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Embolization Treatment for Arteriovenous Malformations (AVMs) of the Brain and Spinal Cord

 

Why Treat My AVM?


Treatment is offered is to try to prevent bleeding from the AVM. Bleeding may injure the surrounding brain resulting in a stroke , with possible permanent disability or even death. The risk of bleeding is 4% per year, which means that 4 out of every 100 people with an AVM will have a bleed (hemorrhage) during any one year. AVM's may also produce headaches, seizures and progressive paralysis, and the treatment may alleviate these symptoms.


 
 

What is Embolization Treatment?


Embolization treatment of AVM is also known as Embolotherapy or Endovascular therapy. Embolization has been used to treat AVM since the early 1980ís. This procedure involves the injection of glue or other non-reactive liquid adhesive material into the AVM in order to block it off. For this purpose, a small catheter is passed through a groin vessel all the way up into the blood vessels supplying the AVM.



 

How Does it work?


The glue rapidly hardens as it is injected into the AVM. The result is that the flow of blood through the AVM is blocked off. When there is no longer any blood passing through an AVM, there is no further risk of bleeding. For the larger size AVM embolization is often done in stages so that each time a portion of the AVM is blocked off. If an AVM is not completely closed off there is still a risk of bleeding.



 

Which AVMs Can be Treated with Embolization?


Not all AVMs can be treated with embolization. AVMs are carefully studied at the time of a preliminary angiogram by highly skilled radiologists to determine if catheters can be passed up into the AVM without any complications before they are considered for embolization.



 

The Procedure


Embolization is not an open surgical procedure and requires specialized training. Most endovascular therapists are neuroradiologists or neurosurgeons who have complete training (ranging from one to two years) in endovascular techniques after their medical (five years) and specialty training (five to seven years)

Before admission
Preadmission will be done one day or two prior to the embolization and routine blood tests will be done. After midnight, no food or drink is allowed.

The Day of the Procedure 
After midnight, no food or drink is allowed .You will be taken from the "same day admit" or "preadmission area" to the Neuroangiography suite where the procedure will be performed. Just before the procedure, the nurses will shave one or both groins. Embolization is done under local or general anaesthesia and sometimes under light sedation. After the anaesthetic is administered, a catheter will be threaded up a blood vessel in your groin all the way up into the AVM. Very tiny catheters are used. This is a similar procedure to a cerebral angiography except that in addition to dye being injected to show the AVM, these tiny catheters are positioned near the AVM and glue or particles are injected into the AVM to block it off. The length of the procedure is often not predictable, and waiting family members need not to be frightened because a case may takes longer than expected. If the doctors do not think that they can safely embolize the AVM, then the embolization procedure will be discontinued. A single AVM may need to be embolized several times before satisfactory results are obtained or until no further embolization is possible. If more than one embolization is necessary, the procedures are usually done in stages spread over weeks or months.

After Treatment 
You will be taken to the Neurosurgical Intensive Care Unit or Step-Down Unit where you will be observed closely overnight. Your doctor will instruct you to remain still, lying flat in bed for up to eight hours. This rest period allows the groin artery to heal. If all goes well, you will be transferred to a neuroscience floor the next day and discharged home the following day. Most patients treated by embolization will also need to return for a follow-up angiogram or magnetic resonance angiogram (MRA), usually performed several months after the treatment. This will show how much, if any, of the AVM remains and if additional embolization is needed.



 

What are the Side Effects?


Every patient is different. Some minor side effects may be observed shortly after embolization of an AVM by some patients, but most feel perfectly fine. The side effects are usually temporary and should subside within a few days to weeks.

Headaches are not infrequently reported. They will usually subside, but if they are persistent, the doctor will prescribe a short course of medication and this will usually take away the headache.

Other possible complications include stroke like symptoms such as weakness in one arm or leg, numbness, tingling, speech disturbances and visual problems. The risk of embolization is low for serious complications such as permanent stroke or death. The estimated risk should be discussed with your doctor.



 

What are the Chances of Completely Curing My AVM with Embolization Treatment?


The chances of completely curing an AVM using only embolization treatment is about 20%. Certain types of AVM are more suitable for embolization and have a much higher cure rate. The AVM is reduced in size most instances and can be suitable for other forms of therapy such as radiation and surgery. It is very common for doctors to recommend embolization prior to the other forms of therapy.  The chances of completely curing an AVM using only embolization treatment is about 20%. Certain types of AVM are more suitable for embolization and have a much higher cure rate. The AVM is reduced in size most instances and can be suitable for other forms of therapy such as radiation and surgery. It is very common for doctors to recommend embolization prior to the other forms of therapy.



 

Bleeding After Embolization Treatment


It is important for you to know that embolization will not usually completely close off an AVM. A person may still bleed from an AVM in such a case. It is not known whether or not partial embolization treatment reduces the risk of future bleeding.



 

What are the Advantages of Embolization Treatment?


  • Embolization is very useful in making the AVM smaller in size in order to be suitable for radiation treatment.
  • Embolization is very useful to reduce the blood flow through the AVM just before surgery. This makes it much easier for the surgeon to remove the AVM.
  • Can be early repeated and staged.
  • Chances of a cure with embolization alone are about 20%.
  • No open surgical procedure.
  • Short hospital stay.


 

What are the Disadvantages?


  • This form of treatment can only be done if the AVM is made up of vessels that can be reached with the catheters.
  • Multiple sessions may be required.
  • There is a small chance of a stroke in about 1-3% occurring as the result of the treatment.
  • The chance of bleeding every year in a partially treated AVMs is likely reduced by embolization, but not eliminated.