I'm gonna talk to you guys a little bit today about stereo EEG or electroencephalography but first let's see I have no disclosures none whatsoever epilepsy we should all certainly as neurosurgeons any ones that seem anyone with epilepsy we should know this paper by Kwan at all just talking about how patients respond to medications if we're seeing these patients maybe because of trauma because of epilepsy evaluation but epilepsy is very common and this paper really puts into perspective how many of these patients are going to be or going to fail medical therapy so if you have one drug about 47 people will be controlled after that and then you can see that the percentage of people that respond to medication drops precipitously as you add medications as you see these patients they look at a history and often they'll have been on multiple you know five six eight medications whether for side effects and or failure but a large portion of these patients no matter what you put them on and after that third medication the chance that they're going to respond is exceedingly low so about a third of people will be uncontrolled on medications so then that what are their options or other options or surgery and what are the goals in surgery the goals in surgery or to cure people's epilepsy and how do we do that and we do that by addressing the epileptic Oh genic area and that's the difficult part for in surgery and in the evaluation by epileptologist s-- and surgeons is where is that area you can see here oh nice so this would be a scenario and there's a failure so you see there there's the actual seizure onset or the epileptic genic area and then you have a say a partial resection of that and yet you have not resected the entire area causing those seizures and you have a failure in your surgery on the other hand we know that if you can identify and then address with either resection or now with dr. Bowman speaking about stimulation you can prevent these seizures from happening but the difficult part is not necessarily the surgery itself or putting your lead in four RNs but is finding what patients can we target and with a focal resection or treatment and where exactly is this area so any workup this is a very standard so it's your phase one workup this is certainly the most extensive workup in all of neurosurgery when you go and see a patient in clinic who comes to speak with you about the next step the amount of time and resources that have gone into acquiring the information to try and locate seizure onset often is is staggering the I would say certainly one of the things that I appreciated especially being here and seeing these patients is you really have to really tease out the Seanie ology and really going to the history about how the seizures what the quality of those seizures are what type of seizures if there's any aura that be important and that's the first sign that the patient's having that something's happening and that may give you a clue as far as what part of the brain is actually being affected and your video eg your EEG your electrical information often your EEG may tell you frontal temporal onset and the laterality but the specific onset or the accuracy of a scalp EEG to locate to isolate an Anatomy if there's no lesion there is limited additional imaging we have to make sure this is concordant with the patient's semiology and putting the whole picture together to try and find out where the seizures are coming from so what happens after phase 1 testing a couple things can happen you can continue medical therapy sometimes people will go through the workup they're tolerating their medications okay there's not a clear cause and they just go back in and continue their medications perhaps they're not ready for additional workup they're very busy they may be having seizures that aren't interrupting that and so they continue and they can come in and out and you'll see people have video monitoring and then they kind of go back to their life and and kind of muddle through the other scenario are patients that come in there see me ology is classic force a temporal lobe epilepsy non-dominant they have an MRI the mesial temporal cirrhosis those patients are surgical candidates they don't need phase 2 monitoring to tell you that that's where their seizures are coming from so those patients can go right to see a surgical treatment others would be say someone that has medically refractory epilepsy and has multifocal onset generalizes very quickly those patients might be saying a candidate for directly to go to B and s but then there's phase 2 testing which is your intracranial monitoring and so when do we do that what patients are appropriate for that and so depending on what you'll read you look at there's no set scenario but I thought all these these were the ones that made sense it made sense is if people have their MRI negative where you don't see necessarily any lesion on their imaging and so you may be able to match their semiology with their clinical data but do MRIs negative and so you want to confirm that that's where you think the seizures are coming from or actually coming from that area well what about where your electrical data or your say your video EEG shows all left frontal onset but then your MRI shows a right frontal calve mal or focal cortical dysplasia well that doesn't make a whole lot of sense so you wouldn't know how to treat those patients so those patients we make a candidate for intracranial monitoring others would be multiple lesions or a very large lesion someone that has a either multiple focal cortical dysplasia or periaqueductal gray matter or nodule heterotopia rather you wouldn't necessarily know which one to target some people are working with packed for tubers and tourists LaRosa's see which one's the active legion so in that scenario that would be a patient that qualify for intracranial monitoring and then if there's a an area that involves a eloquent area where exactly is the border of that onset of a seizure or where is the say especially with speech if that needs to be mapped you would think about say grid for intracranial monitoring so our options are strips grids and strips or subdural electrodes certainly you can do epidural or you can read about them I don't know anybody that does that you certainly it makes it into the textbooks but I don't know anybody that does that so really it's sceptre electrodes or depth electrodes or some combination of those certainly the more common when I started in residency it was not uncommon for us to do a