Presentation, evaluation, and treatment of nonconvulsive status epilepticus

EEG criteria for diagnosing nonconvulsive status epilepticus in comatose - An unsolved puzzle: A narrative review

Introduction

Nonconvulsive status epilepticus (NCSE) is an important and often unrecognized cause of impaired awareness especially in critically ill patients, which can easily be missed. Electroencephalography (EEG) findings in clinically suspected cases are the mainstay of diagnosis.

Review summary

The EEG diagnostic criteria for NCSE have evolved over the past three decades. Furthermore, recent advancements in EEG technologies such as continuous EEG monitoring, and emergency department EEG, along with development of different diagnostic criteria, have increased the detection rate for NCSE in suspected cases. However, treating physicians should have a higher index of clinical suspicion and a lower threshold for recommending this valuable investigation. The introduction of different diagnostic criteria has made it easier for electroencephalographers to report NCSE; nevertheless, diagnosis is not always straightforward. This narrative review aimed to define and discuss the available literature on different EEG diagnostic criteria for NCSE.

Conclusion

There is a need for further prospective research to strengthen the diagnostic accuracy of the available diagnostic criteria, the modified Salzburg Consensus Criteria for NCSE (mSCNC) and updated American Clinical Neurophysiology Society (ACNS) 21 criteria, to verify their accuracy to detect NCSE in comatose patients.

Nonconvulsive Status Epilepticus: A Review for Emergency Clinicians

BACKGROUND

Status epilepticus is associated with significant morbidity and mortality and is divided into convulsive status epilepticus and nonconvulsive status epilepticus (NCSE).

OBJECTIVE

This review provides a focused evaluation of NCSE for emergency clinicians.

DISCUSSION

NCSE is a form of status epilepticus presenting with prolonged seizure activity. This disease is underdiagnosed, as it presents with nonspecific signs and symptoms, most commonly change in mental status without overt convulsive motor activity. Causes include epilepsy, cerebral pathology or injury, any systemic insult such as infection, and drugs or toxins. Mortality is primarily related to the underlying condition. Patients most commonly present with altered mental status, but other signs and symptoms include abnormal ocular movements and automatisms such as lip smacking or subtle motor twitches in the face or extremities. The diagnosis is divided into electrographic and electroclinical, and although electroencephalogram (EEG) is recommended for definitive diagnosis, emergency clinicians should consider this disease in patients with prolonged postictal state after a seizure with no improvement in mental status, altered mental status with acute cerebral pathology (e.g., stroke, hypoxic brain injury), and unexplained altered mental status. Assessment includes laboratory evaluation and neuroimaging with EEG. Management includes treating life-threatening conditions, including compromise of the airway, hypoglycemia, hyponatremia, and hypo- or hyperthermia, followed by rapid cessation of the seizure activity with benzodiazepines and other antiseizure medications.

CONCLUSIONS

An understanding of the presentation and management of NCSE can assist emergency clinicians in the care of these patients.

Nonconvulsive Status Epilepticus With Generalized Spike-and-Wave Discharges: Pathophysiological and Nosological Considerations

Absence status epilepticus (ASE) is the most common type of status epilepticus in patients with idiopathic generalized epilepsy (IGE). Like absence seizure, ASE is characterized by generalized spike-and-wave discharges (GSWDs) on the electroencephalogram (EEG). Once considered specific for IGE, GSWDs have increasingly been observed in other forms of epilepsy, as well as in patients with no prior epilepsy. Here, we report three patients with different types of nonconvulsive status epilepticus (NCSE) in which the EEG correlate was GSWDs: a 44-year-old woman with juvenile absence epilepsy who manifested ASE, a 73-year-old woman with anoxic brain injury complicated by NCSE with well-formed GSWDs (as seen in IGE and de novo ASE), and a 41-year-old woman with frontal lobe epilepsy who developed focal NCSE with impaired consciousness. Evidently, patients with generalized epilepsy, focal epilepsy, and no prior epilepsy can all manifest NCSE with similar electroclinical characteristics, i.e., GSWDs and impaired consciousness. This observation adds to the existing evidence that seizures, whether classified as focal or generalized, often involve focal and generalized elements in their pathophysiology. To fully understand seizure pathophysiology, we must steer away from the focal-versus-generalized paradigm that has dominated the nosology of seizures and epilepsy for a very long time.

Use of Continuous EEG Monitoring and Short-Term Outcomes in Critically Ill Children

This study aimed to compare short-term outcomes at pediatric intensive care unit (PICU) discharge in critically ill children with and without continuous electroencephalography (cEEG) monitoring. We retrospectively compared 234 patients who underwent cEEG with 2294 patients without cEEG. Propensity score matching was used to compare patients with seizures and status epilepticus between cEEG and historical cohorts. The EEG cohort had higher in-hospital mortality, worse Pediatric Cerebral Performance Category (PCPC) scores, and greater PCPC decline at discharge. In patients with status epilepticus, the PCPC decline was higher in the cEEG cohort. PCPC decline at PICU discharge was associated with cEEG monitoring in patients with status epilepticus.

Analysis of electroclinical features of nonconvulsive status epilepticus: a study of four cases

Background

The nonconvulsive status epilepticus (NCSE) is an epileptic condition characterized by little or no obvious symptoms, thus is often easily to be underrecognized, underdiagnosed or even undetected by clinicians. This article is written to advance the recognition and diagnosis of NCSE.

Case presentation

Four cases of NCSE were reported and their semiology, electroencephalogram (EEG) features, etiology, treatment and prognosis were retrospectively analyzed. Most of the 4 cases presented with impaired consciousness (confused, slow reaction and lags in response) and some strange behaviors (being upset and restless or washing hands repeatedly). None of them had any obvious motor symptoms like tonic or clonic movements. EEG of the 4 cases initially manifested with either a focal or a generalized onset, then evolved into spike-and-wave pattern gradually. With a favorable response to antiepileptic drugs, they all had a good outcome without any sequela.

Conclusions

NCSE is much more common than was considered in the past, which is featured by little or no evidence of movement or other symptoms. NCSE can lead to a favorable outcome in most patients.

