Search

International audience; There is a lack of class I evidence concerning the impact of surgery in the treatment of diffuse low-grade glioma; the early maximal resection with preservation of eloquent brain areas has been accepted as the first therapeutic option. We performed a systematic review of the literature using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and protocol. Inclusion criteria: only case series with at least 100 patients containing supratentorial hemispheric diffuse low-grade glioma (according to any of the WHO classification used in papers published between 2000 to 2019), with pre- and postoperative MRI study were included in the qualitative and quantitative analyses. The extent of resection should be defined based on MRI at least in two categories and correlated with patients' outcomes (with univariate or multivariate analyses) using overall survival (OS) or malignant progression-free survival (MPFS). A total of 18 series with 4386 patients, published in 20 papers, were included in this systematic review. All the series that evaluates the relation between the extent of resection (EOR) and OS showed a statistically significant improvement of OS at univariate and/or multivariate analyzes with a greater EOR. Six studies showed a statistically significant improvement of MPFS with a greater EOR. We demonstrate that when a more rigorous analysis of EOR is performed, a benefit of a more aggressive resection on OS and MPFS is observed. Our review about EOR in different molecular groups of DLGG also suggests a benefit of maximum safe resection for all different subtypes, even though "radical surgery" may be associated with better OS and MPFS in tumors with a more aggressive signature.

Brain awake surgery with cognitive monitoring for tumor removal has become a standard of treatment for functional purpose. Yet, little attention has been given to patients’ interpretation and awareness of their own responses to selected cognitive tasks during direct electrostimulation (DES). We aim to report disruptions of self-evaluative processing evoked by DES during awake surgery. We further investigate cortico-subcortical structures involved in self-assessment process and report the use of an intraoperative self-assessment tool, the self-confidence index (SCI). Seventy-two patients who had undergone awake brain tumor resections were selected. Inclusion criteria were the occurrence of a DES-induced disruption of an ongoing task followed by patient’s failure to remember or criticize these impairments, or a dissociation between patient’s responses to an ongoing task and patient’s SCI. Disruptions of self-evaluation were frequently associated with semantic disorders and critical sites were mostly found along the left/right ventral semantic streams. Disconnectome analyses generated from a tractography-based atlas confirmed the high probability of the inferior fronto-occipital fasciculus to be transitory ‘disconnected’. These findings suggest that white matters pathways belonging to the ventral semantic stream may be critically involved in human self-evaluative processing. Finally, the authors discuss the implementation of the SCI task during multimodal intraoperative monitoring.

International audience; Although radiation therapy (RT) is a main treatment of brain tumors, delayed cerebral toxicity may lead to cognitive deteriorations with adverse effects on quality of life. Despite technological advances in RT, the concept of brain connectome has not yet been incorporated in the strategy of irradiation. Because white matter tracts represent the main limitation of neuroplasticity, tumor surgery is increasingly performed with awake cortical-subcortical mapping. Here, the purpose is to reinforce the link between cognitive neurosciences and neurooncology, which is critical for neurosurgeons but also for medical oncologists, especially brain radiation oncologists. The goal is to optimize RT planning by sparing individual critical neural networks. A redefinition of "organs at risk" should be proposed, beyond the few structures (such as brainstem, optic pathway, pituitary gland, hippocampi) which are classically preserved for brain radiation, by considering the structural and functional connectivity in order to evolve toward a RT "à la carte".

Our aim was to evaluate the contribution of pseudo-continuous arterial spin labelling (pCASL) in the detection of a postoperative residual lesion in adult brain tumours. Seventy-five patients were prospectively included. Following the results of preoperative DSC-PWI assessment, intra-axial lesions, including high-grade gliomas (n = 43) and certain metastases (n = 14), were classified as hyper-vascular (HV+ group, n = 57); other lesions, including low-grade gliomas and certain metastases, were classified as non-hyper-vascular (HV− group, n = 18). To confirm the absence/presence of a residual lesion or disease progression, postoperative MRI including pCASL sequence and follow-up-MRI were performed within 72 h and 1–6 months after the resection, respectively. Two raters evaluated the images. Mean and maximal ASL cerebral blood flow (CBF) values were measured in the perioperative region and normalised to the contralateral tissue. The pCASL-CBF maps and post-contrast T1WI were visually assessed for residual lesion. Quantitative data were analysed with unpaired Student t and Mann-Whitney U tests and the visual diagnostic performance with the McNemar test. In the HV+ group, the mean normalised CBF was 1.97 ± 0.59 and 0.97 ± 0.29 (p < 0.0001, AUC = 0.964, cut-off = 1.27) for patients with or without residual tumours, respectively. The mean normalised CBF was not discriminative for assessing residual tumours in the HV− group (p = 0.454). Visual CBF evaluation allowed 92.98% patients belonging to the HV+ group to be correctly classified (sensitivity 93.02%, specificity 92.86%, p < 0.001). Visual evaluation was correlated with contrast enhancement evaluation and with the mean normalised CBF values (r = 0.505, p < 0.0001 and 0.838, p < 0.0001, respectively). Qualitative and quantitative ASL evaluation shows high diagnostic performance in postoperative assessment of hyper-perfused tumours. In this case, postoperative pCASL may be useful, especially if contrast injection cannot be performed or when contrast enhancement is doubtful. • Evaluation of postoperative residual lesion in the case of brain tumours is an imaging challenge. • This prospective monocentric study showed that increased normalised cerebral blood flow assessed by pseudo-continuous arterial spin labelling (pCASL) correlates well with the presence of a residual tumour in the case of hyper-vascular tumour diagnosed on preoperative MRI. • Qualitative and quantitative pCASL is an informative sequence for hyper-vascular residual tumour, especially if acquired more than 48 h after brain tumour surgery, when contrast enhancement can give ambiguous results due to blood-brain barrier disruption.

Objective The structural and functional organization of brain networks subserving basic daily activities (i.e. language, visuo-spatial cognition, movement, semantics, etc.) are not completely understood to date. Here, we report the first probabilistic cortical and subcortical atlas of critical structures mediating human brain functions based on direct electrical stimulation (DES), a well-validated tool for the exploration of cerebral processing and for performing safe surgical interventions in eloquent areas. Methods We collected 1162 cortical and 659 subcortical DES responses during testing of 16 functional domains in 256 patients undergoing awake surgery. Spatial coordinates for each functional response were calculated, and probability distributions for the entire patient cohort were mapped onto a standardized three-dimensional brain template using a multinomial statistical analysis. In addition, matching analyses were performed against prior established anatomy-based cortical and white matter (WM) atlases. Results The probabilistic maps for each functional domain were provided. The topographical analysis demonstrated a wide spatial distribution of cortical functional responses, while subcortical responses were more restricted, localizing to known WM pathways. These DES-derived data showed reliable matching with existing cortical and WM atlases as well as recent neuroimaging and neurophysiological data. Conclusions We present the first integrated and comprehensive cortical-subcortical atlas of structures essential for humans’ neural functions based on highly-specific DES mapping during real-time neuropsychological testing. This novel atlas can serve as a complementary tool for neuroscientists, along with data obtained from other modalities, to improve and refine our understanding of the functional anatomy of critical brain networks.

International audience; Background: Whilst modern awake intraoperative mapping has been widely accepted and implemented in the last decades in neuro-oncology, sparse reports have been published on the safety and efficiency of this approach in epilepsy surgery.Method: This article reports four cases with different locations of epileptogenic zones as examples of possible safe and efficient resections.Result: The results of the resections on seizure control were Engel 1 (no disabling seizures) in all cases and no patient experienced significant neurological deficits.Discussion: The discussion focuses on aspects of the future of epilepsy surgery in a hodotopical paradigm.

