Next, in the last talk before the break, is Dr. Donos, and he'll be speaking to us about seizure outcomes and cognitive deficits following LIT ablation in mesial temporal epilepsy patients. Hello. Thank you for the introduction. My name is Cristian Donos. I'm a physics Ph.D. from Dr. Tandon's lab at University of Texas. And I'm going to discuss the seizure outcomes and cognitive outcomes of laser institutional laser therapy in a cohort of patients with mesial temporal lobe epilepsy. These are our disclosures. LIT was initially a technique used for cancer treatment, but in the last couple of years has been extensively used for epilepsy as well, treating all sorts of etiology. We have a case series of 43 patients over a period of five years. As you can see, the age and gender is normal distribution. Normal adults around 40 years old. They had an epilepsy onset around 70 years old, and they're mostly left hemisphere dominant. We have pre- and post-surgical neuropsychological assessment with six test batteries. In total, 37 subtests. And the hemispheric dominance was mostly assessed with VADA, fMRI, and CSM, cortical stimulation mapping. And whenever that was not possible, we just assumed they have left hemispheric dominance. All of our patients were investigated whether they have or not MTS, mesial temporal sclerosis. Some of the patients also had SEG implantation. And as you can see, about 17 patients that had MTS also had SEG. 17 patients had MTS but no SEG. And there are also nine patients who did not have clear signs of MTS on the MRI, but they also had SEG for determining the seizure onset zone. Our approach is an occipital trajectory along the hippocampus. Entry point is occipital, and it's optimized to avoid blood vessels and maximize the ablation of the hippocampus. As you can see, the method allows for monitoring the thermal damage area in real time. And we usually have time control points placed in the ventral thalamus, and we use a small pulse in the beginning to localize the laser, and then we have subsequent ablations by retracting the laser probe slowly a few millimeters at a time. The surgical outcomes are 80% seizure-free at six months, angle one, and 65% at an average of 20 months at the last follow-up. As you can see, there are some differences in the seizure outcome for patients that had MTS and had or did not have SEG. However, these differences are not significant in our analysis. We also quantified the ablation volumes. We used a pre-op MRI to compute free surfer parcellation, and we manually outlined the ablation mass on the post-op T1 with contrast. We have a cohort of 39 subjects in this analysis. Ablation mass were co-registered with a pre-op MRI, and we were able to quantify how much of each structure has been ablated. As you can see, the average percentage of ablation in amygdala hippocampus is around 75% in our cohort, and there is not a statistically significant difference between the patients who had angle 1A outcome and patients who had angle 2 to 4 outcome. The cognitive outcomes have been assessed in two ways. We did a pairwise test between the pre- and post-neuropsychological assessment, and we found no changes in Boston naming test and category and semantic fluency test. However, we found statistically significant change in some memory tests, although the difference was always less than one standard deviation. And I'm showing here the tests that were found to have some deficits in red, and a couple of tests who actually improved after ablation. A second type of analysis was a linear model in which we looked at a change in neuropsychological score as a factor of using ablation percent of hippocampus and adrenal as predictors, as well as pre-ablation volume of the hippocampus and pre-surgery neuropsychological score. What we found is that, and I'm only showing the tests that have a significant linear model, what we found is that the pre-ablation neuropsychological score is a determining factor whether a patient will or will not have a deficit, which also is in line with what we already know from open surgeries, where people with better cognitive skills are more likely to end up having a deficit after surgery. In conclusion, we have comparable surgical outcomes with open surgeries, traditional surgeries. There is not a correlation between the percentage of ablation and surgical outcome. We found that LIT did not cause any naming and category and fluency deficits in the left hemisphere. We also found that carefully selected mesial temporal lobe epilepsies without MTS can be localized well by intracranial recordings and obtain similar surgical outcomes as in patients that have MTS. I have here an overview of some papers, some of the largest cohorts in the literature. As you can see, the average surgical outcome is about 57% angle 1 and 11% angle 2 all over. In our case, we found 64% angle 1 at 20 months and 16% angle 2 at the same period, 20 months last follow-up. These are our collaborators and co-authors of the study. Any questions for Dr. Donos? Yeah, only three microphones. I took down the last one, it wasn't working. I took one out. If you could go back to the slide with the neuropsych question for a minute. You know, your results are great. Your neuropsych is a little bit worse. You think that's because you're ablating more? Yeah, he's trying. Maybe it's helpful to talk about where this work fits in with everything else a little bit more. Maybe it's helpful to talk about where this work fits in with everything else a little bit more. So we certainly have larger percentages of ablation. Now that could be either because we're ablating a lot more or we are targeting more precisely. It could be either one of those two. It's a little hard to separate them out. The deficits in naming are zero. Essentially there's no statistical significant difference. And I think it's very hard to quantify measures across institutions, but the only deficits that we see in memory are around one standard deviation in size. And that is in the dominant temporal lobe. So that's much smaller than I would expect with the large series in open surgery. And I think pretty comparable to what the Emory data has, which I think is Dan Drain's paper is really the only other one that is similar. And of course, you know, not having patients who fail is of big importance in minimizing those that have both the memory, the prominent memory decline as well as the ablation. Thank you. One more. I just wanted to congratulate the group. This is also, I think, showing what's happening as this evolves. Outcomes are getting better when it becomes more SEG guided. The original Emory series was pre-SEG. So there were a lot of patients in there that were not as well localized as what we are now doing is what you are clearly doing. So even the numbers that we're now comparing to, I think our outcomes can continue to get better as we do more SEG guidance. Just because somebody has MTS doesn't mean that they should just have their hippocampus ablated. And I think the more we study these patients, the better we're going to guide who needs an ablation, who needs a resection, who needs more than one thing ablated, and we'll improve our outcomes on an individual patient basis. Thank you.

seizure outcomes

cognitive deficits

laser ablation therapy

mesial temporal lobe epilepsy

case series