As arteriovenous malformation, a vascular malformation is referred to, which provides a direct connection between the arterial and the venous portion of the circulatory system without the interposition of the capillary system. The rare vascular malformation, which often affects the central nervous system, usually occurs in the form of a plexus of veins. The walls of the blood vessels in the area of the vascular abnormality often do not achieve the normal strength, so that, in connection with the increased blood flow, serious internal bleeding can occur.
What is an arteriovenous malformation?
An arteriovenous malformation (short for AVM by Abbreviationfinder) is characterized by a network of arteries that is directly connected to the venous vascular system. Normally, the arterial blood has to flow through the capillary system. In the case of this disease, it is practically short-circuited before it enters the venous part of the bloodstream.
Only an arteriovenous short circuit created during the embryonic phase is referred to as AVM. This does not mean an acquired or artificially created direct connection between arterial and venous blood flow for therapeutic purposes. The vascular anomaly usually consists of an inextricable tangle of veins, also called nidus (nest), the walls of which are extremely thin and prone to lesions.
Often the draining veins are greatly dilated, so that there is a high risk of the formation of bulges ( aneurysms ). Arteriovenous malformations are mainly found in the anterior region of the central nervous system (CNS), but can in principle also occur anywhere in the body, for example in the lungs, in the spinal canal, on the retina of the eyes and in muscle tissue.
Causes
The causes for the development of arteriovenous malformations are not (yet) sufficiently known. It is considered likely that the malfunctions develop during the early embryonic development phase. It is not certain whether genetic defects are a possible trigger.
A familial accumulation that is observed in certain manifestations of an AVM speaks in favor of the theory of one or more genetic defects. It is also not known whether exposure to certain pollutants or environmental toxins play a role as a possible cause of AVM during the crucial early pregnancy phase.
Symptoms, ailments & signs
Symptoms and complaints of an AVM cover a broad spectrum from weakly perceptible symptoms and unspecific headaches to comatose and life-threatening conditions. Most arteriovenous malformations are noticeable through internal bleeding.
If the bleeding occurs in the brain or spinal cord, it can lead to serious symptoms such as seizures , motor disorders, balance and vision problems, depending on the region concerned .
Often unconsciousness also occurs due to excessive bleeding . The use of space by cerebral haemorrhages can also trigger epileptic seizures or paralysis of the arms and legs as well as speech disorders .
Diagnosis & course
If AVM is suspected, four different diagnostic imaging methods are available. Specifically, these are computed tomography (CT), magnetic resonance tomography (MRT) and angiography or digital subtraction angiography (DAS), a further developed form of conventional angiography.
Color-coded duplex sonography can also be used for diagnostic purposes. In principle, this is a non-invasive diagnostic procedure, unless – with the exception of duplex sonography – a contrast agent is applied to the blood vessels via a catheter in order to improve the informative value of the images.
For a diagnosis that is needed quickly, especially in the case of cerebral haemorrhage, a CT without contrast agent is usually made, which allows precise conclusions to be drawn about the location and size of the hemorrhage. The course of the disease of the AVM can be very different. Cases have also been observed in which the arteriovenous malformation has regressed spontaneously, but this does not correspond to the normal course of the disease.
An AVM always carries the risk of internal bleeding, which can lead to serious problems and neurological failures, especially in the CNS area. With a large-area AVM, there is also the risk of severe blood loss with all the health problems that result from it.
Complications
The arteriovenous malformation is a kind of short-circuit connection between arteries and veins that supply the brain. The congestion causes a blood-enriched tangle of vessels. If the tangle of vessels bursts, life-threatening cerebral haemorrhage is the result. The complications of an arteriovenous malformation can be far-reaching.
Affected persons can develop irreversible neurological deficits as a result of the symptom. If the symptom is in the spinal cord, there is a risk of paraplegia. Epileptics in particular should see a doctor immediately at the first sign of a severe headache. Further signs of bleeding are sensory disturbances, paralysis, speech disorders and epileptic seizures up to unconsciousness.
The medical evaluation is carried out using an MRI, if possible with the administration of a contrast medium, from which the dimensions of the vascular tangle and any cerebral hemorrhage that has already occurred can be clearly identified. A brain wave measurement shows the extent of any neurological failures. Medical therapy is derived from the anamnesis and in rare cases turns out to be problematic.
Surgical intervention is considered depending on the position of the vascular tangle. However, the closure itself can lead to complications if a rupture or acute circulatory disorders occur in the supply area during the operation. This can damage peripheral nerves or cause a stroke. If the symptom occurs in an unfavorable region of the brain, alternatives such as embolization or radiation therapy are initiated.
When should you go to the doctor?
The manifestations of an arteriovenous malformation (AVM) range from minor to severe. It is always a direct connection, a kind of short circuit between the arterial and venous side of the blood circulation, bypassing the capillary system, so that the vascular resistance of the capillary system is also missing. Characteristically, AVMs are already applied during the embryonic phase for reasons that have not yet been fully understood.