International audience; The optimal surgical management of gliomas requires a balance between surgical cytoreduction and preservation of neurological function. Preoperative functional neuroimaging, such as functional MRI (fMRI) and diffusion tensor imaging (DTI), has emerged as a possible tool to inform patient selection and surgical planning. However, evidence that preoperative fMRI or DTI improves extent of resection, limits neurological morbidity, and broadens surgical indications in classically eloquent areas is lacking. In this review, the authors describe facets of functional neuroimaging techniques that may limit their impact on neurosurgical oncology and critically evaluate the evidence supporting fMRI and DTI for patient selection and operative planning in glioma surgery. The authors also propose alternative applications for functional neuroimaging in the care of glioma patients.

International audience; Neurosurgeons have been directly involved with brain mapping efforts for well over a century. Direct access to the functioning human brain during surgery for intrinsic brain tumors, epilepsy, and functional neurosurgical procedures both requires individual functional brain mapping and presents an opportunity to precisely map human brain function. Several papers in this issue of Neurosurgical Focus extend our current understanding of cerebral organization with detailed examination of specific regions. Others introduce new technical nuances for intraoperative brain mapping. A third group of papers focuses on noninvasive brain mapping techniques that have emerged and been refined over the last several years.

Objectif : la craniotomie éveillée a connu un essor récent et fait partie du traitement de première ligne des gliomes. La gestion de l’anesthésie pour une craniotomie éveillée est un défi et il n’existe pas actuellement de recommandations. L’ objectif de cette thèse était d’évaluer la gestion de cette anesthésie dans un premier temps auprès de centres européens expérimentés et dans un second temps au sein de l’hôpital Lariboisière. Matériel et méthodes : une enquête a été envoyée aux membres du Réseau Européen du Gliome de Bas Grade. Les données de l’hôpital Lariboisière ont été divisées entre un groupe historique H de patients opérés entre 2011 et 2013, et un groupe global G de patients opérés de 2016 à 2018. Résultats : l’enquête européenne a révélé que 50% des équipes utilisaient un protocole d’anesthésie générale et 44% un protocole de sédation encadrant la phase d’éveil. En cas d’anesthésie générale, le masque laryngé était utilisé par 82% des équipes en phase d’ouverture et 71% en fermeture. L’hôpital Lariboisière pratique la sédation depuis 9 ans. Entre le groupe H et le groupe G, la durée opératoire médiane a été réduite (415 vs 400 minutes, p=0,03). Il y avait moins de variabilité tensionnelle. Il y avait plus de désaturations (8% vs 40%, p=0,01) et des capnies plus élevées lors de la craniotomie (52 vs 64mmHg, p=0,01) et de la fermeture. Conclusion : la prise en charge de l’anesthésie au niveau européen n’est pas univoque. La technique développée par l’hôpital Lariboisière est fiable et sécuritaire. L’expérience acquise au fil des années a permis d’optimiser la stabilité hémodynamique des patients, d’assurer leur oxygénation et de réduire les durées opératoires.

International audience; Hippocampal sclerosis is the most common cause of pharmacoresistant epilepsy amenable for surgical treatment and seizure control. The aim of this article is to review and evaluate the published literature related to the outcome of the surgical treatment of mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS) and to describe the future prospects in this field. Surgery of MTLE associated with HS achieves long-term seizure freedom in about 70% (62-83%) of cases. Seizure outcome is similar in the pediatric population. Mortality following temporal resection is very rare (

International audience; The aim of this article was to review and evaluate the published literature related to the outcome of epilepsy surgery, while placing it in an historical perspective, and to describe the future prospects in this field. Temporal lobe surgery achieves seizure freedom in about 70% of cases. Seizure outcome is similar in the pediatric population. Extratemporal resections impart good results to 40% to 60% of patients, with a better prognosis in the case of frontal lobe surgery. Pediatric hemispherotomy leads to seizure control in about 80% of children. Radiosurgery used as a treatment for temporal mesial epilepsy has an outcome quite similar to that obtained with surgical resection, but provides a neuropsychological advantage. Radiosurgery is also effective in 60% of children treated for seizures related to hypothalamic hamartoma. Regarding palliative surgery, callosotomy and multiple subpial transections show satisfactory outcomes in over 60% of cases. Neuromodulation techniques (vagus nerve stimulation and bilateral stimulation of the anterior nucleus of the thalamus) allow a 50% reduction of seizures in half of patients. Transcranial magnetic stimulation combined with electroencephalography seems a promising technique because of its diagnostic, prognostic and therapeutic applications. Transcranial ultrasound stimulation, which can reversibly control neuronal activity, is also under consideration. Concerning neuromodulation, trigeminal nerve stimulation may become an alternative to vagus nerve stimulation; while other targets of deep brain stimulation are being evaluated. Also, the possibility of coupling SEEG seizure focus detection with concomitant laser or radiofrequency focus destruction is under development. Constant evolution of epilepsy surgery has improved patient outcomes over time. Current research and development axes suggest the continuation of this trend and a reduction of the invasiveness of surgical procedures.

OBJECT It was initially considered safe for flow-diverting stents to cover the ostia of branching vessels during endovascular procedures for the treatment of intracranial aneurysms. As more recent evidence suggests, however, their use is not always free of ischemic concerns in terms of covered arterial ostia. The authors sought to determine the frequency of silent and clinically evident diffusion-weighted imaging (DWI)–detected abnormalities related to stent placement as a means of elucidating potential clinical risks. METHODS This is a prospective single-center study on a series of patients with intracranial aneurysms that were treated with flow-diverting stents. All patients systematically underwent an MRI protocol that included DWI before treatment, between 24 and 48 hours postprocedure, and 3 months postembolization. Effectiveness of anticoagulation treatment was assessed for all patients. Lesions seen on DWI were correlated to the parent artery and the side-branch territories and were statistically analyzed in relation to their time of occurrence and clinical presentation. The authors compared the DWI findings in these patients to findings obtained in patients treated with a stent-assisted coiling technique during the same time period. RESULTS Over the course of 18 consecutive months, 38 consecutive patients (7 males and 31 females) with 49 intracranial aneurysms were treated using flow-diverting stents. Overall, 81.6% of the DWI spots found remained clinically silent during the follow-up period. Five ischemic clinical complications (13.2%) occurred in the postprocedural period. No statistically significant correlation could be established between DWI spots or aneurysm location and clinical complications or follow-up modified Rankin Scale score at 3 months. The complication rate was 7.8% (n = 3) at the 3-month follow-up, and mortality was 0%. Compared with stent-assisted coiling, use of flow-diverting stents showed a statistically significant correlation with silent DWI findings postintervention. CONCLUSIONS Lesions seen on DWI resulting from the procedure are far more common than anticipated, but the technique remains safe and effective, providing an interesting alternative for “difficult” aneurysms, regardless of location. Late-occurring DWI-detected lesions distal to side arterial branches imply a local pressure gradient drop, related to flow competition by collateral networks. Further research is needed to assess the extent and significance of these events.

Intraneural ganglion cyst of the tibial nerve is very rare. To date, only 5 cases of this entity in the popliteal fossa have been reported. We report a new case and review the previously reported cases. A 40-year-old man experienced a mild vague pain in the medial half of his right foot for 3 years. Magnetic resonance imaging scan demonstrated a soft-tissue mass along the right tibial nerve. At surgery, an intraneural ganglion cyst was evacuated. After 12 months, the patient was pain-free with no signs of recurrence. Trauma might be a contributing factor to the development of intraneural ganglion cysts. Application of microsurgical techniques is encouraged.

