No major effect of dopamine receptor 1/5 antagonist SCH-23390 on epileptic activity in the Tg2576 mouse model of amyloidosis

The excitation-inhibition imbalance manifesting as epileptic activities in Alzheimer's disease is gaining more and more attention, and several potentially involved cellular and molecular pathways are currently under investigation. Based on in vitro studies, dopamine D1-type receptors in the anterior cingulate cortex and the hippocampus have been proposed to participate in this peculiar co-morbidity in mouse models of amyloidosis. Here, we tested the implication of dopaminergic transmission in vivo in the Tg2576 mouse model of Alzheimer's disease by monitoring epileptic activities via intracranial EEG before and after treatment with dopamine antagonists. Our results show that neither the D1-like dopamine receptor antagonist SCH23390 nor the D2-like dopamine receptor antagonist haloperidol reduces the frequency of epileptic activities. While requiring further investigation, our results indicate that on a systemic level, dopamine receptors are not significantly contributing to epilepsy observed in vivo in this mouse model of Alzheimer's disease.

[Evaluation of the relevance of the pharmaceutical educational interview on the knowledge and satisfaction of patients who received a vagus nerve neurostimulator implantation]

INTRODUCTION

Vagal neurostimulation (VNS) medical devices (MDs) are used to treat drug-resistant epilepsy. Using a magnet, the patient can activate on the stimulations in order to stop a seizure or interrupt the adverse effects (AEs) of the device. The objective is to evaluate the improvement of the patients' knowledge about the VNS following a pharmaceutical educational interview (PEI) as well as their satisfaction.

MATERIALS AND METHODS

The pharmaceutical educational interview regarding drugs and DMs was performed by the clinical pharmacist at the patient's bed after VNS implantation. A questionnaire about VNS devices (operation, adverse effects, recommendations) and assessing knowledge was submitted to patients before and after the PEI. Satisfaction was assessed by the Likert scale.

RESULTS

From March 2020 to August 2021, 18 implanted patients were included in the study. In 78% of cases (14/18), the total number of good responses after PEI increased. The mean good response was significantly increased from 16.11/25 (64%) before PEI to 22.33/25 (89%) after PEI (P-value<0.01). The maximum satisfaction score (4/4) was given in 71% of the items.

DISCUSSION-CONCLUSION

The results support the relevance of PEI. Patients feel a need for information and consider the interview useful. An improvement in knowledge was observed, which allows us to hope for an optimization of the effectiveness of the device, in particular, a reduction in seizures and AE. This study shows the feasibility and the interest of the development of clinical pharmacy applied to medical devices in complementarity with the expertise on drugs.

Large-scale network dynamics underlying the first few hundred milliseconds after stimulus presentation: An investigation of visual recognition memory using iEEG

Recognition memory is the ability to recognize previously encountered objects. Even this relatively simple, yet extremely fast, ability requires the coordinated activity of large-scale brain networks. However, little is known about the sub-second dynamics of these networks. The majority of current studies into large-scale network dynamics is primarily based on imaging techniques suffering from either poor temporal or spatial resolution. We investigated the dynamics of large-scale functional brain networks underlying recognition memory at the millisecond scale. Specifically, we analyzed dynamic effective connectivity from intracranial electroencephalography while epileptic subjects (n = 18) performed a fast visual recognition memory task. Our data-driven investigation using Granger causality and the analysis of communities with the Louvain algorithm spotlighted a dynamic interplay of two large-scale networks associated with successful recognition. The first network involved the right visual ventral stream and bilateral frontal regions. It was characterized by early, predominantly bottom-up information flow peaking at 115 ms. It was followed by the involvement of another network with predominantly top-down connectivity peaking at 220 ms, mainly in the left anterior hemisphere. The transition between these two networks was associated with changes in network topology, evolving from a more segregated to a more integrated state. These results highlight that distinct large-scale brain networks involved in visual recognition memory unfold early and quickly, within the first 300 ms after stimulus onset. Our study extends the current understanding of the rapid network changes during rapid cognitive processes.

GWAS meta-analysis of over 29,000 people with epilepsy identifies 26 risk loci and subtype-specific genetic architecture

Epilepsy is a highly heritable disorder affecting over 50 million people worldwide, of which about one-third are resistant to current treatments. Here we report a multi-ancestry genome-wide association study including 29,944 cases, stratified into three broad categories and seven subtypes of epilepsy, and 52,538 controls. We identify 26 genome-wide significant loci, 19 of which are specific to genetic generalized epilepsy (GGE). We implicate 29 likely causal genes underlying these 26 loci. SNP-based heritability analyses show that common variants explain between 39.6% and 90% of genetic risk for GGE and its subtypes. Subtype analysis revealed markedly different genetic architectures between focal and generalized epilepsies. Gene-set analyses of GGE signals implicate synaptic processes in both excitatory and inhibitory neurons in the brain. Prioritized candidate genes overlap with monogenic epilepsy genes and with targets of current antiseizure medications. Finally, we leverage our results to identify alternate drugs with predicted efficacy if repurposed for epilepsy treatment.

Radiosurgical Corpus Callosotomy for Intractable Epilepsy: Retrospective Long-Term Safety and Efficacy Assessment in 19 Patients an Review of the Literature

BACKGROUND

Some patients suffering from intractable epileptic seizures, particularly drop attacks (DAs), are nonremediable by curative techniques. Palliative procedure carries a significant rate of surgical and neurological complications.

OBJECTIVE

To propose evaluation of safety and efficacy of Gamma Knife corpus callosotomy (GK-CC) as an alternative to microsurgical corpus callosotomy.

METHODS

This study included retrospective analysis of 19 patients who underwent GK-CC between 2005 and 2017.

