Stereoelectroencephalography (SEEG), which combines the exploration of identified intracerebral structures using depth electrodes and provides direct recording of local field potentials from multiple brain sites, was designed and developed in the 1950s by Jean Talairach and Jean Bancaud, in Sainte-Anne Hospital, Paris. For patients with focal drug-resistant epilepsy, when the non-invasive phase is insufficiently concordant or when relationships between the epileptogenic network and eloquent areas remain to be defined, the main purpose of SEEG is the optimal electrode implantation based on a main hypothesis and questions formulated during the non-invasive phase. Following an initial historical overview, the different steps of this non-invasive phase are described. Some of these steps, like semiology analysis, have remained relatively preserved, while others have considerably evolved, such as positron emission tomography combined with 3 Tesla magnetic resonance imaging (MRI), functional MRI (fMRI) and high-resolution EEG. We then outline the different steps of the SEEG procedure as performed in our institution. Here also, some steps remain quite unchanged such as intracerebral stimulation, amitriptyline and benzodiazepine tests while some others have strikingly evolved such as frameless robot-assisted, MRI-based implantation, depth-signal analyses and quantifications, and radio-frequency thermocoagulation.

Like fingerprints, cortical folding patterns are unique to each brain even though they follow a general species-specific organization. Some folding patterns have been linked with neurodevelopmental disorders. However, due to the high inter-individual variability, the identification of rare folding patterns that could become biomarkers remains a very complex task. This paper proposes a novel unsupervised deep learning approach to identify rare folding patterns and assess the degree of deviations that can be detected. To this end, we preprocess the brain MR images to focus the learning on the folding morphology and train a beta-VAE to model the inter-individual variability of the folding. We compare the detection power of the latent space and of the reconstruction errors, using synthetic benchmarks and one actual rare configuration related to the central sulcus. Finally, we assess the generalization of our method on a developmental anomaly located in another region. Our results suggest that this method enables encoding relevant folding characteristics that can be enlightened and better interpreted based on the generative power of the beta-VAE. The latent space and the reconstruction errors bring complementary information and enable the identification of rare patterns of different nature. This method generalizes well to a different region on another dataset. Code is available at https://github.com/neurospin-projects/2022_lguillon_rare_folding_detection.

The reconstruction of images observed by subjects from fMRI data collected during visual stimuli has made significant strides in the past decade, thanks to the availability of extensive fMRI datasets and advancements in generative models for image generation. However, the application of visual reconstruction has remained limited. Reconstructing visual imagination presents a greater challenge, with potentially revolutionary applications ranging from aiding individuals with disabilities to verifying witness accounts in court. The primary hurdles in this field are the absence of data collection protocols for visual imagery and the lack of datasets on the subject. Traditionally, fMRI-to-image relies on data collected from subjects exposed to visual stimuli, which poses issues for generating visual imagery based on the difference of brain activity between visual stimulation and visual imagery. For the first time, we have compiled a substantial dataset (around 6h of scans) on visual imagery along with a proposed data collection protocol. We then train a modified version of an fMRI-to-image model and demonstrate the feasibility of reconstructing images from two modes of imagination: from memory and from pure imagination. This marks an important step towards creating a technology that allow direct reconstruction of visual imagery.

Messages à retenir : les causes d’épilepsie chroniques sont différentes de celles découvertes lors d’une première crise de l’adulte, le protocole d’exploration en imagerie est donc très différent. Une exploration « standard » en IRM pour une épilepsie pharmacorésistante est vouée à l’échec. Les séquences 3D et haute résolution sont à privilégier dans ce cas de figure en respectant le protocole proposé par la ILAE (HARNESS). Les principaux défis diagnostiques en imagerie sont la sclérose de l’hipppocampe et la dysplasie corticale focale, mais également les malformations du développement corticale incluant les tumeurs développementales (DNET, gangliogliomes). Une lecture à la lumière de l’ensemble des données cliniques et électrocliniques est essentielle au succès de l’imagerie. Une bonne coordination et communication entre tous les acteurs (neurologues, neurochirurgiens, neuropédiatre et radiologues) est donc indispensable.