Hippocampal injury and learning deficits following non-convulsive status epilepticus in periadolescent rats

The effects of non-convulsive status epilepticus (NCSE) on the developing brain remain largely elusive. Here we investigated potential hippocampal injury and learning deficits following one or two episodes of NCSE in periadolescent rats. Non-convulsive status epilepticus was induced with subconvulsive doses of intrahippocampal kainic acid (KA) under continuous EEG monitoring in postnatal day 43 (P43) rats. The RKA group (repeated KA) received intrahippocampal KA at P43 and P44, the SKA group (single KA injection) received KA at P43 and an intrahippocampal saline injection at P44. Controls were sham-treated with saline. The modified two-way active avoidance (MAAV) test was conducted between P45 and P52 to assess learning of context-cued and tone-signaled electrical foot-shock avoidance. Histological analyses were performed at P52 to assess hippocampal neuronal densities, as well as potential reactive astrocytosis and synaptic dysfunction with GFAP (glial fibrillary acidic protein) and synaptophysin (Syp) staining, respectively. Kainic acid injections resulted in electroclinical seizures characterized by behavioral arrest, oromotor automatisms and salivation, without tonic-clonic activity. Compared to controls, both the SKA and RKA groups had lower rates of tone-signaled shock avoidance (p < 0.05). In contextual testing, SKA rats were comparable to controls (p > 0.05), but the RKA group had learning deficits (p < 0.05). Hippocampal neuronal densities were comparable in all groups. Compared to controls, both the SKA and RKA groups had higher hippocampal GFAP levels (p < 0.05). The RKA group also had lower hippocampal Syp levels compared to the SKA and control groups (p < 0.05), which were comparable (p > 0.05). We show that hippocampal NCSE in periadolescent rats results in a seizure burden-dependent hippocampal injury accompanied by cognitive deficits. Our data suggest that the diagnosis and treatment of NCSE should be prompt.

Salzburg Criteria, A Useful Tool in Non-Convulsive Status Epilepticus Diagnosis: A Retrospective Study

Introduction. Non-convulsive status epilepticus (NCSE) has been traditionally a challenging electroencephalographic (EEG) diagnosis. For this reason, Salzburg consensus criteria (SCC) have been proposed to facilitate correct diagnosis. Methods. We retrospectively reanalyzed 41 cases referred to our department (from 2016 to 2018) under the suspicion of NCSE. In this study, we compared the original description (standard criteria) versus the updated description (SCC) of the same EEG. Results. Originally, 15 patients were diagnosed as NCSE (37%) and 26 patients as no NCSE (63%), using the standard criteria. Then, we analyzed EEGs according to the SCC, which led to the following results: 9 patients fulfilled the criteria for definite NCSE (22%), 20 patients were diagnosed as possible NCSE (49%) and 12 patients were diagnosed as no NCSE (29%). Subsequently, when we analyze the outcome of possible NCSE cases, we note that 50% of these patients presented mild-poor outcome (neurological deficits, deceased). Indeed, we observed worse outcomes in patients previously diagnosed as no NCSE and untreated, specifically post-anoxic cases. Conclusions. Salzburg criteria seem to be a useful tool to support NCSE diagnosis, introducing the category of possible NCSE. In our study, we observed that it contributes to improving the prognosis and management of the patients. However, more prospective studies are needed to demonstrate the accuracy of SCC.

Treating Status Epilepticus: Phenytoin Versus Levetiracetam

For decades, phenytoin has been the drug of choice for the treatment of epilepsy but also the second-line treatment for status epilepticus (SE). However, newer antiepileptic drugs (AEDs) have emerged as safer alternatives for the suppression of seizures. Consequently, phenytoin has recently fallen under scrutiny in the research world, prompting many studies to compare its efficacy to these other drugs, most notably levetiracetam. Levetiracetam is a second-generation AED, which is gaining wide clinical use as the second-line agent in treating SE patients. This review focuses on several clinical studies that have directly compared the effectiveness of phenytoin and levetiracetam in suppressing SE seizure activity. Additionally, this review highlights several advantages of using levetiracetam over phenytoin in this clinical context.

An Insight into the Current Understanding of Status Epilepticus: From Concept to Management

Status epilepticus (SE), a subset of epilepsy, represents a debilitating neurological disorder often associated with alarming mortality and morbidity numbers. Even though SE is one of the extensively researched topics with conspicuous data available in the literature, a scientific gap exists in understanding the heterogeneous facets of the disorder like occurrence, definition, classification, causes, molecular mechanisms, etc., thereby providing a defined management program. Cognizance of this heterogeneity and scientific limitation with its subsequent correlation to the recent advancements in medical and scientific domains would serve not only in bridging the gap but also in developing holistic and prompt management programs. Keeping this as an objective, an extensive literature survey was performed during this study, and key findings have been shared. The present study provides a semantic and perspective synopsis toward acknowledging the diversified nature of SE and its variants with respect to their definition, classification, etiology, diagnosis, and management.

[Pharmacotherapy and intensive care aspects of status epilepticus: update 2020/2021]

Die gezielte Therapie epileptischer Ereignisse und im Speziellen des Status epilepticus (SE) setzt das sichere Erkennen der Krankheitsbilder voraus, wofür gerade bei Formen mit vorwiegend nichtmotorischen Symptomen klinische und elektroenzephalographische Expertise notwendig ist. Die im Jahr 2020 erfolgte Fortschreibung der deutschen Leitlinie zur Behandlung des SE hält an der streng stufengerechten Therapie fest, die eskalierend die Anwendung von Benzodiazepinen, spezifischen Antiepileptika und Anästhetika vorsieht. Bisher ist die Eingrenzung eines in den allermeisten Fällen wirksamen sowie zugleich sicheren und interaktionsfreien Antiepileptikums nicht gelungen. Individuelle Vorerkrankungen und aktuelle Begleitumstände gehen daher genauso wie Erfahrungen des Behandlerteams in die differenzierte Behandlung des SE ein. Insbesondere bei therapierefraktären Formen des SE erweist sich die Therapie als durchaus kompliziert und hat regelhaft intensivmedizinische Implikationen. Mithin ergeben sich im Zuge der modernen SE-Behandlung zahlreiche interdisziplinäre Schnittstellen. Zukünftige wissenschaftliche Fragstellungen werden sich u. a. mit der optimalen Therapie des nonkonvulsiven SE und hier v. a. dem Ausmaß und dem Zeitpunkt von adäquaten Therapieschritten sowie mit assoziierten ethischen Fragen einer Therapieeskalation beschäftigen.

