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Steven D. Chang, MD, on Brain Tumors and Cerebrovascular Disease
An interview with Steven D. Chang, MD, Co-Director, Stanford Cyberknife Program, providing detailed information about ...
About Steven Chang
In a 2009 interview for Stanford Medical Minutes, Steven D. Chang, MD, then a professor of neurosurgery and co-director of the Stanford CyberKnife program, discussed the treatment of brain tumors and cerebrovascular conditions. He described advances such as image-guided navigation and electrophysiologic monitoring, and explained the CyberKnife as a frameless, outpatient radiosurgery system that delivers highly focused radiation in a single session. Chang noted that treatment decisions for benign brain tumors depend on factors like size, symptoms, and patient age, with large tumors often requiring conventional microsurgery and smaller ones suitable for radiosurgery. Chang also addressed malignant gliomas, stating they are managed with a multimodality approach combining surgery, radiation, and chemotherapy. He discussed arteriovenous malformations (AVMs) as abnormal blood vessels at risk of hemorrhage, with treatment options including surgery, radiosurgery, and embolization. For aneurysms, he described surgical clipping and endovascular coiling as available options, and for trigeminal neuralgia, he noted that medications often fail, leading to surgical interventions such as microsurgery or CyberKnife radiosurgery.
Transcript (30 segments)
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Announcer0:00
This program is brought to you by Stanford Hospital and Clinics.
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Stefan Mandia0:10
Hello and welcome to Stanford Medical Minutes. My name is Dr. Stefan Mandia and I'm here with my colleague Steven Chang, professor of neurosurgery. Stephen, give me a little bit of a background on the Stanford program with regard to brain tumors.
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Steven Chang0:26
Well, the Stanford brain tumor program within the department of neurosurgery is a very comprehensive program in terms of managing all types of brain tumors that present. As you may know, brain tumors come in a variety of different types. There are very benign brain tumors and there are much more malignant brain tumors and the treatment challenges for managing each of these tumors is highly patient specific depending upon type of tumor and the specific nuances of each individual patient. So the goal of a comprehensive brain tumor program is to be able to offer a whole variety of different options for each of these patients to optimally treat each one.
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Stefan Mandia1:09
And can you give us a sense of what's new with regard to brain tumor surgery or in the field of brain tumors?
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Steven Chang1:17
Certainly, in terms of actual surgery in the operating room, there are a number of advances that have come along over the last 10 years that really have helped us deliver better care to patients when in the operating room. One of the advances has to do with what's called image-guided navigation. And when do you utilize image-guided navigation? I like to tell patients that image-guided navigation is like a GPS satellite for your brain. It helps the neurosurgeon who's operating on your tumor know precisely where to make the opening into the bone to expose the tumor and really helps guide us through the brain tissue to get to the tumor. Very similar to a GPS navigation system in a car where the navigation system will guide you from point A to point B.
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Stefan Mandia2:10
Mhm. And I also understand that there are numerous monitoring mechanisms by which to perform the surgery in a safe fashion. Can you elaborate on some of those?
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Steven Chang2:22
Certainly, what I think you're alluding to is what's called electrophysiologic monitoring and that is a technique that we do in conjunction with the neurology specialist at Stanford in which during the operation electrodes are placed on the scalp and the arms and legs at the start of the operation and this really allows us to monitor the electrical activity of the brain during the surgery. So while the patient is asleep under anesthesia, we may not be able to ask them how they're doing or talk to them. The next best thing is to monitor this electrical activity in the brain. And it gives us real-time feedback in terms of how the neurologic system is functioning during the surgery. It really allows us to deliver safe care for these patients.
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Stefan Mandia3:08
You mentioned that the Stanford Center has a comprehensive approach to brain tumors. Are there other adjunctive therapies that a patient or a prospective patient can receive at Stanford? And do you work with other departments to provide that comprehensive care?
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Steven Chang3:26
The goal of a comprehensive program is to really have all the aspects of brain tumor care available. So we certainly work with a wide variety of other disciplines. For example, I mentioned the neurologists that work in conjunction with us in the operating room to do the electrophysiologic monitoring. That's certainly one component. We work with the neuroradiologist. They are very useful both before surgery in terms of helping us interpret films as well as during surgery if we need to perform, for example, intraoperative angiogram to give us information about the surgery before it's completed. We also work with a variety of other surgical specialists. For example, when dealing with acoustic neuromas, which is a type of tumor on the hearing nerve, the neurosurgeon works in conjunction with an ear, nose, and throat specialist or a neurotologist. We do the surgery in conjunction with each other combining our collective expertise to deliver the best care for the patient.
