7 e-Letters

published between 2020 and 2023

  • The number of clinical events per variable in logistic regression analysis

    Dear Editor,

    I read with interest the paper by Pierot et al [1]. They conducted a prospective study to examine factors of delayed thromboembolic events in 335 patients after coiling of unruptured intracranial aneurysms. The number of delayed TEEs was 8. The adjusted odds ratios (95% confidence intervals) of autosomal dominant polycystic kidney disease and post-procedure aneurysm remnant at procedure completion for delayed TEEs were 27.3 (3.9 to 190.2) and 9.9 (1.0 to 51.3), respectively. They understand the lack of statistical power in the multivariate analysis and did not intend to examine the causal association. I present a comment regarding the number of events in logistic regression analysis.

    The limitation in the total number of events for logistic regression analysis was simulated to improve statistical power [2]. In addition, Peduzzi et al. evaluated the effect of the number of events per variable (EPV) on the outcome in logistic regression analysis [3], concluding that the number of EPV less than 10 has some problems for the prediction of dependent variable. There is an opinion that EPV value less than 10 is also acceptable to evaluate the association by logistic regression analysis [4]. Pierot et al. observed 8 events, which was not appropriate for multivariate analysis even for examining the association instead of prediction in a prospective study. I think that wide ranges of 95% confidence intervals may reflect unstable estimates in a logistic regr...

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  • Middle meningeal artery embolization versus surgical evacuation, How real-world are we?

    Dear Editor,

    We have read with great interest the article entitled “Efficacy and mid-term outcome of middle meningeal artery embolization with or without burr hole evacuation for chronic subdural hematoma compared with burr hole evacuation alone” by Onyinzo, C., et al, published in Journal of NeuroInterventional Surgery (2021).

    The article has compared the Surgical and Endovascular management of (CSDH) in the elderly population who are at high risk to developing (CSDH) due to their co-morbidities and the use of anti-thrombotic agents.
    It is noted that the anti-thrombotic agents were stopped to both management arms. Upfront Middle meningeal artery embolization without stopping the anti-thrombotics, might be a strategy to mitigate the risk of cardio-embolic events.
    In regards to the evaluation of the patients outcome, clinical parameters did not include motor assessment, which is a significant factor to favor a rapid surgical evacuation in these delicate patients.
    As to the radiological follow up, cured (CSDH) were defined in the article with a thickness less than 10 mm. This is debatable as there are a lot of variations exists for this population in regards to brain volume and brain elasticity.
    Finally, we would like to point out the timing of the follow up was not defines for all patients. This need to be harmonized better to a well-defined follow up timeline. Joyce, MD, et al,2 a suggested a time frame of 6 weeks after the treatment...

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  • Action mechanism of the beveled tip aspiration catheter

    We read with great interest the recent paper by Vargas, et al. describing a novel beveled tip aspiration catheter with improved recanalization and patient outcome compared to conventional non-beveled tip catheters in a single-center retrospective study.[1] We want to express our sincere congratulations to the authors on this finding but also want to respectively present our disagreement on the mechanisms explaining the improved performance of the beveled tip catheter as compared to standard catheters.

    The authors conclude that a primary reason for higher rate of complete clot ingestion for the beveled tip catheter relates to the area of the catheter tip. It is widely accepted that ingestion force predicts recanalization efficacy, and this force is proportional to tip area (A) and pressure drop (P). The authors note that the beveled tip leads to an ovalized tip area with a total tip area that is approximately 15% larger than a catheter with an equivalent inner diameter but standard non-beveled tip. They then propose that this 15% increase in tip area leads to a corresponding increase of ingestion force, using the standard F=A*P equation. However, this proposition is flawed. While it is true the total force is larger for the beveled tip catheter than a standard catheter, this total force includes two separate force components that are orthogonal to each other, including the ingestion force component (along the catheter’s length) that corks or ingests the clot and...

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  • Challenges and subtleties in the evaluation of post-procedural cognitive changes

    We congratulate Drs. Srivatsan and colleagues on their paper examining the effects of endovascular coiling of unruptured intracranial aneurysms (UIAs) on cognition using the Montreal Cognitive Assessment (MoCA).1 In particular, we appreciate the efforts made to sample the patients at multiple time points including pre-intervention and at 1-month and 6-months post-intervention. The study found that coiling did not diminish neurocognitive function per the MoCA, with there also being no correlation between follow-up MoCA scores and imaging findings, the overall results being comparable to the authors’ previous paper on MoCA scores following flow diversion for UIAs.2 Intriguingly, the MoCA scores at baseline were on average below the typical cut-off of 26 points, especially given the relatively young population (mean age 55.5 years).

