Treatment of arteriovenous malformations

On the one hand, to answer the question of which method to treat arteriovenous malformation is quite simple, since only the surgical method allows to relieve the patient from the AVM itself and from those complications to which it leads. But, on the other hand, it is often very difficult to assess the risk of surgical intervention and the risk of these complications. Therefore, every time you should consider a variety of factors, the total assessment of which can induce the physician to active surgical treatment or refuse it. 

Choice of tactics for treatment of arteriovenous malformations

First of all, the clinical manifestation of AVM is important. If the patient had at least one spontaneous intracranial hemorrhage, the conservative method of treatment can be applied only at a certain stage, but surgical treatment is inevitable. The question can consist only in the choice of the method of operation, as will be discussed below. Other variants of the clinical manifestation of AVM represent a lesser risk for the life of the patient, but one should not forget that almost half of such patients can have an AVM rupture within 8-10 years. But without taking into account the threat of rupture, the severity of clinical manifestations and the degree of disability of the patient may be such that the operation becomes absolutely indicated. Thus, migraine-like headache of moderate intensity, rarely (1-2 times a month) disturbing the patient, can not be an indication for surgical treatment, if the operation itself involves a risk for the life of the patient and a high probability of developing a neurological defect. At the same time, AVMs are found (usually extra-intro-cranial or associated with the dura mater), which cause a persistent, almost constant, headache that is not obfuscated by simple analgesics. The pain can be so intense that it does not allow the patient to perform even simple work and actually disables it. Some patients resort to drugs, while others make suicidal attempts. In such situations, the risk of even a complicated operation is justified and the patients willingly agree to it.

Epileptic seizures caused by AVM can be varied in severity and frequency: small seizures such as absences or twilight consciousness, local convulsive attacks such as Jackson and unwrapped seizures. They can be repeated at a frequency of once every few years and several times during the day. At the same time, the social situation of the patient, his profession, his age should be taken into account. If small rare equivalents do not significantly affect the patient's profession, do not limit his freedom and quality of life, then from a complex and dangerous operation should be refrained. But if the risk of the operation is not high, then it should be undertaken, because the risk of rupture of AVM remains and besides seizures themselves, even rare, gradually lead to a change in the personality of the patient, as well as the prolonged use of anticonvulsants. Surgery with a high degree of risk can only be performed in patients who suffer from frequent deployed epileptics, which prevent them from independently even leaving the apartment and practically turning them into invalids.

Severe and dangerous are pseudotemorous and stroke-like variants of the clinical course of AVM, since they lead even without a hemorrhage to the invalidization of the patient, therefore the operation can be contraindicated only if it involves a risk to the life of the patient or the probability of developing a more severe neurological deficit than already attaching. Somewhat less dangerous are transient disorders of cerebral circulation, especially single, but we should not forget that in this version of the course, ischemic stroke can develop. Given the severity of the various variants of the clinical course of AVM and the risk of possible complications in attempting their radical extirpation, we developed a simple technique for determining indications for surgery.

We identified 4 degrees of severity of the clinical course and 4 degrees of operational risk, depending on the size and location of AVM.

Severity of clinical course.

1. degree - asymptomatic course;
2. degree - single epizpripadki, single PIMK, rare migraine attacks;
3. degree - stroke-like course, pseudotumoric course, frequent epi- attacks (often 1 time per month), repeated PIMC, frequent persistent migraine attacks;
4. degree - an apoplectic type of flow, characterized by one or more spontaneous intracranial hemorrhages.

The degree of operational risk in radical extirpation of AVM.

1. degree - AVM of small and medium size, cortical-subcortical, located in the functionally "silent" areas of the brain.
2. degree - AVM of small and medium size, located in the functionally important areas of the brain, and large AVM in the "silent" areas of the brain.
3. degree - AVM of small and medium size, located in the corpus callosum, in the lateral ventricles, in the hippocampus and large AVM in the functionally important areas of the brain.
4. degree - AVM of any size, located in the basal ganglia, AVM functionally important parts of the brain.

In order to determine the indications for open surgical intervention, you need to perform a simple mathematical action: subtract the indicator of the degree of operational risk from the severity of the clinical course. And if the result is positive - the operation is shown; If a negative result is obtained, the operation should be abstained.

Example: In the case of the patient K. AVM manifests as unfolded epipripeds 1-2 times a month (III degree of severity). According to angiography AVM up to 8 cm in diameter is located in the medio-partal regions of the left temporal lobe (IV degree of operational risk): 3-4 = -1 (operation not shown).

