Transcription:
Minimally Invasive Cranial and Endoscopic Skull Base Surgery

Melanie:  Welcome to Better Edge, a Northwestern Medicine podcast for physicians. I'm Melanie Cole, and I invite you to listen as we discuss minimally invasive cranial and endoscopic skull base surgery. Joining me is Dr. Stephen Magill. He's a neurosurgeon at Northwestern Medicine at the Lou and Jean Malnati Brain Tumor Institute in the Feinberg School of Medicine.

Dr Magill, it's a pleasure to have you join us today. Before we get into this very interesting topic, tell us a little bit about yourself and how you came to Northwestern Medicine.

Dr Stephen Magill: Well, thank you for having me. I grew up in Indianapolis, just south of Chicago there and then went to undergraduate at University of Pittsburgh, where I got interested in neuroscience and majored in that. I then went to Oregon Health and Science University in Portland, Oregon, and studied neuroscience for my PhD there and also completed medical school as part of an MD PhD program. And given that background, it was a natural transition to go into neurosurgery. And I went to university of California, San Francisco for neurosurgery residency, where I was there for seven years.

As my training evolved, I became interested in brain tumors and in particular tumors located along the skull base. And I had an excellent training at UCF in those procedures, but I was interested in how can we move that forward with more minimally invasive techniques and expanding endoscopic approaches. So I went to Columbus, Ohio at the Ohio State University to work with Dr. Daniel Prevedello and Ricardo Corral, who are world experts in endoscopic surgery and maximizing what we can do through the nose as well as other minimally invasive techniques, such as using ports and things like that.

I recently got appointed to be a faculty member at the Northwestern University. And I'm really excited to come to Chicago and care for patients there.

Melanie: Well, thank you for that and welcome to our great city. So you specialize in minimally invasive skull base surgery. I'd like you to tell us a little bit more about this rapidly evolving field, how it's helping people with otherwise inoperable tumors. And tell us a little bit about skull base tumors and the type of disease processes that you treat.

Dr Stephen Magill: Yeah. So within neurosurgery, skull base surgery is one of the sub-specialties and the skull base really encompasses everything if you imagine from your eyebrows, the roof of your orbits, all the way along the skull base going posteriorly back to the spinal cord, where it comes out from behind your ears.

And traditionally, this is a difficult area to operate in because these tumors that arise in this area and pathologies in this area can compress the nerves that travel through here. So the space between the brain and your face is really the skull base and the brain controls all of our primary senses through this by controlling smell, controlling our vision, movements of our eyes, facial movements, which are so important for emotional and communication, facial sensation, hearing, swallowing or tongue movements. All of those are controlled by nerves that pass through the bone of the skull base. So when tumors arise along those areas, they can be difficult to operate and the nerves are sensitive. So making sure that you provide the best operation is really important in maintaining patients function.

Melanie: So tell us a little bit about diagnostic criteria and the types of preoperative evaluations. Are there anything new and exciting in radiologic imaging that helps with these complex diagnoses?

Dr Stephen Magill: Yeah. So most patients with tumors along the skull base, the most common tumor would be a meningioma. And then right in the middle of the skull base is the pituitary gland that controls all of hormones in our body. It's kind of the master gland. So tumors arising from the pituitary and then meningiomas arising all along the skull base are the most common conditions.

There's also other tumors that can arise like chordoma, esthesioneuroblastoma, chondrosarcoma epidermoid tumors among others. And when these tumors arise, often patients will present clinically with headaches as well as commonly cranial nerve deficits. So they have issues with the main sensation, facial function, swallowing, vision. Standard workup is typically with a CT or an MRI, and those are three tests. MRI is really kind of the standard of care now or 1.5, depending on where you're at. But a high definition MRI helps us see that.

As different sequences have evolved in the MRI, we've been finding new things like looking at diffusion imaging for tracking chordomas and going from there. But it really takes multiple modalities to diagnose these tumors, oftentimes a CT as well as MRI being the most common.

Melanie: So let's talk about treatment options for these types of tumors. Tell us about some of the advancements that have been made in treatment that can help surgeons to access these hard to reach areas as you mentioned of the skull. Anything that you'd like, intra-operative monitoring anything you'd like to discuss?

Dr Stephen Magill: So because of where these tumors are at, they're difficult to access historically. In the '80s and '90s, people often had to have transfacial approaches where they would split the mandible, and go through the face to get to some of these tumors. In the 2000s really, there was a great advance in technology with endoscopes. And we've been using endoscopic surgery through the nose and continuing to increase our understanding of the anatomy, imaging, interoperative navigation, as well as neuromonitoring to maximize the safety of these approaches.

