Path to success: female leaders in German neurosurgery.

Despite advances in gender equality, only 6% of German neurosurgical departments are currently led by women. With regard to their pioneering work and the importance of their role model effect, we aimed at reporting on the career pathways of the present and former female chairs of neurosurgical departments in Germany. We approached current and former female chairs in German neurosurgery and gathered descriptive information on their ways into leadership positions through structured interviews. Data were obtained from 16/22 (72.7%) female neurosurgical chairs, aged between 44 and 82 years. They completed their training within 6.5 ± 0.6 years, and it took them further 14.5 ± 5.9 years between training completion and chair acquisition. Having obtained their chair positions between 1993 and 2020, six (37.5%) of them have retired or changed career tracks. Of ten (62.5%) chairs still practicing, two are directors of university departments. Twelve (75.0%) hold professorships. Nine chairs (56.3%) are married, eight (50.0%) having children. Five chairs reported having experienced gender-based discrimination. Twelve had a male mentor or role model, two had a female role model, while only one had a female mentor. This study characterizes the to date small number of female neurosurgical chairs in Germany and their paths to neurosurgical leadership positions. In future, these should become historical in order to perceive the presence of women in leadership positions as self-evident normality, reflecting our society. However, further analyses comparing paths of both female and male neurosurgical chairs are necessary to explore gender-based differences in achieving neurosurgical leadership positions.

Dimensionality Reduction: Foundations and Applications in Clinical Neuroscience.

Advancements in population neuroscience are spurred by the availability of large scale, open datasets, such as the Human Connectome Project or recently introduced UK Biobank. With the increasing data availability, analyses of brain imaging data employ more and more sophisticated machine learning algorithms. However, all machine learning algorithms must balance generalization and complexity. As the detail of neuroimaging data leads to high-dimensional data spaces, model complexity and hence the chance of overfitting increases. Different methodological approaches can be applied to alleviate the problems that arise in high-dimensional settings by reducing the original information into meaningful and concise features. One popular approach is dimensionality reduction, which allows to summarize high-dimensional data into low-dimensional representations while retaining relevant trends and patterns. In this paper, principal component analysis (PCA) is discussed as widely used dimensionality reduction method based on current examples of population-based neuroimaging analyses.

Introduction to Machine Learning in Neuroimaging.

Advancements in neuroimaging and the availability of large-scale datasets enable the use of more sophisticated machine learning algorithms. In this chapter, we non-exhaustively discuss relevant analytical steps for the analysis of neuroimaging data using machine learning (ML), while the field of radiomics will be addressed separately (c.f., Chap. 18 -Radiomics). Broadly classified into supervised and unsupervised approaches, we discuss the encoding/decoding framework, which is often applied in cognitive neuroscience, and the use of ML for the analysis of unlabeled data using clustering.

Foundations of Time Series Analysis.

For almost a century, classical statistical methods including exponential smoothing and autoregression integrated moving averages (ARIMA) have been predominant in the analysis of time series (TS) and in the pursuit of forecasting future events from historical data. TS are chronological sequences of observations, and TS data are therefore prevalent in many aspects of clinical medicine and academic neuroscience. With the rise of highly complex and nonlinear datasets, machine learning (ML) methods have become increasingly popular for prediction or pattern detection and within neurosciences, including neurosurgery. ML methods regularly outperform classical methods and have been successfully applied to, inter alia, predict physiological responses in intracranial pressure monitoring or to identify seizures in EEGs. Implementing nonparametric methods for TS analysis in clinical practice can benefit clinical decision making and sharpen our diagnostic armory.

The Artificial Intelligence Doctor: Considerations for the Clinical Implementation of Ethical AI.

The applications of artificial intelligence (AI) and machine learning (ML) in modern medicine are growing exponentially, and new developments are fast-paced. However, the lack of trust and appropriate legislation hinder its clinical implementation. Recently, there is a clear increase of directives and considerations on Ethical AI. However, most literature broadly deals with ethical tensions on a meta-level without offering hands-on advice in practice. In this article, we non-exhaustively cover basic practical guidelines regarding AI-specific ethical aspects, including transparency and explicability, equity and mitigation of biases, and lastly, liability.

Choroidal artery ischemic events after temporal lobe epilepsy surgery: clinical outcome, quality of life, and surgical pitfalls.

