Seizure Termination Research Articles

Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?

The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and cortical regions. Then, we derived synchronization indices, namely global, thalamic, mesio-temporal, and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic “outputs and inputs” connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic synchronization index was significantly more elevated at the end of seizure than at the onset. The global synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-cortical spike-and-wave pattern at the end. They were associated to higher values of all synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of cortical and thalamo-cortical synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-cortical oscillations might contribute to seizure termination via modulation of cortical synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hypersynchronization that ultimately leads to seizure termination.

Termination patterns of complex partial seizures: An intracranial EEG study

PurposeWhile seizure onset patterns have been the subject of many reports, there have been few studies of seizure termination. In this study we report the incidence of synchronous and asynchronous termination patterns of partial seizures recorded with intracranial arrays. MethodsData were collected from patients with intractable complex partial seizures undergoing presurgical evaluations with intracranial electrodes. Patients with seizures originating from mesial temporal and neocortical regions were grouped into three groups based on patterns of seizure termination: synchronous only (So), asynchronous only (Ao), or mixed (S/A, with both synchronous and asynchronous termination patterns). Results88% of the patients in the MT group had seizures with a synchronous pattern of termination exclusively (38%) or mixed (50%). 82% of the NC group had seizures with synchronous pattern of termination exclusively (52%) or mixed (30%). In the NC group, there was a significant difference of the range of seizure durations between So and Ao groups, with Ao exhibiting higher variability. Seizures with synchronous termination had low variability in both groups. ConclusionsSynchronous seizure termination is a common pattern for complex partials seizures of both mesial temporal or neocortical onset. This may reflect stereotyped network behavior or dynamics at the seizure focus.

Single unit action potentials in humans and the effect of seizure activity.

Spike-sorting algorithms have been used to identify the firing patterns of isolated neurons ('single units') from implanted electrode recordings in patients undergoing assessment for epilepsy surgery, but we do not know their potential for providing helpful clinical information. It is important therefore to characterize both the stability of these recordings and also their context. A critical consideration is where the units are located with respect to the focus of the pathology. Recent analyses of neuronal spiking activity, recorded over extended spatial areas using microelectrode arrays, have demonstrated the importance of considering seizure activity in terms of two distinct spatial territories: the ictal core and penumbral territories. The pathological information in these two areas, however, is likely to be very different. We investigated, therefore, whether units could be followed reliably over prolonged periods of times in these two areas, including during seizure epochs. We isolated unit recordings from several hundred neurons from four patients undergoing video-telemetry monitoring for surgical evaluation of focal neocortical epilepsies. Unit stability could last in excess of 40 h, and across multiple seizures. A key finding was that in the penumbra, spike stereotypy was maintained even during the seizure. There was a net tendency towards increased penumbral firing during the seizure, although only a minority of units (10-20%) showed significant changes over the baseline period, and notably, these also included neurons showing significant reductions in firing. In contrast, within the ictal core territories, regions characterized by intense hypersynchronous multi-unit firing, our spike sorting algorithms failed as the units were incorporated into the seizure activity. No spike sorting was possible from that moment until the end of the seizure, but recovery of the spike shape was rapid following seizure termination: some units reappeared within tens of seconds of the end of the seizure, and over 80% reappeared within 3 min (τrecov = 104 ± 22 s). The recovery of the mean firing rate was close to pre-ictal levels also within this time frame, suggesting that the more protracted post-ictal state cannot be explained by persistent cellular neurophysiological dysfunction in either the penumbral or the core territories. These studies lay the foundation for future investigations of how these recordings may inform clinical practice.See Kimchi and Cash (doi:10.1093/awv264) for a scientific commentary on this article.

An EEG-fMRI Study on the Termination of Generalized Spike-And-Wave Discharges in Absence Epilepsy.