In the case of obtaining a zero result, subjective factors should be taken into account: the patient's and relatives' attitude to the operation, experience and qualification of the surgeon. At the same time, we should not forget that 45% of malformations, irrespective of their clinical manifestations, can be ruptured. Therefore, when you get a zero result, you should still lean toward surgical treatment. Malformations, the open removal of which is associated with the risk of IV degree, it is better to operate with the endovascular method, but only if the clinical course of AVM and the degree of operational risk allow to select an adequate treatment tactics. Otherwise, tactics are determined in the acute period of AVM. In this case, the severity of the patient's condition, the volume and localization of intracranial hematoma, the presence of blood in the ventricles of the brain, the severity of the dislocation syndrome, the size and localization of the AVM itself are taken into account. The main issue that needs to be addressed is the choice of the optimal timing and scope of surgical intervention.

[1], [2], [3], [4], [5], [6]

The choice of therapeutic tactics in the acute period of rupture of arteriovenous malformation

Therapeutic tactics in the acute period of the rupture of arteriovenous malformation are determined by many factors: the size and localization of AVM, the volume and localization of intracerebral haemorrhage, the period from the moment of rupture, the severity of the patient's condition, age and physical status, the surgeon's experience in performing such operations, operating equipment and many others. In the overwhelming majority of cases, when the ABM rupture, intramuscular hematomas are formed, which may be limited, but can break into the ventricular system or into the subdural space. Significantly less rupture of AVM is accompanied by subarachnoid hemorrhage without formation of a hematoma. In this case, the therapeutic tactics in the acute period should only be conservative. The operative removal of arteriovenous malformation can be performed only after 3-4 weeks, when the patient's condition becomes satisfactory and signs of cerebral edema disappear. In the case of the formation of an intracerebral hematoma, its volume, localization, severity of the dislocation syndrome and perifocal edema of the brain should be taken into account. It is necessary to assess the severity of the patient's condition and if it is severe, determine the cause: the volume of hematoma and the dislocation of the brain determine the severity of the condition, or it is caused by the localization of hemorrhage in functionally important centers, and possibly other causes. In the first case, the question of surgical intervention is raised, but it is necessary to determine the timing of its conduct and the scope of the operation. Emergency surgical treatment is performed if the severity of the condition progressively increases and is caused by a hematoma having a volume of more than 80 cm3 and a contralateral displacement of the median brain structures by more than 8 mm, and the deformation of the embracing bridge cistern indicates the initial signs of temporo-tentorial wedging. The scope of the operation depends on the patient's condition, size and localization of the malformation itself. Severe condition of the patient with gross violation of consciousness to sopor and coma, elderly and senile age, coarse concomitant pathology do not allow performing the operation in full. This is also impossible if the arteriovenous malformation of medium or large size has been ruptured and requires a multi-hour operation, prolonged anesthesia, and the possibility of blood transfusion. In such cases, the necessary operation for vital indications should be performed in a reduced volume: only the hematoma is removed and bleeding from the malformation vessels stops. If necessary and uncertainty in reliable hemostasis, an inflow and outflow system is established. The malformation itself is not removed. The whole time operation should not exceed one hour. If the source of the hematoma is a small AVM rupture, it can be removed simultaneously with the hematoma, as this will not significantly complicate or prolong the operation.

Thus, emergency surgery with AVM rupture is performed only with large hematomas, causing gross compression and dislocation of the brain, which threatens the life of the patient. In this case only small-sized arteriovenous malformation is removed along with hematoma, and the removal of medium and large AVM should be delayed for 2-3 weeks, until the patient leaves the severe state.

In other cases, when the severity of the condition is not due to the volume of the hematoma, but the localization of hemorrhage in the vital brain structures (cerebral ventricle, corpus callosum, basal ganglia, variolium bridge, brain stem or medulla oblongata), an emergency surgery is not shown. Only with the development of hydrocephalus is a superposition of bilateral ventricular drainage. An emergency operation is also not shown if the volume of the hematoma is less than 80 cm3 and the patient's condition, although severe, but stable and there is no direct threat to his life. In such cases AVM can be removed together with hematoma in a delayed period. The larger the dimensions of the AVM and the more difficult it is to remove it technically, the later the operation must be performed. Usually these terms fluctuate between the second and fourth weeks from the moment of the break. So, when AVM is ruptured in an acute period, conservative tactics are often taken, or urgent surgery for vital indications in a reduced volume. Radical extirpation of AVM should be performed in a delayed period (in 2-4 weeks) if possible.

Intensive therapy in the acute period of rupture of arteriovenous malformation

Patients with severity of I and II degrees in Hunt and Hess do not need intensive therapy. They are prescribed analgesics, sedatives, calcium antagonists, rheological preparations, nootropics. The heavier category of patients - III, IV and V degrees of severity, requires intensive therapy, which along with general measures (ensuring adequate breathing and maintaining a stable central hemogram) should include rheological therapy, decongestant, neuron protective, corrective and restorative.