International audience; Deep brain stimulation (DBS) is a widely accepted therapy for medically refractory Parkinson's disease (PD). Both globus pallidus internus (GPi) and subthalamic nucleus (STN) stimulation are safe and effective in improving the symptoms of PD and reducing dyskinesias. STN DBS is the most commonly performed surgery for PD as compared to GPi DBS. Ventral intermediate nucleus (Vim) DBS is infrequently used as an alternative for tremor predominant PD patients. Patient selection is critical in achieving good outcomes. Differential diagnosis should be emphasized as well as neurological and nonneurological comorbidities. Good response to a levodopa challenge is an important predictor of favorable long-term outcomes. The DBS surgery is typically performed in an awake patient and involves stereotactic frame application, CT/MRI imaging, anatomical targeting, physiological confirmation, and implantation of the DBS lead and pulse generator. Anatomical targeting consists of direct visualization of the target in MR images, formula-derived coordinates based on the anterior and posterior commissures, and reformatted anatomical stereotactic atlases. Physiological verification is achieved most commonly via microelectrode recording followed by implantation of the DBS lead and intraoperative test stimulation to assess benefits and side effects. The various aspects of DBS surgery will be presented.

Display Omitted Surgical procedures performed at three different institutions are analyzed and compared.The comparison is based on the sequences of activities performed by the surgeons during surgery.This approach distinguished the surgical behaviors according to surgeon experience and location. Surgical Process Modelling (SPM) was introduced to improve understanding the different parameters that influence the performance of a Surgical Process (SP). Data acquired from SPM methodology is enormous and complex. Several analysis methods based on comparison or classification of Surgical Process Models (SPMs) have previously been proposed. Such methods compare a set of SPMs to highlight specific parameters explaining differences between populations of patients, surgeons or systems. In this study, procedures performed at three different international University hospitals were compared using SPM methodology based on a similarity metric focusing on the sequence of activities occurring during surgery. The proposed approach is based on Dynamic Time Warping (DTW) algorithm combined with a clustering algorithm. SPMs of 41 Anterior Cervical Discectomy (ACD) surgeries were acquired at three Neurosurgical departments; in France, Germany, and Canada. The proposed approach distinguished the different surgical behaviors according to the location where surgery was performed as well as between the categorized surgical experience of individual surgeons. We also propose the use of Multidimensional Scaling to induce a new space of representation of the sequences of activities. The approach was compared to a time-based approach (e.g. duration of surgeries) and has been shown to be more precise. We also discuss the integration of other criteria in order to better understand what influences the way the surgeries are performed. This first multi-site study represents an important step towards the creation of robust analysis tools for processing SPMs. It opens new perspectives for the assessment of surgical approaches, tools or systems as well as objective assessment and comparison of surgeon's expertise.

International audience; PURPOSE: This study proposes a framework coming from cognitive engineering, which makes it possible to define what information content has to be displayed or emphasised from medical imaging, for assisting clinicians according to their level of expertise in the domain. METHOD: We designed a rating scale to assess visualisation systems in image-guided neurosurgery with respect to the depiction of the neurosurgical work domain. This rating scale was based on a neurosurgical work domain analysis. This scale has been used to evaluate visualisation modes among neurosurgeons, residents and engineers. We asked five neurosurgeons, ten medical residents and ten engineers to rate two visualisation modes from the same data (2D MR image vs. 3D computerised image). With this method, the amount of abstract and concrete work domain information displayed by each visualisation mode can be measured. RESULTS: A global difference in quantities of perceived information between both images was observed. Surgeons and medical residents perceived significantly more information than engineers for both images. Unlike surgeons, however, the amount of information perceived by residents and engineers significantly decreased as information abstraction increased. CONCLUSIONS: We demonstrated the possibility of measuring the amount of work domain information displayed by different visualisation modes of medical imaging according to different user profiles. Engineers in charge of the design of medical image-guided surgical systems did not perceive the same set of information as surgeons or even medical residents. This framework can constitute a user-oriented approach to evaluate the amount of perceived information from image-guided surgical systems and support their design from a cognitive engineering point of view.

International audience; PURPOSE: We describe and validate a novel hybrid nonlinear vessel registration algorithm for intra-operative updating of preoperative magnetic resonance (MR) images using Doppler ultrasound (US) images acquired on the dura for the correction of brain-shift and registration inaccuracies. We also introduce an US vessel appearance simulator that generates vessel images similar in appearance to that acquired with US from MR angiography data. METHODS: Our registration uses the minimum amount of preprocessing to extract vessels from the raw volumetric images. This prevents the removal of important registration information and minimizes the introduction of artifacts that may affect robustness, while reducing the amount of extraneous information in the image to be processed, thus improving the convergence speed of the algorithm. We then completed 3 rounds of validation for our vessel registration method for robustness and accuracy using (i) a large number of synthetic trials generated with our US vessel simulator, (ii) US images acquired from a real physical phantom made from polyvinyl alcohol cryogel, and (iii) real clinical data gathered intra-operatively from 3 patients. RESULTS: Resulting target registration errors (TRE) of less than 2.5 mm are achieved in more than 90 % of the synthetic trials when the initial TREs are less than 20 mm. TREs of less than 2 mm were achieved when the technique was applied to the physical phantom, and TREs of less than 3 mm were achieved on clinical data. CONCLUSIONS: These test trials show that the proposed algorithm is not only accurate but also highly robust to noise and missing vessel segments when working with US images acquired in a wide range of real-world conditions.

International audience; This article describes a two-year surveillance of neurosurgical site infections and an outbreak of infections in deep brain stimulation (DBS) cases. From April to December 2008, six patients had a DBS surgical site infection (SSI). Audits of hygiene practices, infection control of the healthcare environment, and preoperative antimicrobial prophylaxis characteristics were carried out. The results of surgical audits showed that skin preparation and antimicrobial prophylaxis were not being performed adequately. In 2008, the general SSI rate was 1.8% (27 SSIs/1471 patients). Length of preoperative stay was significantly longer among infected patients (2.7 ± 2.9 months) compared with uninfected patients (2.2 ± 4.6 months) (P=0.01). Based on these results, skin preparation and antimicrobial prophylaxis were reviewed with the neurosurgery team. In 2009, the general SSI rate was reduced to 1.1% (16 SSI in 1410 patients), a reduction from 2008 (P=0.12). Although the overall incidence of SSI in 2008 (1.8%) was within the range of published data, this surveillance of SSIs permitted identification of site operative infected patients surgically treated for DBS. A set of actions was then taken to reduce SSI risk. This work demonstrates how an active surveillance programme can successfully change clinical care practice.

International audience; BACKGROUND: After elective craniotomy for brain surgery, patients are usually admitted to an intensive care unit (ICU). We sought to identify predictors of postoperative complications to define perioperative conditions that would safely allow ICU bypass. METHODS: This observational cohort study enrolled 358 patients admitted to neuro-ICU after elective intracranial procedures. Postoperative complications were defined as unexpected events occurring within 24 hours of surgery that required imaging or treatment for neurologic deterioration. RESULTS: Fifty-two patients were transferred postoperatively to neuro-ICU with sedation and mechanical ventilation. Of the remaining 306 patients subjected to an attempt to awake and extubate in the operating room, 26 (8%) developed 1 postoperative complication, primarily a new motor deficit, unexpected awakening delay, or subsequent deterioration in consciousness. Four intracerebral hematomas required surgical evacuation and each of these was detected within 2 hours after surgery. Predictors of postoperative complications included failure to extubate the trachea in operating room [odds ratio 61.8; 95% confidence interval (CI) 12.2-312.5], and, to a lesser extent, a duration of surgery of more than 4 hours (odds ratio 3.3; 95% CI 1.4-7.8), and lateral positioning of the patient during the procedure (odds ratio 2.8, 95% CI 1.2-6.4). CONCLUSIONS: Our results encourage prospectively testing the hypothesis that patients with immediate, successful tracheal extubation after elective craniotomy for brain surgery, with a surgical duration of less than 4 hours in a nonlateral position could be monitored safely in the postanesthesia care unit before being discharged to a neurosurgical ward.