RESULTS

Of the 19 patients, 13 (68%) had improvement in seizure control and 6 had no significant improvement. Of the 13/19 (68%) with improvement in seizures, 3 (16%) became completely seizure-free, 2 (11%) became free of DA and generalized tonic-clonic but with residual other seizures, 3 (16%) became free of DA only, and 5 (26%) had >50% reduction in frequency of all seizure types. In the 6 (31%) patients with no appreciable improvement, there were residual untreated commissural fibers and incomplete callosotomy rather than failure of Gamma Knife to disconnect. Seven patients showed a transient mild complication (37% of patients, 33% of the procedures). No permanent complication or neurological consequence was observed during the clinical and radiological workup with a mean of 89 (42-181) months, except 1 patient who had no improvement of epilepsy and then aggravation of the pre-existing cognitive and walking difficulties (Lennox-Gastaut). The median time of improvement after GK-CC was 3 (1-6) months.

CONCLUSION

Gamma Knife callosotomy is safe and accurate with comparable efficacy to open callosotomy in this cohort of patients with intractable epilepsy suffering from severe drop attacks.

Neuronal hyperexcitability in the Tg2576 mouse model of Alzheimer's disease - the influence of sleep and noradrenergic transmission

The link between Alzheimer's disease (AD) and network hypersynchrony - manifesting as epileptic activities - received considerable attention in the past decade. However, several questions remain unanswered as to its mechanistic underpinnings. Therefore, our objectives were (1) to better characterise epileptic events in the Tg2576 mouse model throughout the sleep-wake cycle and disease progression via electrophysiological recordings and (2) to explore the involvement of noradrenergic transmission in this pathological hypersynchrony. Over and above confirming the previously described early presence and predominance of epileptic events during rapid-eye-movement (REM) sleep, we also show that these events do not worsen with age and are highly phase-locked to the section of the theta cycle during REM sleep where hippocampal pyramidal cells reach their highest firing probability. Finally, we reveal an antiepileptic mechanism of noradrenergic transmission via α1-adrenoreceptors that could explain the intriguing distribution of epileptic events over the sleep-wake cycle in this model, with potential therapeutic implications in the treatment of the epileptic events occurring in many AD patients.

Early identification of seizure freedom with medical treatment in patients with mesial temporal lobe epilepsy and hippocampal sclerosis

BACKGROUND

Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is usually associated with a poor response to antiseizure medications. We focused on MTLE-HS patients who were seizure free on medication to: (1) determine the clinical factors associated with seizure freedom and (2) develop a machine-learning classifier to better earlier identify those patients.

METHODS

We performed a retrospective, multicentric study comparing 64 medically treated seizure-free MTLE-HS patients with 200 surgically treated drug-resistant MTLE-HS patients. First, we collected medical history and seizure semiology data. Then, we developed a machine-learning classifier based on clinical data.

RESULTS

Medically treated seizure-free MTLE-HS patients were seizure-free for at least 2 years, and for a median time of 7 years at last follow-up. Compared to drug-resistant MTLE-HS patients, they exhibited: an older age at epilepsy onset (22.5 vs 8.0 years, p < 0.001), a lesser rate of: febrile seizures (39.0% vs 57.5%, p = 0.035), focal aware seizures (previously referred to as aura)(56.7% vs 90.0%, p < 0.001), autonomic focal aware seizures in presence of focal aware seizure (17.6% vs 59.4%, p < 0.001), dystonic posturing of the limbs (9.8% vs 47.0%, p < 0.001), gestural (27.4% vs 94.0%, p < 0.001), oro-alimentary (32.3% vs 75.5%, p < 0.001) or verbal automatisms (12.9% vs 36.0%, p = 0.001). The classifier had a positive predictive value of 0.889, a sensitivity of 0.727, a specificity of 0.962, a negative predictive value of 0.893.

CONCLUSIONS

Medically treated seizure-free MTLE-HS patients exhibit a distinct clinical profile. A classifier built with readily available clinical data can identify them accurately with excellent positive predictive value. This may help to individualize the management of MTLE-HS patients according to their expected pharmacosensitivity.

Specific profiles of new-onset vs. non-inaugural status epilepticus: From diagnosis to 1-year outcome

While new-onset status epilepticus (NOSE) is a harbinger of chronic epilepsy, prospective medical data are sparse in terms of specifying whether the evolution of status epilepticus (SE) and seizure expression in NOSE resembles what occurs in patients who have already been diagnosed with epilepsy [non-inaugural SE (NISE)] in all aspects apart from its inaugural nature. The aim of this study was to compare the clinical, MRI, and EEG features that could distinguish NOSE from NISE. We conducted a prospective monocentric study in which all patients ≥18 years admitted for SE over a 6-month period were included. A total of 109 patients (63 NISE and 46 NOSE cases) were included. Despite similar modified Rankin scores before SE, several aspects of the clinical history distinguished NOSE from NISE patients. NOSE patients were older and frequently had neurological comorbidity and preexisting cognitive decline, but they had a similar prevalence of alcohol consumption to NISE patients. NOSE and NISE evolve in the same proportions as refractory SE (62.5% NOSE, 61% NISE) and share common features such as the same incidence (33% NOSE, 42% NISE, and p = 0.53) and volumes of peri-ictal abnormalities on MRI. However, in NOSE patients, we observed greater non-convulsive semiology (21.7% NOSE, 6% NISE, and p = 0.02), more periodic lateral discharges on EEG (p = 0.004), later diagnosis, and higher severity according to the STESS and EMSE scales (p < 0.0001). Mortality occurred in 32.6% of NOSE patients and 21% of NISE patients at 1 year (p = 0.19), but with different causes of death occurring at different time points: more early deaths directly linked to SE at 1 month occurred in the NOSE group, while there were more remote deaths linked to causal brain lesions in the NISE group at final follow-up. In survivors, 43.6% of the NOSE cases developed into epilepsy. Despite acute causal brain lesions, the novelty related to its inaugural nature is still too often associated with a delay in diagnosing SE and a poorer outcome, which justifies the need to more clearly specify the various types of SE to constantly raise awareness among clinicians. These results highlight the relevance of including novelty-related criteria, clinical history, and temporality of occurrence in the nosology of SE.

