Publications by authors named "Emmanuel Mandonnet"

123 Publications

Contextualization of post-operative mini-strokes in glioma surgery.

Acta Neurochir (Wien) 2021 Nov 18. Epub 2021 Nov 18.

Department of Neurosurgery, Lariboisière Hospital, AP-HP, 2 rue Ambroise Paré, 75010, Paris, France.

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http://dx.doi.org/10.1007/s00701-021-05052-2DOI Listing
November 2021

Tribute to Professor Bernard George.

Acta Neurochir (Wien) 2021 12 5;163(12):3225-3227. Epub 2021 Nov 5.

Hôpital Lariboisière, Assistance Publique - Hopitaux de Paris, Paris, France.

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http://dx.doi.org/10.1007/s00701-021-05032-6DOI Listing
December 2021

A systematic review of the use of subcortical intraoperative electrical stimulation mapping for monitoring of executive deficits and neglect: what is the evidence so far?

Acta Neurochir (Wien) 2021 Oct 21. Epub 2021 Oct 21.

Department of Cognitive Neuropsychology, Tilburg University, Tilburg, the Netherlands.

Background: Over the past decade, the functional importance of white matter pathways has been increasingly acknowledged in neurosurgical planning. A method to directly study anatomo-functional correlations is direct electrical stimulation (DES). DES has been widely accepted by neurosurgeons as a reliable tool to minimize the occurrence of permanent postoperative motor, vision, and language deficits. In recent years, DES has also been used for stimulation mapping of other cognitive functions, such as executive functions and visuospatial awareness.

Methods: The aim of this review is to summarize the evidence so far from DES studies on subcortical pathways that are involved in visuospatial awareness and in the following three executive functions: (1) inhibitory control, (2) working memory, and (3) cognitive flexibility.

Results: Eleven articles reported on intraoperative electrical stimulation of white matter pathways to map the cognitive functions and explicitly clarified which subcortical tract was stimulated. The results indicate that the right SLF-II is involved in visuospatial awareness, the left SLF-III and possibly the right SLF-I are involved in working memory, and the cingulum is involved in cognitive flexibility.

Conclusions: We were unable to draw any more specific conclusions, nor unequivocally establish the critical involvement of pathways in executive functions or visuospatial awareness due to the heterogeneity of the study types and methods, and the limited number of studies that assessed these relationships. Possible approaches for future research to obtain converging and more definite evidence for the involvement of pathways in specific cognitive functions are discussed.
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http://dx.doi.org/10.1007/s00701-021-05012-wDOI Listing
October 2021

Atypical evolution of meningiomatosis after discontinuation of cyproterone acetate: clinical cases and histomolecular characterization.

Acta Neurochir (Wien) 2021 Oct 6. Epub 2021 Oct 6.

Department of Neurosurgery, Lariboisière Hospital, Assistance Publique - Hopitaux de Paris, University of Paris, Paris, France.

Purpose: The long-term use of cyproterone acetate (CPA) is associated with an increased risk of developing intracranial meningiomas. CPA discontinuation most often induces a stabilization or regression of the tumor. The underlying biological mechanisms as well as the reasons why some meningiomas still grow after CPA discontinuation remain unknown. We reported a series of patients presenting CPA-induced meningiomatosis with opposed tumor evolutions following CPA discontinuation, highlighting the underlying histological and genetic features.

Methods: Patients presenting several meningiomas with opposite tumor evolution (coexistence of growing and shrinking tumors) following CPA discontinuation were identified. Clinical and radiological data were reviewed. A retrospective volumetric analysis of the meningiomas was performed. All the growing meningiomas were operated. Each operated tumor was characterized by histological and genetic analyses.

Results: Four women with multiple meningiomas and opposite tumor volume evolutions after CPA discontinuation were identified. Histopathological analysis characterized the convexity and tentorial tumors which continued to grow after CPA discontinuation as fibroblastic meningiomas. The decreasing skull base tumor was characterized as a fibroblastic meningioma with increased fibrosis and a widespread collagen formation. The two growing skull base meningiomas were identified as meningothelial and transitional meningiomas. The molecular characterization found two NF2 mutations among the growing meningiomas and a PIK3CA mutation in the skull base tumor which decreased.

Conclusion: To our knowledge, this is the first report describing an atypical tumor evolution of CPA-associated meningiomas after CPA discontinuation. The underlying biological mechanisms explaining this observation and especially the close relationship between mutational landscapes and embryologic origins of the meninges in CPA-related meningiomas as well as their clonal origin require further research.
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http://dx.doi.org/10.1007/s00701-021-05005-9DOI Listing
October 2021

Glioblastoma Surgery Imaging-Reporting and Data System: Validation and Performance of the Automated Segmentation Task.

Cancers (Basel) 2021 Sep 17;13(18). Epub 2021 Sep 17.

Department of Clinical Epidemiology and Biostatistics, Amsterdam University Medical Centers, 1105 AZ Amsterdam, The Netherlands.

