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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