grid and then tempera hippocampal depth or Spencer depth electrode not uncommon at all but what's the technique that we want to talk about today and what's really while this is an old technique we'll go into some of the history it's really in the last 10 years it's amazing actually how quickly this is spread across really North America and what the technique is its stereo electroencephalography and it's a technique of using multiple multiple depth electrodes can be there's no set number but usually anywhere from 8 to say 15 you can always put more but probably 8 to 15 and you're doing individualized implantation so you're coming up with a hypothesis from your phase 1 trial about where you think those seizures are coming from whether it's a lesion you see whether it's the limbic circuit whether it's mesial frontal or or the posterior quadrant and then you're using those electrodes to then map out in 3d where the seizure is starting and where is it spreading to and how does that relate to the electrical activity and the clinical onset so you'll see often the an animo electro clinical correlation so you're tying all those things together with stereo EEG and then what it also does is it allows you to record from the entire length of the electrode if you look and imagine if you put a subdural grid on this area you would be say recording from just the surface of each guy right here but if you notice in this depth electrode you're measuring or you're recording all these contacts at say the lateral frontal lobe the depths of each of these sulci and then the mesial temporal lobe which would be very difficult to get to if you had a say an inner hemispheric you'd have to put an inner hemispheric grid in along with strips so it allows you to map out the entire area with multiple electrodes here you can see a patient already in the operating room oops sorry with only four so that would be a rather limited survey but certainly then you're able to record along that entire length of say the frontal lobe parietal over wherever that is and much of the white matter tracks also today seizures are the ability for a seizure to spread I was reading about some of the studies they had done where they were doing complete callosotomy x' and even those patients would have seizure spread to the contralateral side along the deep structures and so with sterile EG you're not only mapping out lobes or isolated structures you're mapping out entire networks and so you need to understand one how the different parts of the brain delinked in order to predict and make your hypothesis and detector seizure spread and onset and then spread so the creator or the person that discovered her first described this technique is Jean Kiley rock he lived from 1911 to 2007 he originally was a psychiatrist in Paris he practice in Saint Anne Hospital and he was very interested in psychosurgery he said psychosurgery is too important to be left to the neurosurgeons so he became a neurosurgeon and he became head of the department of stereotactic surgery most of his own stereotactic frame which you have there oops still getting used to this apologize he developed its own stereotactic frame and he used this for mostly movement disorders in psycho surgery but then when l-dopa came out he directed his attention from movement disorder to epilepsy because there was quite a bit of at that time there was still quite a bit of overlap between psychiatry and epilepsy especially mesial temporal epilepsy sometimes these were diagnosis anxiety disorders or something of that nature which they still are occasionally so then he partnered with the neurologist Sean boo code and the first actual surgery was in 1957 and then he published in 1962 in order to do this he would have his frame there and they would obviously there's no CT scan you could do Neuman cephalic Graham to get your a CPC but he would actually do a an angiogram within with the patient in the frame to identify the vessels and then avoid those vessels but you can see that trajectory which you do see in in some centers where it's straight in it's amazing that they don't hit anything but we'll go into that so this is a technique that was discovered and described in 1962 in France and really stayed in Europe and mostly Italy in France until probably 10 years ago here most of the expertise most of the papers of sinners that are doing it or we're doing this on a regular basis we're all French and Italian and then the group especially dr. Gonzalez Martinez started publishing in early or I'm sorry around 2010 started publishing out of the Cleveland Clinic and has really done an amazing job about spreading this technique in north america advocating for it teaching putting on courses and so a lot of the expertise in north america has come out of cleveland clinic so what is the preoperative workflow well we've already talked about our phase 1 workup this is where you will get all of your information to come up with your clinical or your hypothesis the imaging required is pretty standard in all right I'm sorry MRI brain t1 with contrast and the with contrast is simply because of the vessels this procedure what you're targeting you can see the amygdala the hippocampus likely you'll see focal court legislators or head a toe Pia's but what you have to see are the vessels most centers will get CT angiogram that then you will then blend in with your MRI to assist in your planning of your trajectories trajectory planning once again this has to be focused it has to be it can't it has to be individualized to the patient and where you think those seizures are coming from this is a very accessible or easy to have mission creep what we call where we if you don't start with a very focused hypothesis of where the seizures are coming from all of a sudden you can start going from well I will do a unilateral survey maybe we'll do a bilateral survey and all of a sudden you are trying to cover as much as possible but if you don't have a very focused hypothesis you're not going to answer a question and so it really has to the pre before you get to the operating room is where the important work is done when you do your targeting if you have multiple lesions you want to target those lesions if you're gonna target if you say want to answer the question is this patient having temple of epilepsy you want to target the structures where they'd be on set where you'd have pseudo temporal lobe epilepsy you want to target the insula posterior cingulate orbital frontal because those areas you will not see electrical