Lawton, Michael T.

Introduction Despite hundreds of training models for microsurgery being available in the literature, very few of them are scientifically validated. We chose to validate our low-fidelity training model on flower petals by comparing it head-to-head with a moderate fidelity training model, the anastomosis on chicken leg femoral artery. Materials and methods A total of 16 participants of different levels of expertise were randomized into 2 groups, 1 training on flower petals and 1 on chicken leg femoral arteries. The groups were evaluated on performing a rat femoral artery anastomosis using the validated Stanford Microsurgical Assessment (SMaRT) Scale. The Mann-Whitney U test was used to check for statistically significant differences between the groups. The flower petal sutures were also evaluated and Pearson correlation was used to check for associations between better petal anastomosis scores and better final SMaRT results. Results After 6 weeks of flower petal training, microsurgical trainees had significantly better overall SMaRT scores than trainees using chicken leg training, better fine tissue feeling, and better scores in knot tying. The anastomosis times for the rat femoral arteries did not differ between the 2 groups. Good scores for flower petals strongly correlated with a better SMaRT score for the anastomosis. The number of rats used in training reduced after the implementation of this model in continuous training. Conclusions The flower petal technique, despite being a low-fidelity model, shows superiority in developing fine tissue feeling and improved knot tying in microsurgery beginners and intermediate level practitioners adding this training model to their program. Further research needs to establish if the improvements also apply to already seasoned microsurgeons and whether the petal score has predictive value for future clinical application.

Introduction: Accurately balancing risks of interventional treatment and intracranial hemorrhage (ICH) in the untreated course of unruptured brain arteriovenous malformation (uBAVM) patients is critical for optimal management. Observational studies of uBAVM afford an opportunity to address important gaps and previous criticisms of randomized data to help guide treatment decisions and assess long-term risk/benefit ratio. We previously published an individual patient data meta-analysis (IPDMA) in 4 MARS cohorts and identified ICH presentation and increasing age as significant predictors of ICH during follow-up, but was not powered to detect predictors in those with uBAVM. Thus, the goals of this project are to identify risk factors for ICH in uBAVMs, to estimate the risk with precision, and to create personalized, risk-prediction models. Methods: MARS is an international, multi-center study of 11 cohorts with target enrollment of 4,500 uBAVM patients ascertained through population-based or referral-based studies. We are harmonizing both retrospective and prospective data, including clinical, lifestyle, imaging, and angiographic factors. Treatments, complications, and functional outcomes (physician and patient-reported) will be updated annually between 2018-2022. We propose to: 1) identify predictors of outcome in uBAVMs using IPDMA; 2) test whether long-term outcomes differ by treatment using statistical approaches for causal inference and unbiased estimates; 3) compare treatment outcomes in randomized and non-randomized data to address generalizability; and 4) validate models and provide a novel tool for calculating individualized risks. Eligible sites have: a) prior BAVM publications; b) data from a minimum of 100 uBAVM patients; c) agree to random outcome adjudication; and d) agree to MARS data sharing policy. Discussion: The NIH-funded MARS consortium will provide important and comprehensive characterization of the untreated and treated course of uBAVMs, using large observational datasets and sophisticated epidemiological approaches. The data and models generated will be a useful resource for decision-making. We welcome participation from eligible sites with longitudinal data on uBAVM patients

Background and Purpose— To address the increasing need to counsel patients about treatment indications for unruptured intracranial aneurysms (UIA), we endeavored to develop a consensus on assessment of UIAs among a group of specialists from diverse fields involved in research and treatment of UIAs. Methods— After composition of the research group, a Delphi consensus was initiated to identify and rate all features, which may be relevant to assess UIAs and their treatment by using ranking scales and analysis of inter-rater agreement (IRA) for each factor. IRA was categorized as very high, high, moderate, or low. Results— Ultimately, 39 specialists from 4 specialties agreed (high or very high IRAs) on the following key factors for or against UIA treatment decisions: (1) patient age, life expectancy, and comorbid diseases; (2) previous subarachnoid hemorrhage from a different aneurysm, family history for UIA or subarachnoid hemorrhage, nicotine use; (3) UIA size, location, and lobulation; (4) UIA growth or de novo formation on serial imaging; (5) clinical symptoms (cranial nerve deficit, mass effect, and thromboembolic events from UIAs); and (6) risk factors for UIA treatment (patient age and life expectancy, UIA size, and estimated risk of treatment). However, IRAs for features rated with low relevance were also generally low, which underlined the existing controversy about the natural history of UIAs. Conclusions— Our results highlight that neurovascular specialists currently consider many features as important when evaluating UIAs but also highlight that the appreciation of natural history of UIAs remains uncertain, even within a group of highly informed individuals.