For patients with presumed glioblastoma, essential tumor characteristics are determined from preoperative MR images to optimize the treatment strategy. This procedure is time-consuming and subjective, if performed by crude eyeballing or manually. The standardized GSI-RADS aims to provide neurosurgeons with automatic tumor segmentations to extract tumor features rapidly and objectively. In this study, we improved automatic tumor segmentation and compared the agreement with manual raters, describe the technical details of the different components of GSI-RADS, and determined their speed. Two recent neural network architectures were considered for the segmentation task: nnU-Net and AGU-Net. Two preprocessing schemes were introduced to investigate the tradeoff between performance and processing speed. A summarized description of the tumor feature extraction and standardized reporting process is included. The trained architectures for automatic segmentation and the code for computing the standardized report are distributed as open-source and as open-access software. Validation studies were performed on a dataset of 1594 gadolinium-enhanced T1-weighted MRI volumes from 13 hospitals and 293 T1-weighted MRI volumes from the BraTS challenge. The glioblastoma tumor core segmentation reached a Dice score slightly below 90%, a patientwise F1-score close to 99%, and a 95th percentile Hausdorff distance slightly below 4.0 mm on average with either architecture and the heavy preprocessing scheme. A patient MRI volume can be segmented in less than one minute, and a standardized report can be generated in up to five minutes. The proposed GSI-RADS software showed robust performance on a large collection of MRI volumes from various hospitals and generated results within a reasonable runtime.
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http://dx.doi.org/10.3390/cancers13184674DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8465753PMC
September 2021

Transopercular Insular Approach, Overcoming the Training Curve Using a Cadaveric Simulation Model: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Nov;21(6):E561-E562

Department of Neurological Surgery and Spine Unit, Hospital Universitario Marqués de Valdecilla, Santander, Spain.

Transopercular approach to the insula is indicated for resection of insular low-grade gliomas, particularly for Yasargil's 3B, 5A, and 5B types. Nevertheless, the infrequent location and its challenging approach make it difficult to master the surgery. Consequently, a realistic laboratory training model might help to acquire key surgical skills. In this video, we describe a cadaveric-based model simulating the resection of a temporo-insular low-grade glioma. Kingler's fixation technique was used to fix the cadaver head before injecting red and blue colorants for a realistic vascular appearance. Hemisphere was frozen for white matter tract dissection. Tractography and intraoperative eloquent areas were extrapolated from a glioma patient by using a neuronavigation system. Then, a fronto-temporal craniotomy was performed through a question mark incision, exposing from inferior temporal gyrus up to middle frontal gyrus. After cortical anatomic landmark identification, eloquent areas were extrapolated creating a simulated functional cortical map. Then, transopercular noneloquent frontal and temporal corticectomies were performed, followed by subpial resection. Detailed identification of Sylvian vessels and insular cortex was demonstrated. Anatomic resection limits were exposed, and implicated white matter bundles, uncinate and fronto-occipital fascicles, were identified running through the temporal isthmus. Finally, a temporo-mesial resection was performed. In summary, this model provides a simple, cost-effective, and very realistic simulation of a transopercular approach to the insula, allowing the development of surgical skills needed to treat insular tumors in a safe environment. Besides, the integration of simulated navigation has proven useful in better understanding the complex white matter anatomy involved. Cadaver donation, subject or relatives, includes full consent for publication of the images. For the purpose of this video, no ethics committee approval was needed. Images correspond to a cadaver head donation. Cadaver donation, subject or relatives, includes full consent for any scientific purposes involving the corpse. The consent includes image or video recording. Regarding the intraoperative surgical video and tractography, the patient gave written consent for scientific divulgation prior to surgery.
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http://dx.doi.org/10.1093/ons/opab342DOI Listing
November 2021

Impaired Set-Shifting from Dorsal Stream Disconnection: Insights from a European Series of Right Parietal Lower-Grade Glioma Resection.

Cancers (Basel) 2021 Jul 3;13(13). Epub 2021 Jul 3.

Department of Neurology and Neurosurgery, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands.

Awake surgery with cognitive monitoring has increasingly been implemented to preserve brain networks and functionality. More recently, not only surgery in the left but also in the right hemisphere, i.c., the parietal lobe, was associated with potential risk for deficits in cognitive functions, such as cognitive flexibility. In this explorative pilot study, we compare cognitive performance more than three months after surgery with baseline measurements and explore the association between cognitive decline and subcortical tracts that may have been severed during surgery in the right hemisphere. Twenty-two patients who underwent surgery for a right parietal low-grade glioma were assessed pre- and postoperatively using the Trail Making Test and the Stroop task to administer set-shifting abilities and inhibition. Volume measurements and lesion-symptom mapping analyses were performed on postoperative MRI scans. Careful interpretation of the results shows a change in TMT performance and not on the Stroop Task when the lateral part of the arcuate fasciculus is damaged, indicating that disconnection of the lateral part of the dorsal stream might be correlated specifically with impaired set-shifting and not with inhibition. More importantly, this study underlines the need for international concertation to allow larger studies to increase power and perform more detailed analyses.
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http://dx.doi.org/10.3390/cancers13133337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8267741PMC
July 2021

On the cutting edge of glioblastoma surgery: where neurosurgeons agree and disagree on surgical decisions.

