Next, we have Dr. Chen. She's going to be speaking to us on clinical outcomes in a large series of subtemporal selective amygdalo-hippocampectomies for medically refractory epilepsy. Hi. My name is Shinsu Chen. I'm a chief resident of the Barrow Neurological Institute. Thank you for giving me the opportunity to present our clinical outcomes following a large series of selective amygdalo-hippocampectomies. I have no disclosures. So I think most of you in the audience are familiar with the ongoing discussion regarding which surgical approach is favorable for treatment of mesial temporal lobe epilepsy. And this study from the German group came out last year looking at different surgical approaches. And what they concluded or what they found was that there was no significant differences in seizure outcome between the different respective procedures. And they concluded that different surgical approaches for temporal lobe epilepsy resulted in similar seizure neuropsychological outcomes as well as complication rates. And, of course, now we also have to consider laser ablation. Dr. Gross' group recently published their results stating that seizure-free rates were comparable or lower than but comparable to outcomes typically associated with open temporal lobe epilepsy. And we also heard earlier in this section Dr. Jonas' results on their laser ablation series as well, which were quite excellent. So at our institution where we have a large volume of patients that undergo this selective sub-temporal approach, we thought it would be a good opportunity to look at our clinical series and our outcomes after resection. So we included consecutive patients with medically refractory epilepsy who underwent the sub-temporal selective approach over a 12-year period. And we excluded patients with prior epilepsy surgery as well as the diagnosis of neoplasm. We looked at postoperative outcomes at 12 and 24 months with ENGL classification as well as surgical morbidity and mortality. And at six months we looked at their neuropsychological and neurocognitive testing. So this is what our incision looks like. We use a pretty small incision that starts at the root of the zygoma and curves up superiorly and posteriorly. This is an intraoperative photo of our craniotomy. The zygoma is down here. And a couple CT scans illustrating the size of the craniotomy. And this is nice because it's actually a pretty minimally invasive approach compared to some of the traditional approaches for selective amygdaloid hippocampectomy, which requires a larger teratonal flap and craniotomy. So here are a couple intraoperative photos. This is the initial approach with the dura flapped inferiorly towards the zygoma. And then coming down on the temporal floor, releasing CSF to allow for temporal lobe relaxation. Then entering here around the collateral sulcus and utilizing the ultrasonic aspirator here to remove the amygdala. We then identify the choroidal fissure and follow it posteriorly to remove the hippocampus. Here's a trajectory view of our initial entry site. And another view after the hippocampus has been removed, which shows that we're at the level perpendicular to the collicular plate back here. And here are postoperative images demonstrating preservation of the lateral temporal cortex as well as the temporal stem. So in our study, we had 208 patients who met inclusion criteria. 152 patients who had at least one year follow-up so were included in this study. Slightly more females than males in the study. Average age was about 40 years old. We had slightly more patients who had MTS on their preoperative MRI, 59%. And the majority of patients, 92.8%, had hippocampal sclerosis confirmed in final pathology. Slightly more patients, 58%, did not require stage two monitoring. And about an even split between left and right-sided operations. So 12 months after surgery, our ENGL class one outcome was about 58%. On univariate analysis, patients were more likely to achieve ENGL one. We found if invasive monitoring was not required or there was presence of MTS on MRI. And on multivariate analysis, we did not find any patient characteristics that were predictive of seizure outcome. And of the ENGL one patients, 26% were off AEDs at their final follow-up. At two years after surgery, you can see our follow-up dropped off a little from 152 to 123 patients. However, we did maintain a pretty steady ENGL one outcome at two years, 56.5%. And when comparing patients who had MTS to those who did not, we found that those with MTS fared a little better, 65.6% ENGL one outcome versus 45.9%, which is consistent with what's been previously demonstrated in the literature. In terms of neuropsychological outcomes, we do have a standardized protocol for patients to have both pre- and post-operative testing at six months. Unfortunately, our follow-up at six months was rather low. Twenty-five percent of patients had both pre- and post-operative evaluations. The poor follow-up was multifactorial. But one of the main reasons was that many insurances didn't authorize payment for the follow-up evaluations. So that's something we're working on for the future to get better follow-up. Those who did had various standardized studies tested, intelligence, attention and processing, visual and spatial memory, verbal memory, as well as mood. And in terms of intelligence and processing, we found in the non-dominant hemisphere that there were no significant differences between baseline and pre-operative testing. In the non-dominant hemisphere, also no significant differences between baseline and post-op. In terms of memory and mood, we did find a significant decline in the dominant hemisphere in terms of short delay verbal memory. This was not the case for the non-dominant hemisphere. In the non-dominant hemisphere, we did find a significant improvement in mood on the Beck Depression Inventory. And in terms of complications, we had a 0% mortality rate. Our overall complications was 5.2%. There was a 3.9% transient neurological deficit rate or asymptomatic deficit. So, or asymptomatic complication, excuse me. So one patient had a subdural hematoma, one had an epidural, one had an intraventricular hemorrhage. One patient had blood in the resection cavity that increased seizure frequency the first