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Treatments for Vascular Malformations Moderator: Welcome to this evening’s chat on Vascular
Malformations and Gamma Knife Treatment with Dr. Leon Liem of St.
Francis Health Care System of Hawaii. Dr. Leon K. Liem completed his
undergraduate studies at the Massachusetts Institute of Technology,
and earned his medical degree from Albert Einstein College of
Medicine with a special distinction in research. He is a Major in
the Medical Corps of the United States Army Reserves, and through
June of this year was Chief of Neurosurgery Science at Tripler Army
Medical Center. Dr. Liem is a member of the American Association of
Neurological Surgeons, the congress of Neurological Surgeons, the
American Medical Association, Hawaii Association of Neurological
Surgeons and the North American Spine Society. He is Board Certified
by the National Board of Medical Examiners and the American Board of
Neurological Surgery. Dr. Liem's clinical interests are in complex
spine surgery, Gamma Knife Radiosurgery, endoscopic spine &
cranial surgery, cerebrovascular surgery and pain neurosurgery. To
contact Dr. Liem's office, call 808-547-6950 or email
neurosurgery@hawaii.rr.com. For further information visit
www.gammaknifehawaii.com.
Moderator: Now, AmericasDoctor is proud to present Dr. Leon Liem.
Dr. Liem: Thank you for the opportunity to participate in this
AmericasDoctor Expert chat. The topic for discussion today involves
abnormalities of the blood vessels in the brain. The major
abnormality is known as an arteriovenous malformation (AVM). This is
an abnormal tangle of blood vessels, which is usually a result of
development and is present at birth. Because these blood vessels are
abnormal, they can be very dangerous because they can bleed into the
brain. Other times, they are detected by the development of seizures
or the growth of the AVM can push vital brain structures. With the
increased use of MRI and CT scanning for various conditions, more of
these lesions are also detected incidentally. AVMs are diagnosed
with CT or MRI brain scans or by angiogram. This is where dye is
injected into the blood vessels with the catheter placed in the
groin and x-rays obtained, especially if the patient is young.
Treatment options for AVM include simply following the lesion, but
that does carry a significant risk of bleeding. Surgical removal is
a primary treatment of AVM, however, if the AVM is inaccessible
surgically, or is in a vital structure of the brain, and the AVM is
not too large, there has recently been the option of delivery
high-dose radiation in a very precise manner which is called
radiosurgery. This can obliterate the AVM while sparing the brain
around it. Gamma knife radiosurgery is such a technique that has
become more and more available. Today's discussion will center on
this novel treatment for AVM.
Guest: Can the gamma knife be used anywhere else on the body?
Dr. Liem: Currently, the gamma knife is useful for lesions in the
brain, head and sometimes in the upper neck. Thus far, the gamma
knife itself cannot be used elsewhere in the body, however, there
are other types of radiosurgery that can be used in other portions
of the body. This type of radiosurgery for other sites on the head
is still experimental but is a promising technique.
Guest: What is the gamma knife treatment?
Dr. Liem: Gamma knife is a device which can deliver very focused
beams of radiation such that a very specific volume gets radiated
with relative sparing of the normal structures around the area to be
radiated. This is performed by a team of specialists including a
neurosurgeon, a radiation oncologist, a radiation physicist and a
neuroradiologist. There are no incisions and usually does not
require admission to the hospital. Gamma knife can be an alternative
to conventional surgery. The treatment is done by first placing a
metal box or frame on the patient's head and affixing it to the
skull with four pins. This is done with local anesthesia, which is
injected into the scalp to numb the area. This is the only
uncomfortable part of the procedure and lasts just a few minutes.
The rest of the procedure is painless. The purpose of the metal
frame is to establish a coordinate system so that the abnormal area
can be targeted in three dimensions with an accuracy of under 1 mm.
After the frame is placed, the patient is taken for imaging studies.
