Speaker: Dr. Moreira speaks at Neuro Convention 2017
In June, 2017, Neuro Alert exhibited at the Neuro Convention in London. Here, Dr. Moreira, was asked to present "Introduction to Intraoperative Neurophysiological Monitoring in the International Arena." In his presentation, Dr. Moreira summarizes the role of Intraoperative Neurophysiological Monitoring (IONM), its techniques and utilization during Brain and spine surgery, NeuroInterventional Radiology procedures, head and neck surgery, and Vascular surgery.
About Dr. Moreira:
Dr. Moreira has been an Assistant Clinical Professor of Neurology at Cornell Medical Center, New York Medical College and New York College of Osteopathic Medicine and has served as the director of both the Electromyography lab and Intraoperative Neurophysiology service at St. Vincent’s Hospital. He has been Medical Director and Clinical supervisor of various Departments and Intraoperative monitoring practices. He has expertise in evaluating and treating disorders of the spine and neuromuscular system
and has performed IONM services for over thousands of surgeries both on-site and as a remote supervising physician.
Dr. Moreira is the current President Elect of the American Society of Intraoperative Neurophysiologic Monitoring.
Transcripts to follow:
So what I wanted to do is just give a little introduction to intraop neurophysiology. It's monitoring in the operating room during brain surgery, spine surgery, et cetera. And I just wanted to give our sort of basics, what the modalities are, what the science of it is, a little bit about ... just to give you an idea of what we do, and how it's done, and why.
So, what is IOM? I'll step back here for a little bit. So it's the continuous testing and monitoring of various parts of the nervous system during any procedure that places the nervous system at risk. We also use it for localization of certain parts of the nervous system to assist the surgeon and the team in where they want to operate, what they want to do, identifying crucial structures that should not be touched, or crucial structures that are of interest. It also helps identify vital areas of the motor cortex during tumor resections and things such as that.
It has different names. It goes by IOM, IONM, NIOM, evoke potentials, spinal cord monitoring, the monitoring guys, the monitoring girls, the monitoring team, et cetera. The American Society of Neurophysiologic Monitoring, of actually which I'm president incoming this year, if I'd be honored to serve with them, are currently revising some of our guidelines for monitoring, but we do have present standing guidelines. And the basics of what we do is neurophysiologic monitoring that includes any measure employed to assess ongoing functional integrity of the central and peripheral nervous system in the operating room theater, or in acute care setting.
The mission, basically, is to protect the nervous system. That's our main goal. The identification of certain parts is great, but we really are there to protect the nervous system. The second main idea is to open a real time communication between members of IONM team and the surgeon and the anesthesiologist, or anesthetist. The communication part is the largest connection in monitoring, and I'll talk about little how the ... how our practice works in the states, and how we monitor, and with real time supervision, et cetera, in a little bit, but the communication is a large factor.
How do we communicate with the surgeon, with anesthesia, with the nursing staff, and even with the patient in some instances, and definitely with the patient before and after surgery at times. It plays an important role in several ways. Number one, we want to warn the surgical team of any complications or any abnormalities. We want to identify a serious problem that needs to be corrected, and corrected rather quickly. As you know, with the nervous system, we have very little room for error, and very little wiggle room, so if things are going wrong, we may only have seconds to alert the surgical team. And in that time, we have to identify, is this a real change? Is it an appropriate change? Is it a technical change? Or is it something the surgeon has to act on quickly?
It allows the surgeon to feel comfortable, hopefully, with the patient's neurologic safety, and might allow them to even proceed a little further than they might be comfortable with without the monitoring. Certain times when they're resecting tumors, or dissecting, or clamping, or clipping, et cetera, or distracting, they would like to proceed to the best degree they can possibly proceed to, but sometimes, you just can't. And neurophysiologically, that information can come to us, and tell us, okay, we need to back up a little bit, or you need to take a different route to solve the problem you want to solve. And it gives the patient some comfort, or a lot of comfort as well, that we're reducing the risk of neurologic injury from the surgery or the procedure itself.