day after surgery. One patient had a small posterior capsule infarction that resulted in transient unilateral ham numbness, which improved at follow-up. One had CSF arteria that required return to OR for repair. Our permanent neurological deficit rate was 1.3%. One patient had a superior quadrant field deficit, and one had a PCA infarction that resulted in unilateral hemiparesis, which did not resolve at follow-up. So how does this compare to the literature? Ranges for ENGL-1 outcome at one year for temporal lobectomy ranges between 60 to 73%. And for previous selective series, smaller series in the literature ranges from 40 to 60%. Our series demonstrated a 58% ENGL-1 outcome at a year. And in the study that I mentioned at the beginning of the talk, their ENGL-1 outcome at one year for their selectives were 59%, which is pretty comparable to ours. In terms of complications in the literature, mortality for resective surgeries is generally less than 1%. Permanent morbidity ranges from 2 to 5%, depending on what the series defines as a permanent, classifies as permanent morbidity. And in our study, we had 0% mortality and 1.3% permanent morbidity. So there are limitations to our study. A, it's a retrospective review. And B, it's a single-surgeon series without a comparison group for control. Our follow-up duration does go up to two years for seizure outcome. But again, the neuropsychological testing, we had rather poor follow-up, and it's limited to six months. But in conclusion, this is a large clinical series performed by an experienced surgeon demonstrating that the sub-temporal selective approach can result in seizure outcome rates comparable to temporal lobectomy and in line with previous smaller series using the sub-temporal approach. This, a low morbidity and mortality rate can be achieved. A 1.3% permanent neurological deficit and 0% mortality rate in our series and neuropsychological outcomes are, appear to be favorable. Thank you. So great work, and let me just first say that we all, as surgeons who have practiced the art of temporal lobectomy for years, struggle with two things. How do we keep this going, this tradition of surgery going in the context of laser ablation, and how do we teach it to our next generation? The reality, though, is this, you know, there are two other confounders here, I think, that are important. The first is patient preference, and it's a very hard and unknowable aspect of epilepsy surgery care, but I don't know if any of these patients were given the option of laser ablation, would they have a temporal lobectomy, you know, whether it's sub-temporal or any other kind. And the second question is, I think, for us to say that we would adopt a procedure in this age that has a 5% major complication rate, when there is a minimally invasive procedure with a much smaller complication rate and roughly equivalent outcomes, there has to be something better about it, either in terms of seizure freedom or neuropsych scores. That's just unfortunately the reality, and, you know, we're, I think we're in the same place where the cerebrovascular surgeons were a few years ago, watching aneurysm clipping stip out of our hands into a minimally invasive approach. Yeah, I think those are all excellent points. I think this series that we looked at, we did a 12-year period, and we stopped sort of just at the point when we, before we were discussing laser ablation with patients at our institution. So for that patient cohort, laser ablation was not discussed because it was before, it was in the discussion preoperatively. And I, yeah, I do agree with the fact that, you know, as more minimally invasive procedures like laser ablation arise, it is, you know, that is a debate in terms of complication rates to discuss with the patients. Dr. Schwab? So I was just wondering what your, what the approach has been at your center for patients who have failed, who are not in angle one or two. Has it been to take the patients back, re-explore them, consider taking out more temporal lobe? How do you guys deal with that when you've done a selective lesion like this? Yeah, I think Dr. Smith can answer this too, but generally when the, yeah, when we do, when patients do fail, we have taken them back for a full temporal lobectomy in addition. Yeah, it turns out about 5% of patients would essentially require follow-up completion of a temporal lobectomy. Afterwards, it's a small number, but, and those have gone on to be cured. Again, I think the results of epilepsy surgery have more to do with patient selection than the actual procedure itself. And so you want to give people an opportunity to have seizure-free status, but not all of them are absolutely perfect candidates. So reasons for failure aren't necessarily the procedure, but if they have bilateral inter-ectal spikes, bilateral onset of some type, or non-MTS temporal lobectomy. So that's a very important factor. And I think when, you know, with the laser discussion, I also offer laser procedures now, and there have been some who've been initially better, and then you go back in and they actually have seizure recurrence, and I've converted them to an open amygdala epicanthectomy and have been cured after that. So I don't think they're absolutely equivalent in outcomes. There's a possible edge for a neuropsychological outcome with laser, but in the open discussion with many patients that now, and you tell them, my bias is that I think you have a better chance of being seizure-free with open, but you've got a smaller procedure with laser, which one do they choose? And surprisingly, many of them will still actually choose the open procedure first. They just want to be done. One of the highest chances of being seizure-free, and not worry about their meds and all that stuff later. And I do think that that's a real issue, and we'll have to come up with data over time about how it really pans out. So can you just clarify? So the patient fails laser, you're taking them for a super selective or for a standard ATM? No. They'll laser. I still, if I really believe they have an improvement, they had MTS to begin with, I still just convert them to a sub-temporal selective. Okay. Thank you.

clinical outcomes

epilepsy treatment

selective approach

morbidity rate

laser ablation