IntroductionDifferent studies have investigated by means of EEG-fMRI coregistration the brain networks related to generalized spike-and-wave discharges (GSWD) in patients with idiopathic generalized epilepsy (IGE). These studies revealed a widespread GSWD-related neural network that involves the thalamus and regions of the default mode network. In this study we investigated which brain regions are critically involved in the termination of absence seizures (AS) in a group of IGE patients.MethodsEighteen patients (6 male; mean age 25 years) with AS were included in the EEG-fMRI study. Functional data were acquired at 3T with continuous simultaneous video-EEG recording. Event-related analysis was performed with SPM8 software, using the following regressors: (1) GSWD onset and duration; (2) GSWD offset. Data were analyzed at single-subject and at group level with a second level random effect analysis.ResultsA mean of 17 events for patient was recorded (mean duration of 4.2 sec). Group-level analysis related to GSWD onset respect to rest confirmed previous findings revealing thalamic activation and a precuneus/posterior cingulate deactivation. At GSWD termination we observed a decrease in BOLD signal over the bilateral dorsolateral frontal cortex respect to the baseline (and respect to GSWD onset). The contrast GSWD offset versus onset showed a BOLD signal increase over the precuneus-posterior cingulate region bilaterally. Parametric correlations between electro-clinical variables and BOLD signal at GSWD offset did not reveal significant effects.ConclusionThe role of the decreased neural activity of lateral prefrontal cortex at GSWD termination deserve future investigations to ascertain if it has a role in promoting the discharge offset, as well as in the determination of the cognitive deficits often present in patients with AS. The increased BOLD signal at precuneal/posterior cingulate cortex might reflect the recovery of neural activity in regions that are “suspended” during spike and waves activity, as previously hypothesized.

Initiation, Propagation, and Termination of Partial (Focal) Seizures

The neurophysiological patterns that correlate with partial (focal) seizures are well defined in humans by standard electroencephalogram (EEG) and presurgical depth electrode recordings. Seizure patterns with similar features are reproduced in animal models of partial seizures and epilepsy. However, the network determinants that support interictal spikes, as well as the initiation, progression, and termination of seizures, are still elusive. Recent findings show that inhibitory networks are prominently involved at the onset of these seizures, and that extracellular changes in potassium contribute to initiate and sustain seizure progression. The end of a partial seizure correlates with an increase in network synchronization, which possibly involves both excitatory and inhibitory mechanisms.

Observational study of intravenous lacosamide in patients with convulsive versus non-convulsive status epilepticus.

Status epilepticus (SE) is an important emergency situation associated with high morbidity and mortality. The goal of pharmacological therapy-rapid seizure termination-is only achieved in just over half of patients with first-line anti-epileptic drug (AED) therapy and many patients require second and higher lines of AEDs to achieve seizure termination; therefore, there is a clear need for more effective treatment options. Lacosamide is a relatively new AED and the intravenous formulation has shown promise for treatment of SE. The aim of the current study was to compare electroencephalographic (EEG) response and seizure termination with intravenous lacosamide (±other AEDs) in patients with convulsive versus non-convulsive SE, in a Spanish intensive care setting. In this prospective, observational study, patients with convulsive or non-convulsive SE who received intravenous lacosamide 400 mg/day for 8 days were compared in terms of EEG response and seizure termination. Adverse events were not specifically assessed. Fifty-three patients (69.8 % male; mean age 55.2 years) were treated with lacosamide (mean dose 390.6 mg) as first- (20.8 %), second- (34 %), third (22.6 %) or fourth-line (22.6 %) treatment for convulsive (n = 23, 43.4 %) or non-convulsive (n = 30, 56.6 %) SE. The majority of patients (73.6 %) had a comorbid condition, predominantly hypertension (35.8 %), and most (79.2 %) received at least one concomitant AED, including midazolam (54.7 %), valproic acid (52.8 %), and levetiracetam (30.2 %). Patient characteristics and treatment received did not differ significantly between the convulsive and non-convulsive SE groups. EEG recordings following lacosamide treatment demonstrated the elimination of paroxysmal activity (disappearance and/or attenuation of epileptiform activity in >60 % of recording time) in 56.6 % of patients; 69.6 % of convulsive and 46.7 % of non-convulsive SE groups. Among all patients, 90.6 % showed some EEG improvement (disappearance of epileptiform activity in <30 % total recording time or disappearance and/or attenuation of epileptiform activity in 30-60 % total recording time); and there was no significant between-group difference for achievement of seizure termination (90.0 vs. 91.3 % for non-convulsive vs. convulsive SE). Intravenous lacosamide (±other AEDs) was similarly effective in patients with convulsive or non-convulsive SE. Further investigation into the use of lacosamide in the treatment of SE is warranted.