Local neuronal excitation and global inhibition during epileptic fast ripples in humans

Understanding the neuronal basis of epileptic activity is a major challenge in neurology. Cellular integration into larger scale networks is all the more challenging. In the local field potential, interictal epileptic discharges can be associated with fast ripples (200-600 Hz), which are a promising marker of the epileptogenic zone. Yet, how neuronal populations in the epileptogenic zone and in healthy tissue are affected by fast ripples remain unclear. Here, we used a novel 'hybrid' macro-micro depth electrode in nine drug-resistant epileptic patients, combining classic depth recording of local field potentials (macro-contacts) and two or three tetrodes (four micro-wires bundled together) enabling up to 15 neurons in local circuits to be simultaneously recorded. We characterized neuronal responses (190 single units) with the timing of fast ripples (2233 fast ripples) on the same hybrid and other electrodes that target other brain regions. Micro-wire recordings reveal signals that are not visible on macro-contacts. While fast ripples detected on the closest macro-contact to the tetrodes were always associated with fast ripples on the tetrodes, 82% of fast ripples detected on tetrodes were associated with detectable fast ripples on the nearest macro-contact. Moreover, neuronal recordings were taken in and outside the epileptogenic zone of implanted epileptic subjects and they revealed an interlay of excitation and inhibition across anatomical scales. While fast ripples were associated with increased neuronal activity in very local circuits only, they were followed by inhibition in large-scale networks (beyond the epileptogenic zone, even in healthy cortex). Neuronal responses to fast ripples were homogeneous in local networks but differed across brain areas. Similarly, post-fast ripple inhibition varied across recording locations and subjects and was shorter than typical inter-fast ripple intervals, suggesting that this inhibition is a fundamental refractory process for the networks. These findings demonstrate that fast ripples engage local and global networks, including healthy tissue, and point to network features that pave the way for new diagnostic and therapeutic strategies. They also reveal how even localized pathological brain dynamics can affect a broad range of cognitive functions.

Sleep: The Tip of the Iceberg in the Bidirectional Link Between Alzheimer's Disease and Epilepsy

The observation that a pathophysiological link might exist between Alzheimer's disease (AD) and epilepsy dates back to the identification of the first cases of the pathology itself and is now strongly supported by an ever-increasing mountain of literature. An overwhelming majority of data suggests not only a higher prevalence of epilepsy in Alzheimer's disease compared to healthy aging, but also that AD patients with a comorbid epileptic syndrome, even subclinical, have a steeper cognitive decline. Moreover, clinical and preclinical investigations have revealed a marked sleep-related increase in the frequency of epileptic activities. This characteristic might provide clues to the pathophysiological pathways underlying this comorbidity. Furthermore, the preferential sleep-related occurrence of epileptic events opens up the possibility that they might hasten cognitive decline by interfering with the delicately orchestrated synchrony of oscillatory activities implicated in sleep-related memory consolidation. Therefore, we scrutinized the literature for mechanisms that might promote sleep-related epileptic activity in AD and, possibly dementia onset in epilepsy, and we also aimed to determine to what degree and through which processes such events might alter the progression of AD. Finally, we discuss the implications for patient care and try to identify a common basis for methodological considerations for future research and clinical practice.

Interactions between antiseizure medications and contraception: A study about the knowledge of patients and their specialist physicians

Planning pregnancy is very important for women with epilepsy (WWE), because of the potential teratogenic effects and neurodevelopmental disorders of different antiseizure medications (ASMs). Nevertheless, contraception in WWE can be challenging due to the existence of drug interactions between ASMs and hormonal contraception. The aim of this study was to assess women's knowledge of potential interactions between their ASMs and contraceptive options. The second objective was to assess neurologist's knowledge of the potential interactions between ASMs and contraceptive methods. An anonymous online survey was proposed to reproductive-age WWE during consultation with their neurologist. Another online survey was proposed to neurologists. These surveys were performed through a French regional medical network. A total of 79 patients agreed to respond to the survey. Forty-nine women used lamotrigine alone or in combination, 15 used an enzyme-inducing ASM alone or in combination, 13 used non-enzyme-inducing ASM and 2 used both lamotrigine and an enzyme-inducing ASM. Half of the WWE had mistaken beliefs about interactions between their ASM and contraception. Among them, 35% of the women treated with an enzyme-inducing ASM were unaware of a potential decreased efficacy of hormonal contraception. Moreover, 51% of the women who were taking lamotrigine did not know that combined hormonal contraception might decrease the efficacy of their ASM. On the other hand, 64.5% of WWE without an enzyme-inducing ASM wrongly thought that their ASM can decrease their hormonal contraceptive efficacy. A total of 20 neurologists answered the online survey. It revealed specific gaps concerning interactions between ASM and contraceptives; in fact, 35% of answers concerning the identification of specific enzyme-inducing ASMs were wrong. This study therefore highlights the need for educational efforts for both WWE and their physicians regarding drug interactions between ASMs and hormonal contraceptives.

Coffee consumption and seizure frequency in patients with drug-resistant focal epilepsy

OBJECTIVE

To assess the relation between coffee consumption and seizure frequency in patients with drug-resistant focal epilepsy.

METHODS

Cross-sectional analysis of data collected in the SAVE study, which included patients with drug-resistant focal epilepsy during long-term EEG monitoring. Patients in whom both coffee consumption and data about seizure frequency, including focal to bilateral tonic-clonic seizures (FBTCS), were available were selected. Coffee consumption was collected using a standardized self-report questionnaire and classified into four groups: none, rare (from less than 1 cup/week to up 3 cups/week), moderate (from 4 cups/week to 3 cups/day), and high (more than 4 cups/day).