Members of the team are made up by the technologist and the monitoring personnel that are in the hospital. The technologist in real time supervising professional, it could be ... in the states, it's routinely a neurologist, it can be reading extenders, such as very high level trained neurophysiologists, et cetera. The surgeon is certainly the integral part of that team. We need to know what they're doing, how they're doing it, and sometimes it's nice to know why they're doing it. The anesthesia team itself. Everything that anesthesia uses will affect us to some certain degree or not, and can give us false changes, so we really need to communicate with the anesthesia very completely. Nursing staff, entire team, it's supposed to function as a unit as much as possible.
World-wide, there are ... and these numbers vary, depending on the source, but there's probably a couple million cases that could be monitored annually, at least, and probably double or triple that number, most likely, as the surgical procedures become more complex, requiring more protection of the nervous system.
We do have practice guidelines for how we do this, and again, they're changing and we're revising them as we speak, but the basics of how we test and what we test have been around actually 40 years. We just actually had our society annual meeting in the states at the Cleveland clinic a couple of months ago, and it was the 40th anniversary of intraop neurophysiology as a practice. And we're able to have a lot of the grandfathers and grandmothers of our field come over and celebrate that, and it was amazing to speak to them. Our testing hasn't really changed all that much. The basic tenants of neurophysiology and the testing itself are the same. It's the equipment and the amplification and the technology that's really brought it along.
We need outcome studies. The status right now of outcome studies, it's not that great. We don't have a lot of data that show pre and post monitoring, basically because it's hard to double blind that kind of a procedure where you say, all right, these patients won't get monitoring, these patients will get monitoring, let's see how they do.
So we're basically functioning from this point forward, but the best that we can do is to get some form of outcome study to prove to other bodies, government bodies, institutional bodies, insurance companies, et cetera that this is a very viable way to help protect the patient. And we need to educate. There is some education out there now in intraop neurophys, but not a lot. The model in the states is that individual companies or institutions will hire technical staff members, and train them in house. But unless you're employed by that entity, you really won't get an education. There is no undergrad programs around for it.
We just started a program that can help to train people from the ground up, and then give them the ability to step into the operating room. So we're trying ... we're developing our education program based on the needs out there, and then tailor them to each individual area as we need to. There's, again, a need for formal training, absolutely.
So let's talk a little bit about monitoring itself. What types of procedures and surgeries do we protect? Spine is probably the number one, just based on the sheer numbers of cases that are done. Vascular surgery, brain surgery, peripheral nerves, neurointerventional, that have become a lot more involved as far as procedures like coiling aneurysms and et cetera. So we have to evolve up to the surgical expertise that's out there, and sort of keep up with their technology as quickly as we can.
I have a lot of different slides that just are pictorial, so keeping with our schedule, I'll try to move through some of them quickly, but spine surgery, corrective deformities, kyphosis, scoliosis, et cetera. Basic bread and butter spine discectomies and fusions. More complicated cases, such as this one, that actually ended very well. This was a motorcycle accident. Disc replacements, tumor surgeries, detethering of the final terminal for the spinal cord procedures. Vascular malformations. Carotid surgery, aortic repair, many different vascular surgeries. Brain surgery, certainly, is my favorite. It's the most intricate of what we can monitor, and brings us up to the highest level that we can monitor at.
And probably, in speaking to a lot of folks about this, even recently at this meeting, there's a great need for a high level of intraop monitoring for a lot of these procedures. The approaches have changed. The techniques and the instrumentation have changed. And we're no longer just monitoring one of the cranial nerves because that's where they're operating, but we're monitoring the approach, the pathway, and everything else associated with. So we really have to raise our technique up to a greater level.
Peripheral nerve surgery, decompression, tumor, neoplasm, et cetera. Neurointerventional procedures, again, they've brought that up to a super high standard, so we have to keep up with what they're doing in the neurointerventional suite. And basically, what do we monitor? What structures? It's brain, spinal cord, nerve roots, peripheral nerves, muscles, anything in between. There are even pressure points on the body from just positioning a patient on an OR table that are affected. Nerve points at the elbow, brachial plexus from stretching and taping body parts, that type of thing. So we need to take the whole patient into consideration, and not even just the nervous system, per se.
