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.
Abstract
Extent of resection after surgery is one of the main prognostic factors for patients diagnosed with glioblastoma. To achieve this, accurate segmentation and classification of residual tumor ...from post-operative MR images is essential. The current standard method for estimating it is subject to high inter- and intra-rater variability, and an automated method for segmentation of residual tumor in early post-operative MRI could lead to a more accurate estimation of extent of resection. In this study, two state-of-the-art neural network architectures for pre-operative segmentation were trained for the task. The models were extensively validated on a multicenter dataset with nearly 1000 patients, from 12 hospitals in Europe and the United States. The best performance achieved was a 61% Dice score, and the best classification performance was about 80% balanced accuracy, with a demonstrated ability to generalize across hospitals. In addition, the segmentation performance of the best models was on par with human expert raters. The predicted segmentations can be used to accurately classify the patients into those with residual tumor, and those with gross total resection.
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.
Objective
To assess the feasibility of awake surgery for a brain tumor in a population of non-French-speaking migrants in Paris, France.
Methods
The Lariboisière database of awake surgeries was ...retrospectively reviewed, from the first case in 2011 up to July 2018. Inclusion criteria were patients being migrated in France during their adulthood, patients being unable to speak neither French nor English. Clinical and radiological data were collected from the electronic medical charts.
Results
Five patients fulfilled inclusion criteria. Pathological diagnosis included three glioma, one meningioma, and one melanoma metastasis. The standard awake protocol of our center was followed as usual, with the additional involvement of an interpreter at each step. In the five cases, the awake procedure allowed the surgeon to tailor the resection according to functional boundaries. Resections were complete in three cases and subtotal in two cases. No neurological deficits were observed. All patients returned to their preoperative socio-professional status.
Conclusions
Awake surgery for a brain tumor can be offered to migrants, in spite of the poor verbal communication between the patient and the caring staff. A team dedicated to awake surgery and including an interpreter is the key to successfully overcome the language barrier, before, during, and after the surgery.
In 1861, Paul Broca reported the post-mortem lesion-symptom mapping of two aphasic patients. At that time, his two observations had a tremendous impact, because they gave strong support to a new ...theory of the phrenology of brain convolutions (instead of the phrenology of cranial morphology defended by Joseph Gall), grounding a lesional localizationism, and thus arguing definitely against the holistic theory. Unfortunately, for several reasons,Broca wrongly concluded that the essential centre for producing articulated speech was the posterior end of the inferior frontal gyrus. Since then, this misconception has been so anchored in the neurological community, that it is still taught worldwide to medical students, in textbooks as well as in courses at universities.
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.
Abstract
This study tests the generalisability of three Brain Tumor Segmentation (BraTS) challenge models using a multi-center dataset of varying image quality and incomplete MRI datasets. In this ...retrospective study, DeepMedic, no-new-Unet (nn-Unet), and NVIDIA-net (nv-Net) were trained and tested using manual segmentations from preoperative MRI of glioblastoma (GBM) and low-grade gliomas (LGG) from the BraTS 2021 dataset (1251 in total), in addition to 275 GBM and 205 LGG acquired clinically across 12 hospitals worldwide. Data was split into 80% training, 5% validation, and 15% internal test data. An additional external test-set of 158 GBM and 69 LGG was used to assess generalisability to other hospitals’ data. All models’ median Dice similarity coefficient (DSC) for both test sets were within, or higher than, previously reported human inter-rater agreement (range of 0.74–0.85). For both test sets, nn-Unet achieved the highest DSC (internal = 0.86, external = 0.93) and the lowest Hausdorff distances (10.07, 13.87 mm, respectively) for all tumor classes (
p
< 0.001). By applying Sparsified training, missing MRI sequences did not statistically affect the performance. nn-Unet achieves accurate segmentations in clinical settings even in the presence of incomplete MRI datasets. This facilitates future clinical adoption of automated glioma segmentation, which could help inform treatment planning and glioma monitoring.
Objective
Imaging studies in diffuse low-grade gliomas (DLGG) vary across centers. In order to establish a minimal core of imaging necessary for further investigations and clinical trials in the ...field of DLGG, we aimed to establish the status quo within specialized European centers.
Methods
An online survey composed of 46 items was sent out to members of the European Low-Grade Glioma Network, the European Association of Neurosurgical Societies, the German Society of Neurosurgery and the Austrian Society of Neurosurgery.
Results
A total of 128 fully completed surveys were received and analyzed. Most centers (n = 96, 75%) were academic and half of the centers (n = 64, 50%) adhered to a dedicated treatment program for DLGG. There were national differences regarding the sequences enclosed in MRI imaging and use of PET, however most included T1 (without and with contrast, 100%), T2 (100%) and TIRM or FLAIR (20, 98%). DWI is performed by 80% of centers and 61% of centers regularly performed PWI.
Conclusion
A minimal core of imaging composed of T1 (w/wo contrast), T2, TIRM/FLAIR, PWI and DWI could be identified. All morphologic images should be obtained in a slice thickness of ≤ 3 mm. No common standard could be obtained regarding advanced MRI protocols and PET.
Importance of the study
We believe that our study makes a significant contribution to the literature because we were able to determine similarities in numerous aspects of LGG imaging. Using the proposed “minimal core of imaging” in clinical routine will facilitate future cooperative studies.
Functional independence in glioblastoma (GBM) patients is a key factor in measuring the quality of life. Progression free survival (PFS) and overall survival (OS) have been largely described. ...However, the evolution over time of the performance status during the patients’ life remains understudied. We thus studied the time to loss of functional independence as assessed by a Karnosky Performance Status (KPS) below 70 % in GBM patients. We analysed all GBM patients treated in our institution between 2008 and 2013 and meeting the following criteria: age >18 years, supratentorial location, post-surgical KPS ≥ 70 %, initially treated with concomitant radiotherapy (RT) and Temozolomide. Within the 84 patients studied, the median PFS was 9 months and the median OS was 18.7 months. The median survival time with functional independence (KPS ≥ 70 %) was 14.5 months. On average, the patients spent 73 % of their lifespan with a KPS ≥ 70 %. Surgical resection and low steroid dosage were statistically associated with increased survival time with KPS ≥ 70 % (p = 0.015 and p = 0.03, respectively). Sixty-two (62) patients received one or several lines of chemotherapy at recurrence. Under treatment with Bevacizumab (42 Bev-based regimens), radiological responses were seen in 35 % and improvement in KPS occurred in 24 % whereas no response and rare improvement of KPS (3 %) were seen with other type of chemotherapy (97 non Bev-based regimens). In GBM patients, median survival with KPS ≥ 70 % largely exceeds PFS. Surgical resection and low steroids dosage at RT-onset appeared as good prognosis factors for survival with functional independence.
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