Background: Minimally invasive lumbar decompression (mild ® ) has been shown to be safe and effective for the treatment of lumbar spinal stenosis patients with hypertrophic ligamentum flavum as a contributing factor. This study examines the long-term durability of the mild procedure through 5-year follow-up. Pain relief and opioid medications utilization during 12-month follow-up were also assessed. Methods: All patients diagnosed with lumbar spinal stenosis secondary to ligamentum flavum hypertrophy who underwent mild from 2010 through 2015 at the Cleveland Clinic Department of Pain Management were included in this retrospective longitudinal observational cohort study. The primary outcome measure was the incidence of open lumbar decompression surgery at the same level(s) as the mild intervention during 5-year follow-up. Secondary outcome measures were the change in pain levels using the Numeric Rating Scale and opioid medications utilization using Morphine Milligram Equivalent dose per day from baseline to 3, 6, and 12 months post-mild procedure. Postprocedural complications (minor or major) were also collected.Results: Seventy-five patients received mild during the protocol-defined time period and were included in the study. Only 9 out of 75 patients required lumbar surgical decompression during the 5-year follow-up period. Subjects experienced statistically significant pain relief and reduction of opioid medications utilization at 3, 6, and 12 months compared to baseline. Conclusion:Based on our analysis, the mild procedure is durable over 5 years and may allow elderly patients with symptomatic lumbar spinal stenosis to avoid lumbar decompression surgery while providing significant symptomatic relief.

INTRODUCTION: Endovascular thrombectomy for select patients with anterior circulation stroke can be lifesaving if done in an appropriate therapeutic window. However, studies have demonstrated that failure of treatment ranges from 30-70%. Early determination of patients that are most likely to benefit from early revascularization is of pivotal importance.METHODS: We prospectively collected data from a high-volume stroke center for patients receiving MT for anterior circulation strokes. Outcomes evaluated included final Thrombolysis in Cerebral Infarction (TICI) score, the number of passes, complications from endovascular intervention, discharge NIHSS. Outcomes were clustered using a kmeans model after the number of optimal clusters were obtained using a silhouette algorithm. Uniform manifold projections (UMAP) were used to project the four outcomes into a 2-D space. Upon cluster determination, multivariate regression was used to determine predictors of cluster membership. Univariate comparisons leveraged chi-square and t-tests.RESULTS: 187 consecutive patients were selected for analysis. Included patients had an average age 69.96 (SD -15.14). Two distinct clusters were obtained, confirmed by the Silhouette model (1B). Cluster 2 was found to be associated with improved outcomes on univariate regression. Multivariate regression was used to identify predictors of cluster membership. ICA occlusion (OR = 7.63 (1.40 -48.6), p = 0.02). A onepoint increase in admission NIHSS was associated with an 11% increase in cluster 2 risk.CONCLUSIONS: In this study, we consolidate 4 outcomes using unsupervised machine learning. We found that cluster 2 patients did worse. We also demonstrated that ICA occlusion, Admission NIHSS, and smoking status were significantly associated with cluster 2 membership. Machine learning can be used to identify novel morphological characteristics of specific patient groups.

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