Early and late-onset nonconvulsive status epilepticus after stroke

BACKGROUND

Nonconvulsive status epilepticus (NCSE) is a condition that needs timely diagnosis and treatment. It has insignificant clinical features and presents high risk of misdiagnosis.

OBJECTIVE

To investigate NCSE among patients with stroke, given that stroke plays an important role in the etiology of NCSE.

METHODS

In this retrospective study, acute stroke patients who were admitted and followed up at a stroke outpatient clinic between January 2013 and March 2016 were included. Patients with previous histories of epilepsy, brain tumor, head trauma, hypertensive encephalopathy, arteriovenous malformation, subarachnoid hemorrhage or cerebral venous thrombosis were excluded. Demographic properties, stroke etiology, imaging method, EEG findings, stroke severity according to the NIHSS score, functional disability and modified Rankin Scale were recorded for all patients.

RESULTS

Thirty-nine out of 792 stoke patients experienced NCSE. The mean age of the study population was 70±1.2 years (min-max: 46‒90). The study population was composed of 28 females (71.8%) and 11 males (28.2%). NCSE had early onset in 23 patients (59%) and late onset in 16 (41%). The early-onset NCSE patients were older and this was statistically significant between the groups (early onset: 73.5±11.5; late onset: 65.9±12.1; p=0.04). A history of previous stroke was more frequent in the late-onset NCSE group (14; 87,5%) than in the early-onset group (11; 47.8%) (p=0.01). The prognosis was worse in the early-onset group, but without statistical significance.

CONCLUSION

Changes in mental status in the early stages of stroke are mostly attributed to stroke itself, but NCSE should be suspected in the right clinical setting, such as in older patients with suspicious anatomical and clinical associations.

Diagnosis and Treatment of Status Epilepticus

The definition of status epilepticus (SE) was revised recently in accordance with the various evidences of neuronal injury and changes in clinical settings. Currently, the most acceptable duration of continuous seizure activity is 5 minutes. In 2015, the International League Against Epilepsy Task Force, which was convened to develop a definition and classification of SE, presented a new classification based on four axes: 1) semiology, 2) etiology, 3) electroencephalogram (EEG) correlates, and 4) age. The essential element of nonconvulsive SE (NCSE) is the presence of neurological abnormalities induced by a prolonged epileptic process. The definition of refractory SE involves either clinical or electrographic seizures that persist after adequate doses of an initial benzodiazepine and acceptable second-line antiseizure drugs. The use of EEG is critical in the diagnosis and treatment of NCSE. However, there are a wide range of EEG abnormalities in NCSE. Both the Neurocritical Care Society and the American Epilepsy Society have suggested a paradigm for treating convulsive SE (CSE). The first-line treatment of CSE with benzodiazepine is well-established. The second-line treatment comprises intravenous (IV) doses of fosphenytoin (phenytoin), valproate, phenobarbital, levetiracetam, or midazolam. Although fosphenytoin (phenytoin) and valproate are commonly used in NCSE, the effectiveness of antiepileptic drugs (AEDs) on NCSE has not been well studied. New AEDs such as IV levetiracetam and lacosamide can also be used to treat NCSE with fewer side effects and drug-drug interactions. For refractory SE, general anesthesia with IV midazolam, propofol, pentobarbital, or thiopental could be applied. Use of ketamine, megadose phenobarbital therapy, and multiple combinations of various AEDs including high doses of oral AEDs can also be considered. New-onset refractory status epilepticus (NORSE) and its subcategory, febrile infection-related epilepsy syndrome, involve autoimmune processes. AEDs alone are poorly effective in the treatment of SE in autoimmune encephalitis. Immunotherapy such as steroids, immunoglobulin, rituximab, or tocilizumab can be effective.

Prevalence of electrographic seizure in dogs and cats undergoing electroencephalography and clinical characteristics and outcome for dogs and cats with and without electrographic seizure: 104 cases (2009-2015)

OBJECTIVE

To determine the prevalence of electrographic seizure (ES) and electrographic status epilepticus (ESE) in dogs and cats that underwent electroencephalography (EEG) because of suspected seizure activity and to characterize the clinical characteristics, risk factors, and in-hospital mortality rates for dogs and cats with ES or ESE.

DESIGN

Retrospective case series.

ANIMALS

89 dogs and 15 cats.

PROCEDURES

Medical records of dogs and cats that underwent EEG at a veterinary neurology service between May 2009 and April 2015 were reviewed. Electrographic seizure was defined as ictal discharges that evolved in frequency, duration, or morphology and lasted at least 10 seconds, and ESE was defined as ES that lasted ≥ 10 minutes. Patient signalment and history, physical and neurologic examination findings, diagnostic test results, and outcome were compared between patients with and without ES or ESE.

RESULTS

Among the 104 patients, ES and ESE were diagnosed in 21 (20%) and 12 (12%), respectively. Seventeen (81%) patients with ES had no or only subtle signs of seizure activity. The in-hospital mortality rate was 48% and 50% for patients with ES and ESE, respectively, compared with 19% for patients without ES or ESE. Risk factors for ES and ESE included young age, overt seizure activity within 8 hours before EEG, and history of cluster seizures.

CONCLUSIONS AND CLINICAL REVELANCE

Results indicated that ES and ESE were fairly common in dogs and cats with suspected seizure activity and affected patients often had only subtle clinical signs. Therefore, EEG is necessary to detect patients with ES and ESE.

Time Is Brain: The Use of EEG Electrode Caps to Rapidly Diagnose Nonconvulsive Status Epilepticus

OBJECTIVE

To perform a feasibility pilot study comparing the usefulness of EEG electrode cap versus standard scalp EEG for acquiring emergent EEGs in emergency department, inpatient, and intensive care unit patients.

