Citations

With the increased availability of computational resources, the past decade has seen a rise in the use of computational fluid dynamics (CFD) for medical applications. There has been an increase in the application of CFD to attempt to predict the rupture of intracranial aneurysms, however, while many hemodynamic parameters can be obtained from these computations, to date, no consistent methodology for the prediction of the rupture has been identified. One particular challenge to CFD is that many factors contribute to its accuracy; the mesh resolution and spatial/temporal discretization can alone contribute to a variation in accuracy. This failure to identify the importance of these factors and identify a methodology for the prediction of ruptures has limited the acceptance of CFD among physicians for rupture prediction. The International CFD Rupture Challenge 2013 seeks to comment on the sensitivity of these various CFD assumptions to predict the rupture by undertaking a comparison of the rupture and blood-flow predictions from a wide range of independent participants utilizing a range of CFD approaches. Twenty-six groups from 15 countries took part in the challenge. Participants were provided with surface models of two intracranial aneurysms and asked to carry out the corresponding hemodynamics simulations, free to choose their own mesh, solver, and temporal discretization. They were requested to submit velocity and pressure predictions along the centerline and on specified planes. The first phase of the challenge, described in a separate paper, was aimed at predicting which of the two aneurysms had previously ruptured and where the rupture site was located. The second phase, described in this paper, aims to assess the variability of the solutions and the sensitivity to the modeling assumptions. Participants were free to choose boundary conditions in the first phase, whereas they were prescribed in the second phase but all other CFD modeling parameters were not prescribed. In order to compare the computational results of one representative group with experimental results, steady-flow measurements using particle image velocimetry (PIV) were carried out in a silicone model of one of the provided aneurysms. Approximately 80% of the participating groups generated similar results. Both velocity and pressure computations were in good agreement with each other for cycle-averaged and peak-systolic predictions. Most apparent “outliers” (results that stand out of the collective) were observed to have underestimated velocity levels compared to the majority of solutions, but nevertheless identified comparable flow structures. In only two cases, the results deviate by over 35% from the mean solution of all the participants. Results of steady CFD simulations of the representative group and PIV experiments were in good agreement. The study demonstrated that while a range of numerical schemes, mesh resolution, and solvers was used, similar flow predictions were observed in the majority of cases. To further validate the computational results, it is suggested that time-dependent measurements should be conducted in the future. However, it is recognized that this study does not include the biological aspects of the aneurysm, which needs to be considered to be able to more precisely identify the specific rupture risk of an intracranial aneurysm.

Objective To survey neurology residency program directors (PDs) on trainee exposure, supervision, and credentialing in procedures widely utilized in headache medicine. Background Clinic‐based procedures have assumed a prominent role in headache therapy. Headache fellows obtain procedural competence, but reliance on fellowship‐trained neurologists cannot match the population eligible for treatments. The inclusion of educational modules and mechanisms for credentialing trainees pursuing procedural competence in residency curricula at individual programs is not known. Methods A web‐based survey of US neurology residency PDs was designed by the American Headache Society (AHS) procedural special interest section in collaboration with AHS and American Academy of Neurology's Headache and Facial Pain section leadership. The survey addressed exposure, training, and credentialing in: (1) onabotulinumtoxinA (onabotA) injections, (2) extracranial peripheral nerve blocks (PNBs), and (3) trigger point injections (TPIs). Results Fifty‐five PDs (42.6%) completed the survey. Compared to noncompleters, survey completers were more likely to feature headache fellowships at their institutions (38.2% vs 10.8%, P =0.0002). High exposure (onabotA=90.9%, PNBs=80.0%, TPIs=70.9%) usually featured hands‐on patient instruction (66.2%) and lectures (55.7%). Supervised performance rates were high (onabotA=65.5%, PNBs=60.0%, TPIs=52.7%), usually in continuity clinic (60.0%) or headache elective (50.9%). Headache specialists (69.1%) or general neurology (32.7%) faculty most commonly trained residents. Formal credentialing was uncommon (16.4‐18.2%), mostly by documenting supervised procedures (25.5%). Only 27.3% of programs permitted trainees to perform procedures independently. Most PDs felt procedural exposure (80.0‐90.9%) and competence (50.9‐56.4%) by all trainees was important. Conclusions Resident exposure to procedures for headache is high, but credentialing mechanisms, while desired by most PDs, are not generally in place. Implementation of a credentialing process may ensure trainees enter practice with the ability to perform procedures safely and effectively.