This may consistent of MRI, CT scan and angiography with the frame
in place. A computer is then used to calculate the precise delivery
of the radiation to the AVM. This complicated planning is where the
combined expertise of the various specialists becomes very crucial.
Depending on the treatment plan, several treatments in the gamma
knife unit are performed, each usually taking several minutes.
Again, this is a painless procedure and the radiation beams are not
visible. Once completed, the frame is removed and usually the
patient can go home later the same day. Gamma knife has been useful
for various lesions in the brain including tumors and AVMs.
Guest: What is the typical recovery time?
Dr. Liem: The patient goes home the same day as the treatment.
For a couple of days, the patient may experience swelling and a
slight headache at the areas where the pins were located but that is
temporary. Patients have resumed a pretty normal lifestyle almost
immediately after the procedure.
Guest: Can having an AVM lead to a stroke?
Dr. Liem: Yes, when AVMs bleed, that can injure a portion of the
brain, which is what happens in a stroke.
Guest: Why do they call it a "knife"?
Dr. Liem: They call it a gamma knife because it was first
developed by a neurosurgeon named Lars Leksell. He coined the term
because of its high degree of precision, on the order of 1 mm
accuracy, which is similar to what we achieve with a knife with
surgery.
Guest: Could gamma knife be of help in the case of inoperable
cavernous hemangioma on the brainstem?
Dr. Liem: Cavernous hemangioma is another type of malformation of
blood vessels that can cause problems also by bleeding. Gamma knife
has been used for these types of lesions. The results, so far, are
inconclusive as to whether gamma knife can reduce the risk of
bleeding. There are some cavernous hemangiomas, which have bled
repeatedly which may benefit from gamma knife treatment. However,
more study needs to be done to prove that the gamma knife is having
a beneficial effect.
Guest: You mention that the screws are put in, do they actually
go into the skin?
Dr. Liem: Yes, the pins penetrate the skin and are firmly affixed
to the skull. This is necessary to prevent any movement of the frame
in relationship to the head. As mentioned, this is done with local
anesthesia so the sharp pain that is generally not present with the
use of the local anesthesia. Sometimes sedation can also be given to
specific patients.
Guest: I thought an MRI couldn't be done if metal was done - how
is this done with the metal plate affixed to the head?
Dr. Liem: The MRI has problems if there are ferromagnetic metals.
The material used in the metal frame is not ferromagnetic. I believe
it is made of aluminum and does not cause a problem in the MRI
scanner.
Guest: Who is the best candidate for gamma knife and vascular
malformations?
Dr. Liem: The best candidates for gamma knife treatment are those
in which surgery is not a good option. These are in patients who are
not medically stable for surgery. Other difficult cases include AVMs
deep within the brain. Gamma knife is also more effective in those
AVMs, which are smaller. Gamma knife can be used in AVMs up to 3 cm
in size. But those that are 1 to 2 cm can be treated with more
efficacy. Therefore, those AVMs, which are not amenable to surgery,
which are in a deep location and are relatively small are ideal
candidates for gamma knife treatments. Surgery is still the
preferred treatment for those AVMs, which are accessible in areas of
the brain that are relatively less important. The reason that
surgery is preferable is that the removal of the AVM with surgery
essentially removes the possibility of these AVMs bleeding. With
gamma knife treatment, the AVM does become obliterated but can take
up to two to three years to take place. During this period, there is
still a risk for the AVM bleeding.
Guest: Is GK better than what they have at Queen's?
Dr. Liem: At Queen's, they have a device called the X-Knife,
which is another type of radiosurgery device using a linear
accelerator. This is a similar device that can also be used to treat
these lesions. The gamma knife may, however, have advantages in that
it is more precise in its treatment.
Guest: When did you first learn about Gamma Knife?
Dr. Liem: I have been involved with gamma knife treatment since
1992. However, the gamma knife was a familiar topic even before
then, since the late 1970s.
Guest: Is it common for neurosurgeons to be trained to use the
Gamma Knife?