The major components that make up IONM, if we can shorten it a little bit, are the technical part, which is the technologist in the operating room or physician in the operating room. I've spent of my 25 or 26 years in the field, I've spent about 20 of them in the OR theater myself, monitoring, setting up, working with the staff. And it's ... I realized early on, it's a physical dance to be in the operating room. It's not just sitting there and sticking needles in a patient, but it's getting out of the surgeon's way, light is swinging over so you better duck at the right time, getting out of the nurse's way. You definitely don't want to anger the nurses in the operating room or anywhere else, so, you need to move quickly. Anesthetists putting in their lines, and inducing, and intubating. They're positioning, a Foley catheter's going in, but yet you've got to insert electrodes, that I'll show you in a bit, in every extremity, in the head. There's tape that's coming off, because the patient's diaphoretic, or they used lotions the day before surgery, and you've gotta get this done all within the same timeframe of the surgeon getting ready to perform the surgery. So the last thing you want to do is delay anything.
It becomes a whole physical dance. And then it's the interpretive side. At least, in the US, the model is to have a physician either on site or online real time supporting the technical staff and communicating with the technical staff and the surgeon and anesthesia as well.
The practice models are different combinations of any of the above, depending on the institution, if it's an in house department at a university, or if it's a private company providing service. Certain private practices will have their own in house staff that follows them hospital to hospital. So there's various models that exist for that.
So what is the job of the intraop neurophysiologist? The main thing is to assure quality data. We're amplifying a tiny electrical signal somewhere in the nervous system thousands of times to get something that we can read on a regular and reproducible basis. So unless they can get us beautiful, perfect data on every acquisition, the testing is useless. So they're charged with going in there and trying to eliminate all that electrical noise, all the mechanical noise, all the darts that are being thrown at them, et cetera, and get us some quality data, as well as keeping the patient safe at the same time.
For their part, they have to understand the modality that's ... testing modality that's being used. The literature, the surgery, what the procedure is that they're doing, the pathology that exists, anesthesia and how it interacts, and all the limitations that exist with that system, and communication. Because unless we communicate with all components, as I said earlier, this whole system breaks down.
The education for these folks is of upmost importance, because without tying all that together, and learning the basics, and then some on all these modalities, you're not going to understand what's happening in the OR. And it's integral, and it's a key part of it.
The equipment is basically some computer boxes and wires and cables, and it's a laptop driven system. And they'll take that and they'll develop a monitoring plan. So we don't just walk in there and do a routine set up on ... it's not like looking an EKG. Every EKG is pretty much set up the same way. EEGs, for the most part, electroencephalography, the same thing. You follow your 1020 system, and you put your electrodes on.
Monitoring plan is a little different for intraop monitoring. Depending on where the surgeon is focusing their attention, what levels, what part of the neuraxis they're working on, our testing is going to be geared towards that. There are certain basic things that will always test, for the most part, but then we have to add in different layers of coverage, and different types of tests, depending on what we're doing. Some surgeons do the same procedure, but do it in a little different way. So we may have to monitor certain things differently from one surgeon to the next. So we really need to get to know the operative staff very well.
Anesthesia is a major part of what we do every day in the operating room, because any inhalant they give, any bolus drug they give, temperature, blood pressure changes, et cetera, are all going to affect our potentials and our testing. So we need to be aware of everything they're doing from lower the blood pressure, or raise the blood pressure, to hypothermic cardio cessation, looking for electro-cerebral silence, or anything in that range somewhere.
Many typical anesthetics that are employed, again, each of them have their own effects on the patient and on the neurophysiology. And what I'm showing here is different potentials and the effects of anesthetic on them. So I'll try to be Vanna White, if you were to watch Wheel of Fortune in the US. So just to give you an idea, starting out with very nice potentials on brain stem responses and how as you increase levels of gas, they start to flatten out in this area here. Same here for our [inaudible 00:16:07] potentials. They start out with a nice, large response, and as the level of anesthetic goes up, we lose it. So it's hard to say at that point, unless we know what's happening with anesthesia, is this a real change? Because now there's an ischemic event, or a compressive event. Or is it an anesthetic change that we don't have to really let the surgeon about other than maybe we need to lighten the patient up, et cetera. And the same with the other potentials.
We have to consider all of the other parameters, such as blood pressure, O2, CO2 levels and the balance that exists, temperature, heart rate, blood loss, CSF loss, intercranial pressure, et cetera.