RESULTS

Six hundred and nineteen patients were included. There was no relation between coffee consumption and total seizure frequency (p = 0.902). In contrast, the number of FBTCS reported over the past year was significantly associated with usual coffee consumption (p = 0.029). Specifically, number of FBCTS in patients who reported moderate coffee consumption was lower than in others. In comparison with patients with moderate coffee consumption, the odds ratio (95%CI) for reporting at least 1 FBTCS per year was 1.6 (1.03-2.49) in patients who never take coffee, 1.62 (1.02-2.57) in those with rare consumption and 2.05 (1.24-3.4) in those with high consumption. Multiple ordinal logistic regression showed a trend toward an association between coffee consumption and number of FBTCS (p = 0.08).

CONCLUSIONS AND RELEVANCE

Our data suggest that effect of coffee consumption on seizures might depend on dose with potential benefits on FBTCS frequency at moderate doses. These results will have to be confirmed by prospective studies.

Hidden Objective Memory Deficits Behind Subjective Memory Complaints in Patients With Temporal Lobe Epilepsy

OBJECTIVE

To test the hypothesis that temporal lobe epilepsy (TLE) patients with subjective initial memory complaints (not confirmed by an objective standard assessment) and various phenotypes also show objective very long-term memory deficit with accelerated long-term forgetting. We tested TLE patients with two surprise memory tests after three weeks: the standard Free and Cued Selective Reminding Test (FCSRT), and Epireal, a new test specifically designed to capture more ecological aspects of autobiographical memory.

METHODS

47 TLE patients (12 hippocampal sclerosis, 12 amygdala enlargement, 11 extensive lesions, 12 normal MRI) who complained about their memory, but for whom the standard neuropsychological assessment did not reveal any memory impairment after a standard delay of 20 minutes, underwent two surprise memory tests after three weeks. They were compared to 35 healthy control subjects.

RESULTS

After three weeks, FCSRT and Epireal recall scores were significantly lower in patients than in controls (p<0.001). There was no significant correlation between FCSRT and Epireal scores (p=0.99). Seventy-six percent of TLE patients had objective impairment on at least one of these very long-term memory tests, regardless of the existence and type of lesion or response to antiseizure medication. Easily applicable, Epireal had a higher effect size, detected deficits in 28% more patients, and is a useful addition to the standard workup.

CONCLUSION

Assessing long-term memory should be broadened to a wide spectrum of TLE patients with a memory complaint, regardless of the epileptic syndrome, whether or not associated with a lesion. This could lead to rethinking TLE nosology associated with memory.

Predictive factors of postoperative outcome in the elderly after resective epilepsy surgery

OBJECTIVE

To evaluate the efficiency of resective epilepsy surgery (RES) in patients over 50 years and determine prognostic factors.

RESULTS

Over the 147 patients over 50 years (54.9±3.8 years [50-69]) coming from 8 specialized French centres for epilepsy surgery, 72.1%, patients were seizure-free and 91.2% had a good outcome 12 months after RES. Seizure freedom was not associated with the age at surgery or duration of epilepsy. In multivariate analysis, seizure freedom was associated with MRI and neuropathological hippocampal sclerosis (HS) (P=0.009 and P=0.028 respectively), PET hypometabolism (P=0.013), temporal epilepsy (P=0.01). On the contrary, the need for intracranial exploration was associated with a poorer prognosis (P=0.001). Postoperative number of antiepileptic drugs was significantly lower in the seizure-free group (P=0.001). Neurological adverse event rate after surgery was 21.1% and 11.7% of patients had neuropsychological adverse effects overall transient.

CONCLUSIONS

RES is effective procedure in the elderly. Even safe it remains at higher risk of complication and population should be carefully selected. Nevertheless, age should not be considered as a limiting factor, especially when good prognostic factors are identified.

CACNA1A-associated epilepsy: Electroclinical findings and treatment response on seizures in 18 patients

CACNA1A pathogenic mutations are involved in various neurological phenotypes including episodic ataxia (EA2), spinocerebellar ataxia (SCA6), and familial hemiplegic migraine (FHM1). Epilepsy is poorly documented. We studied 18 patients (10 males) carrying de novo or inherited CACNA1A mutations, with median age of 2,5 years at epilepsy onset. Eight mutations were novel. Two variants known leading to gain of function (GOF) were found in 5 patients. Five other patients had non-sense variants leading to loss of function (LOF). Seizures were most often revealed by either status epilepticus (SE) (n = 8), eventually triggered by fever (n = 5), or absences/behavioural arrests (n = 7). Non-epileptic paroxysmal events were frequent and consisted in recurrent hemiplegic accesses (n = 9), jitteriness in the neonatal period (n = 6), and ocular paroxysmal events (n = 9). Most of the patients had early permanent cerebellar dysfunction (n = 16) and early moderate to severe global developmental delay (GDD)/intellectual deficiency (ID) (n = 17). MRI was often abnormal, with cerebellar (n = 8) and/or cerebral (n = 6) atrophy. Stroke-like occurred in 2 cases. Some antiepileptic drugs including topiramate, levetiracetam, lamotrigine and valproate were effective on seizures. Acetazolamide and calcium channel blockers were often effective when used. More than half of the patients had refractory epilepsy. CACNA1A mutation should be evoked in front of 2 main electro-clinical phenotypes that are associated with permanent cerebellar dysfunction and moderate to severe GDD/ID. The first one, found in all 5 patients with GOF variants, is characterized by intractable seizures, early and recurrent SE and hemiplegic accesses. The second, less severe, found in 5 patients with LOF variants, is characterized by refractory early onset absence seizures.

Awake Craniotomy and Memory Induction Through Electrical Stimulation: Why Are Penfield's Findings Not Replicated in the Modern Era?