Context Assessment is central to medical education and the validation of assessments is vital to their use. Earlier validity frameworks suffer from a multiplicity of types of validity or failure to prioritise among sources of validity evidence. Kane's framework addresses both concerns by emphasising key inferences as the assessment progresses from a single observation to a final decision. Evidence evaluating these inferences is planned and presented as a validity argument. Objectives We aim to offer a practical introduction to the key concepts of Kane's framework that educators will find accessible and applicable to a wide range of assessment tools and activities. Results All assessments are ultimately intended to facilitate a defensible decision about the person being assessed. Validation is the process of collecting and interpreting evidence to support that decision. Rigorous validation involves articulating the claims and assumptions associated with the proposed decision (the interpretation/use argument), empirically testing these assumptions, and organising evidence into a coherent validity argument. Kane identifies four inferences in the validity argument: Scoring (translating an observation into one or more scores); Generalisation (using the score[s] as a reflection of performance in a test setting); Extrapolation (using the score[s] as a reflection of real‐world performance), and Implications (applying the score[s] to inform a decision or action). Evidence should be collected to support each of these inferences and should focus on the most questionable assumptions in the chain of inference. Key assumptions (and needed evidence) vary depending on the assessment's intended use or associated decision. Kane's framework applies to quantitative and qualitative assessments, and to individual tests and programmes of assessment. Conclusions Validation focuses on evaluating the key claims, assumptions and inferences that link assessment scores with their intended interpretations and uses. The Implications and associated decisions are the most important inferences in the validity argument.

Introduction Symptomatic metastatic epidural spinal cord compression (MESCC) afflicts up to 10% of all cancer patients. MESCC is associated with shortened survival and worsened quality of life; thus, early diagnosis and management is crucial. In a multidisciplinary setting, life expectancy must be considered along with other factors, such as patient's symptoms and overall medical condition, to select the optimal patient-specific treatment plan. This study aims to identify and compare key survival prognostic factors in surgically treated symptomatic MESCC patients with a 12-month postoperative follow-up. Materials and Methods Over a 5-year period, 145 patients surgically treated for a single symptomatic MESCC lesion were enrolled in a prospective North American multicenter study. Univariate analyses, Kaplan–Meier methods, and log-rank tests were used to evaluate the prognostic value of various clinical predictors. Preoperative prognostic factors evaluated: age, gender, comorbidities, history of smoking, metastases outside the spine, site of primary tumor, previous systemic treatment for the primary tumor, MESCC location, number of vertebral body involved, previous MESCC treatment, ASIA score, motor deficits, bladder dysfunction, Oswestry Disability Index (ODI), EQ-5D, SF-36v2 mental and physical components, and ability to walk four steps. Predictors with p < 0.2 in univariate analyses were included into the final Cox proportional hazards model. Results The overall median survival was 7.7 months (235 days). Lung and breast cancer had the shortest and longest median survival, respectively (4.5 vs. 12.1 months). Nine patients (6%), whose primary cancer were lung (3), kidney (3), melanoma (1), prostate (1), and breast (1), died within 30 days after surgery; 46 (32%), 61 (42%), 74 (51%), and 86 (59%) patients died at 3, 6, 9, and 12 months, respectively. The site of primary tumor, number of vertebrae involved, ODI, EQ-5D, ASIA score, metastases outside the spine, bladder dysfunction, and ability to walk four steps were significant predictors on the univariate analyses. However, the multivariate Cox-regression analysis demonstrated that only spinal metastasis involving four or more vertebral bodies had a negative impact on survival ( p = 0.002, HR: 25). Conclusion The extent of spinal metastasis, which is regarded as an indicator of the severity of patient's metastasis burden, and the site of the primary tumor, although not statistically significant in our regression model but well recognized in the literature as an important clinical predictor, are considered as independent predictors of poor prognosis in patients with a single-level symptomatic MESCC lesion. MESCC patients are a challenging and vulnerable heterogenous population. It is essential to identify factors predicting survival, functional and clinical outcomes in this population to guide patient-centered management to optimize quality of life.