The set up is basically using anything that can record a response from the nervous system. Most of it is a little bit invasive, there's small, subdermal needles with a wire attached, of which will tangle, invariably, on every single case. And we'll have maybe 30, 40, 50 little needles and electrodes and wires, and I can tell you there is just no way to do it without them tangling. Even if they're braided, and they're paired. Everybody has a couple of little tricks that they employ, but for the most part, you depend of tape, lack of sweat, lack of lotion, and a lot of luck, so. But there are definitely ways, and a lot better needles that actually will stay in place on their own a lot better. So technology has come a long way.
There's adhesive surface sticky pads that will stimulate through or record through clamp electrodes, bar electrodes, et cetera. The ankles are showing you the stimulation pads over the post area tibial nerve. The wrist is showing you needles are recording over a median nerve, or stimulating a median nerve. And different ways of taping down and recording. And this is basically ... that's a very simple set up. Usually there's about 10 times more wires coming off an extremity than that. We just try to keep it simple.
So what modalities are we testing? We're testing evoke potentials, which is stimulating a peripheral nerve and getting a cortical response, or a response anywhere in the neuraxis from the your stimulation. So you stimulate once, and you may get nothing. Or you may get a response, but the next stimulus may look a little different, because you're averaging ... you're recording a lot of noise and a lot of background. But there is, in that one waveform, a reproducible waveform is you continue to average one stimulation trial with the next and with the next.
So it'll do 2, 3, 400, 100, whatever the stimulation point is for that procedure, and try to average out all the noise and get one potential. We can do things like brain stem auditory evoke responses, delivering a click stimulus to the ear, and measuring brain stem responses to that. Electroencephalography, ENG activity from the muscles, we do it as free running activity so that it's always running through through the case. So the surgeon is tractioning, or doing anything to a nerve root, we'll know about it. Or a peripheral nerve, we'll get real time activity immediately, and we'll be able to inform the surgeon right away that things are changing.
Pedicle screw stimulation, as they put in instrumentation, we can stimulate that instrumentation and make sure they're not too close to nerve roots. It's been no breach in the bony process itself, et cetera. Stimulating tumors, stimulating any structure in there to make sure that things are safe.
Going to move through this a little bit quicker just to give you an idea of what the set up is like for somatosensory evoke potential. Stimulating at the ankle, recording behind the knee, recording behind the neck, and then recording from the brain. So we can see our potentials at various levels.
This is what they look like. Those are very nice, clean somatosensory evoke potentials recording from various levels, stimulating from upper extremities and lower extremities. They don't always look that nice, but if you're good, and things are working well in the OR, and the patient has the right substrate, we'll get some nice responses.
This is a typical display of what we'll see on average cases where there are somatosensory evoke potentials and free running electromyography from various muscles bilaterally, and a little bit of EEG, to basically help us a little bit with depth of anesthesia and that type of thing.
So we look for any change in our data, especially with SEPs, we look fr a 50% drop in amplitude, or a 10% increase in latency. Anything suspicious if the morphology is changing. Sometimes you just look at it and you get a [inaudible 00:20:47], you don't have to look at the number, you don't have to do your calculations. You could just say this ins not looking like it was before. You look at your stack, and things are changing. So you get a feel for it. And a lot of times, I've told the surgeon, you know what, are we at 50% or 10%? It's like no, but I just don't like the way it looks. There's something happening, and invariably he'll say yeah, I think there's something cooking here or there. So it takes a little bit of experience as well to look at these changes and interpret them in an holistic manner as well as looking at the data itself. And the only thing from this take away from this is that abrupt changes are bad, usually, unless it's a pulled needle or a dislodged electrode, which you'll know right away. Your slow, gradual changes you're a little less worried about, but you can have more time to make some changes.
Motor evoke potentials stimulate the brain, get a motor response in the same way. And that's what those potentials will look like. And those are very useful, because if we do get changes in motor evoke potentials, we're a lot more concerned of a real change, because they are just more resistant to physiologic changes being with the anesthesia, being held that where we need to have it for those potentials. And that's just what a look at motor evoke potentials.
