Christopher Wilson, speaking on perineal nerve decompression, institutional review and meta-analysis. Hi, I'm Chris Wilson. I'm one of the neurosurgery residents at Indiana University. I appreciate the opportunity to get to present a project that I've worked on with Dr. Barbaro. Addressing the outcomes, or assessing the outcomes of perineal nerve decompression. I have no disclosures. So perineal mononeuropathy, we know it is the most common mononeuropathy in the lower extremity. Luckily, the outcomes from decompression are actually fairly good. Most of the papers in the literature report anywhere from 50 to 80 percent, although there are a few that present lower incidences of a favorable outcome. And several prognostic factors have been reported in these fairly small case series. And their effects are often variable. And so what our goal was, was to publish our results and our experience, as well as combine them with the data available in the literature that we could extract. And we thought that this would aid in both patient selection for this surgery, and then most importantly, I think, preoperative counseling. To do that, we reviewed our peripheral nerve database. We found 21 patients with sufficient data to extract and include. And then we evaluated several different prognostic factors that I'll show you, and their relationship to the outcome of surgery. We defined a favorable outcome as significant improvement in function or the preoperative symptom. We evaluated these statistically with Fisher-Exact tests, and we also conducted a postoperative phone follow-up to confirm the documentation in the EMR, and that no other treatment had been sought. And then we conducted a meta-analysis to combine our data with the literature. And so this is just a highlight of what our experience was. Basically, we found that most patients have a favorable outcome, 15 of our 21 did, regardless of their preoperative symptoms, whether it be pain, paresthesias, weakness, foot drop. And although most patients preoperatively weren't severely disabled, their function improved postoperatively on average. And so we stratified our patients according to their presentation. And at first, we noticed this trend that appeared that those with pain had more favorable outcomes than those, for example, with weakness or paresthesias. Notably, we didn't find a statistical significance in this trend, though. What we did find statistical significance with was our patients with diabetes. There were four of them. Three of them had negative outcomes, and this was statistically significant. And smokers, they had a trend towards more unfavorable outcomes as well. All of the other factors that we evaluated were not statistically significant, including the length of the preoperative symptom duration, their etiology, whether it was compression, some sort of trauma, or iatrogenic injury. They didn't have an effect on our experience. When we looked at the rest of the literature, we found an additional 115 patients that had extractable data. And these were all obtained from case series ranging from 15 to 60 patients. And we evaluated three different variables, the first of which preoperative symptom duration, which I think is the most important thing that we evaluated here. We found that if you operate on these patients more than 12 months after the onset of their symptoms, then their outcomes were – their odds of having a favorable outcome was less. And contrarily, we looked – if you operate on these patients much earlier, less than six months after the onset of their symptoms, we didn't find a statistical benefit there when you consider all patients together. But if you look at just the patients who have paresthesias, there was a trend that didn't quite meet statistical significance. This was a small number of patients, but it appeared that there may be a trend towards more favorable outcomes if you operate within six months. When we looked at age, we didn't find any indicator that older age conferred worse outcomes, and the same was true with gender. So there are a few limitations to our study. Even after the meta-analysis, we still only had 136 patients, and so the power is still limited. And particularly when we stratify the patients according to their presentation, there's still the possibility of type 2 error here. And then secondly, there's no non-surgically treated controls, although all of our patients and all the patients in the literature had at least two months of conservative therapy preoperatively. The benefit, however, is that we summarized and combined the available literature into single overriding statistics, and to our knowledge, this is the first time that this has been done with this particular disease and the surgical outcomes. And this does increase the power as much as possible. And then we evaluated a few factors that had not been previously reported in this disease, particularly smoking. And so the conclusions we were able to make is that perineal nerve decompression within one year of symptom onset is most ideal to promote favorable outcomes, and it may be even earlier for those with paresthesias. The outcome is adversely affected in patients with diabetes, and this should be a point of preoperative counseling. And then smokers may have a similar adverse outcome, and then outcome is not adversely affected by increasing age. Thank you.

neurosurgery

perineal nerve decompression

perineal mononeuropathy

patient selection

preoperative counseling