BACKGROUND

Nonconvulsive status epilepticus (NCSE) is a neurological emergency diagnosed exclusively by EEG. Nonconvulsive status epilepticus becomes more resistant to treatment 1 hour after continued seizure activity. EEG technologists are alerted "stat" when there is immediate need for an EEG during oncall hours, yet delays are inevitable. Alternatively, EEG caps can be quickly placed by in-house residents at bedside for assessment.

DESIGN/METHODS

EEG caps were compared with standard-of-care "stat" EEGs for 20 patients with suspected NCSE. After the order for a stat EEG was placed, neurology residents were simultaneously alerted and placed an EEG cap prior to the arrival of the on-call out-of-hospital technologist. Both EEG cap recordings and standard EEG recordings were visually reviewed at 10 and 20 minutes in a blinded manner by two electroencephalographers. The timing, accuracy of interpretation, and diagnosis between the two techniques were then compared.

RESULTS

Of the 20 adult patients, 70% (14 of 20) of EEG cap recordings were interpretable, whereas 95% (19 of 20) standard EEGs were interpretable; three had findings consistent with NCSE on both the EEG cap and standard EEG recordings. In the time analysis, 16 patients were included. EEG cap placement was significantly more time efficient than an EEG performed by technologist using the usual "stat" EEG protocol, with the median EEG cap electrode placement occurring 86 minutes faster than standard EEG (22.5 minutes vs. 104.5 minutes; P < 0.0001; n = 16).

CONCLUSIONS

New rapid EEG recording using improved EEG caps may allow for rapid diagnosis and clinical decision making in suspected NCSE.

Dispersion in Scores on the Richmond Agitation and Sedation Scale as a Measure of Delirium in Patients with Subdural Hematomas

BACKGROUND

Delirium is a frequent complication of critical illness, but its diagnosis is more difficult in brain-injured patients due to language impairment and disorders of consciousness. We conducted a prospective cohort study to determine whether Richmond Agitation and Sedation Scale (RASS) scores could be used to reliably diagnose delirium in the setting of brain injury. We also examined clinical factors associated with delirium in patients with subdural hematomas (SDH) and assessed its impact on functional outcome at discharge.

METHODS

We prospectively enrolled 55 patients with the primary diagnosis of SDH admitted to the neurological intensive care unit (ICU) and screened them for delirium with the Confusion Assessment Method-ICU (CAM-ICU). As our primary outcome, we examined whether the standard deviation of RASS scores (RASS dispersion) could be used to diagnose delirium. We also looked at trends in RASS scores as a way to distinguish different causes of delirium. Then, using logistic regression, we identified factors associated with delirium in patients with SDH and quantified the impact of delirium on the modified Rankin Scale at discharge.

RESULTS

Delirium as defined by the CAM-ICU was present in 35% (N = 19) of patients. RASS dispersion correlated well with the CAM-ICU (AUC of the ROC was 0.84). Analyzing the temporal trend of changes in the RASS was helpful in identifying new brain injuries as the underlying etiology of CAM-ICU positivity. Age, APACHE II scores on admission, baseline functional impairment, midline shift on initial imaging, and infections were associated with an increased risk of delirium. Delirium was associated with a worse functional outcome.

CONCLUSIONS

RASS dispersion correlates highly with CAM-ICU positivity, and monitoring trends in RASS scores can identify delirium caused by new brain injuries. Delirium as defined by the CAM-ICU is common in patients with SDH and portends worse outcomes.

Towards Successes in the Management of Nonconvulsive Status Epilepticus: Tracing the Detection-to-Needle Trajectories

PURPOSE

Data on the timeliness of emergent medication delivery for nonconvulsive status epilepticus (NCSE) are currently lacking.

METHODS

Retrospective chart reviews (between 2015 and 2018) and analyses of all patients with NCSE were performed at the University of Nebraska Medical Center, a level 4 epilepsy center, to determine the latencies to order and administration of the first, second, and third antiepileptic drugs (AEDs). Recurrent NCSE cases were considered independently and classified as comatose and noncomatose.

RESULTS

There were 77 occurrences of NCSE in 53 patients. The first, second, and third AEDs were delivered with substantial delays at median times of 80 (25%-75% interquartile range, 44-166), 126 (interquartile range, 67-239), and 158 minutes (interquartile range, 89-295), respectively, from seizure detection. The median times to the order of the first and second AEDs were 33 and 134.5 minutes longer in comatose NCSE patients compared with those with noncomatose forms, respectively (P = 0.001 and 0.004, respectively). The median times between the AED orders and their administration in these two groups were the same (P = 0.60 and 0.37, respectively). With bivariate analysis, the median latencies to administration of the first, second, and third AEDs were significantly increased by 33, 109.5, and 173 minutes, respectively, in patients who died within 30 days compared with those who survived (P = 0.047, P = 0.02, P = 0.0007, respectively).

CONCLUSIONS

The administration of the first, second, and third AEDs for NCSE was delayed. Slow initiation of acute treatment in comatose patients was caused by delays in the placement of the medication order.

Role of Epileptic Activity in Older Adults With Delirium, a Prospective Continuous EEG Study

Background/Objectives: Delirium occurs in up to 50 % of hospitalized old patients and is associated with increased morbidity and mortality. Acute medical conditions favor delirium, but the pathophysiology is unclear. Preliminary evidence from retrospective and prospective studies suggests that a substantial minority of old patients with unexplained delirium have non-convulsive seizures or status epilepticus (NCSE). Yet, seeking epileptic activity only in unexplained cases of delirium might result in misinterpretation of its actual prevalence. We aimed to systematically investigate the role of epileptic activity in all older patients with delirium regardless of the underlying etiology.

Design, Setting: Prospective observational study in a tertiary medical center. Adults >65 years with delirium underwent at least 24 h of continuous electro-encephalographic monitoring (cEEG). Background patterns and ictal and interictal epileptic discharges were identified, as well as clinical and biological characteristics.

Participants: Fifty patients were included in the study.

Results: NCSE was found in 6 (12%) patients and interictal discharges in 15 (30%). There was no difference in the prevalence of epileptic activity rates between delirium associated with an acute medical condition and delirium of unknown etiology.

Conclusion: Epileptic activity may play a substantial role in the pathophysiology of delirium by altering brain functioning and neuronal metabolism. No clinical or biological marker was found to distinguish delirious patients with or without epileptic activity, underlining the importance of cEEG in this context.