Objective: To provide recommendations to patients, physicians, and other health care providers on several issues involving deep brain stimulation (DBS) for Parkinson disease (PD). Data Sources and Study Selection: An international consortium of experts organized, reviewed the literature, and attended the workshop. Topics were introduced at the workshop, followed by group discussion. Data Extraction and Synthesis: A draft of a consensus statement was presented and further edited after plenary debate. The final statements were agreed on by all members. Conclusions: (1) Patients with PD without significant active cognitive or psychiatric problems who have medically intractable motor fluctuations, intractable tremor, or intolerance of medication adverse effects are good candidates for DBS. (2) Deep brain stimulation surgery is best performed by an experienced neurosurgeon with expertise in stereotactic neurosurgery who is working as part of a interprofessional team. (3) Surgical complication rates are extremely variable, with infection being the most commonly reported complication of DBS. (4) Deep brain stimulation programming is best accomplished by a highly trained clinician and can take 3 to 6 months to obtain optimal results. (5) Deep brain stimulation improves levodopa-responsive symptoms, dyskinesia, and tremor; benefits seem to be long-lasting in many motor domains. (6) Subthalamic nuclei DBS may be complicated by increased depression, apathy, impulsivity, worsened verbal fluency, and executive dysfunction in a subset of patients. (7) Both globus pallidus pars interna and subthalamic nuclei DBS have been shown to be effective in addressing the motor symptoms of PD. (8) Ablative therapy is still an effective alternative and should be considered in a select group of appropriate patients. Arch Neurol. 2011; 68(2):165-171. Published online October 11, 2010. doi:10.1001/archneurol.2010.260

International audience; BACKGROUND: Evaluating surgical practice in the operating room is difficult, and its assessment is largely subjective. OBJECTIVE: Recording of standardized spine surgery processes was conducted to ascertain whether any significant differences in surgical practice could be observed between senior and junior neurosurgeons. METHODS: Twenty-four procedures of lumbar discectomies were consecutively recorded by a senior neurosurgeon. In 12 cases, surgery was entirely performed by a senior neurosurgeon with the aid of a resident, and in the 12 remaining cases, surgery was performed by a resident with the aid of a senior neurosurgeon. The data recorded were general parameters (operating time for the whole procedure and for each step), and general and specific parameters of the surgeon's activities (number of manual gestures, number and duration of actions performed, use of the instruments, and use of interventions on anatomic structures). The Mann-Whitney U test was used for comparison between the 2 groups of neurosurgeons. RESULTS: The operating time was statistically lower for the group of senior surgeons. The seniors statistically demonstrated greater economy in time and in gestures during the closure step, for sewing and for the use of scissors, needle holders, and forceps. The senior surgeons statistically worked for a shorter time on the skin and used fewer manual gestures on the thoracolumbalis fascia. The number of changes in microscope position was also statistically lower for this group. CONCLUSION: There is a relationship between surgical practice, as determined by a method of objective measurement using observation software, and surgical experience: gesture economy evolves with seniority.

International audience; BACKGROUND: Evaluating surgical practice in the operating room is difficult, and its assessment is largely subjective. OBJECTIVE: Recording of standardized spine surgery processes was conducted to ascertain whether any significant differences in surgical practice could be observed between senior and junior neurosurgeons. METHODS: Twenty-four procedures of lumbar discectomies were consecutively recorded by a senior neurosurgeon. In 12 cases, surgery was entirely performed by a senior neurosurgeon with the aid of a resident, and in the 12 remaining cases, surgery was performed by a resident with the aid of a senior neurosurgeon. The data recorded were general parameters (operating time for the whole procedure and for each step), and general and specific parameters of the surgeon's activities (number of manual gestures, number and duration of actions performed, use of the instruments, and use of interventions on anatomic structures). The Mann-Whitney U test was used for comparison between the 2 groups of neurosurgeons. RESULTS: The operating time was statistically lower for the group of senior surgeons. The seniors statistically demonstrated greater economy in time and in gestures during the closure step, for sewing and for the use of scissors, needle holders, and forceps. The senior surgeons statistically worked for a shorter time on the skin and used fewer manual gestures on the thoracolumbalis fascia. The number of changes in microscope position was also statistically lower for this group. CONCLUSION: There is a relationship between surgical practice, as determined by a method of objective measurement using observation software, and surgical experience: gesture economy evolves with seniority.

International audience; PURPOSE: The determination of epileptogenic structures in partial epilepsy is crucial in the context of epilepsy surgery. In this study we have quantified the "epileptogenicity" of mesial temporal lobe structures (M), lateral neocortical regions (L), and extratemporal perisylvian structures (ET) in patients with temporal lobe epilepsy (TLE), in order to classify the brain networks involved in seizure generation. METHODS: Thirty-four patients having TLE investigated by intracerebral recordings using stereotactic electroencephalography (EEG) (SEEG) were selected. Epileptogenicity of M, L, and ET structures was quantified according to the "epileptogenicity index" (EI), a new way to quantify rapid discharges at seizure onset, ranging from 0 (no epileptogenicity) to 1 (maximal epileptogenicity). RESULTS: Automatic clustering using EI values from M, L, and ET separated patients into four classes: mesial group (max EI in M), lateral group (max EI in L), mesiolateral group (high EI in both M and L) and temporoperisylvian group (TPS) (high values in ET). The median number of highly epileptogenic structures (defined by EI >0.3) was four, a result confirming that most TLE is organized as "epileptogenic networks." We found that the duration of epilepsy was correlated with the number of epileptogenic structures and that surgical prognosis was also related to the extent of the epileptogenicity in the brain. CONCLUSIONS: Several distinct epileptogenic networks are involved in seizure generation in TLE. Findings advocate for a progressive recruitment of epileptogenic structures in human brain with time.

International audience; Many techniques are described to treat Chiari type I malformation. One of them is a splitting of the dura, removing its outer layer only to reduce the risks of cerebrospinal fluid (CSF) leak. We try to show the effectiveness of this technique from histological and biomechanical observations of dura mater. Study was performed on 25 posterior fossa dura mater specimens from fresh human cadavers. Dural composition and architecture was assessed on 47 transversal and sagittal sections. Uniaxial mechanical tests were performed on 22 dural samples (15 entire, 7 split) to focus on the dural macroscopic mechanical behavior comparing entire and split samples and also to understand deformation mechanisms. We finally created a model of volume expansion after splitting. Dura mater was composed of predominant collagen fibers with a few elastin fibers, cranio-caudally orientated. The classical description of two distinct layers remained inconstant. Biomechanical tests showed a significant difference between entire dura, which presents an elastic fragile behavior, with a small domain where deformation is reversible with stress, and split dura, which presents an elasto-plastic behavior with a large domain of permanent strain and a lower stress level. From these experimental results, the model showed a volume increase of approximately 50% below the split area. We demonstrated the capability of the split dura mater to enlarge for suitable stress conditions and we quantified it by biomechanical tests and experimental model. Thus, dural splitting decompression seems to have a real biomechanical substrate to envision the efficacy of this Chiari type I malformation surgical technique.