From the 1930s through the early 1960s, Wilder Penfield12 collected a large number of memories induced by electrical brain stimulation (EBS) during awake craniotomy. As a result, he was a major contributor to several neuroscientific and neuropsychological concepts of long-term memory. His 1963 paper, which recorded all the cases of memories he induced in his operating room, remains a substantial point of reference in neuroscience in 2019, although some of his interpretations are now debatable.  However, it is highly surprising that, since Penfield's12 reports, there has been no other surgical publication on memories induced during awake surgery. In this review, we explore this phenomenon and analyze some of the reasons that might explain it. We hypothesize that the main reasons for lack of subsequent reports are related to changes in operative procedures (ie, use of anesthetics, time constraints, and insufficient debriefings) and changes in EBS parameters, rather than to the sites that are stimulated, the pathology treated, or the tasks used. If reminiscences are still induced, they should be reported in detail to add valuable contributions to the understanding of long-term memory networks, especially memories that are difficult to reproduce in the laboratory, such as autobiographical memories.

Effect of meditation on intracerebral EEG in a patient with temporal lobe epilepsy: A case report

Meditation has been deemed a miracle cure for a wide range of neurological disorders. However, it is unclear whether meditation practice would be beneficial for patients suffering from epilepsy. Here we report on the comparison of the effects of focused-attention meditation and a control task on electroencephalographic (EEG) activity in a patient undergoing stereoencephalographic (SEEG) investigation for drug-resistant epilepsy. The patient routinely practiced focused-attention meditation and reported that she found it beneficial. During the SEEG investigation, intracerebral EEG data were recorded during meditation as well as during mind-wandering task. The EEG data were analyzed for type of electrical activity (labeled) by two expert epileptologists. We found that the proportion of EEG segments containing activity classified as interictal epileptiform discharges (IEDs; abnormal electrical activity that occurs between seizures) increased significantly during meditation practice. Although the finding was surprising, this increase in IEDs may not correlate with an increase in seizure frequency, and the patient might still benefit from practicing meditation. The finding does, however, warrant further studies on the influence of meditation on epileptic activity.

Stereoelectroencephalography (SEEG) and epilepsy surgery in posttraumatic epilepsy: A multicenter retrospective study

PURPOSE

Posttraumatic epilepsy (PTE) is a common cause of drug-resistant epilepsy, especially in young adults. Nevertheless, such patients are not common candidates for intracranial presurgical evaluation. We investigated the role of stereoelectroencephalography (SEEG) in defining epileptogenicity and surgical strategy in patients with PTE.

METHODS

We analyzed ictal SEEG recordings from 18 patients. We determined the seizure onset zone (SOZ) by quantifying the epileptogenicity of the sampled structures, using the "epileptogenicity index" (EI). We also identified seizure onset patterns (SOPs) through visual and frequency analysis. Postsurgical outcome was assessed by Engel's classification.

RESULTS

The SOZ in PTE was most often located in temporal lobes, followed by frontal lobes. The SOZ was network-organized in the majority of the cases. Half of the SOP did not contain fast discharges. Half of the recordings showed SOZ that were less extensive than the posttraumatic lesions seen on brain magnetic resonance imaging (MRI). All but one operated patient benefited from tailored cortectomy. Only 3 patients were contraindicated for surgical resection due to bilateral epileptogenicity. The overall surgical outcome was good in majority of patients (67% Engel I).

CONCLUSION

Despite the potential risk of bilateral or multifocal epilepsy, patients with PTE may benefit from presurgical assessment in well-selected cases. In this context, SEEG allows guidance of tailored resections adapted to the SOZ.

Recording local field potential and neuronal activity with tetrodes in epileptic patients

BACKGROUND

Recordings with tetrodes have proven to be more effective in isolating single neuron spiking activity than with single microwires. However, tetrodes have never been used in humans. We report on the characteristics, safety, compatibility with clinical intracranial recordings in epileptic patients, and performance, of a new type of hybrid electrode equipped with tetrodes.

NEW METHOD

240 standard clinical macroelectrodes and 102 hybrid electrodes were implanted in 28 patients. Hybrids (diameter 800 μm) are made of 6 or 9 macro-contacts and 2 or 3 tetrodes (diameter 70-80 μm).

RESULTS

No clinical complication or adverse event was associated with the hybrids. Impedance and noise of recordings were stable over time. The design enabled multiscale spatial analyses that revealed physiopathological events which were sometimes specific to one tetrode, but could not be recorded on the macro-contacts. After spike sorting, the single-unit yield was similar to other hybrid electrodes and was sometimes as high as >10 neurons per tetrode.

COMPARISON WITH EXISTING METHOD(S)

This new hybrid electrode has a smaller diameter than other available hybrid electrodes. It provides novel spatial information due to the configuration of the tetrodes. The single-unit yield appears promising.

CONCLUSIONS

This new hybrid electrode is safe, easy to use, and works satisfactorily for conducting multi-scale seizure and physiological analyses.

Etiological assessment of status epilepticus

Status epilepticus (SE) is a potentially serious condition that can affect vital and functional prognosis and requires urgent treatment. Etiology is a determining factor in the patient's functional outcome and in almost half of all cases justifies specific treatment to stop progression. Therefore, identifying and addressing the cause of SE is a key priority in SE management. However, the etiology can be difficult to identify among acute and remote causes, which can also be multiple and interrelated. The most common etiologies are the discontinuation of antiepileptic medication in patients with a prior history of epilepsy, and acute brain aggression in cases of new onset SE (cerebrovascular pathologies are the most common). The list of remaining possible etiologies includes heterogeneous pathological contexts. Refractory SE and especially New-Onset Refractory Status Epilepticus (NORSE) lead to an extension of the etiological assessment in the search for encephalitis of autoimmune or infectious origin in adults and in children, as well as a genetic pathology in children in particular. This is an overview of current knowledge of SE etiologies and a pragmatic approach for carrying out an etiological assessment based on the following steps: - Which etiological orientation is identified according to the field and clinical presentation?; - Which etiologies to look for in an inaugural SE?; - Which first-line assessment should be carried out? The place of the biological, EEG and imaging assessment is discussed; - Which etiologies to look for in case of refractory SE?