Dr. Liem: Although it is not a standard part of neurosurgical
training, with the increased ability of Gamma Knife, there are more
and more neurosurgeons who are trained to use the Gamma Knife.
Currently, it is fairly common to have at least a few neurosurgeons
at every major medical center wit experience in radiosurgery.
Guest: If the malformation is located on the brainstem, is this a
problem?
Dr. Liem: Malformations that occur on the brainstem are certainly
higher risk. The brainstem serves in controlling the basic functions
of the body and injury there can be devastating. With the precise
nature of the Gamma Knife, AVMs in that location can be effectively
treated. There is, however, higher risk in that area compared to
AVMs in other locations.
Guest: What does the gamma knife use? Radiation? Laser?
Dr. Liem: The Gamma Knife uses focused beams of radiation. It
uses a cobalt 60 radioactive source. There are actually 201 such
sources, each delivering a beam. It is at the intersection at these
beams at one point where the maximal radiation is delivered.
Guest: What is your success ratio and how do you measure success?
Dr. Liem: The success of treatment of AVMs has been very good for
these smaller AVMs. The larger the AVM, the less likely success is
possible. We measure by performing an angiogram after treatment.
This is usually performed 2 to 3 years after the Gamma Knife
treatment. If the vessels are completely obliterated and we do not
see any evidence of abnormal blood vessels on these angiograms, that
would be a success. The success rate for AVMs, which are less than 3
cm in size, is about 80 to 90 percent. The AVMs that are smaller
have a higher success rate. If there is still persistence of the AVM
on the follow-up angiogram, there is still a possibility for
re-treatment with the Gamma Knife or surgical resection of the
remaining portion of the AVM.
Guest: What is the cost of GK approximately and do health care
plans cover it?
Dr. Liem: The cost of Gamma Knife is very variable depending on
the insurance plan and the location. Most health care plans do cover
the treatment since Gamma Knife is a standard medical treatment
currently.
Guest: Does the GK rays burn the scalp?
Dr. Liem: No, the Gamma Knife rays are very weak at the scalp and
thus commonly do not have any affects on the scalp.
Guest: How many AVMs have you treated with the Gamma Knife?
Dr. Liem: Approximately 50.
Guest: How many people suffer from AVM?
Dr. Liem: Approximately 1 in 1000 people suffer from AVM.
Guest: What happens to the AVM after treatment? Is it reabsorbed
into the brain? Blown out of the nose?
Dr. Liem: After successful treatment of the AVM, the blood
vessels shrivel up and scar down. Sometimes a cyst develops where
the AVM was. Eventually, it does get absorbed. Guest: After a GK, if
it is unsuccessful, could a patient have another or still be a
candidate for another treatment?
Dr. Liem: Yes, if the initial Gamma Knife treatment is
unsuccessful, there is still a possibility for re-treatment with
gamma knife. Surgical intervention can also be entertained as well.
Guest: Does the GK only treat VMs? What other neurodisorders does
the Gamma Knife treat?
Dr. Liem: The Gamma Knife unit treats several conditions of the
brain. There are benign and malignant brain tumors that arise from
the brain, tumors that start in a different location including
breast and lung cancer, which spread to the brain, can also be
treated. Patients with a specific type of facial pain known as
trigeminal neuralgia can also be treated with GK. There are efforts
to treat movement disorders such as Parkinson's disease, also with
the use for the treatment of complicated pain. There are also
efforts for its use with psychiatric conditions including depression
and obsessive/compulsive disorder.
Guest: Can the scar tissue then cause epilepsy/seizures?
Dr. Liem: The presence of an AVM can cause seizures. With
treatment of the AVM with Gamma Knife, it does not seem to increase
the level of seizures. But, it is still unclear exactly how Gamma
Knife treatments affects the seizures.
Guest: What would be a very approximate success rate for use of
gamma knife on a cavernous hemangioma on the brainstem?
