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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.
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
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.
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
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
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
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
The chance of bleeding every year in a partially treated AVMs is likely reduced
by embolization, but not eliminated.