Arteriovenozny malformation of a brain
Arteriovenozny malformation of a brain — the congenital anomalies of cerebral vessels which are characterized by formation of a local vascular conglomerate in which there are no capillary vessels and arteries directly pass into veins. Arteriovenozny malformation of a brain are shown by persistent headaches, an epileptic syndrome, intrakranialny bleeding at a rupture of vessels of a malformation. Diagnostics is performed by means of KT and MPT of vessels of a brain. Treatment is surgical: transkranialny excision, radio surgical intervention, endovascular embolization or combination of these techniques.
Arteriovenozny malformation of a brain
Arteriovenozny malformation of a brain (cerebral AVM) — the changed sites of cerebral vascular network on which instead of capillaries there are numerous branchings of the wavy arteries and veins forming a uniform vascular conglomerate, or a ball. AVM belong to vascular anomalies of development of a brain. Occur at 2 people from 100 thousand population. In most cases clinically debut during from 20 to 40 years, in some cases — at persons 50 years are more senior. The arteries forming AVM have the thinned walls with an underdeveloped muscular layer. It causes the main danger of vascular malformation — a possibility of their gap.
In the presence of brain AVM the risk of its gap is estimated by about 2-4% a year. If hemorrhage already took place, then the probability of its repetition makes 6-18%. Mortality at intra cranial hemorrhage from AVM is observed in 10% of cases, and the resistant invalidization is noted at a half of patients. Because of thinning of an arterial wall on the site of AVM protrusion of a vessel — an aneurysm can be created. The lethality at a rupture of aneurism of vessels of a brain is much higher, than at AVM, and makes about 50%. As AVM are dangerous by intra cranial hemorrhage at young age with the subsequent lethality or an invalidization, their timely diagnostics and treatment are urgent problems of modern neurosurgery and neurology.
Brain AVM reasons
Arteriovenozny malformation of a brain result from pre-natal local violations of formation of cerebral vascular network. Various harmful factors influencing a fruit during the antenatalny period are the reasons of such violations: the raised radioactive background, pre-natal infections, diseases of the pregnant woman (diabetes, chronic glomerulonefrit, bronchial asthma, etc.), intoxications, addictions of the pregnant woman (drug addiction, smoking, alcoholism), inclusion in time of pregnancy of the pharmaceuticals having teratogenny effect.
Cerebral arteriovenozny malformation can settle down in any place of a brain: both on its surface, and in depth. In the place of localization of AVM there is no capillary network, circulation of blood comes from arteries in veins directly that causes the elevated pressure and expansion of veins. At the same time dumping of blood bypassing capillary network can cause deterioration in blood supply of cerebral fabrics in the location of AVM, leading to chronic local ischemia of a brain.
Classification of AVM of a brain
Malformation of cerebral vessels are classified by the type on arteriovenozny, arterial and venous. Arteriovenozny malformation consist of the bringing artery, the draining vein and the conglomerate of the changed vessels located between them. Allocate fistulose AVM, ratsinozny AVM and a mikromalformation. About 75% of cases occupy ratsinozny AVM. The isolated arterial or venous malformation at which the izvitost respectively only of an artery or only veins is observed meet rather seldom.
By the size cerebral AVM are subdivided on small (diameter less than 3 cm), averages (from 3 to 6 cm) and big (over 6 cm). Classify by the nature of drainage of AVM on having and the draining veins which do not have deep, i.e. veins falling into a direct sine or system of a big cerebral vein. Distinguish also AVM which are localized in or outside functionally significant areas. Carry sensomotorny bark, a brain trunk, a thalamus, deep zones of a temporal share, touch speech area (Vernike's zone), Brock's center, occipital shares to the last.
In neurosurgical practice for determination of risk of surgery concerning cerebral vascular malformation the gradation of AVM depending on set of points is used. To each of signs (the size, type of drainage and localization in relation to functional zones) a certain number of points from 0 to 3 is awarded. Depending on the gathered balls of AVM it is classified from having insignificant operational risk (1 point) to connected with high operational risk because of technical complexity of its elimination, big risk of death and disability (5 points).
Brain AVM symptoms
The clinic of cerebral AVM allocates hemorrhagic and torpedo options of a current. According to various data, the hemorrhagic option makes from 50% to 70% of cases of AVM. It is typical for AVM of the small size having the draining veins and also for AVM which are settling down in back a cranial pole. As a rule, in such cases at patients arterial hypertension is observed. Depending on localization of AVM perhaps subarakhnoidalny hemorrhage which occupies about 52% of all cases of a rupture of AVM. Other 48% it is the share of the complicated hemorrhages: parenchymatous with formation of an intracerebral hematoma, obolochechny with formation of a subduralny hematoma and mixed. In some cases the complicated hemorrhages are followed by hemorrhage in brain ventricles.