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Stefan Mandia4:31
I see. Once the patient has been treated with surgery, what other options are available with regard to again the comprehensive care a patient with a brain tumor can receive?
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Steven Chang4:44
That's a very good question, Stefan. Some patients the surgery alone is sufficient to deliver the best care for their tumor. In other patients we will often use post-operative radiation and there's a variety of different types for that. We also have a very strong neuro-oncology program. So these are neurologists that specialize in management of brain tumors from a chemotherapy standpoint. And so as neurosurgeons, we work closely with those specialists as well.
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Stefan Mandia5:12
I think most people are certainly familiar with the standard radiation therapy that's been around for decades. Can you introduce the term cyber knife and distinguish that from conventional radiation therapy?
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Steven Chang5:26
The cyber knife is really one of the centers of excellence at Stanford. It's something that was developed at Stanford and we have a significant level of expertise with cyber knife radiosurgery. So what the cyber knife is is a machine to deliver a very highly focused beam of radiation to a tumor. So unlike conventional radiation which is a wide field of radiation beam which both treats the tumor but exposes a lot of normal tissue to the radiation. For example, whole brain radiation you're radiating the tumor in the brain but you're also exposing the rest of the normal brain to the radiation. Unlike that conventional radiation, the cyber knife is pinpoint accuracy. It's like a laser beam of radiation to zap a target within the brain. So the advantage of the Cyber Knife is severalfold. First, it's an outpatient non-invasive treatment. It doesn't require any downtime or hospitalization from the patient standpoint. And unlike conventional radiation, which can take several weeks, if not over a month of treatment, coming in every day for a treatment, the Cyber Knife can often be done in a single session of 30 to 60 minutes. So the attractiveness of the cyber knife is it's truly kind of cutting edge medicine, outpatient, non-invasive, highly successful at killing specific types of tumors in the brain.
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Stefan Mandia6:57
With regard to the cyber knife system, how would that be distinguished from other stereotactic radiosurgery possibilities, if you will, considering for example gamma knife or some of the other commercial systems available?
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Steven Chang7:12
That's a good question, Stefan, because the differences can often be subtle and patients can have a hard time distinguishing between the different systems out there. The Cyber Knife is the latest generation of what's called radiosurgery. And radiosurgery is the use of a machine to deliver this highly focused beam of radiation. And unlike the gamma knife, which is an older technique, it requires a metal frame to be rigidly attached to your skull with four screws that screw into your skull. The cyber knife is a completely frameless system. So we can deliver the radiosurgery with just as high a degree of accuracy as the gamma knife, for example, without the invasiveness of having to have a metal frame or screws attached to your skull.
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Stefan Mandia7:59
I see. And the absence of the frame is what lends itself to being this outpatient procedure.
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Steven Chang8:08
Certainly that's one of the aspects of it. It allows us to deliver the radiation in a comfortable setting to the patient without any kind of the fear of surgery or cutting or hospitalization that patients typically associate with conventional surgery.
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Stefan Mandia8:25
Can you comment perhaps on the treatment of benign brain tumors and how they would be different from malignant brain tumors?
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Steven Chang8:35
The treatment of benign brain tumors depends upon several factors: size of the tumor in the brain, what underlying neurologic symptoms the patient is currently having, the age of the patient, as well as medical comorbidities. In certain cases, when you're dealing with a large brain tumor, even if it's benign, there's usually mass effect on the brain where the tumor is pushing on the brain. In those situations, conventional surgery in the operating room under a microscope is perhaps the ideal situation because we have to really take pressure off of the brain to maximize the chance of the patient having normal neurologic function after treatment. But for small to medium-sized benign brain tumors, some examples would be meningiomas, acoustic neuromas, or hemangioblastomas, radiosurgery in the form of a cyber knife is a very effective treatment. Very high control rates, very low side effects or patient morbidity. It's certainly an attractive alternative to conventional surgery for these patients.