International audience; Intraoperative brain deformations decrease accuracy in image-guided neurosurgery. Approaches to quantify these deformations based on 3-D reconstruction of cortectomy surfaces have been described and have shown promising results regarding the extrapolation to the whole brain volume using additional prior knowledge or sparse volume modalities. Quantification of brain deformations from surface measurement requires the registration of surfaces at different times along the surgical procedure, with different challenges according to the patient and surgical step. In this paper, we propose a new flexible surface registration approach for any textured point cloud computed by stereoscopic or laser range approach. This method includes three terms: the first term is related to image intensities, the second to Euclidean distance, and the third to anatomical landmarks automatically extracted and continuously tracked in the 2-D video flow. Performance evaluation was performed on both phantom and clinical cases. The global method, including textured point cloud reconstruction, had accuracy within 2 mm, which is the usual rigid registration error of neuronavigation systems before deformations. Its main advantage is to consider all the available data, including the microscope video flow with higher temporal resolution than previously published methods.

International audience; Grade II gliomas grow slowly and linearly (at rates about 4 mm/year) before undergoing anaplastic transformation. In order to analyze how surgery may affect radiological grade II glioma kinetics, we restrospectively reviewed our national database searching for patients operated on for a supratentorial grade II glioma between 1997 and 2007. We selected patients with at least two postoperative MRI with a minimal delay of 6 months. For each patient, postoperative residues were segmented on successive MRIs. Velocities of diameter expansion were estimated by linear regression of mean diameter evolution for each patient. Fifty-four patients fulfilled inclusion criteria. Median postoperative follow-up was 1.6 years with, on average, 3.4 MRI examinations per patient. Postoperative growth rates of mean diameter were normally distributed, around a mean value of 4.3 mm/year (SD = 3.2 mm/year). Statistical analysis showed no difference between this distribution and the distribution of preoperative growth rates in a previous series of 143 grade II gliomas. For a subset of 23 patients, delay between first MRI and surgery made it possible to estimate also preoperative growth rates. Intrapatient comparison revealed that growth rates were grossly unchanged for 80% of cases. In summary, inter- and intrapatient comparison of pre- and postoperative growth rates proves that surgery does not change grade II glioma dynamics, thus, acting as a cytoreduction.

International audience; High-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN-HFS) is the preferred surgical treatment for advanced Parkinson's disease. In the 15 years since its introduction into clinical practice, many studies have reported on its benefits, drawbacks, and insufficiencies. Despite limited evidence-based data, STN-HFS has been shown to be surgically safe, and improvements in dopaminergic drug-sensitive symptoms and reductions in subsequent drug dose and dyskinesias are well documented. However, the procedure is associated with adverse effects, mainly neurocognitive, and with side-effects created by spread of stimulation to surrounding structures, depending on the precise location of electrodes. Quality of life improves substantially, inducing sudden global changes in patients' lives, often requiring societal readaptation. STN-HFS is a powerful method that is currently unchallenged in the management of Parkinson's disease, but its long-term effects must be thoroughly assessed. Further improvements, through basic research and methodological innovations, should make it applicable to earlier stages of the disease and increase its availability to patients in developing countries.

International audience; Since the 1960s, deep brain stimulation and spinal cord stimulation at low frequency (30 Hz) have been used to treat intractable pain of various origins. For this purpose, specific hardware have been designed, including deep brain electrodes, extensions, and implantable programmable generators (IPGs). In the meantime, movement disorders, and particularly parkinsonian and essential tremors, were treated by electrolytic or mechanic lesions in various targets of the basal ganglia, particularly in the thalamus and in the internal pallidum. The advent in the 1960s of levodopa, as well as the side effects and complications of ablative surgery (e.g., thalamotomy and pallidotomy), has sent functional neurosurgery of movement disorders to oblivion. In 1987, the serendipitous discovery of the effect of high-frequency stimulation (HFS), mimicking lesions, allowed the revival of the surgery of movement disorders by stimulation of the thalamus, which treated tremors with limited morbidity, and adaptable and reversible results. The stability along time of these effects allowed extending it to new targets suggested by basic research in monkeys. The HFS of the subthalamic nucleus (STN) has profoundly challenged the practice of functional surgery as the effect on the triad of dopaminergic symptoms was very significant, allowing to decrease the drug dosage and therefore a decrease of their complications, the levodopa-induced dyskinesias. In the meantime, based on the results of previous basic research in various fields, HFS has been progressively extended to potentially treat epilepsy and, more recently, psychiatric disorders, such as obsessive-compulsive disorders, Gilles de la Tourette tics, and severe depression. Similarly, suggested by the observation of changes in PET scan, applications have been extended to cluster headaches by stimulation of the posterior hypothalamus and even more recently, to obesity and drug addiction. In the field of movement disorders, it has become clear that STN stimulation is not efficient on the nondopaminergic symptoms such as freezing of gait. Based on experimental data obtained in MPTP-treated parkinsonian monkeys, the pedunculopontine nucleus has been used as a new target, and as suggested by the animal research results, its use indeed improves walking and stability when stimulation is performed at low frequency (25 Hz). The concept of simultaneous stimulation of multiple targets eventually at low or high frequency, and that of several electrodes in one target, is being accepted to increase the efficiency. This leads to and is being facilitated by the development of new hardware (multiple-channel IPGs, specific electrodes, rechargeable batteries). Still additional efforts are needed at the level of the stimulation paradigm and in the waveform. The recent development of nanotechnologies allows the design of totally new systems expanding the field of deep brain stimulation. These new techniques will make it possible to not only inhibit or excite deep brain structures to alleviate abnormal symptoms but also open the field for the use of recording cortical activities to drive neuroprostheses through brain-computer interfaces. The new field of compensation of deficits will then become part of the field of functional neurosurgery.

International audience; The use of nerve conduits as an alternative for nerve grafting has a long experimental and clinical history. Luminal additives, factors introduced into these nerve conduits, were later developed to enhance the nerve regeneration through conduits. This chapter generalizes the types of additives used, and the reported performance of luminal additives in conduits to present a preference list for the most effective additives to use over specific distances of nerve defect.

International audience; BACKGROUND: Hypermotor seizures (HMS) are characterized by complex movements involving the proximal segment of the limbs and trunk. Although they are primarily reported in mesial frontal or orbitofrontal epilepsies, they have also been described in patients with temporal or insular epilepsies, questioning the localizing value of HMS in patients contemplating epilepsy surgery. Furthermore, HMS can include different forms of HM behaviors. Whether these clinical variations may be systematized and may reflect different locations of the epileptogenic zone (EZ) has not been evaluated yet. METHODS: We have retrospectively analyzed ictal signs and intracerebral EEG data in 11 patients presenting with HMS who became seizure free following epilepsy surgery with a minimum follow-up of 24 months. Clinical phenomena were reviewed blinded to seizure onset zone. RESULTS: Two types of HMS could be distinguished in this population: HMS1, observed in six patients, mainly consisted of marked agitation that either included body rocking, kicking, or boxing, associated with a facial expression of fear. HMS2, observed in the five other patients, mainly consisted of mild agitation that included either horizontal movements or rotation of trunk and pelvis while lying on the bed, usually associated with tonic/dystonic posturing. SEEG findings showed that the EZ associated with HMS1 was mainly centered on the ventromesial frontal cortex. Conversely, HMS2 was primarily associated with an EZ localized within the mesial premotor cortex. CONCLUSIONS: Although these findings remain to be confirmed by larger studies, they may help optimize the placement of intracerebral electrodes in patients contemplating epilepsy surgery.