Risks, there are some risks of burns, skin burns. Have not seen on in 25 years. Some tongue bits, for sure, so you have to make sure a good bite block is in place, et cetera. Different criteria for change for motor evoke potentials. All or none phenomenon, either it's there or it's not. Or different levels of stimulation increase and intensity that you need to use to illicit a response. EMGs, we just look at the MG tracing, wee if there's any abnormal activity as the surgeon's proceeding with the case. And they'll be either bursts in EMG, or they'll be a sustained activity, so that will tell us what's happening as well. Our recording electrodes, the subdermals, their surface electrodes. We can do EMGs with the cranial nerve innovated muscles, et cetera, not just a peripheral system. And that's just showing you a little bit of abnormal EMG activity right there. In that particular ... that's a tibial [inaudible 00:22:56] anterior, so there's probably something going on in L45 level that can give the surgeon an indication of what's happening. Same thing there. And there.
We can do direct nerve stimulation. Stimulating structures, looking for responses. We can test the hardware. Pedicle screw stimulation is one of the bigger things and ore common things that we do to make sure that the pedicle is in tact, it's not breaching a nerve root. EEGs, very classic electroencephalographies, just to help us ... if it's a vasculous case, or a carotid case, it helps looking for cortical ischemia when they clamp, et cetera. So I'll just move through.
Auditory brain stem evoke response testing, we talked about a little bit. And [inaudible 00:23:43] criteria is, you know, if they're tractioning the cerebellum out of the way, let's say to get to an acoustic neuroma, or a microvascular decompression of a trigeminal nerve, then we look to see that our waveforms are not exceeding a certain amount of increase in latency, because you will stretch things. As you stretch things you make them narrow, if you make [inaudible 00:24:04] narrow, you get less blood flow, and something will suffer on the other end, for sure.
This is just showing a little change as they're tractioning the cerebellum up. It may be hard to see, but the red tracing was the baseline here, and out here to the right is the peak of the new baseline. That's showing you that there's a little ischemia on the eighth nerve. So what you don't want is to have a patient come out of a surgery with no facial pain, which is great, but be deaf. So we need to watch all other areas, not just the areas of operative interest.
Here, we look to see if there's any neuromuscular blockade issues, because they will give an indication to paralyze the patient during surgery, which can hamper some of our monitoring as well. So we do four stimulations on a nerve, we get a muscle response. Cortical mapping, try to guide the surgeon in to a safe area of the brain. Any tumor edema will mess up the architecture terribly on the surface of the brain, so you might not see the central nerve, you may have to do some phase reversal testing and things like that to assist the surgeon in approaching the tumor from the safest place possible. Direct cortical stimulation is another way of just stimulating the brain at different areas with a handheld probe to assess, is this a motor area? Is this a sensory area?
Things like positional changes that I mentioned before are very common, and I see them probably several times a week. So in looking at this, this is stimulating the upper extremity for somatosensory evoke potential. Getting a nice response. And then having a positional change where the patients elbow is bent, so at the elbow now, they have either a traction or a compression, and losing that response that's circled in yellow. And then moving the patients arm into a positive position, and then losing ... and then regaining function quickly.
The last thing you want is to have a patient go in for a microdiscectomy of L5 in the low back, and then wake up with an unknown paralysis in the hand. So it's common. It does happen frequently. So it's something to be aware of. You can see in the red tracing a nice, healthy looking tracing, especially on the left side of the screen, and the white, new tracing is just basically some fade from anesthesia. So is that a real fade or is it anesthesia fade? So that's something we need to know from communication.
Blood pressure changes, the top tracing in red, those red traces, a nice, robust motor potentials. Actually, I'm sorry. The top tracing, the green, are flat, showing that we've lost our motor potentials. The lower tracing, normalized blood pressure, the green tracings are back, because we've now raised the blood pressure back.
Operating room is definitely a hostile environment. Electrically speaking, mechanically speaking, and every other way. So we need to help the surgeon to get through things, we need to not mess up our wires and our connections, we need to know what anesthesia's doing, et cetera. And it's all about communication.
These are my five kids that have all rode on the crew team at some point through high school, and in college, in two instances, and what they do is all about communication. The coxswain is basically telling the rest of those eight rowers one at a time down the road what they should be doing, how fast they should be doing, and their timing can't be off a split second, or that boat's not going to move. So it's a great lesson in how we should communicate.
