I am pleased to introduce our first speaker, who is also the winner of the William Sweet Young Investigator Award. This is an award that the pain section gives to a resident or young neurosurgeon within five years of completion of their training. And we're very pleased to present it today to Kunal Raghur, who is a resident at UCSF. So, Kunal, this is yours. Thank you. So, congratulations. Thank you very much. Appreciate it. Okay. Thank you very much, and thank you for having me here today. I'll be presenting our work on the long-term pain outcomes for recurrent idiopathic trigeminal neuralgia after stereotactic radiosurgery. So as everyone knows here, a number of studies have sought to determine the efficacy of various surgical treatments for trigeminal neuralgia. However, prospective comparisons of those techniques are rarely seen. We recently published our experience at UCSF comparing at least two first-line surgical options, microvascular decompression and stereotactic radiosurgery, in patients who had failed medical therapy. As you can see in this figure, and I certainly won't go into all the details. I think one of the most important findings was that in both the microvascular decompression cohort as well as the stereotactic radiosurgery cohort in our prior studies, both of those patient cohorts have pain recurrence over time, despite the fact that microvascular decompression seems to have a slightly longer duration of pain freedom compared to the SRS patients. Seeing this, it begged the question for us, which is that, what is the ideal retreatment option for patients who have pain recurrence after an initial surgical operation? And in our study specifically today, we'll be focusing on those patients who have failed stereotactic radiosurgery and answer the question of, what is the better retreatment option for those patients? So in our study, we used a large prospectively collected database to do two things. Number one was directly compare long-term pain control rates for first-time microvascular decompression patients as well as those with repeat SRS, and then to identify predictors of pain control in each group. The clinical data for all of our patients in the study were collected in a prospective longitudinal database over many years. We looked at both preoperative clinical characteristics, intraoperative characteristics, as well as settings for the gamma knife radiosurgery, as well as postoperative variables. The primary pain outcome that we used to score our patients' pain was the Bare Neurological Institute Pain Intensity Score, as you can see here. I apologize for the small size. It's a scale from 1 to 5. And we further subclassified this into a favorable outcome group and an unfavorable outcome group. The favorable outcome patients had a BNI score of 1 to 3a, and patients with unfavorable outcomes had scores from 3b to 5. We also looked at secondary outcomes, including sensory changes as well as any complications from the procedures. And in terms of inclusion criteria, we only included patients with type 1 idiopathic trigeminal neuralgia without any mass lesions or multiple sclerosis and had at least one year of follow-up. Of a total of 700 patients, or 700 procedures that occurred in our prospective database, 364 underwent stereotactic radiosurgery. And again, we used exclusively gamma knife radiosurgery at UCSF. Of those, 168 had a first-time procedure, which was stereotactic radiosurgery, and had at least one year of follow-up. And that's what was shown in that initial Kaplan-Meier survival analysis. Of those patients, 90 ended up having residual or recurrent symptoms over our follow-up with those patients. Unfortunately, we lost 60 of those patients to follow-up. But this study looked at those 30 patients who continued to follow-up at UCSF and looked to see what treatment options were best for those patients. In that group, we found that 15 of them underwent microvascular decompression as a re-treatment option, and 15 underwent repeat radiosurgery. This figure is just looking at those 30 patients who had initial SRS and then were in our cohort of patients for this study. And the key here is just to say that these patients tended to have recurrence much earlier than the overall population of SRS patients that we had in our initial overall cohort of patients, with about median pain recurrence at about one year, and only 20% of patients, again, in this cohort, who were still pain-free at five years. We looked at the preoperative characteristics for these patients and tried to determine if there were any differences between those patients that underwent microvascular decompression versus repeat SRS as their re-treatment procedure, and only found that the patients who underwent microvascular decompression were younger by an average of about 12 years, compared to those who underwent repeat SRS. We looked at a number of other variables, which were not statistically significant, including there were two patients in each arm that had transient sensory changes after their initial SRS procedure, but both of those patients regained full facial sensation prior to their second procedure. In addition, there were no significant differences in vascular compression seen on preoperative MRI in the two cohorts. We then looked at overall pain outcomes in the two cohorts and found, interestingly, that every patient that underwent a second procedure had a BNI-1 pain outcome at some point in their follow-up, so at some point they were pain-free without any medications. However, those who underwent microvascular decompression achieved that BNI-1 score much faster, on average zero weeks, compared to 10 weeks in the SRS cohort. Overall, we, again, found at last follow-up that the patients who underwent microvascular decompression had better pain outcome scores compared to those who underwent repeat radiosurgery. And then, again, using our composite outcome, which we just defined as a BNI of 1 to 3a, we found that, again, many more patients who underwent microvascular decompression had that favorable outcome. There were two patients in the microvascular decompression cohort that had a complication. There was one CSF leak that required a wound revision and one case of unilateral hyperacusis that was probably due to intraoperative injury to the acoustic portion of the eighth cranial nerve. But no complications in the SRS cohort, and specifically, there were no painful dysesthesias and no cases of anesthesia dolorosa in those patients. And this is just sort of graphically showing that those patients who underwent microvascular decompression had improved pain freedom compared to those who underwent stereotactic radiosurgery over time. We then performed both univariate as well as multivariate regression analyses to try to determine the predictors of pain freedom in our patient cohort of 30 patients. And these variables here were all statistically significant on univariate analysis. However, the only one of those variables that was significant on the multivariate Cox regression was undergoing microvascular decompression as opposed to stereotactic radiosurgery as a second procedure, which again tells us pretty definitively that in at least this patient, this cohort of patients who failed initial stereotactic radiosurgery, microvascular decompression is a good next option. We tried to further analyze the predictors of pain freedom in those two individual cohorts and actually did not find any specific predictors of pain freedom after retreatment with microvascular decompression, including with these specific predictor variables. So none of these were statistically significant in comparing between those patients that had a favorable outcome versus those who had an unfavorable outcome. And on the other hand, with the SRS cohort, we did find that patients who had documented sensory changes after the repeat SRS were much more likely to have pain freedom. And this has been described many times in the literature in patients overall who have stereotactic radiosurgery for trigeminal neuralgia pain. But we didn't see any statistical significance with cumulative SRS dose or with the number of isocenters used for the stereotactic radiosurgery. And this just, again, shows that, again, within the patients who underwent repeat SRS, those who had sensory changes had improved pain freedom compared to those that did not have sensory change. In conclusion, although this was a relatively small sample size, of course, we feel pretty strongly that both microvascular decompression and stereotactic radiosurgery can be used as retreatment procedures with relatively low complication rates for patients who have failed initial SRS. We show that those who undergo microvascular decompression do have a longer duration of favorable pain outcome compared to those who have repeat radiosurgery. And that in those patients who have repeat radiosurgery, the presence of postoperative sensory change does predict a longer duration of favorable pain outcome. I'd just quickly like to thank Dr. Cheng and Dr. Barbaro, two of our mentors, as well as the rest of the UCSF staff. And thank you to the pain section as well. Thank you.

Kunal Raghur

UCSF

trigeminal neuralgia

microvascular decompression

pain control