    However, as acknowledged by the authors, the ability of the study to discern post-coiling imaging changes was limited by both the small subset of the population that received follow-up imaging (17 of 33 patients, 51.5%) and the smaller subset that underwent MRI (9 patients, 27.3%).1 Diffusion-weighted imaging (DWI) sequences of MRI are most sensitive to identifying post-procedural ischemic injury following neuro-interventional procedures like coiling.3 DWI lesions occur quite frequently; for example, in the ENACT trial (Evaluating Neuroprotection in Aneurysm Coiling Therapy), 68% of patients had new lesions post-procedure, with an average o...

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  • Technical feasibility and clinical impact.

    After reading the interesting article by Jeon et al, indeed, the first series of cases of revascularization in cerebral infarction, it is important to point out several aspects related to the cancer patient. Cancer is a heterogeneous group of diseases with some points in common related to cellular behavior in the face of cell division controls and their local and systemic effects. Its incidence and prevalence are increasing, and the borders of treatment are changing, as is the disease itself. Patients with active cancer, therefore, should be approached in a multidisciplinary strategy, for the management of their oncological pathology or associated patient comorbidities. Stroke does not escape this strategy, because it does not have the same clinical impact to treat a patient with an oncological disease in early staging compared to one in advanced staging or in disease progression in palliative care and short calculated survival. It is not possible to establish a general rule of treatment in stroke with active cancer for these reasons, and a careful analysis of which primary tumors, their staging or clinical evolution of response to treatment, are necessary to clarify the clinical picture of stroke treatment in the oncological disease context.

  • Regarding: Outcome of patients with large vessel occlusion stroke after first admission in telestroke spoke versus comprehensive stroke center

    Dear Editor,

    Kaminsky et al1 present an interesting study regarding the logistics of patients eligible for endovascular stroke therapy (EVT). They conclude that whether patients with large vessel occlusion (LVO) are first admitted to a hospital with or without this treatment does not affect patient outcome.
    However, there are some difficulties interpreting the main statistical multivariate analyses. Firstly, although there is a clear presentation of how the main multivariate logistic regression analysis is performed, the covariates included in the model are not presented, and the model is not shown in any table. Secondly, the authors have included variables solely based on the strength of their association with the outcome, and not based on the potential of the variable to confound the relationship between the variable of interest (which center the patient is admitted to first), and the outcome. In this setting, it is our opinion that selecting covariates based on an etiological model, that focuses on the variable of interest, and includes covariates based on the potential for confounding, would be the best strategy.2 We disagree with the authors` choice of a prognostic model.
    We urge the authors to provide a table showing the main analysis, or even repeat the main analysis using an etiological approach to model building and variable selection.
    Despite these shortcomings, we commend the authors for undertaking such a relevant clinical study, and we...

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  • Letter to the Editor, JNIS Editorial Board

    Dear Editor:

    We read with great joy the recent article by Kuhn et al entitled, “ Distal radial access in the anatomical snuffbox for neurointerventions: a feasibility, safety, and proof-of-concept study.” The authors should be congratulated on their work, as well as the use and maturation of the distal radial technique from diagnostic to interventional procedures. The authors detail their use of the Prelude sheaths which we agree are excellent low profile large lumen sheaths for radial access. We typically utilize the Glide Slender sheaths (Terumo) but both are excellent options. We also agree that the distal radial approach can be used for numerous interventions with access sizes from 4 to 6F, including 6F sheathless long 088 guides. Our choice for distal radial sheathless long 088 guides is Infinity LS (Stryker), and for 071 guides the Benchmark (penumbra) via a 6F sheath.

    The authors noted their series was the first series to cover numerous neurointerventions with distal transradial access, however we would like to respectfully point out that we published on this topic in January of 2019 (accepted in March of 2019). Our paper by Rajah et al entitled, “ Snuff box radial access: A technical note on distal radial access for neuroendovascular procedures” can be found in Brain Circulation at the following citation available in PUBMED.

    Rajah G, Garling RJ, Hudson M, Luqman A. Snuff box radial access: A technical note on distal radial access for neuroe...

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