Co-administration of Anti microRNA-124 and -137 Oligonucleotides Prevents Hippocampal Neural Stem Cell Loss Upon Non-convulsive Seizures

Convulsive seizures promote adult hippocampal neurogenesis (AHN) through a transient activation of neural stem/progenitor cells (NSPCs) in the subgranular zone (SGZ) of the dentate gyrus (DG). However, in a significant population of epilepsy patients, non-convulsive seizures (ncSZ) are observed. The response of NSPCs to non-convulsive seizure induction has not been characterized before. We here studied first the short-term effects of controlled seizure induction on NSPCs fate and identity. We induced seizures of controlled intensity by intrahippocampally injecting increasing doses of the chemoconvulsant kainic acid (KA) and analyzed their effect on subdural EEG recordings, hippocampal structure, NSPC proliferation and the number and location of immature neurons shortly after seizure onset. After establishing a KA dose that elicits ncSZ, we then analyzed the effects of ncSZ on NSPC proliferation and NSC identity in the hippocampus. ncSZ specifically triggered neuroblast proliferation, but did not induce proliferation of NSPCs in the SGZ, 3 days post seizure onset. However, ncSZ induced significant changes in NSPC composition in the hippocampus, including the generation of reactive NSCs. Interestingly, intrahippocampal injection of a combination of two anti microRNA oligonucleotides targeting microRNA-124 and -137 normalized neuroblast proliferation and prevented NSC loss in the DG upon ncSZ. Our results show for the first time that ncSZ induce significant changes in neuroblast proliferation and NSC composition. Simultaneous antagonism of both microRNA-124 and -137 rescued seizure-induced alterations in NSPC, supporting their coordinated action in the regulation of NSC fate and proliferation and their potential for future seizure therapies.

Epidemiology of status epilepticus in adults: A population-based study on incidence, causes, and outcomes

Objective

In 2015, the International League Against Epilepsy (ILAE) proposed a new definition of status epilepticus (SE): 5 minutes of ongoing seizure activity to diagnose convulsive SE (CSE, ie, bilateral tonic–clonic SE) and 10 minutes for focal SE and absence SE, rather than the earlier criterion of 30 minutes. Based on semiology, several types of SE with prominent motor phenomena at any time (including CSE) were distinguished from those without (ie, nonconvulsive SE, NCSE). We present the first population‐based incidence study applying the new 2015 ILAE definition and classification of SE and report the impact of the evolution of semiology and level of consciousness (LOC) on outcome.

Methods

We conducted a retrospective population‐based incidence study of all adult patients with SE residing in the city of Salzburg between January 2011 and December 2015. Patients with hypoxic encephalopathy were excluded. SE was defined and classified according to the ILAE 2015.

Results

We identified 221 patients with a median age of 69 years (range 20‐99 years). The age‐ and sex‐adjusted incidence of a first episode of SE, NCSE, and SE with prominent motor phenomena (including CSE) was 36.1 (95% confidence interval [CI] 26.2‐48.5), 12.1 (95% CI 6.8‐20.0), and 24.0 (95% CI 16.0‐34.5; including CSE 15.8 [95% CI 9.4‐24.8]) per 100 000 adults per year, respectively. None of the patients whose SE ended with or consisted of only bilateral tonic–clonic activity died. In all other clinical presentations, case fatality was lower in awake patients (8.2%) compared with patients with impaired consciousness (33%).

Significance

This first population‐based study using the ILAE 2015 definition and classification of SE found an increase of incidence of 10% compared to previous definitions. We also provide epidemiologic evidence that different patterns of status evolution and LOCs have strong prognostic implications.

Continuous EEG in Pediatric Critical Care: Yield and Efficiency of Seizure Detection

PURPOSE

Our goal was to define the duration of continuous EEG (cEEG) monitoring needed to adequately capture electrographic seizures and EEG status epilepticus in the pediatric intensive care unit using clinical and background EEG features.

METHODS

Retrospective study of patients aged 1 month to 21 years admitted to a tertiary pediatric intensive care unit and undergoing cEEG (>3 hours). Clinical data collected included admission diagnosis, EEG background features, and time variables including time to first seizure after initiation of cEEG.

RESULTS

Four hundred fourteen patients aged 4.2 (0.75-11.3) years (median, interquartile range) were included. With a median duration of 21 (16-42.2) hours of cEEG monitoring, we identified electrographic seizure or EEG status epilepticus in 25% of subjects. We identified three features that could improve the efficiency of cEEG resources and provide a decision-making framework: (1) clinical history of acute encephalopathy is not predictive of detecting electrographic seizure or EEG status epilepticus, whereas a history of status epilepticus or seizures is; (2) normal EEG background or absence of epileptiform discharges in the initial 24 hours of recording informs the decision to discontinue cEEG; (3) failure to record electrographic ictal events within the first 4 to 6 hours of monitoring may be sufficient to predict the absence of subsequent ictal events.

CONCLUSIONS

Individualized monitoring plans are necessary to increase seizure detection yield while improving resource utilization. A strategy using information from the clinical history, initial EEG background, and the first 4 to 6 hours of recording may be effective in determining the necessary duration of cEEG monitoring in the pediatric intensive care unit.

Novel TBC1D24 Mutations in a Case of Nonconvulsive Status Epilepticus

Objective: Nonconvulsive status epilepticus (NCSE) is an uncommon clinical manifestation in patients with TBC1D24 mutations. In addition, NCSE has not been reported as a syndrome together with cerebellar ataxia and ophthalmoplegia.

Methods: We herein report the clinical and genetic features of a four-year-old patient with NCSE, cerebellar ataxia, and ophthalmoplegia caused by hitherto unidentified TBC1D24 mutations. We performed 24-h video electroencephalogram (EEG), magnetic resonance imaging, and gene sequencing on the patient and her parents to determine the diagnosis.