The study of local cortical folding patterns showed links with psychiatric illnesses as well as cognitive functions. Despite the tools now available to visualize cortical folds in 3D, manually classifying local sulcal patterns is a time-consuming and tedious task. In fact, 3D visualization of folds helps experts to identify different sulcal patterns but fold variability is so high that the distinction between these patterns sometimes requires the definition of complex criteria, making manual classification difficult and not reliable. However, the assessment of the impact of these patterns on the functional organization of the cortex could benefit from the study of large databases, especially when studying rare patterns. In this paper, several algorithms for the automatic classification of fold patterns are proposed to allow morphological studies to be extended and confirmed on such large databases. Three methods are proposed, the first based on a Support Vector Machine (SVM) classifier, the second on the Scoring by Non-local Image Patch Estimator (SNIPE) approach and the third based on a 3D Convolution Neural Network (CNN). These methods are generic enough to be applicable to a wide range of folding patterns. They are tested on two types of patterns for which there is currently no method to automatically identify them: the Anterior Cingulate Cortex (ACC) patterns and the Power Button Sign (PBS). The two ACC patterns are almost equally present whereas PBS is a particularly rare pattern in the general population. The three models proposed achieve balanced accuracies of approximately 80% for ACC patterns classification and 60% for PBS classification. The CNN-based model is more interesting for the classification of ACC patterns thanks to its rapid execution. However, SVM and SNIPE-based models are more effective in managing unbalanced problems such as PBS recognition.

PURPOSE Hybrid PET/MR is a promising tool in focal drug-resistant epilepsy, however the additional value for the detection of epileptogenic lesions and surgical decision-making remains to be established. METHODS We retrospectively compared 18F-FDG PET/MR images with those obtained by a previous 18F-FDG PET co-registered with MRI (PET+MR) in 25 consecutive patients (16 females, 13-60 years) investigated for focal drug-resistant epilepsy. Visual analysis was performed by two readers blinded from imaging modalities, asked to assess the technical characteristics (co-registration, quality of images), the confidence in results, the location of PET abnormalities and the presence of a structural lesion on MRI. Clinical impact on surgical strategy and outcome was assessed independently. RESULTS The location of epileptic focus was temporal in 9 patients and extra-temporal in 16 others. MRI was initially considered negative in 21 patients. PET stand-alone demonstrated metabolic abnormalities in 19 cases (76%), and the co-registration with MRI allowed the detection of 4 additional structural lesions. Compared to PET+MR, the PET/MR sensitivity was increased by 13% and new structural lesions (mainly focal cortical dysplasias) were detected in 6 patients (24%). Change of surgical decision-making was substantial for 10 patients (40%), consisting in avoiding invasive monitoring in 6 patients and modifying the planning in 4 others. Seizure-free outcome (follow-up>1 year) was obtained in 12/14 patients who underwent a cortical resection. CONCLUSION Hybrid PET/MR may improve the detection of epileptogenic lesions, allowing to optimize the presurgical work-up and to increase the proportion of successful surgery even in the more complex cases.