activity and if it's necessarily on your scalp EEG and because the seizure per spread can be so quick you may not see that in semiology either so you need to know what the mimics are of certain seizure types and then cover those the intraoperative workflow these are always done under general anesthesia you the frame is placed or whatever device if you're using safe area guide you can use just the radiolucent skull clamp the this is a technique that has gone hand in hand and really promoted the use of robotics and the reason for that is the robots of this is the top there is the neuro matron a'shawn there's the Roza which is probably you are probably more familiar with we have one of those here today robotics has have been around in neurosurgery for decades but there hasn't been a huge application for them it seems that or it doesn't seem but really stereotactic techniques are the most likely to take advantage of this just because it's not it's about very fine measurements and very consistent measurements as opposed to a technique of say clipping an aneurysm or something of that sort the problem with it before the popularity of s e-g is Lexel frame is a very powerful tool and if you're putting in two leads the advantage of using the Lexile frame to say arosa is pretty minimal but if you have to change the coordinates on your luck cell frame 15 times all of a sudden your one and a half hour surgery with your rosa robot and turns into an eight after surgery with multiple chances for mistakes and measurements I'm not sure how many of you all have done DBS but how many times have you made a mistake where you thought it was your ex was say 45 or and you put it at 46 and the robot doesn't do that but so this is a technique because hand-in-hand with robotics we start once you have your trajectory planned you come in to bring the leave their flexible armor or robotic arm in a place just an incision and then you're using a 2.5 millimeter drill bit to drill through the skull some of the software you can actually plan your drilling along where you just hub the drill and your millimeter down others you have to actually it's a field technique where you're feeling to where you're through the inner table of skull and then you come out and you place your bolt which we'll do today and that's going to give you your trajectory move your stereo tech equipment out of the way Pierce the dura measure to your target and then place your electrode this is very quick you can see there that is a patient that has their electrodes in place that patient had already had craniotomy we'll talk about that as well but this is also an excellent technique if someone's already had a craniotomy has scarring you're not having to dissect the 7th row space to then put a grid in where is this you're just putting your electrode straight in the electorate itself is only point eight millimeters so very fine very delicate and the accuracy even with non robotic your accuracy certainly you can be very accurate we have unpublished data here that we're well under two millimeters on all of our placements once the leads in place you put the cap on tighten it and get a CT in trop you don't have any leads that are too far off I would say that the only thing that we've seen is sometimes you can your depth in your lead you you can that can slip a little bit a few millimeters but that that's really the only mouth placements that we've seen once you're happy with your placement either then place we put the patients in a head wrap and then they're to the ICU overnight we get another CT scan afterwards to actually see a brain window make sure there's no hemorrhage and then you can start monitoring once the electrodes are in place you're gonna do the same as any monitoring session same as video EEG where the day after you would start weaning seizure medications to then try and have a seizure to record that seizure and you're also doing video at the same time to see if the clinical onset matches your electrical onset they're typically this at least here it's usually about a week when these leads are in place once they're in place you want the patient to have several seizures that you've been recorded and you also want that to be the patient's typical seizure you don't want them to come in and have say they have several absence seizures that don't really bother them a month but but you're trying to capture say they're more comp they're more typical seizure you want to see the typical seizure and then see that electrical activity before you're happy with that the longest I think we've ever kept leads was one gentleman that it was for three weeks but that that is is rare stimulation with these electrodes is certainly more difficult than scepter oh I don't know if you interview ever chance and you're at a Center where you're doing epilepsy surgery and you have somebody with a grid in go with the neurologist or neurosurgeon to see the mapping it's very interesting and it gives you and then you can draw out on the cortex where speech is where motor is how that relates and then relate that to your either seizure onset epileptic a genetic area or some places will even do these for tumors but with stereo EEG it's a little more difficult because you're dealing you're not dealing with an easily described cortical surface you're dealing with a depth and so as you stimulate across that depth it's difficult to use that at least from a surgical standpoint to use that as a definitive test of function because you're stimulating across multiple white matter pass and it's certainly not the same as a grid so they're stimulating functionality and then there's also stimulating to bokeh or to cause a seizure this was the technique of finding the epileptic oh genic zone by the pin feel use where you do a craniotomy and keep the patient awake and stimulate until you cause their seizure well that's the place and some centers do advocate that this is if you can cause a seizure stimulating area and cause their typical clinical and electrographic seizure that is a high predictor that that removal of that area will then result in seizure freedom I think certainly some people a little wary about causing or evoking or I'm sorry provoking seizures in patients and certainly you would want to do that if you were going to do that at the end of their hospitalization but but that that that's not across all centers but some centers do advocate that after you have enough information from your leads it's a very quick procedure to take those out go to the operating room light