Results: We identified a novel c.1416_1437del (p.Ser473Argfs^*43) mutation, as well as the previously identified c.1499C>T (p.Ala500Val) mutation in TBC1D24, by using targeted next-generation sequencing. The novel mutation (inherited from the mother) is the first reported deletion mutation longer than 20 bp in TBC1D24. The p.Ala500Val mutation inherited from father has been reported in a German patient with infantile myoclonic, for whom results from the EEG and neuroimaging were normal. These two mutations resulted in the severe phenotypes observed in our patient

Conclusions: The identification of the novel TBC1D24 mutation and consequent complicated clinical manifestations suggest that patients with NCSE and ataxia demand more attention. We further recommend that genetic test should be administered to these patients to avoid genetic inheritance of this mutation.

Nonconvulsive status epilepticus after cessation of convulsive status epilepticus in pediatric intensive care unit patients

Little is known about pediatric patients suffering from nonconvulsive status epilepticus (NCSE) after convulsive status epilepticus (CSE) cessation. The aim of this study was to identify in pediatric patients the clinical characteristics of NCSE after CSE cessation and the factors that contribute to patient outcomes. Data from clinical features, electroencephalography (EEG) characteristics, neuroimaging findings, treatments, and prognosis were systematically summarized, and the associations between clinical characteristics and prognosis were quantified. Thirty-eight children aged 51days-14years, 2months were identified in the Chongqing Medical University pediatric intensive care unit as having experienced NCSE after CSE cessation between October 1, 2014 and April 1, 2017. All patients were comatose, 15 of whom presented subtle motor signs. The most common underlying etiology was acute central nervous system (CNS) infection. Electroencephalography (EEG) data showed that, during the NCSE period, all patients had several discrete episodes (lasting from 30s to 6h long), and the most common duration was 1-5min. The ictal onset locations were classified as focal (16 patients, 42.1%), multiregional independent (10 patients, 26.3%), and generalized (12 patients, 31.6%). Wave morphologies varied during the ictal and interictal periods. Neuroimaging detected signal abnormalities in the cerebral cortex or subcortex of 33 patients with NCSE (87%), which were classified as either multifocal and consistent with extensive cortical edema (21 patients, 55.3%) or focal (12 patients, 31.6%). Twelve patients were on continuous intravenous phenobarbital, and 31 were on continuous infusion of either midazolam (27 patients) or propofol (4 patients). At least one other antiepileptic drug was prescribed for 32 patients. Three patients were on mild hypothermia therapy. The duration of NCSE lasted <24h for 20 patients and >24h for 18 patients. The mortality rate was 21.1%, and half of the surviving patients had severe neurological morbidity. Our results indicated that EEG monitoring after treatment of CSE was essential to the recognition of persistent seizures. The clinical features, EEG characteristics, and neuroimaging findings varied during the NCSE period. The morbidity is high in pediatric patients who had NCSE after CSE. Convulsive status epilepticus (CSE) duration and neuroimaging results may be related to the prognosis.

Seizure prophylaxis in the neuroscience intensive care unit

Background

Seizures are a considerable complication in critically ill patients. Their incidence is significantly high in neurosciences intensive care unit patients. Seizure prophylaxis with anti-epileptic drugs is a common practice in neurosciences intensive care unit. However, its utility in patients without clinical seizure, with an underlying neurological injury, is somewhat controversial.

Body

In this article, we have reviewed the evidence for seizure prophylaxis in commonly encountered neurological conditions in neurosciences intensive care unit and discussed the possible prognostic role of continuous electroencephalography monitoring in detecting early seizures in critically ill patients.

Conclusion

Based on the current evidence and guidelines, we have proposed a presumptive protocol for seizure prophylaxis in neurosciences intensive care unit. Patients with severe traumatic brain injury and possible subarachnoid hemorrhage seem to benefit with a short course of anti-epileptic drug. In patients with other neurological illnesses, the use of continuous electroencephalography would make sense rather than indiscriminately administering anti-epileptic drug.

Successful Use of Therapeutic Hypothermia for Refractory Nonconvulsive Status Epilepticus

Therapeutic hypothermia (TH) has rarely been utilized as an adjunct to anticonvulsants in treating patients with refractory convulsive status epilepticus (CSE). However, determining the effectiveness of TH in CSE is difficult due to the unavoidable use of sedative drugs to manage hypothermia. Additionally, the effectiveness of TH has not been studied in patients with refractory non-convulsive status epilepticus (NCSE). Here, we report the successful use of TH without additional sedative drugs in a patient with temporal lobe epilepsy and refractory NCSE. A 46-year-old man was referred to the neurology department because of recurrent seizure attacks. Electroencephalography (EEG) after first-line status treatment showed continuous periodic discharges consistent with NCSE. He was started simultaneously on continuous EEG monitoring and TH, but was not administered any benzodiazepines to control shivering or maintain TH. During TH, EEG abnormalities gradually improved, and the patient regained consciousness in accordance with the improvement in EEG. The patient was alert and his EEG had normalized a few days after starting TH. To the best of our knowledge, this is the first report describing the successful treatment of refractory NCSE with TH. As no sedative drugs were used during the maintenance of hypothermia, NCSE control may have been achieved by TH alone.

Clinical course and long-term outcome in children with alteration of consciousness underwent continuous EEG monitoring: A prospective observational study in Thailand

The study aims to explore the clinical course and long-term outcome in children with altered consciousness who underwent cEEG monitoring. A prospective observational study was conducted in neonatal and pediatric intensive care units from 1 September 2014 through 31 March 2017. Standard 10-20 cEEG monitoring was applied. Twenty children were included in this study. Their ages ranged from 1 day to 142.7 months (median age 40.6 months). Continuous EEG was commenced from 5 h to 5 days after the onset of alteration of consciousness (median 40.2 h). The range of EEG monitoring duration was 6.7-256.3 h (mean 50.4 h). Four patients (20%) had preexisting neurological diseases, which were 2 epilepsy, adrenoleukodystrophy and unknown cause of brain atrophy. Eleven patients (55%) had principle neurological diagnosis and the others 9 (45%) had systemic illnesses. Sixteen patients (80%) had clinical seizures prior to the commencement of cEEG monitoring. Fifteen patients (75%) received antiepileptic drugs before cEEG monitoring. NCSE was diagnosed in 25%. Comparison of patients' characteristics and long-term outcome between the NCSE and non NCSE groups, there was statistical significance between the two groups only with respect to epileptiform discharges. The patients are being follow up for a period of 24 months after the end of cEEG monitoring. The outcome of patients divided into those with a favorable outcome and those with poor outcome according to modified Rankin scale. The patients with isoelectric EEG background had relatively poorer outcomes than those with normal or slow background activities. The overall mortality rate for the entire population was 15%.