Dr. Liem: That is very difficult to estimate because the judgment
of success is very difficult to ascertain. In cavernous hemangiomas,
the angiogram is typically normal. Therefore, the angiogram cannot
be used as a determinate of success. The goal of treatment would be
to reduce the risk of bleeding. There have been some studies that
have suggested that treatment of GK in high-risk patients, that is
patients who have bled 2 or more times may have a reduced risk of
bleeding with GK treatment. However, there are conflicting reports
with that as well. At this point, there is not enough data to
advocate the routine use of GK for cavernous hemangiomas.
Moderator: When you treat the blood vessels, do you also lose
some brain tissue?
Dr. Liem: The GK is specially designed to be extremely precise,
however, there is still radiation that is given to the brain
surrounding the abnormal area being treated. Therefore, there can be
injury to the brain tissue surrounding the lesion. We, of course,
try to minimize this in our treatment planning.
Guest: What tests are used to see the blood vessels in the head?
Dr. Liem: The AVMs are usually diagnosed initially with either an
MRI or a CT scan of the brain. The method of establishing the
diagnosis is with an angiogram, which consists of a placement of a
catheter in the groin, injection of dye into the blood vessels of
the brain and taking x-rays to look at these abnormal blood vessels.
There are some techniques that can be used with MRI called MRI
angiography, which delineates the blood vessels using MRI
technology. Similarly, there is a capacity for CT scan to also
delineate the blood vessels in the head called CT angiography (CTA).
Guest: What is the evaluation process for gamma knife surgery?
Dr. Liem: If a physician has a patient that he feels is a
potential candidate for gamma knife surgery, what we will do is
evaluate these patients in a conference with all of the specialists
from the area. At this conference, usually a consensus is reached as
to whether GK treatment is appropriate. The diagnostic studies that
help us to determine this are MRI, CT scan and angiography. The
patient's clinical history is most important to determine whether
they will be a good candidate for treatment with GK. Once it is
thought that GK is a good option, the patient will be scheduled for
the procedure. It is usually a one-day procedure. It involves
placing a metal frame on the head affixed with four pins, which are
inserted through the scalp and into the skull. This is done with
local anesthesia to numb the four areas where it penetrates the
scalp. From then on, the procedure is painless. The next step would
be the performance of imaging studies, which could consist of MRI,
scan, CT scan or angiography. Then, a specialized computer is used
to calculate the treatment plan and again, this is performed with a
team of specialists including a neurosurgeon, a radiation
oncologist, a radiation physicist and a neuroradiologist. Once the
treatment planning is completed, the patient is placed through a
series of treatments in the GK unit itself where the radiation is
delivered. This typically consists of several treatments of several
minutes each. The entire procedure takes about 1 to 2 hours.
Afterwards, the frame is removed and the patient typically can go
home later the same day and resume fairly normal activities.
Guest: Can strokes or TIAs be treated with GK?
Dr. Liem: The typical type of TIA or stroke where there is lack
of blood going to the brain cannot be treated with GK currently. If
the stroke were caused by a brain tumor or an arteriovenous
malformation, those conditions would be amenable to treatment with
Gamma Knife.
Guest: is the patient awake throughout the treatment?
Dr. Liem: Yes, the patient is awake throughout the whole
treatment. In some patients, sedation can be given for the placement
of the frame but that is not routine. In some cases, for instance in
children, there may be a need to put the patient under general
anesthesia so that they will not move.
Guest: Is Hawaii the only place to get the Gamma Knife treatment?
Dr. Liem: No, there are over 100 centers throughout the world.
Mostly, in North America and Europe. There are also several hundred
other centers that perform radiosurgery using other techniques.
Guest: After you screw on the metal frame to the skull, are there
scars?
Dr. Liem: There are puncture sites at the four areas where the
metal frame is screwed into the skull but typically, these heal very
well and are difficult to notice once fully healed.
Guest: Does the head need to be shaved?
Dr. Liem: Typically, the head is not shaved. We usually place two
pins in the forehead and two in the back part of the head through
the hair.