sedation leads are out in about five maybe ten minutes patient stays one more night and then goes home the nice part about stereo EEG or the depths is that everything's collected the leads are removed the patient goes home and everything can then be reviewed in a relaxed manner and discussed in epilepsy conference with a grid once you have a grid in when you take that patient back to remove that grid you're removing that create your one for mapping purposes and - you're not you you're not gonna remove that grid and then talk about it and then go back six weeks later to do a resection you're gonna do it right then so to have a very in-depth informed consent with the patient and their family stereo EEG allows you to do that in addition to a more thorough potentially evaluation of the data so that is something that certainly people are fond of once you do decide if a surgical treatment is appropriate or could be beneficial then you can come back and do that we wait six weeks to allow any contamination from the previous procedure to have resolved and then you can do a surgical intervention if we've indicated once again with the stereotactic placement this leaves it dovetails or if it's nicely with a lot of our stereotactic treatments whether it's stimulation with RNs or whether it's laser ablation because you just go back you use the same trajectory you had on your initial plan and you can do your ablation if needed and so these are this is really true you guys hear this before but a time where stereo taxes and an epilepsy are really going hand-in-hand so when do you use or what are the advantages there subdural and scg we talked about reoperation if someone's already had a craniotomy there's published literature to show that you is more dangerous to do a sub drill grid you have a higher risk of hemorrhage if people have hard to access areas or deep areas so periventricular heterotopia s-- those you're not going to see with a grid if they have say mesial frontal parietal once again it can put an inner hemispheric grids in it can be a little challenging whereas accessing that with stereo AG is very easy so those would be areas where certainly stereo EEG has advantages with subdural grids the the clear advantage there is mapping eloquent areas more difficult with stereo EEG so is it safe I'm not sure his can I see a show of hands how many people have seen this at their Center has anybody seen it you guys have all seen it do you get does it bother you all that you're drilling into the skull and you don't see anything any vessels making on if you're right if you if this is you're just used to it and everything's fine maybe you don't you know no doesn't bother you but certainly the one of the Epilepsy surgeons when I was a resident when he saw it he said this is madness this is a cult why would you do that and and that if you're used to looking at the brain and not hitting things just drilling straight in the brain and sticking electrodes the question would be is that safe and so this is a meta-analysis from dr. Mullins he's also was at Cleveland Clinic and they looked at 30 studies 2,000 up more than 2,000 patients and they found that the surgical the surgical morbidity was 1.3 percent it was something but the risk was point 6 percent risk of a permanent neurological deficit and we'll get into that a little bit so there's a point six percent risk that you will have a permanent neurological deficit so that's not zero that's almost with one in 200 patients will could have a permanent neurologic risk and so similar paper it's almost the same paper out of University in Cincinnati they look at subdural grids and they found all sorts of risks that we all know patients with grids when patients have grids in if there children it's a lot of mass effects you can have hemorrhage and and you can have infection they're always leaking CSF a lot of times and so the risk was certainly higher overall from and then a 3% risk of unanticipated surgery but from subdural Gribbs but the but the difference here is I think it's like all minimally invasive techniques it's great until it isn't and it's very slick until something goes wrong whereas this when you're putting in a stereo EEG if you get a hemorrhage it's gonna be an intraparenchymal hemorrhage likely you can you could get a subdural hemorrhage but if you get a hemorrhage it's gonna be a from a depth electrode and so you get an intracranial hemorrhage so there's that I think that's the difference whereas if you're doing any open procedure usually the things are upfront you see them and while in say except through a grid you may have a hematoma but it's gonna be a probably a subdural hematoma it'll grow over time and then you have to take that out but the chance for permanent deficit was about the same maybe at least on this paper a little higher for stereo EEG so does it work I think that's hard not with any epilepsy technique it can be hard to standardize and look at but this was one of the papers from Cleveland Clinic where they looked at their one-year follow-up for 200 patients that undergone serial G and what they found was at one-year follow-up 68 percent of the patients were seizure free that is one-year follow-up and if you look at all of the reported case Erie's of stereo EEG patients that then went on to resection it somewhere before 44 and 68 percent I would say as you go on with any epilepsy patients more people have seizures so 68% at one year that's certainly going to go down at two years but if you look at the published data for people that used subdural grids it's around 50 percent so probably about the same so I always like the where are we on this curve as far as adaptation you know this is an actually an old technique yet with the advent of robotics and popularity North America this has really taken off I saw even in some well I won't say where but a smaller Hospital I'm familiar with there was a article in the local paper that they had gotten a roasted robot and I thought wow this is really this is really gone primetime so we're we're not I think that the tolerability of this procedure and the information that it gives you whether it's better or not than subdural electrodes it certainly is something that patients tolerate very well and we're able to get excellent information with it so this is something that's certainly going to be part of any institution that's doing epilepsy surgery so looking forward will show you some of the technical parts in the lab does anybody have any questions okay great thanks so much [Applause]