Genetic mutations associated with status epilepticus.

This paper reports the results of a preliminary search of the literature aimed at identifying the genetic mutations reported to be strongly associated with status epilepticus. Genetic mutations were selected for inclusion if status epilepticus was specifically mentioned as a consequence of the mutation in standard genetic databases or in a case report or review article. Mutations in 122 genes were identified. The genetic mutations identified were found in only rare conditions (sometimes vanishingly rare) and mostly in infants and young children with multiple other handicaps. Most of the genetic mutations can be subdivided into those associated with cortical dysplasias, inborn errors of metabolism, mitochondrial disease, or epileptic encephalopathies and childhood syndromes. There are no identified 'pure status epilepticus genes'. The range of genes underpinning status epilepticus differs in many ways from the range of genes underpinning epilepsy, which suggests that the processes underpinning status epilepticus differ from those underpinning epilepsy. It has been frequently postulated that status epilepticus is the result of a failure of 'seizure termination mechanisms', but the wide variety of genes affecting very diverse biochemical pathways identified in this survey makes any unitary cause unlikely. The genetic influences in status epilepticus are likely to involve a wide range of mechanisms, some related to development, some to cerebral energy production, some to diverse altered biochemical pathways, some to transmitter and membrane function, and some to defects in networks or systems. The fact that many of the identified genes are involved with cerebral development suggests that status epilepticus might often be a system or network phenomenon. To date, there are very few genes identified which are associated with adult-onset status epilepticus (except in those with preexisting neurological damage), and this is disappointing as the cause of many adult-onset status epilepticus cases remains obscure. It has been suggested that idiopathic adult-onset status epilepticus might often have an immunological cause but no gene mutations which relate to immunological mechanisms were identified. Overall, the clinical utility of what is currently known about the genetics of status epilepticus is slight and the findings have had little impact on clinical treatment despite what has been a very large investment in money and time. New genetic technologies may result in the identification of further genes, but if the identified genetic defects confer only minor susceptibility, this is unlikely to influence therapy. It is also important to recognize that genetics has social implications in a way that other areas of science do not. This article is part of a Special Issue entitled "Status Epilepticus".

Genetic mapping of ASIC4 and contrasting phenotype to ASIC1a in modulating innate fear and anxiety.

Although ASIC4 is a member of the acid-sensing ion channel (ASIC) family, we have limited knowledge of its expression and physiological function in vivo. To trace the expression of this ion channel, we generated the ASIC4-knockout/CreERT(2)-knockin (Asic4(Cre) (ERT) (2)) mouse line. After tamoxifen induction in the Asic4(Cre) (ERT)(2)::CAG-STOP(floxed)-Td-tomato double transgenic mice, we mapped the expression of ASIC4 at the cellular level in the central nervous system (CNS). ASIC4 was expressed in many brain regions, including the olfactory bulb, cerebral cortex, striatum, hippocampus, amygdala, thalamus, hypothalamus, brain stem, cerebellum, spinal cord and pituitary gland. Colocalisation studies further revealed that ASIC4 was expressed mainly in three types of cells in the CNS: (i) calretinin (CR)-positive and/or vasoactive intestine peptide (VIP)-positive interneurons; (ii) neural/glial antigen 2 (NG2)-positive glia, also known as oligodendrocyte precursor cells; and (iii) cerebellar granule cells. To probe the possible role of ASIC4, we hypothesised that ASIC4 could modulate the membrane expression of ASIC1a and thus ASIC1a signaling in vivo. We conducted behavioral phenotyping of Asic4(Cre) (ERT)(2) mice by screening many of the known behavioral phenotypes found in Asic1a knockouts and found ASIC4 not involved in shock-evoked fear learning and memory, seizure termination or psychostimulant-induced locomotion/rewarding effects. In contrast, ASIC4 might play an important role in modulating the innate fear response to predator odor and anxious state because ASIC4-mutant mice showed increased freezing response to 2,4,5-trimethylthiazoline and elevated anxiety-like behavior in both the open-field and elevated-plus maze. ASIC4 may modulate fear and anxiety by counteracting ASIC1a activity in the brain.