J Neurosurg 2021 Jul 9:1-11. Epub 2021 Jul 9.

1Department of Neurosurgery, Amsterdam UMC, Vrije Universiteit, Cancer Center Amsterdam.

Objective: The aim of glioblastoma surgery is to maximize the extent of resection while preserving functional integrity. Standards are lacking for surgical decision-making, and previous studies indicate treatment variations. These shortcomings reflect the need to evaluate larger populations from different care teams. In this study, the authors used probability maps to quantify and compare surgical decision-making throughout the brain by 12 neurosurgical teams for patients with glioblastoma.

Methods: The study included all adult patients who underwent first-time glioblastoma surgery in 2012-2013 and were treated by 1 of the 12 participating neurosurgical teams. Voxel-wise probability maps of tumor location, biopsy, and resection were constructed for each team to identify and compare patient treatment variations. Brain regions with different biopsy and resection results between teams were identified and analyzed for patient functional outcome and survival.

Results: The study cohort consisted of 1087 patients, of whom 363 underwent a biopsy and 724 a resection. Biopsy and resection decisions were generally comparable between teams, providing benchmarks for probability maps of resections and biopsies for glioblastoma. Differences in biopsy rates were identified for the right superior frontal gyrus and indicated variation in biopsy decisions. Differences in resection rates were identified for the left superior parietal lobule, indicating variations in resection decisions.

Conclusions: Probability maps of glioblastoma surgery enabled capture of clinical practice decisions and indicated that teams generally agreed on which region to biopsy or to resect. However, treatment variations reflecting clinical dilemmas were observed and pinpointed by using the probability maps, which could therefore be useful for quality-of-care discussions between surgical teams for patients with glioblastoma.
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http://dx.doi.org/10.3171/2020.11.JNS202897DOI Listing
July 2021

Glioblastoma Surgery Imaging-Reporting and Data System: Standardized Reporting of Tumor Volume, Location, and Resectability Based on Automated Segmentations.

Cancers (Basel) 2021 Jun 8;13(12). Epub 2021 Jun 8.

Department of Neurosurgery, Amsterdam University Medical Centers, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands.

Treatment decisions for patients with presumed glioblastoma are based on tumor characteristics available from a preoperative MR scan. Tumor characteristics, including volume, location, and resectability, are often estimated or manually delineated. This process is time consuming and subjective. Hence, comparison across cohorts, trials, or registries are subject to assessment bias. In this study, we propose a standardized Glioblastoma Surgery Imaging Reporting and Data System (GSI-RADS) based on an automated method of tumor segmentation that provides standard reports on tumor features that are potentially relevant for glioblastoma surgery. As clinical validation, we determine the agreement in extracted tumor features between the automated method and the current standard of manual segmentations from routine clinical MR scans before treatment. In an observational consecutive cohort of 1596 adult patients with a first time surgery of a glioblastoma from 13 institutions, we segmented gadolinium-enhanced tumor parts both by a human rater and by an automated algorithm. Tumor features were extracted from segmentations of both methods and compared to assess differences, concordance, and equivalence. The laterality, contralateral infiltration, and the laterality indices were in excellent agreement. The native and normalized tumor volumes had excellent agreement, consistency, and equivalence. Multifocality, but not the number of foci, had good agreement and equivalence. The location profiles of cortical and subcortical structures were in excellent agreement. The expected residual tumor volumes and resectability indices had excellent agreement, consistency, and equivalence. Tumor probability maps were in good agreement. In conclusion, automated segmentations are in excellent agreement with manual segmentations and practically equivalent regarding tumor features that are potentially relevant for neurosurgical purposes. Standard GSI-RADS reports can be generated by open access software.
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http://dx.doi.org/10.3390/cancers13122854DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8229389PMC
June 2021

A new simple and free tubular device for microscopic transcortical approach to deep-seated lesions: technical note and case example.

Acta Neurochir (Wien) 2021 Jul 1. Epub 2021 Jul 1.

Department of Neurosurgery, Lariboisière Hospital, University of Paris, 2 rue Ambroise Paré, 75010, Paris, France.

Background: Surgery for deep-seated brain tumors remains challenging. Transcortical approaches often require brain retraction to ensure an adequate surgical corridor, thus possibly leading to brain damage. Various techniques have been developed to minimize brain retraction such as self-retaining retractors, endoscopic approaches, or tubular retractor systems. Even if they evenly distribute the mechanical pressure over the parenchyma, rigid retractors can also cause some degree of brain damage and have significant disadvantages. We propose here a soft cottonoid retractor for microscopic resection of deep-seated and ventricular lesions.

