What Is Spinal Arteriovenous Malformation?

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Spinal arteriovenous malformation

In arteriovenous malformations of the spinal cord, there are mainly thick, twisted veins. The most common site is the posterior part of the thoracic spinal cord. Epidermal hemangiomas are sometimes found on the spinal arteriovenous malformations. Arteriovenous malformations may be small and limited, and there are deformities as large as 1/2 of the spinal cord. They can have the effect of space-occupying lesions, compressing or even replacing the spinal cord tissue; they can also rupture, causing focal or comprehensive bleeding. Bleeding can cause sudden pain in the diseased area and loss of nerve function below the bleeding level; blood entering the subarachnoid space can cause fever and neck stiffness. Arteriovenous malformations that cause compression or infiltration of the spinal cord usually cause progressive subacute spinal cord disease, or signs of intramedullary spinal cord disease with isolated sensory impairment and segmental motor weakness.

Diagnosis of spinal arteriovenous malformations

If the function of the spinal cord is threatened, microsurgery can be performed, but it needs to be performed by a doctor with professional experience. In a few larger medical centers, there are also treatments that occlude the arterial supply of malformed arteries through arterial catheters. Measures.

(AVM) Spinal arteriovenous malformation What is arteriovenous malformation (AVM)

The abnormal accumulation of blood vessels in the brain or spinal cord is called arteriovenous malformation (AVM). Nutrients for most of the body's organs and tissues are carried by the blood and transported from the arteries away from the heart to various organs. Within the organ, the artery branches into very thin blood vessels, called microvessels. The function of microvessels is to transport nutrients and oxygen from the blood to the organs and tissues. After the blood nourishes the organs, it flows back to the heart through the venous system.

When there is an arteriovenous malformation in the brain or spinal cord, blood in the arteries is injected directly into the veins without passing through the microvessels. Therefore, blood flowing through arteriovenous malformations does not transport oxygen or nutrients to the brain or spinal cord, but instead forms a high-flow "blood short circuit", which constantly causes blood to flow from the heart to arteriovenous malformations and quickly return. The heart, the burden on the heart. Such pathological blood flow will often lead to some specific symptoms of the patient.

Spinal arteriovenous malformation

Although there are many theories about the occurrence of arteriovenous malformations, most researchers believe that almost all arteriovenous malformations are congenital. In the developing fetal brain, there will be an anatomical structure similar to arteriovenous malformations, but it will disappear as the fetus gradually grows. When the structure of the arteriovenous malformation of the brain or spinal cord of the mother and fetus does not successfully disappear, the patient will be born with arteriovenous malformations of the brain or spinal cord. In rare cases, arteriovenous malformations may be caused by head trauma. This type of arteriovenous malformations is called Dura fistula, but physicians can usually distinguish between arteriovenous malformations and dural canal.

Spinal arteriovenous malformations

The most devastating symptom of arteriovenous malformation is bleeding in the brain or spinal cord. Such bleeding is unpredictable and recurs. Patients with arteriovenous malformations have a 3 to 4% risk of bleeding each year. When patients experience such bleeding, there is a 10% chance of death and a 20% chance of permanent neurological symptoms (ie, stroke). Arteriovenous malformations are generally thought to stop on their own, with bleeding conditions ranging from just seconds to minutes. Therefore, patients with arteriovenous malformations have a higher chance of hemorrhagic stroke.

Symptoms of arteriovenous malformations include epilepsy, headaches, or any progressive neurological deficiency symptoms. For example, arteriovenous malformations are often found unexpectedly when evaluating other neurological diseases. Because arteriovenous malformations pose a significant bleeding risk, patients are generally advised to treat them.

Spinal arteriovenous malformation

Arteriovenous malformations are primarily diagnosed by computed tomography or magnetic resonance scanning, and then diagnosed by angiography of the brain. Computed tomography and MRI scans can show the location of arteriovenous malformations in the brain or spinal cord, and provide information on the size of the lesion. The location of arteriovenous malformations is very important in determining the risk and treatment of the disease. Cerebral angiography is to introduce the catheter into the body from the arteries in the rat sacral site, and then reach the main blood vessels in the brain from the inside up, and then inject the contrast agent into the catheter and irradiate the X-rays at the same time. Such examinations can reveal the direction and details of blood vessels in the brain, especially those that supply arteriovenous malformations.

In addition, this test can also show the veins connected to arteriovenous malformations, which is very important to choose the best treatment for the patient.

Spinal arteriovenous malformations

In very few cases, such as elderly patients, it may be acceptable to choose not to treat arteriovenous malformations and only observe the patient's symptoms, but in most patients, there are mainly three treatment options: Endovascular catheter therapy and stereotactic radiosurgery.

Surgery is performed directly on the brain to remove arteriovenous malformations. If the arteriovenous malformation can be completely removed, the patient can be considered cured. However, surgery on the brain is obviously invasive and is accompanied by many risks, including stroke, infection, complications from anesthesia, and other neurological loss.