Purpose: The purpose of the study was to determine the correlations between brain metabolism and cognitive impairment in patients with drug-resistant mesial temporal lobe epilepsy (MTLE). Methods: [F-18]-FluoroDeoxyGlucose positron emission tomography [F-18]-FDG-PET) and neuropsychological assessment were performed in 97 patients with MILE (53 females, 15-56 years old, mean: 31.6 years, standard de- viation (SD) 10.4) with unilateral hippocampal sclerosis (HS, 49 left). We compared brain metabolism and gray matter volume (GMV) between patients with cognitive impairment (intelligence quotient (IQ) and memory index <-80) and patients with normal cognition, using statistical parametric mapping (SPM), in the whole population then in right and left HS (RHS, LHS) separately. Results: Intelligence quotient (40-121, mean: 83.7 16.9) and memory index (45-133, mean: 80.7 +/- 19.3) were impaired in 43% and 51% of the patients, respectively, similarly in RHS and LHS. We did not find any correlations between IQ and clinical factors related to epilepsy; however, there was a significant correlation between low memory index and early age of onset in LHS (p 0.021), and widespread cpileptogenic zone in the whole population (p 0.033). Impaired IQcorrelated with extratemporal hypometabolism, involving frontoparietal networks implicated in the default mode network (DMN), predominantly in the midline cortices. Metabolic asymmetry regarding HS lateralization included the precuneus (pC) in LHS and the anterior cingulate cortex (ACC) in RHS, both areas corresponding to key nodes of the DMN. Memory index correlated with the same frontoparietal networks as for IQ with an additional involvement of the temporal lobes, which was ipsilateral in RHS and contralateral in LHS. A diffuse decrease of GMV including the ipsilateral hippocampus correlated with cognitive impairment; however, the structural alterations did not match with the hypometabolic areas. Conclusions: Cognitive impairment in MILE correlates with extratemporal hypometabolism, involving the mesial frontoparietal networks implicated in the DMN and suggesting a disconnection with the affected hippocampus. Asymmetric alterations of connectivity may sustain the predominant ACC and pC metabolic decrease in patients with cognitive impairment. (C) 2020 Elsevier Inc. All rights reserved.

We report a case series of four patients operated on for a glioma in awake conditions and in whom task-based functional magnetic resonance imaging (fMRI) demonstrated right-dominant activity during a language production task. Language functional sites were identified intraoperatively by electrical stimulations only in the patient with a right-sided lesion. Furthermore, the pre- or postoperative cognitive evaluations in the three patients operated on for a left-sided glioma revealed right spatial neglect and dysexecutive syndrome, hence demonstrating that, in patients with right-dominant activity on language fMRI, the left hemisphere is implicated in spatial consciousness and cognitive control. This study supports the interest of presurgical task-based language fMRI to identify patients with a reversed lateralization of cognitive functions and to make an adequate selection of the battery of intraoperative cognitive tasks to be monitored in those rare outliers.

Objective To assess factors associated with favorable outcome in refractory insular epilepsy treated by volume-based stereotactic radiofrequency thermocoagulation (RFTC). Methods We performed volume-based RFTC in 19 patients (11 males, 7-44 years old). The volume for thermocoagulation was identified by multimodal data including electroencephalography (EEG)-video, magnetic resonance imaging (MRI), and fluorodeoxyglucose-positron emission tomography (PET) in all patients, and epileptogenic zone (EZ) was assessed by stereo-electroencephalography (SEEG) in 16. MRI showed insular lesions in four patients (benign tumors, n = 2; focal cortical dysplasia [FCD], n = 1; polymicrogyria, n = 1). MRI was negative in 15 cases; however, PET was positive in 18, and FCD pattern was detected by SEEG in nine cases. The dominant hemisphere was involved in 12 cases. RFTC was performed as a separate procedure after SEEG, or as a single MRI-guided procedure. The insular volume to be coagulated was determined by a tridimensional identification of the epileptogenic cortex using MRI, PET, and SEEG, and was destroyed with coalescent thermal lesions. Results Seizure-free outcome was achieved in 10 patients (53%), including Engel class IA in three (follow-up = 1-12 years, mean = 5.4). The responder rate (including Engel classes I-III) was 89%. Transient postoperative deficits (mild hemiparesia, dysarthria, hypoesthesia, dysgeusia) were observed in eight patients (42%), with rapid and total recovery in all but one with persistent mild dysarthria. Neurological deficits were related to higher number of RFTC procedures (P = .036) and greater volume of RFTC (P = .028). Neuropsychological status was unchanged or improved in all; however, psychiatric status transitorily worsened in three patients. Factors contributing to seizure-free outcome were the detection of FCD pattern (P = .009), localized EZ (P = .038), low RFTC volume (P = .002), low number of RFTC procedures (P = .001), and low RFTC volume/number ratio (P = .012). Optimal volume of RFTC around 2 cm(3) offered the best compromise between efficacy and safety. Significance RFTC may be curative in insular epilepsy after accurate localization of EZ with SEEG. Best outcome was associated with low volume of thermolesions.