Methods: Through a small corticectomy, a channel route with a blunt cannula is developed until the lesion is reached. Then, a "balloon-like system" made with a surgical glove is progressively inflated, dilatating the surgical corridor. A mini-tubular device, handmade by suturing a surgical cottonoid, is positioned into the corridor, unfolded, and sutured to the edge of the dura, to prevent it from being progressively expelled from the working channel. This allows a good visualization of the lesion and surrounding structures under the microscope.

Results: Advantages of this technique are the softness of the tube walls, the absence of rigid arm to hold the tube, and the possibility for the tube to follow the movements of the instruments and to modify its orientation according to the working area.

Conclusion: This simple and inexpensive tubular working channel for microscopic transcortical approach is a valuable alternative technique to traditional self-retaining retractor and rigid tube for the microsurgical resection of deep-seated brain tumors.
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http://dx.doi.org/10.1007/s00701-021-04927-8DOI Listing
July 2021

Intracranial Meningiomas Decrease in Volume on Magnetic Resonance Imaging After Discontinuing Progestin.

Neurosurgery 2021 07;89(2):308-314

Department of Neurosurgery, Lariboisiere Hospital, University of Paris Diderot, Paris, France.

Background: The behavior of meningiomas under influence of progestin therapy remains unclear.

Objective: To investigate the relationship between growth kinetics of intracranial meningiomas and usage of the progestin cyproterone acetate (PCA).

Methods: This study prospectively followed 108 women with 262 intracranial meningiomas and documented PCA use. A per-meningioma analysis was conducted. Changes in meningioma volumes over time, and meningioma growth velocities, were measured on magnetic resonance imaging (MRI) after stopping PCA treatment.

Results: Mean follow-up time was 30 (standard deviation [SD] 29) mo. Ten (4%) meningiomas were treated surgically at presentation. The other 252 meningiomas were followed after stopping PCA treatment. Overall, followed meningiomas decreased their volumes by 33% on average (SD 28%). A total of 188 (72%) meningiomas decreased, 51 (20%) meningiomas remained stable, and 13 (4%) increased in volume of which 3 (1%) were surgically treated because of radiological progression during follow-up after PCA withdrawal. In total, 239 of 262 (91%) meningiomas regressed or stabilized during follow-up. Subgroup analysis in 7 women with 19 meningiomas with follow-up before and after PCA withdrawal demonstrated that meningioma growth velocity changed statistically significantly (P = .02). Meningiomas grew (average velocity of 0.25 mm3/day) while patients were using PCA and shrank (average velocity of -0.54 mm3/day) after discontinuation of PCA.

Conclusion: Ninety-one percent of intracranial meningiomas in female patients with long-term PCA use decrease or stabilize on MRI after stopping PCA treatment. Meningioma growth kinetics change significantly from growth during PCA usage to shrinkage after PCA withdrawal.
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http://dx.doi.org/10.1093/neuros/nyab175DOI Listing
July 2021

Correction to: Voxel-wise glioblastoma-survival mapping: new tool, new questions.

Acta Neurochir (Wien) 2021 Jul;163(7):1909

Frontlab, Institut du Cerveau (ICM), CNRS UMR 7225, INSERM U1127, Paris, France.

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http://dx.doi.org/10.1007/s00701-021-04872-6DOI Listing
July 2021

Timing of glioblastoma surgery and patient outcomes: a multicenter cohort study.

Neurooncol Adv 2021 Jan-Dec;3(1):vdab053. Epub 2021 Apr 8.

Amsterdam University Medical Centers, location VU University Medical Center, Neurosurgical Center Amsterdam, Amsterdam, Netherlands.

Background: The impact of time-to-surgery on clinical outcome for patients with glioblastoma has not been determined. Any delay in treatment is perceived as detrimental, but guidelines do not specify acceptable timings. In this study, we relate the time to glioblastoma surgery with the extent of resection and residual tumor volume, performance change, and survival, and we explore the identification of patients for urgent surgery.

Methods: Adults with first-time surgery in 2012-2013 treated by 12 neuro-oncological teams were included in this study. We defined time-to-surgery as the number of days between the diagnostic MR scan and surgery. The relation between time-to-surgery and patient and tumor characteristics was explored in time-to-event analysis and proportional hazard models. Outcome according to time-to-surgery was analyzed by volumetric measurements, changes in performance status, and survival analysis with patient and tumor characteristics as modifiers.

Results: Included were 1033 patients of whom 729 had a resection and 304 a biopsy. The overall median time-to-surgery was 13 days. Surgery was within 3 days for 235 (23%) patients, and within a month for 889 (86%). The median volumetric doubling time was 22 days. Lower performance status (hazard ratio [HR] 0.942, 95% confidence interval [CI] 0.893-0.994) and larger tumor volume (HR 1.012, 95% CI 1.010-1.014) were independently associated with a shorter time-to-surgery. Extent of resection, residual tumor volume, postoperative performance change, and overall survival were not associated with time-to-surgery.

