the appearance of motor aphasia, the manifestation of the pathological sucking reflex, the unsteadiness in walking, the tendency to convulsive seizures
The most specific manifestations of cerebellar arteriovenous malformation are coordination disorders, uncertainty in walking and the appearance of large-scale horizontal nystagmus, muscle hypotension.
Arteriovenous malformation in the temporal lobe is accompanied by development of sensory aphasia, loss of visual fields and increased convulsive readiness.
With the location of arteriovenous malformation in the region of the base of the brain, the patient develops visual disturbances in the form of strabismus, loss of visual fields up to complete blindness, as well as impaired motor activity in the limbs.
With the development of a complicated course of arteriovenous malformation as a rupture of the vascular wall, the patient develops a clinical picture of subarachnoid hemorrhage in the form of sudden severe headache, photophobia, nausea and vomiting that does not bring relief, short-term or prolonged loss of consciousness.
In some situations, blood spilled out of the blood vessels accumulates and forms a hematoma, which is manifested by visual disturbances in the form of partial or complete blindness, strabismus and immobilization of the eye, paralysis of the limbs, speech disorders, epileptic seizures and persistent loss of consciousness.
With regard to diagnostic measures that reliably not only verified the diagnosis of "arteriovenous malformation of the brain," but also indicate the exact location of the problem, cerebral contrast arteriography is used.
Treatment of arteriovenous malformation
When choosing the optimal expedient and pathogenetically grounded method of treating a patient suffering from arteriovenous malformation, the task of the correct evaluation of the patient's health, the intensity of clinical manifestations, the precise localization of the anomaly and its size is before the treating physician.
Drug treatment for arteriovenous malformation, as a rule, is exclusively symptomatic and implies the use of analgesic drugs, anticonvulsant action.
Until recently, neurologists preferred to use expectant management in patients with arteriovenous malformation, provided that it had a favorable course. Currently, there is a whole range of operational aids that allow eliminating arteriovenous malformation, and at the same time, to minimize the risks of complications.
Operation with arteriovenous malformation implies surgical resection and finds its application only for small malformations. In the case of a deep location of arteriovenous malformation of the brain, this technique is not applied because of the high degree of risk of development of intraoperative complications.
Another effective surgical method for correcting arteriovenous malformation is embolization, which involves the insertion of a catheter into the site of the malformation site and the introduction of a special substance with adhesive properties, through which the changed area is turned off from the total blood flow. This technique acts as the main treatment, and as an addition to the classical version of surgical resection, thereby minimizing the risks of development of intraoperative complications in the form of bleeding.
In the absence of the patient's risk of developing complications of hemorrhagic nature, the use of radiosurgery is allowed, in which the influence of radioactive substances that exert a destructive effect on arteriovenous malformation is focused on the malformation node. This technique involves the use of radiosurgery courses lasting several years until the appearance of a persistent effect in the form of disappearance of arteriovenous malformation.
? Arteriovenous malformation - which doctor will help ? If there is or suspected the development of arteriovenous malformation, you should immediately seek advice from such doctors as neuropathologist and neurosurgeon.