Post-traumatic Stress Disorder With Flashbacks of an Old Childhood Memory Triggered by Right Temporal Lobe Epilepsy Surgery in Adulthood

BACKGROUND

A plethora of data show that the hippocampus and the amygdala are involved in post-traumatic stress disorder (PTSD). Neural dysfunctions leading to PTSD (e.g. how the amygdala and the hippocampus are altered) are only partially known. The unusual case of a patient presenting with refractory epilepsy and developing PTSD immediately after surgery is described. Such symptoms in epileptic patients may help to explore PTSD mechanisms.

CASE REPORT

A 41-year-old male suffering from partial refractory temporal lobe epilepsy was operated in May 2017. A right amygdala, hippocampus, and temporal pole selective resection was performed. He experienced intense PTSD symptoms 1 month after surgery. He complained about repetitive intrusive memories of abuse. The PTSD checklist score was equal to 62/80. He reported a history of childhood abuse: physical and emotional abuse as well as emotional negligence, assessed with the Childhood Trauma Questionnaire. No other medical history was recorded. He never complained about PTSD or any other psychiatric symptoms before surgery.

CONCLUSION

this case indicates that PTSD may occur after temporal lobe epilepsy surgery and may specifically stem, as in this context, from the excision of part of the medial temporal lobe structures. Although rarely reported, PTSD may be undiagnosed when not selectively detected via multi-disciplinary neurological and psychiatric management, in the preoperative period and the immediate and delayed postoperative period.

A Fast Visual Recognition Memory System in Humans Identified Using Intracerebral ERP

One key item of information retrieved when surveying our visual world is whether or not objects are familiar. However, there is no consensus on the respective roles of medial temporal lobe structures, particularly the perirhinal cortex (PRC) and hippocampus. We considered whether the PRC could support a fast recognition memory system independently from the hippocampus. We recorded the intracerebral electroencephalograph activity of epileptic patients while they were performing a fast visual recognition memory task, constraining them to use their quickest strategy. We performed event-related potential (ERP) and classification analyses. The PRC was, by far, the earliest region involved in recognition memory. This activity occurred before the first behavioral responses and was found to be related to reaction times, unlike the hippocampus. Single-trial analyses showed that decoding power was equivalent in the PRC and hippocampus but occurred much earlier in the PRC. A critical finding was that recognition memory-related activity occurred in different frontal and parietal regions, including the supplementary motor area, before the hippocampus. These results, based on ERP analyses, suggest that the human brain is equipped with a fast recognition memory system, which may bypass the hippocampus and in which the PRC plays a critical role.

Suicidal Ideation and Traumatic Exposure Should Not Be Neglected in Epileptic Patients: A Multidimensional Comparison of the Psychiatric Profile of Patients Suffering From Epilepsy and Patients Suffering From Psychogenic Nonepileptic Seizures

Introduction: Patients with psychogenic nonepileptic seizures (PNESs) have often been exposed to traumatic events, which is a risk factor for suicidal behavior. This would suggest that the severity of suicidal ideation is greater in PNES than in patients suffering only from epileptic seizures (ESs). However, these psychiatric symptoms may be underestimated in the ES population. The specific features or similarities between the psychiatric clinical profiles of these two groups should be elaborated to improve therapeutic management. Our study is the first to compare suicidal ideation, suicide risk, posttraumatic stress disorder (PTSD), and depression disorder simultaneously in both groups, in a tertiary care epilepsy center. Material and methods: We prospectively enrolled patients hospitalized for video-electroencephalography (EEG) monitoring to assess repeated seizures before an ES or a PNES diagnosis was made. During the psychiatric consultation that accompanied the video EEG, we rated the severity of suicidal ideation and depressive symptoms, suicidal risk, traumatic exposure history, and PTSD symptoms. Results: Eighteen subjects were enrolled and diagnosed with PNES, and 42, with ES. The PNES group reported more exposures to traumatic events and more intense PTSD symptoms (median: 17 vs. 27; p = 0.001). The severity of suicidal ideation did not differ significantly between the two groups. Conclusion: It is the severity of PTSD symptoms in PNES patients that differentiates them from ES patients, although exposure to traumatic events is also frequent in ES patients. We demonstrated that suicidal ideation and suicide risk are equally high in the ES and PNES groups. Therefore, both groups require extreme vigilance in terms of suicidal risk.

Hypoxemia following generalized convulsive seizures

Objective

To analyze the factors that determine the occurrence or severity of postictal hypoxemia in the immediate aftermath of a generalized convulsive seizure (GCS).

Methods

We reviewed the video-EEG recordings of 1,006 patients with drug-resistant focal epilepsy included in the REPO2MSE study to identify those with ≥1 GCS and pulse oximetry (SpO2) measurement. Factors determining recovery of SpO2 ≥ 90% were investigated using Cox proportional hazards models. Association between SpO2 nadir and person- or seizure-specific variables was analyzed after correction for individual effects and the varying number of seizures.

Results

A total of 107 GCS in 73 patients were analyzed. A transient hypoxemia was observed in 92 GCS (86%). Rate of GCS with SpO2 <70% dropped from 40% to 21% when oxygen was administered early (p = 0.046). Early recovery of SpO2 ≥90% was associated with early administration of oxygen (p = 0.004), absence of postictal generalized EEG suppression (PGES) (p = 0.014), and extratemporal lobe epilepsy (p = 0.001). Lack of early administration of O2 (p = 0.003), occurrence of PGES (p = 0.018), and occurrence of ictal hypoxemia during the focal phase (p = 0.022) were associated with lower SpO2 nadir.

Conclusion

Postictal hypoxemia was observed in the immediate aftermath of nearly all GCS but administration of oxygen had a strong preventive effect. Severity of postictal hypoxemia was greater in temporal lobe epilepsy and when hypoxemia was already observed before the onset of secondary GCS.

