Increasing the effectiveness of intracerebral injections in adult and neonatal mice: a neurosurgical point of view

International audienceIntracerebral injections of tracers or viral constructs in rodents are now commonly used in the neurosciences and must be executed perfectly. The purpose of this article is to update existing protocols for intracerebral injections in adult and neonatal mice. Our procedure for stereotaxic injections in adult mice allows the investigator to improve the effectiveness and safety, and save time. Furthermore, for the first time, we describe a two-handed procedure for intracerebral injections in neonatal mice that can be performed by a single operator in a very short time. Our technique using the stereotaxic arm allows a higher precision than freehand techniques previously described. Stereotaxic injections in adult mice can be performed in 20 min and have >90% efficacy in targeting the injection site. Injections in neonatal mice can be performed in 5 min. Efficacy depends on the difficulty of precisely localizing the injection sites, due to the small size of the animal. We describe an innovative, effortless, and reproducible surgical protocol for intracerebral injections in adult and neonatal mice

Intraoperative Ultrasound Shear-Wave Elastography in Focal Cortical Dysplasia Surgery

International audiencePrevious studies reported interest in intraoperative shear-wave elastography (SWE) guidance for brain-tumor and epilepsy surgeries. Focal cortical dysplasia (FCD) surgery is one of the most appropriate indications for using SWE guidance. The aim of this study was to evaluate the efficacy of ultrasound SWE techniques for the intraoperative detection of FCDs. We retrospectively analyzed data from 18 adult patients with drug-resistant epilepsy associated with FCD who had undergone SWE-guided surgery. Conventional B-mode images detected FCD in 2 patients (11.1%), while SWE detected FCD in 14 patients (77.8%). The stiffness ratios between MRI-positive and -negative cases were significantly different (3.6 ± 0.4 vs. 2.2 ± 0.6, respectively; p < 0.001). FCDs were significantly more frequently detected by interoperative SWE in women (OR 4.7, 95% CI (1.7–12.7); p = 0.004) and in patients in whom FCD was visible on magnetic resonance imaging (MRI; OR 2.3, 95% CI (1.3–4.3); p = 0.04). At 1 year after surgery and at last follow-up (mean = 21 months), seizure outcome was good (International League Against Epilepsy (ILAE) Class 1 or 2) in 72.2% and 55.6% of patients, respectively. Despite some limitations, our study highlighted the potential of SWE as an intraoperative tool to detect FCD. Future technical developments should allow for optimizing intraoperative surgical-cavity evaluation from the perspective of complete FCD resection. Interobserver reliability of SWE measurements should also be assessed by further studies. View Full-Tex

Perturbed chloride homeostasis and GABAergic signaling in human temporal lobe epilepsy.: GABAergic Signaling in Human Epileptic Tissue.

International audienceChanges in chloride (Cl-) homeostasis may be involved in the generation of some epileptic activities. In this study, we asked whether Cl- homeostasis, and thus GABAergic signaling, is altered in tissue from patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis. Slices prepared from this human tissue generated a spontaneous interictal-like activity that was initiated in the subiculum. Records from a minority of subicular pyramidal cells revealed depolarizing GABA(A) receptor-mediated postsynaptic events, indicating a perturbed Cl- homeostasis. We assessed possible contributions of changes in expression of the potassium-chloride cotransporter KCC2. Double in situ hybridization showed that mRNA for KCC2 was absent from approximately 30% of CaMKIIalpha (calcium/calmodulin-dependent protein kinase IIalpha)-positive subicular pyramidal cells. Combining intracellular recordings with biocytin-filled electrodes and KCC2 immunochemistry, we observed that all cells that were hyperpolarized during interictal events were immunopositive for KCC2, whereas the majority of depolarized cells were immunonegative. Bumetanide, at doses that selectively block the chloride-importing potassium-sodium-chloride cotransporter NKCC1, produced a hyperpolarizing shift in GABA(A) reversal potentials and suppressed interictal activity. Changes in Cl- transporter expression thus contribute to human epileptiform activity, and molecules acting on these transporters may be useful antiepileptic drugs

Different mechanisms of ripple-like oscillations in the human epileptic subiculum