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Stefan Mandia9:46
I understand that one of the vexing questions in neurosurgery over the last several decades has been malignant gliomas and their management once a patient receives surgery which is standard of care for that type of lesion. What concepts or how can local control best be achieved?
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Steven Chang10:05
Malignant gliomas are tough tumors to manage because they have a tendency to recur. We often say with these tumors it's not a matter of if the tumor is going to recur, it's a matter of when. So malignant gliomas are typically managed with a multimodality approach: combining surgery with radiation and chemotherapy. That's why it's important to have a comprehensive brain tumor program so that you have experts in all these disciplines to optimally manage the patient.
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Stefan Mandia10:47
Now there's certainly other brain lesions that you also treat. Give us a sense of AVMs and AV fistulas, how they present and what treatment options are available for these problems.
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Steven Chang10:56
AVMs, which stands for arteriovenous malformations, are not a tumor but an abnormal cluster of blood vessels within the brain. The primary risk to the patient is these blood vessels can rupture and hemorrhage. For a lay person, you might think of them as a type of stroke. When these vascular malformations are discovered, we try to treat them in most patients to prevent catastrophic hemorrhages. Treatment can include surgery in the operating room, but also radiosurgery, like cyber knife radiosurgery, as an outpatient alternative. Like brain tumors, we tailor treatment to the individual patient. We spend a lot of time studying pre-treatment MRI scans, angiograms, interview the patient, do a thorough clinical workup to come up with the best treatment. Sometimes it's a combination: surgery to treat a portion of the AVM followed by embolization, which is a procedure where the interventional radiologist shoots glue into the AVM to seal off blood vessels. That can even be combined with radiosurgery. We certainly have AVM patients that receive all three modalities: surgery, embolization, and radiosurgery to optimally obliterate the AVM.
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Stefan Mandia12:42
With regard to aneurysms, the options include surgical clipping and coiling or endovascular therapies. Both are available at Stanford and there is a means to discuss these treatment options and tailor that treatment specifically to the patient and their condition.
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Steven Chang13:00
That's correct, Stefan. Aneurysms are a small bubble or blister on the side of a normal blood vessel. Similar to a balloon, an aneurysm can pop or rupture, causing a catastrophic hemorrhage. Treatment can be challenging, especially when the patient is already ill from a rupture. At Stanford, we have a comprehensive program including neurosurgeons and interventional radiologists. The two primary treatments are surgical clipping, where we go into the brain, identify the aneurysm under a microscope, and place a tiny clip across it to obliterate it, preventing rupture. The other is coiling, often used when clipping is not optimal or coiling is the best option. In coiling, performed in the angiography suite, the interventional radiologist feeds a catheter through the blood vessels to the aneurysm and fills it from the inside with coils, which prevent blood from entering and thus prevent bleeding. The take-home message is that for aneurysms, like brain tumors, you want a comprehensive facility with all options available to optimally manage patients.
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Stefan Mandia15:18
I understand that you also treat a condition called trigeminal neuralgia. Tell us a little bit more about that condition.
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Steven Chang15:26
Trigeminal neuralgia is a syndrome where a patient suffers severe facial pain, often described as electrical shock-like pain when they move or touch their face. Common triggers include brushing teeth, washing your face, or eating dinner. The pain can be very debilitating. This is not a standard headache; it's sharp, electrical shock-like pain, sometimes described as an ice pick in the face or behind the eye. Treatment usually starts with medication, but when that fails, we consider surgical options like microsurgery in the operating room or cyber knife radiosurgery.
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Stefan Mandia16:29
Okay. If there's a patient in the audience that has questions on some of the topics we've discussed, what's the best means by which they can contact someone to have these questions answered or if they perhaps want to be evaluated in a medical consultation?
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Steven Chang16:46
We're always more than happy to evaluate any patients that desire neurosurgical consultation at Stanford. We have a variety of specialists in the neurosurgery department with particular expertise across all disciplines of neurosurgery. So if a patient has a spine problem, they would see one of our spine surgeons. If they have a brain tumor, they may see myself or another brain tumor specialist. Our contact number is on the Stanford University School of Medicine website and the Stanford Hospital website.
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Stefan Mandia17:28
Thank you, Stephen. We appreciate it.