Arteriovenous Malformation (AVM) Embolization
What are Arteriovenous Malformations?
Arteriovenous malformations (AVMs) of the brain or spine refer to abnormal
connections between arteries and veins. AVMs can be difficult or dangerous
to treat and may cause bleeding into or around the brain, most commonly in
young adults. Although AVMs can cause headaches or other symptoms, they
are often discovered on CT or MRI scans performed for other reasons. Left
untreated, there is a 4% risk that they may start to bleed, causing severe
neurologic damage and even death. Safe, surgical removal of AVMs or treat-
ment with radiation may require partial or complete closure of the AVM through
embolization (blocking) techniques. This preparation improves the safety,
effectiveness and outcome of surgery. 
What Causes Arteriovenous Malformations?
People are born with AVMs, although they do not appear to inherit them from
their parents nor do they give them to their children. It appears that AVMs may
be caused by a rupture or clotting of a blood vessel that happens during devel-
opment before one is born. It is usually not associated with either other mal-
developments or with other AVMs.
What are the Symptoms of Arteriovenous Malformations?
Seizures and headaches are the most generalized symptoms of AVMs, but no
particular type of seizure or headache pattern has been identified. Seizures
can be partial or total, involving a loss of control over movement, convulsions,
or a change in a person's level of consciousness. Headaches can vary greatly
in frequency, duration, and intensity, sometimes becoming as severe as migraines.
Sometimes a headache consistently affecting one side of the head may be closely
linked to the site of an AVM. More frequently, however, the location of the pain is
not specific to the lesion and may encompass most of the head.
AVMs also can cause a wide range of more specific neurological symptoms that
vary from person to person, depending primarily upon the location of the AVM.
Such symptoms may include muscle weakness or paralysis in one part of the body;
a loss of coordination (ataxia) that can lead to such problems as gait disturbances;
apraxia, or difficulties carrying out tasks that require planning; dizziness; visual
disturbances such as a loss of part of the visual field; an inability to control eye
movement; papilledema (swelling of a part of the optic nerve known as the optic
disk); various problems using or understanding language (aphasia); abnormal sens-
ations such as numbness, tingling, or spontaneous pain (paresthesia or dysesthesia);
memory deficits; and mental confusion, hallucinations, or dementia.
What is Embolization?
Embolization is a method of plugging the blood vessels of the AVM. Under X-ray
guidance, a small tube, a catheter, is guided from the femoral artery in the leg
up into the area to be treated.
A neurological exam is performed before and after a small amount of medicine is
injected. This can help tell if the vessel that feeds the AVM also feeds normal and
important portions of the brain. After this, a permanent agent is injected into the
AVM and the catheter removed. This is repeated for each vessel that feed the AVM.
During the embolization, the patient is awake but is made comfortable with the help
of the anesthesia team that monitors them and gives them medicines by an intrav-
enous line. After the embolization the patients usually spend the night in the
Neurological Intensive Care Unit (NICU) where they can be monitored closely.
Patients are usually hospitalized for 3 nights for each embolization and usually req-
uire 2-3 embolizations at 2-6 week intervals. Patients resume their normal full activity
immediately upon each discharge. There may be some mild headache after the embo-
lization related to the blood vessels of the AVM clotting, or some nausea related to
some of the medicines that are given.