Conclusions: With current decision-making for urgent surgery in selected patients with glioblastoma and surgery typically within 1 month, we found equal extent of resection, residual tumor volume, performance status, and survival after longer times-to-surgery.
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http://dx.doi.org/10.1093/noajnl/vdab053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8156977PMC
April 2021

Broca's area: why was neurosurgery neglected for so long when seeking to re-establish the scientific truth?

Brain 2021 08;144(7):e60

Gui de Chauliac Hospital, 34295 Montpellier, France.

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http://dx.doi.org/10.1093/brain/awab195DOI Listing
August 2021

Tumor Growth Rate as a New Predictor of Progression-Free Survival After Chordoma Surgery.

Neurosurgery 2021 07;89(2):291-299

Department of Neurosurgery, Lariboisière Hospital, Assistance Publique - Hôpitaux de Paris, University of Paris, Paris, France.

Background: Currently, different postoperative predictors of chordoma recurrence have been identified. Tumor growth rate (TGR) is an image-based calculation that provides quantitative information of tumor's volume changing over time and has been shown to predict progression-free survival (PFS) in other tumor types.

Objective: To explore the usefulness of TGR as a new preoperative radiological marker for chordoma recurrence.

Methods: A retrospective single-institution study was carried out including patients reflecting these criteria: confirmed diagnosis of chordoma on pathological analysis, no history of previous radiation, and at least 2 preoperative thin-slice magnetic resonance images available to measure TGR. TGR was calculated for all patients, showing the percentage change in tumor size over 1 mo.

Results: A total of 32 patients were retained for analysis. Patients with a TGR ≥ 10.12%/m had a statistically significantly lower mean PFS (P < .0001). TGR ≥ 10.12%/m (odds ratio = 26, P = .001) was observed more frequently in recurrent chordoma. In a subgroup analysis, we found that the association of Ki-67 labeling index ≥ 6% and TGR ≥ 10.12%/m was correlated with recurrence (P = .0008).

Conclusion: TGR may be considered as a preoperative radiological indicator of tumor proliferation and seems to preoperatively identify more aggressive tumors with a higher tendency to recur. Our findings suggest that the therapeutic strategy and clinical-radiological follow-up of patients with chordoma can be adapted also according to this new parameter.
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http://dx.doi.org/10.1093/neuros/nyab164DOI Listing
July 2021

Robust Deep Learning-based Segmentation of Glioblastoma on Routine Clinical MRI Scans Using Sparsified Training.

Radiol Artif Intell 2020 Sep 30;2(5):e190103. Epub 2020 Sep 30.

Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands (R.S.E., M.v.H., M.G.W.); Department of Radiology and Nuclear Medicine, Amsterdam UMC, Location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands (M.V., F.B., H.V., J.C.d.M.); Neurosurgical Center Amsterdam, Amsterdam UMC, Location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands (D.M.J.M., P.C.D.W.H.); Institutes of Neurology & Healthcare Engineering, University College London, London, England (F.B.); Faculty of Biology, Medicine & Health, Division of Cancer Sciences, University of Manchester and Christie NHS Trust, Manchester, England (M.v.H.); Neurosurgical Oncology Unit, Department of Oncology and Hemato-Oncology, Università degli Studi di Milano, Humanitas Research Hospital, IRCCS, Milan, Italy (L.B., M.C.N., M.R., T.S.); Department of Neurologic Surgery, University of California-San Francisco, San Francisco, Calif (M.S.B., S.H.J.); Department of Neurosurgery, Medical University Vienna, Vienna, Austria (B.K., G.W.); Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria (J.F.); Department of Neurology & Neurosurgery, University Medical Center Utrecht, Utrecht, the Netherlands (P.A.J.T.R.); and Department of Neurologic Surgery, Hôpital Lariboisière, Paris, France (E.M.).

Purpose: To improve the robustness of deep learning-based glioblastoma segmentation in a clinical setting with sparsified datasets.

Materials And Methods: In this retrospective study, preoperative T1-weighted, T2-weighted, T2-weighted fluid-attenuated inversion recovery, and postcontrast T1-weighted MRI from 117 patients (median age, 64 years; interquartile range [IQR], 55-73 years; 76 men) included within the Multimodal Brain Tumor Image Segmentation (BraTS) dataset plus a clinical dataset (2012-2013) with similar imaging modalities of 634 patients (median age, 59 years; IQR, 49-69 years; 382 men) with glioblastoma from six hospitals were used. Expert tumor delineations on the postcontrast images were available, but for various clinical datasets, one or more sequences were missing. The convolutional neural network, DeepMedic, was trained on combinations of complete and incomplete data with and without site-specific data. Sparsified training was introduced, which randomly simulated missing sequences during training. The effects of sparsified training and center-specific training were tested using Wilcoxon signed rank tests for paired measurements.

Results: A model trained exclusively on BraTS data reached a median Dice score of 0.81 for segmentation on BraTS test data but only 0.49 on the clinical data. Sparsified training improved performance (adjusted < .05), even when excluding test data with missing sequences, to median Dice score of 0.67. Inclusion of site-specific data during sparsified training led to higher model performance Dice scores greater than 0.8, on par with a model based on all complete and incomplete data. For the model using BraTS and clinical training data, inclusion of site-specific data or sparsified training was of no consequence.