P9 – 2231: The efficacy of Levetiracetam for the treatment of neonatal seizures

Objective Neonatal seizures are often refractory to treatment with the standard antiseizure medications. Current therapeutic options for treatment of neonatal seizures, such as phenobarbital and phenytoin lack efficacy, and potentially harmful to the developing brain. Thus, we tried any alternatives to achieve controls in neonatal seizures that were refractory to standard antiseizure agents. Despite the lack of published data regarding the safety, tolerability and efficacy of Levetiracetam (LVT) in the neonatal age group. Methods We report a retrospectively identified cohort of 17 neonates who received Levetiracetam. They were thoroughly investigated including EEGs and neuroimaging. Levetiracetam was considered effectives if administration associated with more than 50 reduction in seizures within 48 hours. Levetiracetam was initiated to full term babies only. The mean initial dose was 20 mg/kg and the mean maintenance dose was 40 mg/kg in two divided doses. Results No respiratory or cardiac side effects were detected. Levetiracetam was associated with a greater than 50% seizure reduction in 8 out of the 17 neonates (47%) including seizure termination in 5 (29%). Conclusion Further multicenter larger studies is recommended to determine the safety and the optimal dosing of Levetiracetam in neonates and to compare it is efficacy to other antiseizure medications in order to assess whether this medication deserve widespread use in clinical practice.

Complete seizure freedom is possible in patients with MTLE-HS after surgery in spite of extratemporal electro-clinical features

The aim was to identify the common typical and atypical ictal semiologic and EEG features of patients with mesial temporal lobe epilepsy and hippocampal sclerosis who became seizure-free postoperatively. The semiologic and EEG findings of 126 ictal video-EEG recordings of 50 patients who remained seizure-free for at least 2 years (mean=9.46±3.20; range=3-14.5 years) after surgery were reviewed. Statistical analysis was used to determine the frequencies of the most common auras, semiologic features and EEG patterns and to define the symptom clusters. Aura was reported in 82% (n:41) of patients and the most common type was epigastric sensation. Early symptoms were contralateral upper extremity dystonic posturing (66%), oro-alimentary automatisms (50%) and ipsilateral hand automatisms (40%). Ictal EEG findings revealed localized and lateralized activity in 62% of patients. Of the 17 most common early symptoms, there was a tendency toward two clusters. Cluster 2 consisted of findings that were typical for patients with mesial temporal lobe epilepsy whereas Cluster 1 mostly consisted of atypical findings. This study demonstrated two clusters of the semiologic repertoire, and the most frequent EEG finding was lateralized and localized ictal activity, while other types of EEG patterns were also recorded. Although the presence of atypical findings may suggest a more extended or even extratemporal zone, the seizure-free outcome demonstrated that if the critical amount of tissue can be resected within the epileptogenic network, this may be sufficient for termination of seizures.

Intravenous levetiracetam in Thai children and adolescents with status epilepticus and acute repetitive seizures.