Probabilistic functional tractography of the human cortex revisited

In patients with pharmaco-resistant focal epilepsies investigated with intracranial electroencephalography (iEEG), direct electrical stimulations of a cortical region induce cortico-cortical evoked potentials (CCEP) in distant cerebral cortex, which properties can be used to infer large scale brain connectivity. In 2013, we proposed a new probabilistic functional tractography methodology to study human brain connectivity. We have now been revisiting this method in the F-TRACT project (f-tract.eu) by developing a large multicenter CCEP database of several thousand stimulation runs performed in several hundred patients, and associated processing tools to create a probabilistic atlas of human cortico-cortical connections. Here, we wish to present a snapshot of the methods and data of F-TRACT using a pool of 213 epilepsy patients, all studied by stereo-encephalography with intracerebral depth electrodes. The CCEPs were processed using an automated pipeline with the following consecutive steps: detection of each stimulation run from stimulation artifacts in raw intracranial EEG (iEEG) files, bad channels detection with a machine learning approach, model-based stimulation artifact correction, robust averaging over stimulation pulses. Effective connectivity between the stimulated and recording areas is then inferred from the properties of the first CCEP component, i.e. onset and peak latency, amplitude, duration and integral of the significant part. Finally, group statistics of CCEP features are implemented for each brain parcel explored by iEEG electrodes. The localization (coordinates, white/gray matter relative positioning) of electrode contacts were obtained from imaging data (anatomical MRI or CT scans before and after electrodes implantation). The iEEG contacts were repositioned in different brain parcellations from the segmentation of patients' anatomical MRI or from templates in the MNI coordinate system. The F-TRACT database using the first pool of 213 patients provided connectivity probability values for 95% of possible intrahemispheric and 56% of interhemispheric connections and CCEP features for 78% of intrahemisheric and 14% of interhemispheric connections. In this report, we show some examples of anatomo-functional connectivity matrices, and associated directional maps. We also indicate how CCEP features, especially latencies, are related to spatial distances, and allow estimating the velocity distribution of neuronal signals at a large scale. Finally, we describe the impact on the estimated connectivity of the stimulation charge and of the contact localization according to the white or gray matter. The most relevant maps for the scientific community are available for download on f-tract. eu (David et al., 2017) and will be regularly updated during the following months with the addition of more data in the F-TRACT database. This will provide an unprecedented knowledge on the dynamical properties of large fiber tracts in human.

Déjà-rêvé: Prior dreams induced by direct electrical brain stimulation

BACKGROUND

Epileptic patients sometimes report experiential phenomena related to a previous dream they had during seizures or electrical brain stimulation (EBS). This has been alluded to in the literature as "déjà-rêvé" ("already dreamed"). However, there is no neuroscientific evidence to support its existence and this concept is commonly mixed up with déjà-vu. We hypothesized that déjà-rêvé would be a specific entity, i.e., different from other experiential phenomena reported in epileptic patients, induced by EBS of specific brain areas.

METHODS

We collected all experiential phenomena related to dreams induced by electrical brain stimulations (EBS) in our epileptic patients (2003-2015) and in a review of the literature. The content of these déjà-rêvé and the location of EBS were analyzed.

RESULTS

We collected 7 déjà-rêvé in our database and 35 from the literature, which corresponds to an estimated prevalence of 0.3‰ of all EBS-inducing déjà-rêvé. Déjà-rêvé is a generic term for three distinct entities: it can be the recollection of a specific dream ("episodic-like"), reminiscence of a vague dream ("familiarity-like") or experiences in which the subject feels like they are dreaming (literally "a dreamy state"). EBS-inducing "episodic-like" and "familiarity-like" déjà-rêvé were mostly located in the medial temporal lobes. "Dreamy states" were induced by less specific EBS areas although still related to the temporal lobes.

CONCLUSIONS

This study demonstrates that déjà-rêvé is a heterogeneous entity that is different from déjà-vu, the historical "dreamy state" definition and other experiential phenomena. This may be relevant for clinical practice as it points to temporal lobe dysfunction and could be valuable for studying the neural substrates of dreams.

Memory scrutinized through electrical brain stimulation: A review of 80 years of experiential phenomena

Electrical brain stimulations (EBS) sometimes induce reminiscences, but it is largely unknown what type of memories they can trigger. We reviewed 80 years of literature on reminiscences induced by EBS and added our own database. We classified them according to modern conceptions of memory. We observed a surprisingly large variety of reminiscences covering all aspects of declarative memory. However, most were poorly detailed and only a few were episodic. This result does not support theories of a highly stable and detailed memory, as initially postulated, and still widely believed as true by the general public. Moreover, memory networks could only be activated by some of their nodes: 94.1% of EBS were temporal, although the parietal and frontal lobes, also involved in memory networks, were stimulated. The qualitative nature of memories largely depended on the site of stimulation: EBS to rhinal cortex mostly induced personal semantic reminiscences, while only hippocampal EBS induced episodic memories. This result supports the view that EBS can activate memory in predictable ways in humans.

Efficacy of naloxone in reducing postictal central respiratory dysfunction in patients with epilepsy: study protocol for a double-blind, randomized, placebo-controlled trial

Background

Generalized tonic-clonic seizures (GTCSs) are the main risk factor for sudden unexpected death in epilepsy (SUDEP). Experimental and clinical data strongly suggest that the majority of SUDEP results from a postictal respiratory dysfunction progressing to terminal apnea. Postictal apnea could partly derive from a seizure-induced massive release of endogenous opioids. The main objective of this study is to evaluate the efficacy of an opioid antagonist, naloxone, administered in the immediate aftermath of a GTCS, in reducing the severity of the postictal central respiratory dysfunction.