Conclusion: Accurate and automatic segmentation of glioblastoma on clinical scans is feasible using a model based on large, heterogeneous, and partially incomplete datasets. Sparsified training may boost the performance of a smaller model based on public and site-specific data.Published under a CC BY 4.0 license.
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http://dx.doi.org/10.1148/ryai.2020190103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8082349PMC
September 2020

Proposed definition of competencies for surgical neuro-oncology training.

J Neurooncol 2021 May 21;153(1):121-131. Epub 2021 Apr 21.

Department of Neurosurgery, Justus-Liebig University Giessen, Giessen, Germany.

Objective: The aim of this work is to define competencies and entrustable professional activities (EPAs) to be imparted within the framework of surgical neuro-oncological residency and fellowship training as well as the education of medical students. Improved and specific training in surgical neuro-oncology promotes neuro-oncological expertise, quality of surgical neuro-oncological treatment and may also contribute to further development of neuro-oncological techniques and treatment protocols. Specific curricula for a surgical neuro-oncologic education have not yet been established.

Methods: We used a consensus-building approach to propose skills, competencies and EPAs to be imparted within the framework of surgical neuro-oncological training. We developed competencies and EPAs suitable for training in surgical neuro-oncology.

Result: In total, 70 competencies and 8 EPAs for training in surgical neuro-oncology were proposed. EPAs were defined for the management of the deteriorating patient, the management of patients with the diagnosis of a brain tumour, tumour-based resections, function-based surgical resections of brain tumours, the postoperative management of patients, the collaboration as a member of an interdisciplinary and/or -professional team and finally for the care of palliative and dying patients and their families.

Conclusions And Relevance: The present work should subsequently initiate a discussion about the proposed competencies and EPAs and, together with the following discussion, contribute to the creation of new training concepts in surgical neuro-oncology.
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http://dx.doi.org/10.1007/s11060-021-03750-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8131302PMC
May 2021

Voxel-wise glioblastoma-survival mapping: new tool, new questions.

Acta Neurochir (Wien) 2021 07 12;163(7):1907-1908. Epub 2021 Apr 12.

Frontlab, Institut du Cerveau (ICM), CNRS UMR 7225, INSERM U1127, Paris, France.

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http://dx.doi.org/10.1007/s00701-021-04843-xDOI Listing
July 2021

Endoscope-assisted far-lateral transcondylar approach for craniocervical junction chordomas: a retrospective case series and cadaveric dissection.

J Neurosurg 2021 04 2:1-12. Epub 2021 Apr 2.

1Department of Neurosurgery, Lariboisière Hospital, Assistance Publique-Hôpitaux de Paris.

Objective: Craniocervical junction (CCJ) chordomas are a neurosurgical challenge because of their deep localization, lateral extension, bone destruction, and tight relationship with the vertebral artery and lower cranial nerves. In this study, the authors present their surgical experience with the endoscope-assisted far-lateral transcondylar approach (EA-FLTA) for the treatment of CCJ chordomas, highlighting the advantages of this corridor and the integration of the endoscope to reach the anterior aspect and contralateral side of the CCJ and the possibility of performing occipitocervical fusion (OCF) during the same stage of surgery.

Methods: Nine consecutive cases of CCJ chordomas treated with the EA-FLTA between 2013 and 2020 were retrospectively reviewed. Preoperative characteristics, surgical technique, postoperative results, and clinical outcome were analyzed. A cadaveric dissection was also performed to clarify the anatomical landmarks.

Results: The male/female ratio was 1.25, and the median age was 36 years (range 14-53 years). In 6 patients (66.7%), the lesion showed a bilateral extension, and 7 patients (77.8%) had an intradural extension. The vertebral artery was encased in 5 patients. Gross-total resection was achieved in 5 patients (55.6%), near-total resection in 3 (33.3%), and subtotal resection 1 (11.1%). In 5 cases, the OCF was performed in the same stage after tumor removal. Neither approach-related complications nor complications related to tumor resection occurred. During follow-up (median 18 months, range 5-48 months), 1 patient, who had already undergone treatment and radiotherapy at another institution and had an aggressive tumor (Ki-67 index of 20%), showed tumor recurrence at 12 months.

Conclusions: The EA-FLTA provides a safe and effective corridor to resect extensive and complex CCJ chordomas, allowing the surgeon to reach the anterior, lateral, and posterior portions of the tumor, and to treat CCJ instability in a single stage.
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http://dx.doi.org/10.3171/2020.9.JNS202611DOI Listing
April 2021

Patterns of axono-cortical evoked potentials: an electrophysiological signature unique to each white matter functional site?

Acta Neurochir (Wien) 2021 11 12;163(11):3121-3130. Epub 2021 Jan 12.