Intravenous levetiracetam is an option for treatment of status epilepticus (SE) and acute repetitive seizures (ARS). However, there have been relatively few studies with children and adolescents. Also, an appropriate dosage has yet to be determined. This study investigated the safety and the efficacy of levetiracetam for intravenous treatment of convulsive status epilepticus and acute repetitive seizures in children and adolescents. Retrospectively, the study reviewed the medical records of 19 male and 31 female patients under 18 years of age who had received intravenous levetiracetam treatment either for acute repetitive seizures or for convulsive status epilepticus. The patients were admitted between April 1st, 2010 and December 31st, 2011 to the Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. Data were collected on underlying illnesses, etiology of seizures, indication for levetiracetam therapy, initial dosage, rate of infusion, untoward effects during infusion and emerged complications. Efficacy of treatment was defined as the termination of seizure within 30 min of completing levetiracetam infusion and no seizure recurrence within 6 h of initial treatment. The age range of the 50 patients was from one day to 18 years (mean 79.6 months). The analysis included 52 episodes of 34 acute repetitive seizures (63.4%) and 18 convulsive status epilepticus (34.6%). Infusion rates ranged from 2 to 66 mg/kg/min (mean 29.6). Cessation of seizure was obtained in 59.6% of 52 episodes. Patients with underlying drug resistant epilepsy did not respond to levetiracetam therapy as well as patients with other etiology of seizures. There were no adverse drug reactions or untoward effects observed during the therapy. Intravenous administration of levetiracetam is safe and effective for treatment of acute repetitive seizures and convulsive status epilepticus in children and adolescents. Failure of treatment may be related to underlying drug resistant epilepsy. Further study of appropriate initial dosage and pharmacokinetic variations in the patients is needed as possible explanation of the unresponsiveness.

A biologically constrained, mathematical model of cortical wave propagation preceding seizure termination.

Epilepsy—the condition of recurrent, unprovoked seizures—manifests in brain voltage activity with characteristic spatiotemporal patterns. These patterns include stereotyped semi-rhythmic activity produced by aggregate neuronal populations, and organized spatiotemporal phenomena, including waves. To assess these spatiotemporal patterns, we develop a mathematical model consistent with the observed neuronal population activity and determine analytically the parameter configurations that support traveling wave solutions. We then utilize high-density local field potential data recorded in vivo from human cortex preceding seizure termination from three patients to constrain the model parameters, and propose basic mechanisms that contribute to the observed traveling waves. We conclude that a relatively simple and abstract mathematical model consisting of localized interactions between excitatory cells with slow adaptation captures the quantitative features of wave propagation observed in the human local field potential preceding seizure termination.

Comparison of intranasal and intravenous diazepam on status epilepticus in stroke patients: a retrospective cohort study.

Administering diazepam intravenously or rectally in an adult with status epilepticus can be difficult and time consuming. The aim of this study was to examine whether intranasal diazepam is an effective alternative to intravenous diazepam when treating status epilepticus.We undertook a retrospective cohort study based on the medical records of 19 stroke patients presenting with status epilepticus to our institution. We measured the time between arrival at the hospital, the intravenous or intranasal administration of diazepam, and the seizure termination.Intranasal diazepam was administered about 9 times faster than intravenous diazepam (1 vs 9.5 minutes, P = 0.001), resulting in about 3-fold reduction in the time to termination of seizure activity after arrival at the hospital (3 minutes compared with 9.5 minutes in the intravenous group, P = 0.030). No adverse effects of intranasal diazepam were evident from the medical records.Intranasal diazepam administration is safer, easier, and quicker than intravenous administration.

Chronic Recording Electrocorticography Guided Resective Epilepsy Surgery: Overview and Future Directions