[Objective]: Transient high‐frequency oscillations (HFOs; 150–600Hz) in local field potentials generated by human hippocampal and parahippocampal areas have been related to both physiological and pathological processes. The cellular basis and effects of normal and abnormal forms of HFOs have been controversial. This lack of agreement is clinically significant, because HFOs may be good markers of epileptogenic areas. Better defining the neuronal correlate of specific HFO frequency bands could improve electroencephalographic analyses made before epilepsy surgery. [Methods]: Here, we recorded HFOs in slices of the subiculum prepared from human hippocampal tissue resected for treatment of pharmacoresistant epilepsy. With combined intra‐ or juxtacellular and extracellular recordings, we examined the cellular correlates of interictal and ictal HFO events. [Results]: HFOs occurred spontaneously in extracellular field potentials during interictal discharges (IIDs) and also during pharmacologically induced preictal discharges (PIDs) preceding ictal‐like events. Many of these events included frequencies >250Hz and so might be considered pathological, but a significant proportion were spectrally similar to physiological ripples (150–250Hz). We found that IID ripples were associated with rhythmic γ‐aminobutyric acidergic and glutamatergic synaptic potentials with moderate neuronal firing. In contrast, PID ripples were associated with depolarizing synaptic inputs frequently reaching the threshold for bursting in most pyramidal cells. [Interpretation]: Our data suggest that IID and PID ripple‐like oscillations (150–250Hz) in human epileptic hippocampus are associated with 2 distinct population activities that rely on different cellular and synaptic mechanisms. Thus, the ripple band could not help to disambiguate the underlying cellular processes. Ann Neurol 2015;77:281–290.CAR, GH, MB, SC, SC, RM, and MLVQ were supported by grants from the Institut National de la Santé et de la Recherche Médicale; Centre National pour la Recherche Scientifique; Assistance Publique–Hopitaux de Paris; European Research Council (322721); Fédération pour la Recherche sur le Cerveau; Pierre and Marie Curie University; ENP Foundation; Investissements d'avenir ANR‐10‐IAIHU‐06; LMdP was supported by the Spanish Ministry of Innovation and Science (BFU2009–07989, BFU2012–37156‐C03‐01); Programa Salvador de Madariaga of the Spanish Ministry of Education, Culture, and Sports (PR2011‐0226); Intramural CSIC Grant 201220E084; and CAR was supported by the Administrative Department for Science, Technology, and Innovation (COLCIENCIAS), Colombia

Temporal pole epilepsy surgery—Sparing the hippocampus

International audienceTemporal pole epilepsy (TPE) is a poorly known and difficult to individualize subtype of temporal lobe epilepsy. Consequently, in drug‐resistant TPE, there is still a debate on the need for a large surgical removal of the temporal pole and mesial temporal structures or a limited resection of the temporal pole. We reviewed all patients who underwent presurgical evaluation for drug‐resistant epilepsy over a 17‐year period, and report here 19 patients with proven drug‐resistant temporal pole epilepsy who underwent a selective temporal pole resection with respect to mesial structures. Most (15) TPE patients exhibited seizures resembling mesiotemporal seizures, whereas the others exhibited nocturnal hyperkinetic seizures or an association of both seizure types. MRI revealed a temporal pole lesion in 58% of patients. Long‐term postoperative outcome after a conservative surgery was excellent: 63% of patients were seizure‐free (International League Against Epilepsy [ILAE] 1) at 1‐year postsurgery and 78% at 5 years. These results show that TPE has no specific electroclinical features but is a distinct type of temporal lobe epilepsy allowing a conservative surgery. Respecting the mesiotemporal structures is a valid surgical approach for drug‐resistant temporal pole epilepsy

Outpatient vagus nerve stimulation surgery in drug-resistant epilepsy patients with severe intellectual disability

International audiencePurpose: Vagus nerve stimulation (VNS) implantation is increasingly proposed in outpatient procedure. Some epilepsy syndromes are associated with severe neurodevelopmental disabilities (intellectual disability, autism) and often motor or sensory handicaps, making ambulatory surgery more complex. Methods: We prospectively assessed the feasibility and safety of outpatient VNS implantation in 26 adult drug-resistant epilepsy patients with severe intellectual disability between December 2017 and October 2020. Results: The male-to-female ratio was 0.9 and the mean age on surgery day was 23.1 years. Seventeen patients (65.4%) suffered from epileptic encephalopathy, 7 (26.9%) from cryptogenic or genetic generalized epilepsy and 2 (7.7%) from severe multifocal epilepsy. Postoperatively, all patients discharged the day of surgery. No patient was admitted to a hospital or have consulted within one month due to postoperative complications. No surgeryrelated complication underwent during the patients' follow-up. Conclusion: Our study highlights the safety and feasibility of VNS surgery in an outpatient setting for patients with severe intellectual disability. We report detailed protocol and preoperative checklist to optimize outpatient VNS surgery in these not able-bodied patients. Severe disabilities or epilepsy-associated handicaps should not be an exclusion criterion when considering ambulatory VNS implantation

Surgical technique

International audienc

A monoclonal antibody to O-acetyl-GD2 ganglioside and not to GD2 shows potent anti-tumor activity without peripheral nervous system cross-reactivity.

BACKGROUND: Monoclonal antibodies (mAb) against GD2 ganglioside have been shown to be effective for the treatment of neuroblastoma. Beneficial actions are, however, associated with generalized pain due to the binding of anti- GD2 mAbs to peripheral nerve fibers followed by complement activation. Neuroblastoma cells that express GD2 also express its O-acetyl derivative, O-acetyl- GD2 ganglioside (OAcGD2). Hence, we investigated the distribution of OAcGD2 in human tissues using mAb 8B6 to study the cross-reactivity of mAb 8B6 with human tissues. METHODOLOGY/PRINCIPAL FINDINGS: The distribution of OAcGD2 was performed in normal and malignant tissues using an immunoperoxydase technique. Anti-tumor properties of mAb 8B6 were studied in vitro and in vivo in a transplanted tumor model in mice. We found that OAcGD2 is not expressed by peripheral nerve fibers. Furthermore, we demonstrated that mAb 8B6 was very effective in the in vitro and in vivo suppression of the growth of tumor cells. Importantly, mAb 8B6 anti-tumor efficacy was comparable to that of mAb 14G2a specific to GD2. CONCLUSION/SIGNIFICANCE: Development of therapeutic antibodies specific to OAcGD2 may offer treatment options with reduced adverse side effects, thereby allowing dose escalation of antibodies