Frontlab, Institut du Cerveau, ICM, CNRS UMR 7225, INSERM, U1127, Paris, France.

Background: Brain-to-brain evoked potentials constitute a new methodology that could help to understand the network-level correlates of electrical stimulation applied for brain mapping during tumor resection. In this paper, we aimed to describe the characteristics of axono-cortical evoked potentials recorded from distinct, but in the same patient, behaviorally eloquent white matter sites.

Methods: We report the intraoperative white matter mapping and axono-cortical evoked potentials recordings observed in a patient operated on under awake condition of a diffuse low-grade glioma in the left middle frontal gyrus. Out of the eight behaviorally eloquent sites identified with 60-Hz electrical stimulation, five were probed with single electrical pulses (delivered at 1 Hz), while recording evoked potentials on two electrodes, covering the inferior frontal gyrus and the precentral gyrus, respectively. Postoperative diffusion-weighted MRI was used to reconstruct the tractograms passing through each of the five stimulated sites.

Results: Each stimulated site generated an ACEP on at least one of the recorded electrode contacts. The whole pattern-i.e., the specific contacts with ACEPs and their waveform-was distinct for each of the five stimulated sites.

Conclusions: We found that the patterns of ACEPs provided unique electrophysiological signatures for each of the five white matter functional sites. Our results could ultimately provide neurosurgeons with a new tool of intraoperative electrophysiologically based functional guidance.
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http://dx.doi.org/10.1007/s00701-020-04656-4DOI Listing
November 2021

Electrophysiological Mapping During Brain Tumor Surgery: Recording Cortical Potentials Evoked Locally, Subcortically and Remotely by Electrical Stimulation to Assess the Brain Connectivity On-line.

Brain Topogr 2021 03 5;34(2):221-233. Epub 2021 Jan 5.

CAMIN, INRIA, LIRMM, Université de Montpellier, 34090, Montpellier, France.

Direct electrical stimulation (DES) is used to perform functional brain mapping during awake surgery and in epileptic patients. DES may be coupled with the measurement of Evoked Potentials (EP) to study the conductive and integrative properties of activated neural ensembles and probe the spatiotemporal dynamics of short- and long-range networks. However, its electrophysiological effects remain by far unknown. We recorded ECoG signals on two patients undergoing awake brain surgery and measured EP on functional sites after cortical stimulations and were the firsts to record three different types of EP on the same patients. Using low-intensity (1-3 mA) to evoke electrogenesis we observed that: (i) "true" remote EPs are attenuated in amplitude and delayed in time due to the divergence of white matter pathways; (ii) "false" remote EPs are attenuated but not delayed: as they originate from the same electrical source; (iii) Singular but reproducible positive components in the EP can be generated when the DES is applied in the temporal lobe or the premotor cortex; and (iv) rare EP can be triggered when the DES is applied subcortically: these can be either negative, or surprisingly, positive. We proposed different activation and electrophysiological propagation mechanisms following DES, based on the nature of activated neural elements and discussed important methodological pitfalls when measuring EP in the brain. Altogether, these results pave the way to map the connectivity in real-time between the DES and the recording sites; to characterize the local electrophysiological states and to link electrophysiology and function. In the future, and in practice, this technique could be used to perform electrophysiological mapping in order to link (non)-functional to electrophysiological responses with DES and could be used to guide the surgical act itself.
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http://dx.doi.org/10.1007/s10548-020-00814-0DOI Listing
March 2021

Axono-cortical evoked potentials as a new method of IONM for preserving the motor control network: a first study in three cases.

Acta Neurochir (Wien) 2021 04 7;163(4):919-935. Epub 2020 Nov 7.

Frontlab, Institut du Cerveau, CNRS UMR 7225, INSERM U1127, Paris, France.

Background: White matter stimulation in an awake patient is currently the gold standard for identification of functional pathways. Despite the robustness and reproducibility of this method, very little is known about the electrophysiological mechanisms underlying the functional disruption. Axono-cortical evoked potentials (ACEPs) provide a reliable technique to explore these mechanisms.

Objective: To describe the shape and spatial patterns of ACEPs recorded when stimulating the white matter of the caudal part of the right superior frontal gyrus while recording in the precentral gyrus.

Methods: We report on three patients operated on under awake condition for a right superior frontal diffuse low-grade glioma. Functional sites were identified in the posterior wall of the cavity, whose 2-3-mA stimulation generated an arrest of movement. Once the resection was done, axono-cortical potentials were evoked: recording electrodes were put over the precentral gyrus, while stimulating at 1 Hz the white matter functional sites during 30-60 s. Unitary evoked potentials were averaged off-line. Waveform was visually analyzed, defining peaks and troughs, with quantitative measurements of their amplitudes and latencies. Spatial patterns of ACEPs were compared with patients' own and HCP-derived structural connectomics.

Results: Axono-cortical evoked potentials (ACEPs) were obtained and exhibited complex shapes and spatial patterns that correlated only partially with structural connectivity patterns.