OBJECTIVE: Ischemic events within the territory of the choroidal artery are an important cause of morbidity after temporal lobe epilepsy (TLE) surgery. The aim of the present study was to evaluate the rate of these ischemic events, their clinical presentation, and impact on patients' health-related quality of life (HRQoL) after TLE surgery. METHODS: Four hundred twenty-two consecutive patients undergoing temporal resections for drug-resistant TLE were retrospectively analyzed. All patients underwent presurgical multidisciplinary assessment using a standard protocol comprising clinical, neuroradiological, neuropsychological, and EEG data. Postoperative complications with corresponding imaging, neurological deficits, and disease-specific HRQoL questionnaires were evaluated. RESULTS: The overall complication rate was 7.8% (n = 33). Fourteen patients (3.3%) suffered from ischemic events causing 6 permanent motor deficits, 3 with permanent aphasias, and 6 visual field defects that exceeded quadrantanopia. In 8 patients with anterior choroidal artery infarction, accounting for 57% of all ischemic events, infarction volume correlated positively with the occurrence of new permanent neurological deficits (8666 vs 1692 mm3, p = 0.032). Despite the occurrence of ischemic events, HRQoL improved in 71% of patients. However, infarction volume showed a negative correlation trend with HRQoL (Pearson's r = -0.390, p = 0.094). There was a trend toward increased risk for ischemic events in patients who underwent selective amygdalohippocampectomy compared to patients who underwent anterior temporal lobectomy or temporal lesionectomy (RR 0.96, 95% CI 0.93-0.99, p = 0.08). CONCLUSIONS: Choroidal artery infarctions are rare but relevant complications after TLE surgery, presenting with variable clinical courses ranging from devastating neurological deterioration to complete recovery. Despite the occurrence of postoperative infarction, most patients report improvement of HRQoL after TLE surgery. This study showed that the type of surgery appears to modulate the risk for these ischemic events.

18F-FET-PET-guided gross total resection improves overall survival in patients with WHO grade III/IV glioma: moving towards a multimodal imaging-guided resection.

PURPOSE: PET using radiolabeled amino acid [18F]-fluoro-ethyl-L-tyrosine (FET-PET) is a well-established imaging modality for glioma diagnostics. The biological tumor volume (BTV) as depicted by FET-PET often differs in volume and location from tumor volume of contrast enhancement (CE) in MRI. Our aim was to investigate whether a gross total resection of BTVs defined as < 1 cm3 of residual BTV (PET GTR) correlates with better oncological outcome. METHODS: We retrospectively analyzed imaging and survival data from patients with primary and recurrent WHO grade III or IV gliomas who underwent FET-PET before surgical resection. Tumor overlap between FET-PET and CE was evaluated. Completeness of FET-PET resection (PET GTR) was calculated after superimposition and semi-automated segmentation of pre-operative FET-PET and postoperative MRI imaging. Survival analysis was performed using the Kaplan-Meier method and the log-rank test. RESULTS: From 30 included patients, PET GTR was achieved in 20 patients. Patients with PET GTR showed improved median OS with 19.3 compared to 13.7 months for patients with residual FET uptake (p = 0.007; HR 0.3; 95% CI 0.12-0.76). This finding remained as independent prognostic factor after performing multivariate analysis (HR 0.19, 95% CI 0.06-0.62, p = 0.006). Other survival influencing factors such as age, IDH-mutation, MGMT promotor status, and adjuvant treatment modalities were equally distributed between both groups. CONCLUSION: Our results suggest that PET GTR improves the OS in patients with WHO grade III or IV gliomas. A multimodal imaging approach including FET-PET for surgical planning in newly diagnosed and recurrent tumors may improve the oncological outcome in glioma patients.

Female Participation in Academic European Neurosurgery-A Cross-Sectional Analysis.

The study aims to provide data on authors' gender distribution with special attention on publications from Europe. Articles (October 2019-March 2020) published in three representative neurosurgical journals (Acta Neurochirurgica, Journal of Neurosurgery, Neurosurgery) were analyzed with regard to female participation. Out of 648 publications, 503 original articles were analyzed: 17.5% (n = 670) of the 3.821 authors were female, with 15.7% (n = 79) females as first and 9.5% (n = 48) as last authors. The lowest ratio of female first and last authors was seen in original articles published in the JNS (12.3%/7.7% vs. Neurosurgery 14.9%/10.6% and Acta 23.0/11.5%). Articles originated in Europe made up 29.8% (female author ratio 21.1% (n = 226)). Female first authorship was seen in 20.7% and last authorship in 10.7% (15.3% and 7.3% were affiliated to a neurosurgical department). The percentages of female authorship were lower if non-original articles (n = 145) were analyzed (11.7% first/4.8% last authorships). Female participation in editorial boards was 8.0%. Considering the percentages of European female neurosurgeons, the current data are proportional. However, the lack of female last authors, the discrepancy regarding non-original articles and the composition of the editorial boards indicate that there still is a structural underrepresentation and that females are limited in achieving powerful positions.

Shedding light on human cerebral lipofuscin: An explorative study on identification and quantification.