Sensing, modeling, and neuromodulation technologies are profoundly advancing the practice of epilepsy surgery. Chronically implanted neural monitoring technologies developed for seizure termination and seizure prediction have each been found to be useful in unintended applications, specifically for the planning of resective surgery. We review and summarize the use of chronic monitoring in an unanticipated context in which it was found to be invaluable in the planning of surgery; this was observed in a pivotal study of a seizure detection and termination system. Monitoring of patients chronically in their normal ambulatory setting, as facilitated by this technology, allows unperturbed assessment of patients while on outpatient medication regimens and without the time and space constraints imposed by cost and infection risk inherent in subacute inpatient invasive monitoring. Five patients in the NeuroPace US pivotal trial underwent resective surgery which was subsequent to and enabled by chronic recordings from the implanted monitoring system. These resective surgeries were independent from the primary intended function of the implanted neural monitoring device. Chronic monitoring facilitated greater anatomical localization of the sources and allowed for a deeper understanding of the dynamic network behavior of interconnected seizure foci, thereby facilitating a substantially more sophisticated approach to resective surgery. In the NeuroPace trial, monitoring and analysis of chronic unlimited recording electrocorticography (CURE) from chronically implanted subdural and depth electrodes facilitated planning of resective surgery that resulted in near or complete seizure freedom in 4 patients. This series suggests that chronic recording of electrocorticographic signals is a therapeutic modality meritorious of further investigation. Note: This was analysis and study was performed on patients previously enrolled in the NeuroPace® RNS® Ststem Pivotal trial: http://clinicaltrials.gov/show/NCT00572195

Electrogenic properties of the Na⁺/K⁺ ATPase control transitions between normal and pathological brain states.

Ionic concentrations fluctuate significantly during epileptic seizures. In this study, using a combination of in vitro electrophysiology, computer modeling, and dynamical systems analysis, we demonstrate that changes in the potassium and sodium intra- and extracellular ion concentrations ([K(+)] and [Na(+)], respectively) during seizure affect the neuron dynamics by modulating the outward Na(+)/K(+) pump current. First, we show that an increase of the outward Na(+)/K(+) pump current mediates termination of seizures when there is a progressive increase in the intracellular [Na(+)]. Second, we show that the Na(+)/K(+) pump current is crucial in maintaining the stability of the physiological network state; a reduction of this current leads to the onset of seizures via a positive-feedback loop. We then present a novel dynamical mechanism for bursting in neurons with a reduced Na(+)/K(+) pump. Overall, our study demonstrates the profound role of the current mediated by Na(+)/K(+) ATPase on the stability of neuronal dynamics that was previously unknown.

Clinical investigation of vagus nerve stimulation for treatment of drug-resistant epilepsy and the experience of neuromodulation

Objective To explore the curative effect and parameter settings of vagus nerve stimulation (VNS) therapy in refractory epilepsy. Methods VNS was performed in 71 patients with drug-resistant epilepsy, and McHugh classification was used to evaluate the curative effect of VNS. Programmable pulse parameters included output current, frequency, pulse width, and On/Off times. The optimum settings for each patient should balance the goals of maximizing efficacy, minimizing side effects, and preserving battery life. Results After operation, all patients were followed up for 3-56 months (median 22 months), and experienced a significantly reduced seizure frequency compared with before operation [18 (3, 92) vs 30 (5, 145) times/month; Z = 826.500, P = 0.000]. In these patients, 20 cases (28.17% ) had < 50% reduction of seizure frequency, and 51 cases (71.83% ) had ≥ 50% reduction of seizure frequency, including 27 cases (38.03%) with ≥ 80% reduction and 14 cases (19.72%) with seizure free. Seizure termination or seizure diminution was reported in 8 patients (11.27% ) after using magnet. Conclusions VNS is a safe and effective therapy in medically refractory epilepsy. Optimized output current is generally 1.00-1.75 mA, however, 0.75 mA is also an efficient current. Besides, parameter settings should be considered to reach the maximizing efficacy. DOI: 10.3969/j.issn.1672-6731.2015.09.008

A portion of inhibitory neurons in human temporal lobe epilepsy are functionally upregulated: an endogenous mechanism for seizure termination.

