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What is an AVF?
Dural arteriovenous fistulae are abnormal connections between arteries in the
head and the large veins draining the brain that are found in the covering of
the brain (dural sinuses). There is a direct connection between the arteries and
the sinus without any vessels between. These fistulae can result from trauma,
infections (such as sinus infections or mastoiditis), or from clotting of the
vein (the fistula forms as a result of the body trying to reopen the vein).
The symptoms of a fistula can vary. An unusual sound may be heard in one ear
(pulsating or humming). If the fistula causes the pressure in the veins draining
the brain to increase, there may be neurological symptoms and headaches. A
dangerous complication of a fistula is rupture of the vein, resulting in
hemorrhage in or around the brain.
What is a Carotid-Cavernous Fistulae (CCF)?
Carotid-cavernous fistulae are abnormal connections between the carotid
artery (or its branches) and a large vein (cavernous sinus) behind the eye that
receives blood from the orbit, the pituitary gland, and the brain. These
fistulae can form as a result of trauma, clotting of the sinus with subsequent
reopening, or rupture of an aneurysm (weak spot) of the carotid artery where it
passes through the sinus.
The symptoms include pulsating bulging of the eye (proptosis), redness and
swelling of the conjunctiva, increased pressure in the eye (glaucoma), loss of
vision in the eye, double vision, and pain.
How are AVF’s and CCF’s diagnosed?
AVF’s and CCF’s are usually difficult to diagnose with imaging studies such
as CT or MRI. Cerebral angiography is the best way to evaluate these disorders.
Angiography is the only test currently available which provides sufficiently
detailed information on which to plan and carry out therapy of most AVF’s and
CCF’s.
Angiography is a study of the brain blood vessels. It is performed by a
physician experienced and trained in performing and interpreting blood vessel
examinations of the brain, using X-rays to map the specific blood vessels
involved in the AVF or CCF. A small tube or catheter is inserted into the
femoral artery in the groin and maneuvered into the vessels in the neck
supplying the brain. Material called contrast or "dye" which is visible on the
X-ray is injected into the vessel and images are taken as the liquid flows
through the AVF or CCF. The angiogram gives a detailed picture of the vessels
involved and the flow through the AVF or CCF. Based on the information gained by
the angiogram, treatment options can be determined for each patient.
How are AVF’s and CCF’s treated?
The treatment for a dural fistula depends on the vessels involved. Surgery
or radiation therapy may be recommended. Often, these fistulae are treated by
placement of a catheter into the blood vessels (like an angiogram) to inject
materials to block off the vessels (embolization). Blockage of arteries, vein
(sinus), or both may be needed. Multiple treatments may be needed to close the
fistula.
What is embolization?
Embolization is an endovascular technique, (performed from within the blood
vessels) to block vessels of the AVF. Embolization is performed using catheters
and angiographic techniques similar to those discussed above. For the
embolization procedure, a very tiny catheter is threaded from the groin directly
into the AVF or CCF vessels within or around the brain. Under X-ray guidance,
material is injected through the catheter to permanently block and close off the
vessels of the AVF or CCF. Materials used might include particles, small
platinum coils, and/or liquid embolic agents similar to glue.
Embolization of an AVF or CCF is usually performed before treatment by either
surgery or radiosurgery. Embolization is often able to decrease the size of the
AVF or CCF making the surgery or radiosurgery much safer than would otherwise be
the case. However, certain AVF’s and CCF’s blood flow may be totally blocked by
embolization techniques, and no further therapy may be required.
Who performs endovascular embolization procedures?
Endovascular treatment is a relatively new type of treatment requiring
specialized training. Most physicians who perform endovascular embolization are
neuroradiologists or neurosurgeons who have received several years of additional
training in navigating inside the brain blood vessels to treat a variety of
blood vessel disorders.
What do I need to know before having an embolization?
very important in that any food in the The patient should not eat or drink
anything after midnight on the night before the procedure. This is stomach
will make the patient nauseated during the procedure and may cause vomiting with
severe consequences. Patients should take their normal medications the morning
of the procedure with a small amount of water. Embolizations are performed
either under sedation or under general anesthesia. Procedures frequently take 4
to 6 hours and the time necessary is often not predictable before the procedure
begins.
After the procedure, the patient will need to remain still and avoid bending
the hip where the puncture occurred for at least 6-8 hours. This means lying
flat and is often the portion of the entire experience that is most
uncomfortable. The period of rest is very important since it allows the small
puncture hole in the artery to heal.
Patients usually remain in the hospital for several days following an
embolization procedure. The first night may be spent in the neurological
intensive care unit for close monitoring, and this may be followed by transfer
to a regular hospital room for 24 hours before discharge. The potential
complications and risks of the procedure should be discussed with your doctor.
For more information go to: www.asitn.org
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