Objective: This study aimed to create a stereotactic two-dimensional description of the human insula based on accurate radiological morphometric studies. Methods: Seventy-five normal cerebral MRIs were selected and drawings of the insula then obtained from serial sagittal slices. These drawings were digitalized before superimposing the anterior (AC) and posterior (PC) commissures as references. This allowed us to quantify interindividual anatomical variations in a large cohort of subjects. Results: The morphometric analysis of the insula revealed a more complex shape than previously described. This structure is delimited by four peri-insular sulci (anterior, superior, posterior and inferior) instead of the three sulci classically mentioned. Males have a statistically larger surface area than females, according to a correlated index. Precise measurements of the different insular components allowed us to quantify their potential interindividual anatomical variations and to define their average shapes and stereotactic locations. Conclusion: These data create a two-dimensional template of the human insula, with regard to the classical AC-PC stereotactic reference system. They furthermore allow us to quantify the probability that a given element of this structure is located at a predefined position. This should be useful in functional neuroimaging studies and in insular surgery for diagnostic and therapeutic goals.

International audience; A microsubthalamotomy (mSTN) effect is commonly described after implantation that improves Parkinson's motor disability and is considered to be an obvious sign of good placement of the definitive electrode within the subthalamic nucleus (STN). There has been no formal study, however, demonstrating whether this mSTN effect can predict the long-term efficacy of STN stimulation in Parkinson Disease. The mSTN effect was defined by the percentage improvement of unified parkinson's disease rating scale (UPDRS III) baseline score assessed the third day morning following STN implantation, after at least a 12 hour withdrawal of dopaminergic treatment and before the programmable pulse generator was switched on. It was assessed in 30 consecutive patients with PD submitted for STN stimulation. Multiple stepwise regression analysis showed that mSTN effect (P = 0.005) and global mean intensity of stimulation (P = 0.004) were accurate independent predictors of the 6-month postoperative UPDRS III motor score improvement in the off-drug/on-stimulation condition.

International audience; In the stereo-electro-encephalography (SEEG) methodology developed by Talairach and Bancaud in Sainte-Anne Hospital in Paris, France, the objective of placing depth electrode recordings in presurgical evaluation is to study the spatial and temporal organization of a seizure. This defines for each patient the cortical onset zone, the propagation pattern of the seizure, and the possible involvement of eloquent areas of the cortex. This methodology requires a meticulous stereotactic surgical technique. We report here the SEEG methodology, surgical technique, and morbidity.

International audience; Drug-resistant mesial temporal lobe epilepsy with hippocampal sclerosis is associated with anatomical, ultrastructural and functional changes that facilitate generation and spread of epileptic seizures. Intrahippocampal circuits are modified in their transversal lamellar and longitudinal translamellar organization. Neuronal death and the neuroplasticity of surviving cells contribute to major phenomena: an increased hyperexcitability of the hippocampal formation and an increased synchronization of its principal cells. Selective disruption of the epileptic networks that are involved in mesial temporal lobe epilepsy may have a therapeutic effect. We present here the preliminary results of a selective intrahippocampal transection in a chronic model of mesial temporal lobe epilepsy after focal injection of kainic acid in adult mice. A complete transection of the hippocampal formation (including dentate gyrus and hippocampus proper, sparing the fimbria) results in a blockade of ictal activities spread from the generator, a reduction in their frequency and an increase in their duration. In contrast, after a transection sparing the dentate gyrus and hilus, no modification was noted. In this model of mesial temporal lobe epilepsy, longitudinally projecting axonal circuits of the dentate gyrus and hilus appear to be implicated in generation, propagation and interruption of ictal activities within hippocampal formation.

International audience; PURPOSE: To compare resective surgery and medical therapy in a cost-effectiveness analysis in a multicenter cohort of adult patients with partial intractable epilepsy. POPULATION AND METHODS: Adult patients with partial, medically intractable, potentially operable epilepsy were eligible and followed every year over five years. Effectiveness was defined as one year without seizure. The long-term costs and effectiveness were extrapolated over the patients' lifetime with a Markov model. Productivity (indirect costs) and quality of life (QOLIE-31, SEALS) were also assessed. Changes before and after surgery were compared between the two groups. RESULTS: Two hundred and eighty-nine patients were included (119 with surgery, 161 medically treated, six not eligible, three lost to follow-up). One year after surgery, 81% of the patients were seizure-free; at two and three years, this rate was 78%. In the medical group, these rates were 10, 18, and 15%, respectively. The cost of the explorations was euro 8464; including surgery, it was euro 19,700. In the medical group, the average annual direct costs were between 3500 and euro 6000. At two years after surgery, the annual direct cost decreased to euro 2768, at three years, it was euro 1233, predominately antiepileptic drug costs. Surgery became cost-effective between seven and eight years. In the surgical group, all the quality-of-life scores improved at one year after surgery and were stable during the second and third years. CONCLUSION: Surgical therapy was cost-effective at the middle term even though indirect costs were not considered.

International audience; The definition of the epileptogenic zone is a concept proposed by Jean Bancaud and Jean Talairach based on the anatomical, electrical and clinical correlations established from stereoelectroencephalographic recordings. They believed the epileptogenic zone to be the "region of the beginning and the primary organization" of ictal discharges. The opinion of North American authors is different: the epileptogenic zone is the "what to remove area" to produce freedom from seizures. This surgical definition assumes postsurgical validation. The aim of this paper is to show how to define the epileptogenic zone from all the stereoelectroencephalographic recording data.

International audience

International audience

Keywords Claustrum AE Plasticity AE Low-grade glioma AEBrain mappingDespite many anatomical, histological and electro-physiological studies, essentially performed in animals,the function of the claustrum remains unclear [1]. Weknow only one lesional report in humans, which sug-gested, using somatosensory evoked potentials, thatthis structure might influence deeply the contralateralsomatosensory cortex [2]. Recently, PET studies inhealthy volunteers supported its involvement in moti-vational processes [3]. Moreover, because of a wide-spread connectivity of the claustrum, Crick and Kochproposed that this area could play a key role in con-sciousness [4]. Nevertheless, they also raised the fol-lowing question ‘‘What happens when the claustrum,or parts of it, have been transiently or permanentlyremoved? The answer to this important question is,unfortunately, not known’’ [5].Here, we report a series of 42 patients operated for acerebral glioma involving the claustrum, with func-tional recovery in all cases but three, despite a claustralremoval.We consecutively operated 42 right-handed patients(28 men, 14 women, mean age 36 years) harboring aparalimbic WHO grade II glioma developed primi-tively within the insula, and invading the claustrum.There was no previous medical history. The presentingsymptom was seizure in the 42 cases. Preoperatively, 40patients had a normal examination (2 mild dysphasias).The Mini Mental Status Examination (MMSE) was>27, and the Karnofsky Performance Status (KPS) >70in all cases. The Boston Diagnosis Aphasia Examina-tion (BDAE) was performed in the 12 patients har-boring a left tumor, with a normal score in 10 cases.All surgeries were conducted under intraoperativecortico-subcortical electrical mapping [6, 7]. A func-tional response was systematically induced by sub-cortical stimulation, leading to stop the resection inthe depth: motor response in the 30 patients operatedunder general anesthesia for a right tumor by stim-ulating the pyramidal pathways [8]; and languageresponse in the 12 patients operated whilst awake fora left tumor by stimulating the lateral part of thelentiform nucleus [9].Due to the absence of response before the stimula-tion of these deep eloquent structures, the claustrumwas removed in the 42 patients, as confirmed by controlMRI (Fig. 1). The glioma resection was total or sub-total in 31 patients, and partial in 11 patients due to theinvasion of structures which were still functional andthus surgically preserved—but not the claustrum.Postoperatively, 39 patients recovered a normalneurological examination within 3 months, withMMSE >27 and KPS >70. In addition, in the 12patients with a left tumor, BDAE score was normal,thus with an improvement in the 2 patients with apreoperative dysphasia. The 39 patients returned to anormal socio-professional life. Three patients experi-enced a permanent left hemiparesis because of a

Despite the lack of class I evidence, it is widely agreed that surgery can improve the functional and vital prognosis for WHO grade II gliomas when the resection is at least subtotal radiologically, that is, leaving less than 10 cm(3) of visible residual tumor. Because these tumors frequently invade functional areas, the preoperative estimation of the probable residual volume remains challenging. This article presents a probabilistic map of postoperative residues, with the aim of predicting before the decision for surgical intervention whether the resection could be subtotal. We selected 65 patients who underwent surgery with intraoperative functional mapping between 1999 and 2004 for a WHO grade II glioma located in a sensorimotor and/or language area. For each case, the postoperative image was normalized on a standard atlas, and the residual tumor was segmented. A probabilistic map of residues was then computed. The fusion between the map and a preoperative image allowed a preoperative estimation of the expected extent of resection. The map enhances the regions where grade II glioma cannot be resected. The success rate for the preoperative classification of partial versus subtotal resection is 82%. Although both its reliability and accuracy have to be improved, this probabilistic map gives preoperatively an objective estimation of the expected extent of resection for grade II glioma resected under intraoperative functional mapping. This rationale will assist in decisions regarding surgical resection and may thus contribute to the elaboration of a therapeutic consensus for WHO grade II glioma.