Guest: Why doesn't Gamma replace traditional neurosurgery for
brain tumors? Since it is non-invasive, isn't this a win-win for
patient and Doctor?
Dr. Liem: Gamma Knife is very good for the treatment of certain
types of brain tumors and vascular malformation but it is limited in
that larger lesions are not effectively treated with the Gamma
Knife, particularly those greater than 3 cm in size. Microsurgical
techniques are still the preferred treatment for those larger
lesions as well as lesions which are easily accessible with surgery
since surgery will remove the entire tumor. Radiosurgery with the
Gamma Knife for tumors typically control the tumors by slowing or
stopping the growth of the tumor. The tumor itself is still present
within the brain. This is in contrast to conventional surgery where
the tumor is completely removed. The GK is a very good treatment for
certain tumors and other lesions but cannot treat every possible
condition of the brain.
Guest: Do you believe that gamma knife is the most precise form
of radiosurgery?
Dr. Liem: Gamma Knife is a very accurate and precise form of
radiosurgery and does have advantages over other types of
radiosurgery, namely use of the linear accelerator, however, there
are advances being made in the sophistication of the treatments with
other radiosurgical devices that make them very precise as well.
Gamma Knife does have the longest track record. It has been used
since the 1960s, with very little modification in its design. The
other advantage of GK is that there are no moving parts during the
treatment. Thus, thought to be more precise and accurate because of
that.
Guest: Are there any long-term effects of this surgery?
Dr. Liem: With any type of treatment, there are always risks and
potential side effects. Fortunately, with the GK, the risk is
relatively small but some of the long-term risks with Gamma Knife
include injury to the surrounding brain, which may cause swelling
and usually the swelling is temporary. Rarely does it cause
permanent deficits.
Dr. Liem: Thank you again for allowing me to participate in this
Expert chat. In summary, Gamma Knife is a very promising and
effective treatment for various pathologies of the brain. More and
more indications are being discovered as we progress. If you have
further questions about Gamma Knife or arteriovenous malformations,
you may wish to consult a neurosurgeon who is familiar with the
surgical and radiosurgical treatment options. I hope this has been
helpful and informative.
Moderator: This concludes this evening's chat on Vascular
Malformations and Gamma Knife treatment. AmericasDoctor would like
to thank Dr. Leon Liem of St. Francis Health Care System in Hawaii.
Dr. Leon K. Liem completed his undergraduate studies at the
Massachusetts Institute of Technology, and earned his medical degree
from Albert Einstein College of Medicine with a special distinction
in research. He is a Major in the Medical Corps of the United States
Army Reserves, and through June of this year was Chief of
Neurosurgery Science at Tripler Army Medical Center. Dr. Liem is a
member of the American Association of Neurological Surgeons, the
congress of Neurological Surgeons, the American Medical Association,
Hawaii Association of Neurological Surgeons and the North American
Spine Society. He is Board Certified by the National Board of
Medical Examiners and the American Board of Neurological Surgery.
Dr. Liem's clinical interests are in complex spine surgery, Gamma
Knife Radiosurgery, endoscopic spine & cranial surgery,
cerebrovascular surgery and pain neurosurgery. To contact Dr. Liem's
office, call 808-547-6950 or email neurosurgery@hawaii.rr.com. For
further information visit www.gammaknifehawaii.com.
Moderator: If you would like more information on Gamma Knife
treatments at St. Francis in Hawaii, please check their sponsor page
on www.AmericasDoctor.com. Also, be sure to check back for Upcoming
Expert Chats on www.AmericasDoctor.com. Our community rooms,
articles, medical library and message boards are available to you 24
hours a day, 7 days a week only on www.AmericasDoctor.com. Thank you
for participating in this Expert Chat and have a pleasant evening.
Reviewed by Steven J. Adashek, MD, FACOG, March 27, 2001
Copyright 2001 Americasdoctor.com, Inc. All rights reserved
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