During functional-based resection under awake conditions of a left frontal isocitrate dehydrogenase-wildtype glioblastoma, the initial intralesional debulking performed to alleviate mass effect unmasked the right hemibody negative motor networks that were identified on the neocortex by direct electric stimulation. As compared with preoperative evaluation, the 3-month postoperative functional magnetic resonance imaging (MRI) confirmed unmasked cortical clusters for the right hemibody that were absent preoperatively using the same functional MRI parameters; language clusters were also better seen. The glioma-induced mass effect can mask eloquent brain areas, and surgical decompression can unmask intraoperatively eloquent brain areas.

BACKGROUND: We report the surgical management of a lesional drug resistant epilepsy caused by a meningioangiomatosis associated with a type Illc focal cortical dysplasia located in the left supplementary motor area in a young male patient. CASE DESCRIPTION: A first anatomically based partial surgical resection was performed on an 11-year-old under general anesthesia without infra operative mapping, which allowed for postoperative seizure control (Engel IA) for 6 years. The patient then exhibited intractable right sensatory and aphasic focal onset seizures despite 2 appropriate antiepileptic drugs. A second functional-based surgical resection was performed using intraoperative corticosubcortical functional mapping with direct electrical stimulation under awake conditions. A complete surgical resection was performed, and a left partial supplementary motor area syndrome was observed. At 6 months post-operatively, the patient is seizure free (Engel IA) with an ongoing decrease in antiepileptic drug therapy. CONCLUSIONS: Intraoperative functional brain mapping can be applied to preserve the brain function and networks around a meningioangiomatosis to facilitate the resection of potentially epileptogenic perilesional dysplastic cortex and to tailor the extent of resection to functional boundaries.

The original version of this article has added numbers in the text which are unnecessary. Correct line should be: "We also performed PET/MRI based surgical resections in an increasing number of MRI negative/ doubtful cases with favourable outcome."

OBJECTIVE: We assessed the impact of surgery on postoperative cognitive function and ability to work in adult patients with a diffuse low-grade glioma involving eloquent brain regions and having a functional-based maximal surgical resection using intraoperative cortico-subcortical mapping under awake conditions. METHODS: We prospectively included 39 consecutive patients with diffuse isocitrate dehydrogenase-mutant low-grade glioma without preoperative and adjuvant oncologic treatment and assessed preoperative (mean, 24.1 +/- 21.2 days before surgery) and postoperative (mean, 14.6 +/- 13.2 months after surgery) cognitive evaluations and ability to work together with clinical, imaging, therapeutic, and follow-up characteristics before tumor progression. RESULTS: None of the 3 patients without preoperative cognitive deficit had postoperative worsening. We observed a significant inverse interaction between worsened postoperative cognitive function and extent of resection: 80.0%, 18.8%, and 16.7% of worsening after partial, subtotal, and total resection, respectively (P = 0.020). We observed an independent interaction between improved postoperative cognitive function and extent of resection: 20.0%, 43.7%, and 44.4% of improvement after partial, subtotal, and total resection, respectively (P = 0.022). Of the employed patients, 61.8% were unable to work preoperatively and 82.4% resumed their employment postoperatively (mean, 6.9 +/- 5.5 months). We observed an independent interaction between postoperative ability to work, similar or superior to preoperative work capacity and extent of resection (P < 0.001): 20.0%, 87.5%, and 100% ability to work after partial, subtotal resection, and total resection. CONCLUSIONS: The extent of the functional-based surgical resection and the residual tumor for diffuse low-grade gliomas involving eloquent brain regions correlate with postoperative cognitive outcomes and return to work rates.