Arteriovenous Malformation (cont.)
How can AVMs and other vascular lesions be treated?
Medication can often alleviate general symptoms such as headache, back pain, and
seizures caused by AVMs and other vascular lesions. However, the definitive
treatment for AVMs is either surgery or focused irradiation therapy. Venous
malformations and capillary telangiectases rarely require surgery; moreover,
their structures are diffuse and usually not suitable for surgical correction
and they usually do not require treatment anyway. Cavernous malformations are
usually well defined enough for surgical removal, but surgery on these lesions
is less common than for AVMs because they do not pose the same risk of
hemorrhage.
The decision to perform surgery on any individual with an AVM requires a
careful consideration of possible benefits versus risks. The natural history of
an individual AVM is difficult to predict; however, left untreated, they have
the potential of causing significant hemorrhage, which may result in serious
neurological deficits or death. On the other hand, surgery on any part of the
central nervous system carries its own risks as well; AVM surgery is associated
with an estimated 8 percent risk of serious complications or death. There is no
easy formula that can allow physicians and their patients to reach a decision on
the best course of therapy-all therapeutic decisions must be made on a
case-by-case basis.
Today, three surgical options exist for the treatment of AVMs:
conventional surgery, endovascular embolization, and radiosurgery. The
choice of treatment depends largely on the size and location of an AVM.
Conventional surgery involves entering the brain or
spinal cord and removing the central portion of the AVM, including the fistula,
while causing as little damage as possible to surrounding neurological
structures. This surgery is most appropriate when an AVM is located in a
superficial portion of the brain or
spinal cord and is relatively small in size. AVMs located deep inside the brain
generally cannot be approached through conventional surgical techniques because
there is too great a possibility that functionally important brain tissue will
be damaged or destroyed.
Endovascular embolization and radiosurgery are less
invasive than conventional surgery and offer safer treatment options for some
AVMs located deep inside the brain. In endovascular embolization the surgeon
guides a catheter though the arterial network until the tip reaches the site of
the AVM. The surgeon then introduces a substance that will plug the fistula,
correcting the abnormal pattern of blood flow. This process is known as
embolization because it causes an embolus (a blood clot) to travel through blood vessels,
eventually becoming lodged in a vessel and obstructing blood flow. The materials
used to create an artificial blood clot in the center of an AVM include
fast-drying biologically inert glues, fibered titanium coils, and tiny balloons.
Since embolization usually does not permanently obliterate the AVM, it is
usually used as an adjunct to surgery or to radiosurgery to reduce the blood
flow through the AVM and make the surgery safer.
Radiosurgery is an even less invasive therapeutic
approach. It involves aiming a beam of highly focused radiation directly on the
AVM. The high dose of radiation damages the walls of the blood vessels making up
the lesion. Over the course of the next several months, the irradiated vessels
gradually degenerate and eventually close, leading to the resolution of the AVM.
Embolization frequently proves incomplete or temporary, although in recent
years new embolization materials have led to improved results. Radiosurgery
often has incomplete results as well, particularly when an AVM is large, and it
poses the additional risk of radiation damage to surrounding normal tissues.
Moreover, even when successful, complete closure of an AVM takes place over the
course of many months following radiosurgery. During that period, the risk of
hemorrhage is still present. However, both techniques now offer the possibility
of treating deeply situated AVMs that had previously been inaccessible. And in
many patients, staged embolization followed by conventional surgical removal or
by radiosurgery is now performed, resulting in further reductions in mortality and
complication rates.
Because so many variables are involved in treating AVMs,
doctors must assess the danger posed to individual patients largely on a
case-by-case basis. The consequences of hemorrhage are potentially disastrous,
leading many clinicians to recommend surgical intervention whenever the physical characteristics of an
AVM appear to indicate a greater-than-usual likelihood of significant bleeding
and resultant neurological damage.
Next: What research is being done? »
- CT Scan (Computerized Axial Tomography) - CT Scan (Computerized Axial Tomography, CAT scan) is a procedure that assists in diagnosing tumors, fractures, bony structures, and infections in the organs and tissues of the body.
- Headache - Learn about the different types of headaches, migraine, tension, cluster, menstrual, and spinal headaches; and their causes, symptoms, diagnosis and treatment.
- MRI (Magnetic Resonance Imaging Scan) - Medical information on magnetic resonance imaging (MRI) used in detecting structural abnormalities of the body. Learn uses, risks, and how to prepare for an MRI scan
Latest Medical News
Neurology RSS