Methods/design

The Efficacy of Naloxone in Reducing Postictal Central Respiratory Dysfunction in Patients with Epilepsy (ENALEPSY) study is a multicenter, double-blind, randomized, placebo-controlled trial conducted in patients with drug-resistant focal epilepsy who are undergoing long-term video-electroencephalogram (EEG) monitoring (LTM) in an epilepsy monitoring unit (EMU). We plan to randomize 166 patients (1:1) to receive intravenous naloxone (0.4 mg) or placebo in the immediate aftermath of a GTCS. Because inclusion in the study needs to take place prior to the occurrence of the GTCS, and because such occurrence is observed in about one-fourth of patients undergoing LTM, we plan to include a maximum of 700 patients upon admission in the EMU. The primary endpoint will be the proportion of patients whose oxygen saturation is <90 % between 1 and 3 min after the end of a GTCS. Secondary outcomes will include the following: the proportion of patients who show postictal apnea, the occurrence and duration of postictal generalized EEG suppression, the total duration of the postictal coma, postictal pain, and the number of patients who have a second GTCS within 120 min after the intravenous injection.

Discussion

The demonstration of naloxone’s efficacy on the severity of postictal hypoxemia will have two primary consequences. First, naloxone would be the first and only therapeutic approach that could be delivered immediately to reverse postictal apnea. Second, demonstration that an opioid antagonist can effectively reduce postictal apnea would pave the way for an assessment of a preventive therapy for SUDEP targeting the same pathophysiological pathway using oral administration of naltrexone.

Trial registration

ClinicalTrials.gov identifier: NCT02332447. Registered on 5 January 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1653-1) contains supplementary material, which is available to authorized users.

Risk factors of postictal generalized EEG suppression in generalized convulsive seizures

OBJECTIVE

To identify the clinical determinants of occurrence of postictal generalized EEG suppression (PGES) after generalized convulsive seizures (GCS).

METHODS

We reviewed the video-EEG recordings of 417 patients included in the REPO2MSE study, a multicenter prospective cohort study of patients with drug-resistant focal epilepsy. According to ictal semiology, we classified GCS into 3 types: tonic-clonic GCS with bilateral and symmetric tonic arm extension (type 1), clonic GCS without tonic arm extension or flexion (type 2), and GCS with unilateral or asymmetric tonic arm extension or flexion (type 3). Association between PGES and person-specific or seizure-specific variables was analyzed after correction for individual effects and the varying number of seizures.

RESULTS

A total of 99 GCS in 69 patients were included. Occurrence of PGES was independently associated with GCS type (p < 0.001) and lack of early administration of oxygen (p < 0.001). Odds ratio (OR) for GCS type 1 in comparison with GCS type 2 was 66.0 (95% confidence interval [CI 5.4-801.6]). In GCS type 1, risk of PGES was significantly increased when the seizure occurred during sleep (OR 5.0, 95% CI 1.2-20.9) and when oxygen was not administered early (OR 13.4, 95% CI 3.2-55.9).

CONCLUSION

The risk of PGES dramatically varied as a function of GCS semiologic characteristics. Whatever the type of GCS, occurrence of PGES was prevented by early administration of oxygen.

Preserved anterograde and remote memory in drug-responsive temporal lobe epileptic patients

PURPOSE

To investigate cognition, particularly anterograde and remote memory, in patients suffering from unilateral drug-responsive mesial temporal lobe epilepsy (mTLE) patients and to compare their performance with that observed in drug-resistant mTLE patients.

METHODS

Sixteen drug-responsive mTLE patients, with only infrequent seizures in their lifetime, were matched for demographic and clinical variables to 18 patients suffering from drug-resistant unilateral mTLE. A comprehensive neuropsychological examination, including baseline, anterograde memory tasks, and a large range of remote memory tests was carried out.

RESULTS

Patients with drug-responsive epilepsy obtained average scores on every anterograde memory test. Although in general, they obtained lower scores than the healthy controls on remote memory tests, the differences failed to reach significance. Moreover, the drug-responsive group performed significantly better than the drug-resistant group on anterograde recall tests and an episodic autobiographical memory test. Performance was not significantly different between the patient groups in personal semantics or memory for public events.

CONCLUSION

Our results show that a mild clinical course of mTLE with no cognitive deficits can occur notwithstanding hippocampal sclerosis. The differences in cognitive function between the two groups are likely due to distinct pathophysiology of the underlying cause of epilepsy. Drug-resistant seizures and cognitive deficits may be the consequence of a more severe underlying cerebral process. Better understanding of the variety of pathogenesis of mTLE could help to answer this open question.

Generalized convulsive status epilepticus management in adults: a cohort study with evaluation of professional practice

PURPOSE

Generalized convulsive status epilepticus (GCSE) needs immediate management. Despite guidelines, adherence to management protocols is often poor, this contributing to poor outcome. We aimed to evaluate the usefulness of a management protocol in GCSE.

METHODS

This is a prospective population-based study of consecutive adults with GCSE in Haute-Garonne district, France. Demographics and treatment procedures were documented. Factors associated with seizure termination and refractoriness were analyzed using logistic regression.

RESULTS

One hundred eighteen episodes in 111 adults (mean age 55 years) between October 2006 and February 2008 were included. SE was convulsive in 101 episodes. Incidence was 6.6 per 100,000 and case fatality was 9%. Adequate initial treatment according to protocol was observed in 38%; 64% were treated out-of-hospital, and SE was refractory in 27% [no response after two antiepileptic drugs (AED)]. Patients who received adequate first-line treatment were 6.8 times [95% confidence interval (CI) 2.8-16.9] more likely to have seizure termination, with 74% versus 29% efficacy rate (p < 0.0001). Inadequate initial management was 4.7 times (1.9-11.1) more likely to need several benzodiazepine doses (p = 0.0004) and 9.1 times (3.7-20) more likely to require a long-acting AED as next treatment (p < 0.0001). Seizure termination after initial treatment was associated with decreased intensive care unit stay [1 (1-2) versus 2 (1-5.5) days, p < 0.0001] and hospital stay [3 (2-11) versus 7 (3-18) days, p = 0.009].

DISCUSSION

GCSE termination and outcome seem clearly associated with adherence to treatment protocol. Results add to the debate on appropriate allocation of resources for out-of-hospital treatment, licensed drugs, and achievement of guideline implementation to improve SE outcome.