Intravascular catheter therapy is the injection of glue-like substances into arteriovenous malformations, which is similar to the angiographic examination. When doing angiography, a very thin catheter is used to identify the blood vessels supplying arteriovenous malformations and then inject a glue-like substance into the arteriovenous malformations. This method is less invasive than surgery, and most arteriovenous malformations can be embolized by endovascular catheter therapy. Such localized arteriovenous malformations may still cause bleeding and stroke. Therefore, most neurosurgeons believe that embolization of arteriovenous malformations cannot effectively reduce the possibility of bleeding in the future. Endovascular catheter therapy is often used as a method to reduce the volume of arteriovenous malformations before surgical resection or stereotactic radiosurgery.

Stereotactic radiosurgery can destroy abnormal blood vessels through a large number of very accurate and staggered radiation lines. Over time, radiation can cause arteriovenous malformations to narrow the blood vessels and eventually become completely tight. Once the arteriovenous malformation is closed and no other blood can flow through it, the patient is no longer at risk of bleeding or stroke.

What are the advantages of stereotactic radiosurgery for spinal arteriovenous malformations?

Compared with surgical resection, the main benefit of stereotactic radiosurgery is non-invasive, so there is no risk of brain surgery. In addition, some arteriovenous malformations are located in areas where brain surgery cannot be safely accessed, so radiosurgery may be the only viable option for patients. Radiation surgery can be used with other therapies to treat arteriovenous malformations. For example, radiation surgery can be used for residual arteriovenous malformations that persist after partial surgical resection or after endovascular catheter therapy.

One of the most attractive aspects is that radiosurgery can be performed in an outpatient manner and does not require any recovery period. The patient can continue to live a normal life.

What are the disadvantages of stereotactic radiosurgery for arteriovenous malformations?

There are three major disadvantages to radiotherapy. First, it can take up to three years to completely eliminate arteriovenous malformations; radiation is a gentle treatment process that gradually shrinks arteriovenous malformations. During these 3 years, patients are still at risk of arteriovenous malformation bleeding (3 to 4% per year). During radiation surgery, bleeding may still occur even if the arteriovenous malformation is already shrinking. Second, not all arteriovenous malformations will disappear after radiation surgery. An arteriovenous malformation with a diameter of 3 cm or less usually has an 80% chance of disappearing after only one radiation operation.

Large arteriovenous malformations have a relatively low disappearance rate, and patients often need to undergo more than one stereotactic radiation surgery. Even with radiation surgery, not all patients' symptoms will completely disappear. In some patients with headache or epilepsy symptoms, symptoms may persist after arteriovenous malformations have been completely treated. These symptoms are often caused by scarring of the brain near arteriovenous malformations. These scars may be arteriovenous malformations Generated during formation or disappearance.

What are the differences between CyberKnife & reg; computer knife radiosurgery systems and other radiosurgery systems?

In order to accurately target the lesion site, most radiosurgery treatment systems must use a metal frame head frame. The metal frame head frame is penetrated into the patient's scalp to the skull with four screws, which is used to connect and fix the position of the patient's skull and the metal frame head frame.

Although a local anesthetic injection is used at the site where the screw is screwed in, patients inevitably still feel pain and discomfort. The computer knife (CyberKnife) system is a system that does not require the use of a metal frame head frame to aim, so the patient can not have to endure the pain and discomfort of using a metal positioning head frame. The computer knife treatment system is not only less painful, the accuracy of the radiation aiming is also comparable to other stereotactic radiosurgery systems using metal frame head frames.

In addition, other radiation surgery systems can only treat arteriovenous malformations in the brain. Because the computer knife system does not require the positioning of a metal frame head frame, arteriovenous malformations in the spinal cord can also be treated.

What can arteriovenous malformations be expected after radiation surgery?

Most patients can undergo radiosurgery for arteriovenous malformations in an outpatient setting. During the actual treatment, the patient can continue to lead a normal life. After treatment, patients will be followed by clinical examinations and MRI scans. Most patients undergo MRI scans every six to twelve months to monitor whether arteriovenous malformed blood vessels are gradually shrinking, and to observe whether there are side effects after radiation treatment, or the surrounding normal brain tissue.

Usually only MRI scans are not enough to determine whether arteriovenous malformations have completely disappeared after radiation surgery. Therefore, after three years of radiation surgery, angiography will be needed again to confirm the complete atrophy of arteriovenous malformations.

Spinal arteriovenous malformation

The main potential complication of radiosurgery for arteriovenous malformations is that radiation may harm normal surrounding brain tissue during the gradual atrophy of arteriovenous malformations. This process is called radiation edema, or in the worst case, radiation necrosis. But compared to the untreated arteriovenous malformations that can bleed at any time, the risk of radiation damage to the brain is actually lower. Moreover, the radiation edema symptoms in most patients can be significantly improved by oral steroid treatment.

Spinal Arteriovenous Malformations

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