The clinic of a rupture of AVM depends on its localization and speed of the expiration of blood. Sharp deterioration in a state, the accruing headache, disorder of consciousness is in most cases observed (from confusion to a coma). The parenchymatous and mixed hemorrhages along with it are shown by focal neurologic symptomatology: hearing disorder, visual frustration, paresis and paralyzes, sensitivity loss, motor aphasia or dizartriya.
The torpedo option of a current is more typical for the cerebral AVM of the average and big size which are settling down in brain bark. Cluster tsefalgiya — the following one after another the headache paroxysms lasting not longer than 3 hours are characteristic of it. Tsefalgiya has no such intensive character as at a rupture of AVM, but is regular. Against the background of tsefalgiya a number of patients has convulsive attacks which often have generalized character. In other cases torpedo cerebral AVM can imitate symptoms of an intracerebral tumor or other volume education. Emergence and gradual increase of focal neurologic deficiency is in that case observed.
At children's age the separate type of a cerebral vascular malformation — AVM of a vein of Galen meets. Pathology is congenital and AVM in a big vein of a brain consists available. AVM of a vein of Galen occupy about a third of all cases of the vascular cerebral malformation which are found in pediatrics. Are characterized by a high lethality (to 90%). The surgical treatment which is carried out on the first year of life is considered the most effective.
Diagnostics of AVM of a brain
Persistent headaches, for the first time arisen , emergence of focal symptomatology can be a reason for the address to the neurologist to a rupture of AVM. To the patient the planned examination including EEG, Ekho-EG and REG is conducted. At a rupture of AVM diagnostics is performed in the emergency order. Tomographic methods are most informative in diagnostics of vascular malformation. The computer tomography and a magnetic and resonant tomography can be used both for visualization of tissues of brain, and for a research of vessels. In case of a rupture of ABM MPT of a brain more informatively, than KT. It gives the chance to reveal localization and the size of hemorrhage, to otdifferentsirovat it from other volume intrakranialny educations (a chronic hematoma, a tumor, abscess of a brain, a cerebral cyst).
At a torpedo current of ABM MPT and KT of a brain can remain normal. Only the cerebral angiography and its modern analogs — KT of vessels and the MR-angiography allows to find a vascular malformation in such cases. Researches of cerebral vessels are conducted with use of contrast substances. Diagnostics is performed by the neurosurgeon who also estimates operational risk and expediency of surgical treatment of AVM. At the same time it is necessary to consider that at a gap, in connection with a compression of vessels in the conditions of a hematoma and hypostasis of a brain, the AVM tomographic size can be significantly less real.
Treatment of AVM of a brain
Arteriovenozny malformation of a brain at their gap or at danger of such complication are subject to removal. Preferably planned expeditious treatment of AVM. In case of a gap it is carried out after elimination of the sharp period of hemorrhage and a rassasyvaniye of a hematoma. In the sharp period according to indications perhaps surgical removal of the formed hematoma. Simultaneous elimination and hematomas, and AVM is carried out only at lobarny localization of a vascular malformation and its small diameter. At hemorrhage in ventricles first of all external ventrikulyarny drainage is shown.
Classical surgical removal of AVM is carried out by cranial trepanation. Coagulation of the bringing vessels, allocation of AVM, bandaging of the vessels departing from a malformation and excision of AVM is made. Such radical transkranialny removal of AVM is feasible at its volume no more than 100 ml and an arrangement out of functionally significant zones. At the AVM big size often resort to the combined treatment.
When transkranialny removal of AVM is difficult because of its arrangement in functionally significant areas of a brain and deep structures, radio surgical removal of AVM is carried out. However this method is effective only for malformation no more than 3 cm in size. If the AVM size does not exceed 1 cm, then its full obliteration occurs in 90% of cases, and at the sizes over 3 cm — in 30%. To a lack of a method the long period (from 1 to 3 years) necessary for a full obliteration of AVM belongs. In some cases stage-by-stage radiation of a malformation is required for a number of years.
Also X-ray endovascular embolization of the arteries leading to AVM belongs to ways of elimination of cerebral AVM. Its carrying out is possible when there are available to a kateterization bringing vessels. Embolization is carried out step by step, and its volume depends on a vascular structure of AVM. The full embolization manages to be reached only at 30% of patients. The subtotal embolization turns out at 30%. In other cases the embolization works well only partially.
The combined landmark treatment of AVM consists in phasic use of several listed above methods. For example, at an incomplete embolization of AVM the following stage carries out transkranialny excision of its rest. In cases when full removal of AVM does not work well, radio surgical treatment is in addition applied. Such multimodal approach to treatment of cerebral vascular malformation proved to be as the most effective and justified concerning AVM of the big size.