In principle, an AVM can be located anywhere in the bloodstream, but is mainly found in the front part of the CNS. It is noticeable that the vascular walls of an AVM, which are often braid-like, are not particularly strong, so that bleeding can occur, which can cause severe neurological complications in the CNS due to space occupation. Some of the complications are comparable to those of a stroke. Smaller AVMs in the CNS area can be almost asymptomatic and are often overlooked.
In these cases there is no need to ask whether medical treatment should be sought. In the case of an already diagnosed AVM outside the CNS and outside the spinal canal, the risks and opportunities of therapy should be carefully weighed against each other.
The primary goal is to shut down the AVM through surgical removal or to sclerosing or sclerotizing it. In the CNS, the shutdown of an AVM turns out to be much more complicated because bleeding must be avoided under all circumstances in order not to provoke additional neurological damage.
Treatment & Therapy
Therapy goals in the treatment of an AVM depend primarily on the location and its size. In the case of a minor, symptom-free malformation, only regular observation is recommended. For arteriovenous malformations that are located outside the head and the spinal canal, the therapeutic goal is usually a complete removal of the AVM in a surgical procedure.
In some cases, a function shutdown in the form of sclerotherapy or embolization can also be used. While sclerotization is triggered by direct injection of a special fluid into the vessels of the AVM, embolization is an artificial blockage of the affected veins. For the treatment of an AVM in the brain, there are several different treatment methods or forms of therapy to stop the function of the malformed blood vessels.
In the case of very small malformations, precision irradiation can lead to the obliteration of the small vessels. However, the risk of bleeding is not eliminated immediately by the radiation, but only gradually diminishes over a period of around two years. In some cases, a catheter can be advanced down the inguinal artery to the facial artery, which supplies blood to the malformed vascular network.
An embolizing liquid can then be introduced directly into the affected veins via the catheter. Regardless of the method used to shut down or surgically remove the affected vascular network, it is very important that the malformed veins are fully captured, otherwise undesirable recurrences will occur.
Outlook & forecast
The prognosis of an arteriovenous malformation is very poor without medical care. The vascular malformation leads to bleeding in most patients in the course of their lives. The result is an acute life-threatening condition that can be fatal. Various functional disorders occur and the patient is threatened with multiple organ failure .
If the person concerned survives an acute condition that manifests itself as a heart attack or stroke , life-long impairments remain. These include paralysis, speech disorders or motor problems that are no longer repairable. In some cases, years of therapy can provide relief. Nevertheless, the initial situation is no longer established.
Patients who are diagnosed early and undergo immediate medical treatment are more likely to have a positive prognosis. If there are no other previous illnesses, the patient has a good chance of being discharged as permanently cured after a corrective operation. As soon as the wound healing is complete, normal participation in everyday life can take place. Nevertheless, overexertion and heavy loads should be avoided.
In the case of additional illnesses, the prognosis must be assessed according to the overall situation. If there are chronic diseases or there are other vascular disorders, the prospect of a complete cure is minimized. In addition, the recovery process is immensely prolonged.
Prevention
Since the causes of an arteriovenous malformation are not sufficiently known and genetic defects probably also play a role in certain manifestations, preventive measures that could prevent the development of an AVM are not in place. All that remains is the recommendation to seek medical help at the first suspicion.
Aftercare
With this malformation, in most cases the patient has no or very few measures and options for follow-up care. First and foremost, the disease itself must be recognized early and then treated so that there are no further complications. In the worst case, these malformations can also lead to internal bleeding, which can lead to the death of the person concerned.
Therefore, the early detection and treatment of this disease is in the foreground. In most cases, the symptoms are relieved by surgery. There are no particular complications. After the procedure, the person affected should definitely rest and take care of their body.
Stressful or strenuous activities should be avoided so that the body can recover. Further checks and examinations by a doctor after the procedure are also necessary to check whether the wound has healed. No further follow-up measures are necessary after the treatment.
However, if the person concerned notices changes at the site of the operation, it is advisable to consult a doctor in order to quickly identify tumors. With early and successful treatment, this disease does not reduce life expectancy.
You can do that yourself
An arteriovenous malformation (AVM) can have very different manifestations. The immediate danger that an AVM can pose depends on the severity and location of the occurrence. An AVM is often located in the CNS or in the spinal canal.
In these cases, medical help should be sought immediately. There is a risk of bleeding in the area of the AVM, which can lead to breakdowns in the CNS due to the space occupied and in some cases can also be directly life-threatening.
A low-severity AVM outside the CNS and outside the spinal canal that shows no signs of rupture or bleeding should be evaluated from time to time. There are no known typical everyday and self-help measures that could prevent the occurrence of an AVM.
There are also no known measures that could minimize the risk of bleeding associated with an AVM. The risk of a vascular rupture with subsequent bleeding is significantly greater with an AVM than with healthy vessels because the individual wall layers of the vessels in the area of the AVM are particularly thin or completely absent.