Management of acute seizures in children: A review with special consideration of care in resource-limited settings

INTRODUCTION

We sought to review recent evidence-based guidelines and where applicable, primary data to extrapolate insights into the appropriate management of acute seizures in children in resource-limited settings.

METHODS

PubMed and Google scholar searches were conducted with attention to publications from the last three to five years, including a focused search for acute seizure management guidelines relevant to resource limited settings. Since all guidelines to date, except the World Health Organization's, assume ready access to invasive ventilation and advanced diagnostic testing, guidelines and primary data were used to propose management appropriate for resource-limited settings where respiratory suppression from treatment presents a major challenge in management.

RESULTS

Acute seizures are among the commonest medical emergencies encountered in the African settings. Seizure management must occur simultaneously with the diagnostic assessment, which should include addressing life threatening causes (e.g. hypoglycaemia, malaria) and with attention given to the most likely aetiology in a particular region or setting. For ongoing seizures, initial treatment with benzodiazepines is indicated. There is evidence of efficacy for several agents and delivery modes. Longer-acting antiepileptic drugs (AEDs) should be on hand if acute seizures fail to respond to two doses of benzodiazepines. There is little direct evidence comparing the relative efficacy of different long-acting AEDs for acute seizure management in African children. Findings suggest that generalising data from Western settings, where different aetiologies and risk factors for seizures prevail, may be inappropriate.

DISCUSSION

Though treatment options and diagnostics may be dictated by available medications and capacity, it is possible for virtually any healthcare setting to develop a relevant and feasible local guideline for seizure management. Clear specifications on when to refer to a higher level of care should be part of the care plan.

Hidden in plain sight: Non-convulsive status epilepticus-Recognition and management

Non-convulsive status epilepticus (NCSE) is an electroclinical state associated with an altered level of consciousness but lacking convulsive motor activity. It can present in a multitude of ways, but classification based on the clinical presentation and electroencephalographic appearances assists in determining prognosis and planning treatment. The aggressiveness of treatment should be based on the likely prognosis and the underlying cause of the NCSE.

Electrographic Seizures in Preterm Neonates in the Neonatal Intensive Care Unit

OBJECTIVE

Characterize clinical and electroencephalography (EEG) characteristics of preterm neonates undergoing continuous EEG in the neonatal intensive care unit.

METHODS

Retrospective study of preterm neonates born less than 37 weeks' gestational age undergoing continuous EEG in the neonatal intensive care unit at Boston Children's Hospital over a 2-year period.

RESULTS

Fifty-two preterms (46% male) had a mean gestational age of 32.8 weeks (standard deviation = 4.17). Seizures were detected in 12/52 (23%), with EEG seizures detected in 4/12 (33%). The median time from EEG to the first seizure was 0.5 hours (interquartile range 0.24-4). Factors associated with seizures were male gender (odds ratio = 4.65 [95% confidence interval = 1.02-21.24], P = .047) and lack of EEG state change (odds ratio = 0.043 [95% confidence interval = 0.005-0.377], P = .04).

CONCLUSION

Twenty-three percent of preterms undergoing continuous EEG had EEG seizures or electrographic seizures with no clear clinical correlate. This confirms recent American Clinical Neurophysiology Society guidelines suggesting that preterm neonates are at high risk for seizures.

Can patients with non-convulsive seizure be identified in the emergency department?

BACKGROUND

Non-convulsive seizure (NCS) is an underdiagnosed, potentially treatable emergency with significant mortality and morbidity. The objective of this study is to examine the characteristics of patients with NCS presenting with altered mental status (AMS) and diagnosed with electroencephalography (EEG), to identify the factors that could increase the pre-test probability of NCS.

METHODS

Retrospective study using the data collected prospectively. Inclusion criteria: patients older than 13 years with AMS. Exclusion criteria: (1) immediately correctable AMS (e.g., hypoglycemia, opiod overdose); (2) inability to undergo EEG; (3) hemodynamic instability. Outcomes compared between NCS and non-NCS cases: vital signs, lactate level, gender, witnessed seizure, use of anticonvulsive in the field or in the ED, history of seizure or stroke, head injury, abnormal neurological finding and new abnormal findings on head CT. Data presented as medians and quartiles for categorical and percentages with 95%CI for continuous variables. Univariate analyses were performed with Man-Whitney U and Fisher's Exact tests. A multivariate analysis model was used to test the predictive value of clinical variables in identifying NCS.

RESULTS

From 332 patients (median age 66 years, quartiles 50-78), 16 were diagnosed with NCS (5%, 95%CI 3%-8%). Only age was significantly different between the NCS vs. non-NCS groups in both univariate (P=0.032) and multivariate analyses (P=0.016).

CONCLUSION

Other than age, no other clinically useful variable could identify patients at high risk of NCS. ED physicians should have a high suspicion for NCS and should order EEG for these patients more liberally.

Response Rates to Anticonvulsant Trials in Patients with Triphasic-Wave EEG Patterns of Uncertain Significance

BACKGROUND

Generalized triphasic waves (TPWs) occur in both metabolic encephalopathies and non-convulsive status epilepticus (NCSE). Empiric trials of benzodiazepines (BZDs) or non-sedating AED (NSAEDs) are commonly used to differentiate the two, but the utility of such trials is debated. The goal of this study was to assess response rates of such trials and investigate whether metabolic profile differences affect the likelihood of a response.

METHODS

Three institutions within the Critical Care EEG Monitoring Research Consortium retrospectively identified patients with unexplained encephalopathy and TPWs who had undergone a trial of BZD and/or NSAEDs to differentiate between ictal and non-ictal patterns. We assessed responder rates and compared metabolic profiles of responders and non-responders. Response was defined as resolution of the EEG pattern and either unequivocal improvement in encephalopathy or appearance of previously absent normal EEG patterns, and further categorized as immediate (within <2 h of trial initiation) or delayed (>2 h from trial initiation).