OBJECT: While scarcely reported in low-grade glioma (LGG), accurate assessment of higher functions is essential to evaluate then preserve the quality of life. We assessed verbal working memory (vWM) in patients with LGG in language areas, before and after surgery, to evaluate the effect of glioma and resection on cognition, respectively. METHODS: About 23 patients harboring a LGG in language areas underwent awake surgery. All patients had a vWM assessment, before and immediately after the resection, in addition to KPS. vWM was also evaluated 3 months after surgery in eight patients (KPS in all cases), who performed postoperative rehabilitation. RESULTS: Preoperatively, 91% of patients had vWM disorders (KPS > or =90 in 22 patients). Immediately after surgery, 96% of patients had vWM worsening (50% of KPS > or =90). At 3 months, among the eight patients examinated, five recovered their preoperative vWM score, and three significantly improved it (KPS > or =90 in 23 patients). CONCLUSION: In LGG, neuropsychological assessment is encouraged in addition to KPS. vWM evaluation before treatment showed that most patients had a cognitive deficit. Moreover, surgery induced a transient vWM worsening, which nevertheless recovers within 3 months. Specific rehabilitation might help to recover and even to improve the preoperative cognitive status.

Intraneural ganglion cyst of the tibial nerve is very rare. To date, only 5 cases of this entity in the popliteal fossa have been reported. We report a new case and review the previously reported cases. A 40-year-old man experienced a mild vague pain in the medial half of his right foot for 3 years. Magnetic resonance imaging scan demonstrated a soft-tissue mass along the right tibial nerve. At surgery, an intraneural ganglion cyst was evacuated. After 12 months, the patient was pain-free with no signs of recurrence. Trauma might be a contributing factor to the development of intraneural ganglion cysts. Application of microsurgical techniques is encouraged.

Despite a recent literature supporting the impact of surgery on the natural history of low-grade glioma (LGG), the indications of resection still remain a matter of debate, especially because of the frequent location of these tumors within eloquent brain areas – thus with a risk to induce a permanent postoperative deficit. Therefore, since the antagonist nature of this surgery is to perform the most extensive glioma removal possible, while preserving the function and the quality of life, new concepts were recently applied to LGG resection in order to optimize the␣benefit/risk ratio of the surgery. First, due to the development of functional mapping methods, namely perioperative neurofunctional imaging and intrasurgical direct electrical stimulation, the study of cortical functional organization is currently possible for each patient – in addition to an extensive neuropsychological assessment. Such knowledge is essential because of the inter-individual anatomo-functional variability, increased in tumors due to cerebral plasticity phenomena. Thus, brain mapping enables to envision and perform a resection according to individual functional boundaries. Second, since LGG invades not only cortical but also subcortical structures, and shows an infiltrative progression along the white matter tracts, new techniques of anatomical tracking and functional mapping of the subcortical white matter pathways were also used with the goal to study the individual effective connectivity – which needs imperatively to be preserved during the resection. Third, the better understanding of brain plasticity mechanisms, induced both by the slow-growing LGG and by the surgery itself, were equally studied in each patient and applied to the surgical strategy by incorporating individual dynamic potential of reorganization into the operative planning. The integration of these new concepts of individual functional mapping, connectivity and plastic potential to the surgery of LGG has allowed an extent of surgical indications, an optimization of the quality of resection (neuro-oncological benefit), and a minimization of the risk of sequelae (benefit on the quality of life). In addition, such a strategy has also fundamental applications, since it represents a new door to the connectionism and cerebral plasticity.

INTRODUCTION: Nerve injury compromises sensory and motor functions. Techniques of peripheral nerve repair are based on our knowledge regarding regeneration. Microsurgical techniques introduced in the late 1950s and widely developed for the past 20 years have improved repairs. However, functional recovery following a peripheral mixed nerve injury is still incomplete. STATE OF ART: Good motor and sensory function after nerve injury depends on the reinnervation of the motor end plates and sensory receptors. Nerve regeneration does not begin if the cell body has not survived the initial injury or if it is unable to initiate regeneration. The regenerated axons must reach and reinnervate the appropriate target end-organs in a timely fashion. Recovery of motor function requires a critical number of motor axons reinnervating the muscle fibers. Sensory recovery is possible if the delay in reinnervation is short. Many additional factors influence the success of nerve repair or reconstruction. The timing of the repair, the level of injury, the extent of the zone of injury, the technical skill of the surgeon, and the method of repair and reconstruction contribute to the functional outcome after nerve injury. CONCLUSION: This review presents the recent advances in understanding of neural regeneration and their application to the management of primary repairs and nerve gaps.

OBJECTIVE: Statistical analysis of patients previously operated on may improve our methods of performing subsequent surgical procedures. In this article, we introduce a method for studying the functional properties of cerebral structures from electrophysiological and neuroimaging data by using the probabilistic functional atlas (PFA). The PFA provides a spatial distribution of the clinically most effective contacts normalized to a common space. This distribution is converted into a probability function for a given point in space to be inside an effective contact. The PFA was used to analyze spatial properties of the functional subthalamic nucleus (STN), defined as the spatial volume corresponding to the distribution of effective contacts. These results may potentially be useful in planning subthalamic implantation of electrodes. METHODS: In all, 168 bilateral subthalamic stimulations were examined. An algorithm was developed for converting these data into the PFA. The PFA for the STN (here called “atlas”) was calculated with 0.25-mm3 resolution, and several features characterizing the left and right STN were studied. The analysis was performed with and without lateral compensation against the width of the third ventricle. The key feature introduced here used for analysis of the functional STN is a (probabilistic) functional volume of structure (defined for a given probability as the volume of a region whose every point has a probability equal to or greater than this given probability). RESULTS: The analysis has been performed for two situations: with and without lateral compensation against the width of the third ventricle. Without lateral compensation, the differences between the mean values and standard deviations of their barycenter coordinates for the left and right functional STNs are 0.31 and 0.18 mm, respectively. The left STN and right STN exhibit differences in functional volume size and probability distribution. The entire functional volume is 240 mm3 for the left and 229 mm3 for the right STN. A more prominent difference exists in the region of high probabilities (0.7 or higher), called “hot STN.” The volume of the left hot STN is 5.52 mm3, whereas that of the right is 3.92 mm3. The left hot STN is 1.41 times bigger and 20% more dense than the right hot STN. For a given probability, the corresponding functional volume for the left hot STN is up to 43 times larger than that for the right STN. Practically speaking, lateral compensation does not change these results qualitatively. Quantitatively, differentiation between the left and right STNs is lower. For instance, for a given probability, the corresponding functional volume for the left hot STN is only up to 11 times larger than that for the right one. In either situation (i.e., with and without lateral compensation), the size of the hot STN in relation to the whole STN remains very small (1–2%). In addition, statistical analysis shows that in either situation, the means of the left and right functional STNs are significantly different. CONCLUSION: PFA-based planning may be superior to the current practice of using anatomic atlases that provide delineation of the target structure only, because it is more precise and provides a unique target point in the stereotactic space. This best stereotactic target is the point in the individualized atlas with the highest probability, meaning the highest probability of having the best target on the basis of the patients previously operated on. This best target is located in the hot STN, the size of which determines the precision of targeting. Because the size of the hot STN in comparison to the whole STN remains very small (1–2%) independent of whether or not lateral compensation is applied, target planning and execution have to be performed with high precision. The methodology presented, based on the PFA and on the functional volume, is general and can be applied to other structures and data sets. As numerous centers keep gathering large amounts of electrophysiological human and animal data, this work may facilitate opening new avenues in exploiting these data.