Rheological therapy includes the introduction of plasma-substituting solutions (0.9% solution of NaCl, Ringer's solution, plasma, polarizing mixture), rheopolyglucin, etc. In small amounts (200-400 ml per day) an isotonic glucose solution can be used. The use of hypertonic glucose solutions is accompanied by increased metabolic acidosis, therefore it is not recommended. The total daily volume of intravenous infusion should be 30-40 ml / kg of body weight. The main criterion for calculating this volume is hematocrit. It should be within 32-36. With spontaneous intracranial hemorrhages, as a rule, there is a thickening of the blood, an increase in its viscosity and coagulability, which leads to difficulty in hemocirculation in the smallest vessels - precapillaries and capillaries, microvascular coagulation and capillarostasis. Rheological therapy is aimed at preventing or minimizing these phenomena. Along with hemodilution, a disaggregant and anticoagulant (trental, sermion, heparin, and fractiparin) is performed. Anti-edematous therapy includes measures aimed at the maximum elimination of any negative influences on the brain. This is, first of all, hypoxia. It can be caused either by a violation of external respiration or by hemocirculatory disorders. Intracranial hypertension also hampers blood flow through the cerebral vessels. Promotes the development of edema and intoxication, due to the disintegration of blood elements, and the absorption of the products of this decay into the blood, acidosis (mainly lactic and pyruvic acids), increasing the level of proteolytic enzymes, vasoactive substances. Therefore, hemodilution itself eliminates some of the listed negative factors (blood thickening, increased viscosity, sludge syndrome, capillarostasis, intoxication). To eliminate acidosis, 4-5% of soda is assigned, the amount of which is calculated from the acid-base state. Well protect neurons from edema corticosteroid hormones (prednisolone, dexamethasone, dexazone, etc.). They are administered intramuscularly 3-4 times a day. So prednisolone is prescribed in a dose of 120-150 mg per day. At the same time, blood pressure may slightly increase, which is well-adjusted by the introduction of calcium antagonists.

Under conditions of hypoxia, effective defense of brain cells from edema of antihypoxants - drugs that inhibit the rate of biochemical reactions, and therefore reduces the need for cells in oxygen. These include: sodium oxybutyrate or GOMK, seduxen, sibazone, sodium thiopental, hexenal. The daily dose of thiopental and hexenal can reach 2 g. Sodium oxybutyrate is administered in a dose of 60-80 ml per day. Especially shown these drugs in patients with psychomotor agitation and with the development of diencephalic syndrome. In cases of prevalence of mesencephaloplasmic syndrome (low blood pressure, muscle hypotension, normo- or hypothermia, bulbar type of respiratory failure), antihypoxants are not shown.

Since all patients with intracranial hemorrhage sharply increase the activity of the kallikrein-kinin system and proteolytic enzymes, it is advisable to prescribe protease inhibitors. Contrikal, trasilol, gordoks are introduced on physiological solution of Ringer drip on 30-50 thousand units. Per day, for 5 days. By this time, the activation of kallikrein-kinin system is reduced.

Important in the treatment of spontaneous intracerebral hemorrhage is the appointment of calcium antagonists. Blocking the calcium channels of cell membranes, they protect the cell from excessive penetration of calcium ions into it, which always rushes into cells that suffer from hypoxia and leads to their death. Calcium antagonists also, acting on the myocytes of the arteries of the brain, prevent the progression of angiospasm, which is very important in patients with rupture of malformations and developing as a result of compression of the brain. Various representatives of this group of drugs are used: isoptin, phenoptin, veropamil, nifedipine, corinfar, etc. The most active of them in regard to brain pathology is the nemotope of Bayer (Germany). Unlike other similar drugs, the nimotope has the ability to penetrate the hemato-encephalic barrier. In an acute period nimotop is administered intravenously drip constantly for 5-7 days. For this purpose, a nimotope is used in 50 ml vials containing 4 mg of active substance. It is better to use a dispenser for this purpose. The rate of administration is controlled by the pulse rate (nimotope slows the heart rate) and by arterial pressure. With the rapid administration of the drug may develop a hypotomy. Arterial pressure should be maintained at a moderate level of hypertension (140-160 mm Hg). On average, one bottle of nimotope is diluted in 400 ml of saline and this amount is enough for 12-24 hours. After 5-7 days, if the patient's condition improves, he is given tablet nimotol for 1 -2 tablets four times a day.

With respect to nootropics and cerebrolysin, glycine should be followed by expectant tactics. In the acute period of the rupture, when nerve cells suffer from hypoxia and edema to stimulate their activity is inexpedient. These drugs will play an important role in the restoration of brain function after the surgery is performed.

Important is the appointment of antioxidants: vitamins A, E, preparations of selenium. Along with this, corrective therapy is carried out aimed at normalizing all indices of homeostasis. In cases where hemorrhage is not classified as incompatible with life, such therapy leads to an improvement in the condition of patients with severity of III-IV degrees within 7-10 days, after which the question of the timing of a radical operation can be decided.