Conclusion: ACEPs is a new IONM methodology that could both contribute to elucidate the propagation of neuronal activity within a distributed network when stimulating white matter and provide a new technique for preserving motor control abilities during brain tumor resections.
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http://dx.doi.org/10.1007/s00701-020-04636-8DOI Listing
April 2021

Augmented reality for the virtual dissection of white matter pathways.

Acta Neurochir (Wien) 2021 04 7;163(4):895-903. Epub 2020 Oct 7.

Department of Neurosurgery, TUM Neuroimaging Center, Technical University of Munich, Germany, School of Medicine, Klinikum rechts der Isar, Ismaninger Str. 22, 81675, Munich, Germany.

Background: The human white matter pathway network is complex and of critical importance for functionality. Thus, learning and understanding white matter tract anatomy is important for the training of neuroscientists and neurosurgeons. The study aims to test and evaluate a new method for fiber dissection using augmented reality (AR) in a group which is experienced in cadaver white matter dissection courses and in vivo tractography.

Methods: Fifteen neurosurgeons, neurolinguists, and neuroscientists participated in this questionnaire-based study. We presented five cases of patients with left-sided perisylvian gliomas who underwent awake craniotomy. Diffusion tensor imaging fiber tracking (DTI FT) was performed and the language-related networks were visualized separated in different tracts by color. Participants were able to virtually dissect the prepared DTI FTs using a spatial computer and AR goggles. The application was evaluated through a questionnaire with answers from 0 (minimum) to 10 (maximum).

Results: Participants rated the overall experience of AR fiber dissection with a median of 8 points (mean ± standard deviation 8.5 ± 1.4). Usefulness for fiber dissection courses and education in general was rated with 8 (8.3 ± 1.4) and 8 (8.1 ± 1.5) points, respectively. Educational value was expected to be high for several target audiences (student: median 9, 8.6 ± 1.4; resident: 9, 8.5 ± 1.8; surgeon: 9, 8.2 ± 2.4; scientist: 8.5, 8.0 ± 2.4). Even clinical application of AR fiber dissection was expected to be of value with a median of 7 points (7.0 ± 2.5).

Conclusion: The present evaluation of this first application of AR for fiber dissection shows a throughout positive evaluation for educational purposes.
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http://dx.doi.org/10.1007/s00701-020-04545-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7966623PMC
April 2021

Network-level causal analysis of set-shifting during trail making test part B: A multimodal analysis of a glioma surgery case.

Cortex 2020 11 12;132:238-249. Epub 2020 Sep 12.

Frontlab, CNRS UMR 7225, Inserm U1127, Sorbonne Université ICM, Paris, France.

The trail making test part B (TMT-B) is one of the most widely used task for the assessment of set-shifting ability in patients. However, the set of brain regions impacting TMT-B performance when lesioned is still poorly known. In this case report, we provide a multimodal analysis of a patient operated on while awake for a diffuse low-grade glioma located in the right supramarginal gyrus. TMT-B performance was probed intraoperatively. Direct electrical stimulation of the white matter in the depth of the resection generated shifting errors. Using the recent methodology of axono-cortical-evoked potentials (ACEP), we demonstrated that the eloquent fibers were connected to the posterior end of the middle temporal gyrus (MTG). This was further confirmed by a tractography analysis of the postoperative diffusion MRI. Finally, the functional connectivity maps of this MTG seed were assessed in both pre- and post-operative resting state MRI. These maps matched with the Control network B (13th) and Default B (17th) from the 17-networks parcellation of (Yeo et al., 2011). Last but not least, we showed that the dorsal attention B (6th), the control A & B networks (12th and 13th) and the default A (16th) have been preserved here but disconnected after a more extensive resection in a previous glioma case within the same area, and in whom TMT-B was definitively impaired. Taken together, these data support the need of a network-level approach to identify the neural basis of the TMT-B and point to the Control network B as playing an important role in set-shifting.
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http://dx.doi.org/10.1016/j.cortex.2020.08.021DOI Listing
November 2020

"I do not feel my hand where I see it": causal mapping of visuo-proprioceptive integration network in a surgical glioma patient.

Acta Neurochir (Wien) 2020 08 13;162(8):1949-1955. Epub 2020 May 13.

Frontlab, ICM, Paris, France.

A recent tasked-based fMRI study unveiled a network of areas implicated in the process of visuo-proprioceptive integration of the right hand. In this study, we report a case of a patient operated on in awake conditions for a glioblastoma of the left superior parietal lobule. When stimulating a white matter site in the anterior wall of the cavity, the patient spontaneously reported a discrepancy between the visual and proprioceptive perceptions of her right hand. Using several multimodal approaches (axono-cortical evoked potentials, tractography, resting-state functional connectivity), we demonstrated converging support for the hypothesis that tumor-induced plasticity redistributed the left-lateralized network of right-hand visuo-proprioceptive integration towards its right-lateralized homolog.
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http://dx.doi.org/10.1007/s00701-020-04399-2DOI Listing
August 2020
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