Another challenge that happened early on, and it is the instrumentation. Obviously, if you have a nice big open corridor, it's easy to use traditional microsurgical instruments in the operating microscope. But when you're working through the nostrils, going through the nose to reach some of these regions, you need really specialized instrumentation.

So some of the big advances has been instrumentation and visualization with endoscopy. And then neuromonitoring to maximize safety. We can monitor all the cranial nerves. And depending on where the tumor is located, we can tailor that to each patient's condition to try to give them the safest operation.

Melanie: And doctor, given the complexity as you've been discussing of many skull based disorders and with increasingly complex treatment algorithms that add new options to your armamentarium of available therapies, can you speak about the multidisciplinary approach? Who would be in charge of guiding patients care? And has the introduction of this involvement of multiple subspecialists and this multidisciplinary team really been a benefit for these complex patients and for managing these patients? Tell us a little bit about a multidisciplinary team, why it's so important for these patients.

Dr Stephen Magill: Yeah, I think you hit on one of the true tenets of skull base surgery and that is that it is a team-based approach. These surgeries, because they involve both the face, head and neck, they can involve the orbit, they can involve the lateral skull base, hearing, the discipline has grown with a team-based approach and it's really bridging across disciplines that has let this field evolve.

So the key members of the team are the neurosurgeon like myself, the ENT surgeons. And within ENT, we have both rhinologists who are trained in accessing things through the nose, as well as otologist who are trained with coming through the bone behind the ear, the temporal bone. And then we also have radiation oncologists as an important part of our team. Many of these tumors will need adjuvant treatment with proton therapy or stereotactic radiosurgery. So we have ENT involved and then for all of our pituitary patients and tumors around the pituitary, we work closely with endocrinologists to optimize the endocrine care of patients because they can have hormonal abnormalities that are really devastating and replacing hormones and monitoring them before and after surgery is a really important part of this.

So as we come together, it's really important to have a good team with dialogue across all parts. For most meningiomas or pituitary tumors, usually working through a neurosurgical treatment team is we're the primary people who follow those patients long-term. And then pituitary tumors are also followed by our endocrine colleagues. Some of the tumors and things in the lateral skull base, like vestibular schwannomas, a lot of times those patients are co-followed with our otologist and us. And then for the more rare tumors, but they're true cancers of the skull base, which are not as common, but are really important, those often work through the head and neck ENT cancer team as part of that. And then we, as the neurosurgeon, will assist them when the cancer invades close to the skull base. We also work closely with our ophthalmology and oculoplastics colleagues, because oftentimes these tumors invade the orbit and we work together with intraorbital surgery as well.

Melanie: Absolutely fascinating. As we wrap up, Dr. Magill, what's on the horizon for treatment of these and other skull base tumors? Anything else that you'd like providers to know? And when do you feel that it's important that they refer to the specialists at Northwestern Medicine?

Dr Stephen Magill: You know, what's exciting is really the molecular diagnosis. In the past, skull base surgery was just "Get the tumor out" and it evolved to "Let's get the tumor out and preserve function." Then it was maybe "Don't take out all the tumor, but take out most of it, preserve function and radiate what's left." What we're finding now, and especially for a meningioma, is that we're beginning to develop some improved diagnostics based off molecular characteristics. And that's been an important part of my research and research going forward. The same is true for craniopharyngioma and other tumor up there, where depending on the mutation in the tumor, we can be much less aggressive because medical therapies are starting to come on board.

So I think for all of these tumors, being at a specialty center where you have a high volume of cases and access to clinical trials for tumors that are refractory to radiation and surgery or improve diagnostics, particularly looking at molecular and genetic-based diagnosis to predict recurrence and then to guide treatment at the time of recurrence. And we've been developing some very exciting work that will be coming out soon, looking at different molecular inhibitors for meningiomas that are very aggressive and recurrent. So I'm really optimistic for the future of that.

And I think getting patients to a center like ours allows us to follow them, allows us to care for them and walk through them. And then also connect them and being a part of the latest research and the latest genetic diagnoses and molecular testing that can really, in some cases, especially even the best example is with BRAF inhibitors for craniopharyngiomas is really transforming how we treat those patients. So that's when I would think to send patients.

Melanie: Thank you so much, Dr. Magill. Absolutely fascinating. And again, I want to welcome you to Chicago and we are so lucky to have you here. So thank you again.

And to refer your patient or for more information, please visit breakthroughforphysicians.nm.org. That concludes this episode of Better Edge, a Northwestern Medicine podcast for physicians. Please remember to subscribe, rate and review this podcast and all the other Northwestern Medicine podcasts. I'm Melanie Cole.