International audience; The incidence of deep vein thrombosis (DVT) is between 20 and 35% using contrast venography, with a rate of symptomatic DVT between 2.3 and 6% in neurosurgery without any prophylaxis. The risk of DVT is poorly evaluated in head injured patients but is around 5%. Specific risk factors in neurosurgery are: a motor deficit, a meningioma or malignant tumour, a large tumour, age over 60 years, surgery lasting more than 4 hours, a chemotherapy. The benefit of mechanical methods or low molecular weight heparin (LMWH) for the prevention of DVP in neurosurgery is demonstrated (grade A). Each method decreases the risk by about 50%. A postoperative prophylaxis with a LMWH does not seem to increase the risk of intracranial bleeding (grade C). There is no demonstrated benefit to begin a prophylaxis with LMWH before the intervention. The duration of the prophylaxis is 7 to 10 days but this has not been scientifically determined.

International audience; High-resolution MRI of the brain has made it possible to identify focal cortical dysplasia (FCD) in an increasing number of patients. There is evidence for structural abnormalities extending beyond the visually identified FCD lesion. Voxel-based morphometry (VBM) has the potential of detecting both lesions and extra-lesional abnormalities because it performs a whole brain voxel-wise comparison. However, on T1-weighted MRI, FCD lesions are characterized by a wide spectrum of signal hyperintensity that may compromise the results of the segmentation step in VBM. Our purpose was to investigate gray matter (GM) changes in individual FCD patients using voxel-based morphometry (VBM). In addition, we sought to assess the performance of this technique for FCD detection with respect to lesion intensity using an operator designed to emphasize areas of hyperintense T1 signal. We studied 27 patients with known FCD and focal epilepsy and 39 healthy controls. We compared the GM map of each subject (controls and patients) with the average GM map of all controls and obtained a GM z-score map for each individual. The protocol being designed to achieve a maximal specificity, no differences in GM concentration were found in the control group. The z-score maps showed an increase in GM that coincided with the lesion in 21/27 (78%) patients. Five of the six remaining patients whose lesions were not detected by VBM presented with a strong lesion hyperintensity, and a significant part of their lesion was misclassified as white matter. In 16/27 (59%) patients, there were additional areas of GM increase distant from the primary lesion. Areas of GM decrease were found in 8/27 (30%) patients. In conclusion, individual voxel-based analysis was able to detect FCD in a majority of patients. Moreover, FCD was often associated with widespread GM changes extending beyond the visible lesion. In its current form, however, individual VBM may be unable to detect lesions characterized by strong signal intensity abnormalities.

International audience; Patients with refractory epilepsy suffer from an increased risk of death, primarily due to seizure-related fatalities including sudden unexpected death (SUDEP), which could be conceivably avoided by surgical cure of the epilepsy. Several series have addressed this issue by comparing the mortality rate between medically and surgically treated drug resistant populations, as well as between patients, seizure free and non seizure free post-operatively. Results from some studies suggest that successful temporal lobe surgery reduced the risk of death to that observed in the normal population, whereas patients who continue to suffer recurrent seizures still present an increased standardized mortality ratio (SMR). However, other series have failed to replicate this finding, or found no difference in the overall mortality and SUDEP rates between operated and medically treated patients. All the above studies suffer various types of methodological limitations, hampering any definite conclusion regarding the impact of epilepsy surgery on mortality. However, part of the apparently discordant reported findings might be reconciled through the following framework. Patients who will eventually respond favourably or unfavourably to an anterior temporal lobectomy might already differ in the risk of seizure-related death, pre-operatively. Specifically, patients whose temporal lobe epileptogenic network extends to the perisylvian region (temporal plus epilepsy) appear to be at higher risk of failed TLE surgery, secondary generalised tonic-clonic seizures, ictal apnoea or insula-driven severe cardiac arrhytmias. This population might carry most of the SUDEP burden, both pre- and post-operatively, accounting for the lack of an obvious net reduction of seizure related deaths after temporal lobe surgery. A multicentric study has recently been launched in order to test this hypothesis, and will hopefully help to conclude on the impact of epilepsy surgery on mortality outcome.

Background: Patients undergoing surgical resection of medial frontal lesions may present transient postoperative speech disorders that remain largely unpredictable.Objective: To relate the occurrence of this speech deficit to the specific surgical lesion of the supplementary motor area (SMA) involved during language tasks using fMRI.Methods: Twelve patients were studied using a verbal fluency task before resection of a low-grade glioma of the medial frontal lobe and compared with six healthy subjects. Pre- and postoperative MR variables including the hemispheric dominance for language, the extent of SMA removal, and the volume of resection were compared to the clinical outcome.Results: Following surgery, 6 of 12 patients presented speech disorders. The deficit was similar across patients, consisting of a global reduction in spontaneous speech, ranging from a complete mutism to a less severe speech reduction, which recovered within a few weeks or months. The occurrence of the deficit was related to the resection of the activation in the SMA of the dominant hemisphere for language (p < 0.01). Increased activation in the SMA of the healthy hemisphere on the preoperative fMRI was observed in patients with postoperative speech deficit.Conclusions: fMRI is able to identify the area at risk in the SMA, of which resection is related to the occurrence of characteristic transient postoperative speech disorders. Increased SMA activation in the healthy hemisphere suggested that a plastic change of SMA function occurred in these patients.

International audience; OBJECTIVE: Improvement of the planning stage of image-guided surgery requires a better anticipation of the surgical procedure and its anatomical and functional environment. This anticipation should be provided by acquisition of multimodal medical images of the patient and by a better understanding of surgical procedures. In this paper, we propose improvements to the planning and performance of multimodal image-guided neurosurgery through the use of information models related to neurosurgical procedures. MATERIALS AND METHODS: A new generic model of surgical procedures is introduced in the context of multimodal image-guided craniotomies. The basic principle of the model is to break down the surgical procedure into a sequence of steps defining the surgical script. In the model, a step is defined by an action. The model assigns to each surgical step a list of image entities extracted from multimodal preoperative images (i.e., anatomical and/or functional images) which are relevant to the performance of that particular step. A semantic validation of the model was performed by instantiating the model entities for 29 surgical procedures. RESULTS: The resulting generic model is described by a UML class diagram and a textual description. The validation showed the relevance of the model, confirming the main underlying assumptions. It also provided some leads to improve the model. CONCLUSION: While further validation is needed, the initial benefits of this approach can already be outlined. It should add real value to the different levels of image-guided surgery, from preprocessing to planning, as well as during surgery. Models of surgical procedures can manage image data according to the surgical script, which should lead to better anticipation of surgery through the development of simulation tools. Furthermore, the models may improve the performance of surgery using microscope-based neuronavigation systems by making it possible to adapt both visualization and interaction features of multimodal preoperative images according to the model.