Increased oxidative stress has been associated with several neurodegenerative diseases such as Alzheimer's disease, but also with neurological diseases sharing pathophysiological pathways like epilepsy. Lipofuscin is a nondegradable end-product of oxidative stress; its cerebral presence reflects the cumulative amount of oxidative stress the brain has endured. In this study, we have observed prominent autofluorescent particles in the pial arterial wall and in neocortical parenchyma of young, drug-resistant epilepsy patients (18-28 years old) who underwent resective brain surgery (n = 6), as well as in older control patients (n = 3). With fluorescence spectroscopic imaging, brightfield microscopy, histochemistry and fluorescence lifetime imaging, these autofluorescent particles were identified as the age pigment lipofuscin. An evaluation of these lipofuscin particles using Imaris© software allowed robust quantification, while the 3D properties allowed visualization of the complex configuration. We elaborate on the usefulness of lipofuscin as a marker of cumulative oxidative stress in the brain. Furthermore, we speculate on the observed differences in particle size and density that we found between young patients and older controls, which could imply a role for lipofuscin in the pathophysiology of epilepsy and possibly other neurological diseases.

Quality of life in elderly patients after surgery for drug-resistant epilepsy - The impact of seizure outcome, neurological deficits and anxiety.

INTRODUCTION: Health related quality of life (HRQoL) has become a pivotal outcome parameter after surgery for drug-resistant epilepsy. The aim of the study was to investigate HRQoL and its relationship to seizure outcome, neurological deficits and anxiety after epilepsy surgery in a specific subpopulation of elderly patients. METHODS: A total of 85 elderly patients (older than 50 years) answered a standardized HRQoL questionnaire one year after epilepsy surgery. The questionnaire addressed the present self-assessed HRQoL in four subdomains (physical function, cognitive function, mood, social interaction). The questionnaire was based on the "Epilepsy Surgery Inventory-55", adapted for use in German speaking patients and validated by the QOLIE -10 and Beck Depression Inventory. RESULTS: A total of 51 patients (60%) were completely seizure free (ILAE1) at last available outcome (LAO). Permanent neurological deficits were observed in 8 patients (7%). Correlation analysis confirmed significant association between seizure outcome and overall HRQoL (r = -0.368, p < .001). New permanent neurological deficits showed impact on both HRQoL and the "cognitive function" subdomain. Anxiety and subjective assessment of postoperative status were strongly correlated with overall HRQoL (r = 0.692, p < .001 and r = 0.591, p < .001 respectively) and remained as independent prognostic factors in a multivariate regression analysis. CONCLUSION: Surgery for drug-resistant epilepsy in elderly improves patients' HRQoL. Both seizure freedom and new neurological deficits influence overall HRQoL. Interestingly, anxiety and patients' subjective assessment of postoperative status showed the highest impact on HRQoL in this subpopulation of epilepsy patients.

Surgery for temporal lobe epilepsy in the elderly: Improving quality of life despite cognitive impairment.

INTRODUCTION: Temporal lobe epilepsy (TLE) surgery is still underutilized, especially in the elderly population because of concerns related to postoperative complication rate and cognitive deterioration. The aim of the study was to evaluate surgical data, quality of life and neuropsychological outcome in elderly patients, who underwent resective surgery for drug resistant TLE. METHODS AND MATERIALS: All patients underwent standardized presurgical assessment including clinical, neuroradiological, neuropsychological, and EEG examination. Elderly were considered all patients being 50 years or above (mean 56 yr., range 50-71 yr.). Neuropsychology was assessed before and after surgery, health-related quality of life (HRQOL) only after surgery. RESULTS: A total of 94 consecutive elderly patients were analyzed. Temporo-mesial resections were performed in 85 patients (90 %). Seizure outcome was available in all patients with a mean follow-up of 5.2 years (1.2-19 ± 3.75 years). 57 patients (60.6 %) were completely seizure free (ILAE 1). The overall morbidity was 10 % including 5 surgical complications and 5 permanent neurological deficits. Neuropsychological assessments in 60 patients showed considerable preoperative impairment, losses in different domains in 25-45 % and gains in about 25 % of the patients. Postoperative HRQOL data was available in 75 patients, revealing significant increase of HRQOL in all domains. Complete seizure freedom was the strongest predictor for postoperative HRQOL (p < 0.001). CONCLUSION: Surgery for drug resistant temporal lobe epilepsy is a feasible option for elderly patients as seizure control rates are comparable to the younger population. The acceptable rate of permanent neurological deficits and relevant improvements in quality of life, despite considerable postoperative cognitive impairment, justify surgical resection in properly selected elderly patients.

Pneumocephalus: a rare and life-threatening, but reversible, complication after penetrating lumbar injury.

Pneumocephalus, the presence of intracranial air, is a complication especially seen after neurotrauma or brain surgery. When it leads to a pressure gradient, a so-called tension pneumocephalus, it may require emergency surgery. Clinical symptomatology, especially in young children, does not differentiate between a pneumocephalus and a tension pneumocephalus. An additional CT scan is therefore warranted. Here, we report on a rare case of pneumocephalus after penetrating lumbar injury. Additionally, the pathophysiology of pneumocephalus, as well as its recommendations for diagnosis and treatment, will be elucidated.