Mapping and Monitoring of the Corticospinal Tract by Direct Brainstem Stimulation

Background: Direct stimulation and diffusion tensor imaging/tractography are established techniques that assist in complex surgery for lesions in the eloquent area of the central nervous system. Objective: To continuously map the corticospinal tract (CST) by direct stimulation during brainstem surgery and to explore the association between direct brainstem stimulation and the shortest distance from the stimulation point to the CST (DS-to-T). Methods: We prospectively enrolled 30 consecutive patients for microsurgical resection of lesions within or in proximity to the brainstem between January 2019 and August 2021. Direct stimulation with initially 2 mA was performed for mapping and monitoring the motor fiber tracts. To evaluate CST status and measure DS-to-T, postoperative diffusion tensor imaging/tractography was used. Preoperative and postoperative modified Ranking Scale and motor function were evaluated to assess the clinical outcome. Results: Intraoperative direct brainstem stimulation was successfully performed in all patients with a total of 909 stimulation points. One patient experienced a temporary neurological deficit postoperatively. Mapping of the CST was achieved in 5 patients. DS-to-T was ≤4 mm when motor-evoked potential responses were positive under 2 mA stimulation and ≤2 mm under 1 mA. Overall sensitivity and specificity for this association were 84.7% and 100%, respectively. Conclusion: This study further supports the paradigm for continuous CST monitoring and mapping through direct brainstem stimulation. The relationship between stimulation intensity and DS-to-T in brainstem surgery could help surgeon's better estimate the safe edge intraoperatively

Safety of microneurosurgical interventions for superficial and deep-seated brain metastases: single-center cohort study of 637 consecutive cases

PURPOSE Microneurosurgical techniques have greatly improved over the past years due to the introduction of new technology and surgical concepts. To reevaluate the role of micro-neurosurgery in brain metastases (BM) resection in the era of new systemic and local treatment options, its safety profile needs to be reassessed. The aim of this study was to analyze the rate of adverse events (AEs) according to a systematic, comprehensive and reliably reproducible grading system after microneurosurgical BM resection in a large and modern microneurosurgical series with special emphasis on anatomical location. METHODS Prospectively collected cases of BM resection between 2013 and 2022 were retrospectively analyzed. Number of AEs, defined as any deviations from the expected postoperative course according to Clavien-Dindo-Grade (CDG) were evaluated. Patient, surgical, and lesion characteristics, including exact anatomic tumor locations, were analyzed using uni- and multivariate logistic regression and survival analysis to identify predictive factors for AEs. RESULTS We identified 664 eligible patients with lung cancer being the most common primary tumor (44%), followed by melanoma (25%) and breast cancer (11%). 29 patients (4%) underwent biopsy only whereas BM were resected in 637 (96%) of cases. The overall rate of AEs was 8% at discharge. However, severe AEs (≥ CDG 3a; requiring surgical intervention under local/general anesthesia or ICU treatment) occurred in only 1.9% (n = 12) of cases with a perioperative mortality of 0.6% (n = 4). Infratentorial tumor location (OR 5.46, 95% 2.31-13.8, p = .001), reoperation (OR 2.31, 95% 1.07-4.81, p = .033) and central region tumor location (OR 3.03, 95% 1.03-8.60) showed to be significant predictors in a multivariate analysis for major AEs (CDG ≥ 2 or new neurological deficits). Neither deep supratentorial nor central region tumors were associated with more major AEs compared to convexity lesions. CONCLUSIONS Modern microneurosurgical resection can be considered an excellent option in the management of BM in terms of safety, as the overall rate of major AEs are very rare even in eloquent and deep-seated lesions

Trends and outcomes for non‑elective neurosurgical procedures in Central Europe during the COVID‑19 pandemic

The world currently faces the novel severe acute respiratory syndrome coronavirus 2 pandemic. Little is known about the efects of a pandemic on non-elective neurosurgical practices, which have continued under modifed conditions to reduce the spread of COVID-19. This knowledge might be critical for the ongoing second coronavirus wave and potential restrictions on health care. We aimed to determine the incidence and 30-day mortality rate of various non-elective neurosurgical procedures during the COVID-19 pandemic.A retrospective, multi-centre observational cohort study among neurosurgical centres within Austria, the Czech Republic, and Switzerland was performed. Incidence of neurosurgical emergencies and related 30-day mortality rates were determined for a period refecting the peak pandemic of the frst wave in all participating countries (i.e. March 16th–April 15th, 2020), and compared to the same period in prior years (2017, 2018, and 2019).A total of 4,752 emergency neurosurgical cases were reviewed over a 4-year period. In 2020, during the COVID-19 pandemic, there was a general decline in the incidence of non-elective neurosurgical cases, which was driven by a reduced number of traumatic brain injuries, spine conditions, and chronic subdural hematomas. Thirty-day mortality did not signifcantly increase overall or for any of the conditions examined during the peak of the pandemic.The neurosurgical community in these three European countries observed a decrease in the incidence of some neurosurgical emergencies with 30-day mortality rates comparable to previous years (2017–2019). Lower incidence of neurosurgical cases is likely related to restrictions placed on mobility within countries, but may also involve delayed patient presentation.Medicine, Faculty ofOther UBCNon UBCReviewedFacultyResearcherPostdoctora