Communication is one thing, but we need to educate. If we don't have education in this field, we're going to have standards that are all over. And the surgeons need to go in there having a sense of security that when we step into that room with them, we know what they're doing, we have a good handle on what they're doing, we are communicating for them with all parts of our team, and we're providing the best care that we can possibly provide for that patient. The patient comes in, they're asleep, and now their lives and their nervous system, at least from map points, are in our hands. Surgeon has an incredibly tough job to get in there and fix something, and sometimes a microscopic area through an approach that's tiny.
Talks like Thomas this morning, talking about a very small, tiny area of interest ... whoop, sorry. And having to negotiate in there and not cause any damage, but yet still see your surgery, still see what you're doing, and still be effective.
So we've developed a program called CED, which is the Center for Electrodiagnostics, which trains people from the ground up in intraop neurophysiology. It's a didactic program, it's online web based, as well as in house, as well as in the operating room theater, to give them that well rounded education. And I can tell you from training people over the years, over 25 years, there's always something missing from the piece of any educational program, which is an in house, company based, or institutional based program. We've develoPed with that experience a very well rounded program that takes on a 360 degree approach, and gives our folks the experience to sort of step out and start monitoring at a basic level, because this is something that does take years to develop, but with the right supervision, you can start doing some high level cases, and really start to accelerate your education.
We have our students shadowing our senior neurophysiologist in the operating room as well, doing some high level cases, observing high level cases, and we train them to be certifiable. So in the states, we have the CNIM, which is the Certificate of Intraoperative Neurophysiologic Monitoring, which is offered by, I believe it's ABRET, which is A-B-R-E-T, it's a board of electrophysiology in the states, and it's a very rigorous exam. Takes into account anatomy, physiology, surgery, instrumentation, electricity, amplification, anesthesia, the whole picture. And it is ... if most physicians take it in the states that practice neurology, we don't even come close to passing it, because this is such a specialized exam to take. So the program's designed to get them through that exam as well, and come out the other end so they can be certified, and have a higher status in their field, and be able to provide a great function.
It's a self-paced learning for a six month period. There are certain benchmarks that need to be reached at certain times. There's live classroom training. And the hands-on part is the biggest, because unless you're in there, and again, you're getting used to that dance, it's going to be very difficult to set up and to do a proper job. So the on site training is a key piece of it.
Dr. Seshan who was the founder of the program, and a physician and intraop neurophysiology expert for years, was one of the grandfathers of the field, started the program with the thought in mind of nothing but academic excellence. And the reason I'm currently with this program is because of that level of excellence. To much bad things could happen in the OR just normally on a routine day. So that if you're not at the top of your game, and you don't do the state of the art monitoring, something's going to be missed. And if you miss a little something in the operating room, you're missing a tiny neurofiber that controls such a tremendous amount of function anywhere in the body, patient has devastating ... it has devastating effects on the patient. So it's really key to be at the top of our game when we're training these folks to do this the proper way.
We do have an eight week prep course, as well, to get people ready for the scene in exam, so they can get out of their training, get their certification. Most hospitals in the states now will not even allow them to be credentialed to practice unless they do have the CNIM exam at this point. So it's becoming a standard of care for us.
We cover the fundamentals, all the way up through the most intricate parts of neurophysiology and monitoring itself. It helps with finding jobs. The field is wide open. We found, from being here a little bit, and doing some exploration out in the international community is that there's an amazing need for intraop neurophysiology. The manufacturers have come to us and pleaded with us, we've just sold a bunch of systems to a hospital system, no one there knows how to use it. The surgeons want the monitoring, we bought the systems, but now, no one knows how to monitor. And that's been the case in almost every country we've looked at. UK's a little different, because they do have a great system of monitoring in place, but there's also a need, a drastic need, for education, and for more people to enter the field.
Job requirements, basically you need to be able to get in the operating room and deal with split second decisions, deal with pressure from surgery, anesthesia, from the supervising neurologist, et cetera. And understand what's happening with the patient.
So with that, I want to thank you guys for hanging in there with me. I know I presented a lot in a short period of time, but I just want to ... what everybody's appetite as to what intraop neurophys is. If there's any questions, I'll yield the floor to our next speaker, and I'll be outside the booth. We also have our booth, the CEN, right out in the front main entrance right here. It's a green booth on the corner, so please stop by and say hi, and we'll tell you some more.