Epilepsy is one of the more common neurological disorders. The medication is often ineffective to the patients suffering from intractable temporal lobe epilepsy (TLE). As their seizures are usually self-terminated, the elucidation of the mechanism underlying endogenous seizure termination will help to find a new strategy for epilepsy treatment. We aim to examine the role of inhibitory interneurons in endogenous seizure termination in TLE patients. Whole-cell recordings were conducted on inhibitory interneurons in seizure-onset cortices of intractable TLE patients and the temporal lobe cortices of nonseizure individuals. The intrinsic property of the inhibitory interneurons and the strength of their GABAergic synaptic outputs were measured. The quantitative data were introduced into the computer-simulated neuronal networks to figure out a role of these inhibitory units in the seizure termination. In addition to functional downregulation, a portion of inhibitory interneurons in seizure-onset cortices were upregulated in encoding the spikes and controlling their postsynaptic neurons. A patch-like upregulation of inhibitory neurons in the local network facilitated seizure termination. The upregulations of both inhibitory neurons and their output synapses synergistically shortened seizure duration, attenuated seizure strength, and terminated seizure propagation. Automatic seizure termination is likely due to the fact that a portion of the inhibitory neurons and synapses are upregulated in the seizure-onset cortices. This mechanism may create novel therapeutic strategies to treat intractable epilepsy, such as the simultaneous upregulation of cortical inhibitory neurons and their output synapses.

Some considerations of the tolerability of ketamine for ECT anesthesia: a case series and review of the literature.

Most anesthetic agents used for electroconvulsive therapy (ECT) have few intrinsic adverse effects. Ketamine, however, is well known to be associated with a variety of adverse effects including nausea, dizziness, and psychotomimetic phenomena. Over the past several decades, there have been numerous reports on the use of ketamine for ECT anesthesia, with varied assessments on how prominent these adverse effects are in the ECT situation. Ketamine has received a resurgence of interest as an ECT anesthetic of late owing to its established independent antidepressant effects and to theoretical reasons why it might lessen the cognitive adverse effects of ECT. In this case series, the author reviews the experience with 14 patients who had undergone ECT who were switched to ketamine as anesthetic from methohexital at the preference of the treating anesthesiologist. All 14 patients spontaneously reported a strong preference not to be given ketamine again due to bothersome adverse effects. The latter consisted of either vestibular-type symptoms (nausea/vomiting, dizziness, and vertigo) or psychotomimetic effects (dissociative phenomena). It is concluded that ketamine is not free of adverse effects when used as an ECT anesthetic. Electroconvulsive therapy clinicians should be vigilant about assessing for these effects when ketamine is used, and consideration should be given to using a benzodiazepine such as diazepam or midazolam at seizure termination when ketamine anesthesia is used to prevent bothersome adverse effects seen upon awakening.

Pediatric status epilepticus management

This review discusses the management of status epilepticus in children, including both anticonvulsant medications and overall management approaches. Rapid management of status epilepticus is associated with a greater likelihood of seizure termination and better outcomes, yet data indicate that there are often management delays. This review discusses an overall management approach aiming to simultaneously identify and manage underlying precipitant causes, administer anticonvulsants in rapid succession until seizures have terminated, and identify and manage systemic complications. An example management pathway is provided. Status epilepticus is a common neurologic emergency in children and requires rapid intervention. Having a predetermined status epilepticus management pathway can expedite management.

Estimation of effective connectivity via data-driven neural modeling

This research introduces a new method for functional brain imaging via a process of model inversion. By estimating parameters of a computational model, we are able to track effective connectivity and mean membrane potential dynamics that cannot be directly measured using electrophysiological measurements alone. The ability to track the hidden aspects of neurophysiology will have a profound impact on the way we understand and treat epilepsy. For example, under the assumption the model captures the key features of the cortical circuits of interest, the framework will provide insights into seizure initiation and termination on a patient-specific basis. It will enable investigation into the effect a particular drug has on specific neural populations and connectivity structures using minimally invasive measurements. The method is based on approximating brain networks using an interconnected neural population model. The neural population model is based on a neural mass model that describes the functional activity of the brain, capturing the mesoscopic biophysics and anatomical structure. The model is made subject-specific by estimating the strength of intra-cortical connections within a region and inter-cortical connections between regions using a novel Kalman filtering method. We demonstrate through simulation how the framework can be used to track the mechanisms involved in seizure initiation and termination.