RESULTS

We identified 64 patients with TPWs who had an empiric trial of BZD and/or NSAED. Most patients (71.9%) were admitted with metabolic derangements and/or infection. Positive clinical responses occurred in 10/53 (18.9%) treated with BZDs. Responses to NSAEDs occurred in 19/45 (42.2%), being immediate in 6.7%, delayed but definite in 20.0%, and delayed but equivocal in 15.6%. Overall, 22/64 (34.4%) showed a definite response to either BZDs or NSAEDs, and 7/64 (10.9%) showed a possible response. Metabolic differences of responders versus non-responders were statistically insignificant, except that the 48-h low value of albumin in the BZD responder group was lower than in the non-responder group.

CONCLUSIONS

Similar metabolic profiles in patients with encephalopathy and TPWs between responders and non-responders to anticonvulsants suggest that predicting responders a priori is difficult. The high responder rate suggests that empiric trials of anticonvulsants indeed provide useful clinical information. The more than twofold higher response rate to NSAEDs suggests that this strategy may be preferable to BZDs. Further prospective investigation is warranted.

Management of status epilepticus

Status epilepticus is a neurologic and medical emergency manifested by prolonged seizure activity or multiple seizures without return to baseline. It is associated with substantial medical cost, morbidity, and mortality. There is a spectrum of severity dependent on the type of seizure, underlying pathology, comorbidities, and appropriate and timely medical management. This chapter discusses the evolving definitions of status epilepticus and multiple patient and clinical factors which influence outcome. The pathophysiology of status epilepticus is reviewed to provide a better understanding of the mechanisms which contribute to status epilepticus, as well as the potential long-term effects. The clinical presentations of different types of status epilepticus in adults are discussed, with emphasis on the hospital course and management of the most dangerous type, generalized convulsive status epilepticus. Strategies for the evaluation and management of status epilepticus are provided based on available evidence from clinical trials and recommendations from the Neurocritical Care Society and the European Federation of Neurological Societies.

Catatonia: Our current understanding of its diagnosis, treatment and pathophysiology

Catatonia is a psychomotor syndrome that has been reported to occur in more than 10% of patients with acute psychiatric illnesses. Two subtypes of the syndrome have been identified. Catatonia of the retarded type is characterized by immobility, mutism, staring, rigidity, and a host of other clinical signs. Excited catatonia is a less common presentation in which patients develop prolonged periods of psychomotor agitation. Once thought to be a subtype of schizophrenia, catatonia is now recognized to occur with a broad spectrum of medical and psychiatric illnesses, particularly affective disorders. In many cases, the catatonia must be treated before any underlying conditions can be accurately diagnosed. Most patients with the syndrome respond rapidly to low-dose benzodiazepines, but electroconvulsive therapy is occasionally required. Patients with longstanding catatonia or a diagnosis of schizophrenia may be less likely to respond. The pathobiology of catatonia is poorly understood, although abnormalities in gamma-aminobutyric acid and glutamate signaling have been suggested as causative factors. Because catatonia is common, highly treatable, and associated with significant morbidity and mortality if left untreated, physicians should maintain a high level of suspicion for this complex clinical syndrome. Since 1989, we have systematically assessed patients presenting to our psychiatry service with signs of retarded catatonia. In this paper, we present a review of the current literature on catatonia along with findings from the 220 cases we have assessed and treated.

Status epilepticus associated with pregnancy: A cohort study

BACKGROUND

Status epilepticus (SE) is a neurological emergency associated with a high mortality rate and long-term cognitive sequelae. Status epilepticus in pregnancy poses a tremendous threat to both mother and fetus, making a correct diagnosis and treatment a challenging task for clinicians. The prevalence, underlying etiology, and outcomes of pregnancy-related SE remain largely unknown.

METHODS

We retrospectively studied all SE episodes (n=366) in patients admitted to our neurological ICU over a period of 8.5years. The patients who developed SE during pregnancy and within 6months after delivery were considered to have pregnancy-related SE. Patients with eclampsia were not included as they were usually cared for in our obstetric unit.

RESULTS

Seven patients with pregnancy-related SE were identified (2.1% of all cases of SE), with the majority (85%) occurring de novo except for one patient who had a previous history of epilepsy-related SE due to withdrawal of antiepileptic medication. In terms of etiology, limbic encephalitis and cerebral venous sinus thrombosis were the two main etiologies of de novo SE associated with pregnancy. The overall mortality rate was 28.5% at discharge, and poor outcomes were especially noted in the patients with limbic encephalitis compared to other etiologies.

CONCLUSIONS

Pregnancy-associated SE is rare and predominantly occurs in patients without a history of epilepsy. An autoimmune etiology should be considered in pregnant patients with de novo SE, which was associated with poor outcomes. Thorough investigations and prompt treatment according to the etiology may be required to improve the final outcomes of both mother and fetus.

Pharmacotherapy for Status Epilepticus

Status epilepticus (SE) represents the most severe form of epilepsy. It is one of the most common neurologic emergencies, with an incidence of up to 61 per 100,000 per year and an estimated mortality of 20 %. Clinically, tonic-clonic convulsive SE is divided into four subsequent stages: early, established, refractory, and super-refractory. Pharmacotherapy of status epilepticus, especially of its later stages, represents an "evidence-free zone," due to a lack of high-quality, controlled trials to inform clinical decisions. This comprehensive narrative review focuses on the pharmacotherapy of SE, presented according to the four-staged approach outlined above, and providing pharmacological properties and efficacy/safety data for each antiepileptic drug according to the strength of scientific evidence from the available literature. Data sources included MEDLINE and back-tracking of references in pertinent studies. Intravenous lorazepam or intramuscular midazolam effectively control early SE in approximately 63-73 % of patients. Despite a suboptimal safety profile, intravenous phenytoin or phenobarbital are widely used treatments for established SE; alternatives include valproate, levetiracetam, and lacosamide. Anesthetics are widely used in refractory and super-refractory SE, despite the current lack of trials in this field. Data on alternative treatments in the later stages are limited. Valproate and levetiracetam represent safe and effective alternatives to phenobarbital and phenytoin for treatment of established SE persisting despite first-line treatment with benzodiazepines. To date there are no class I data to support recommendations for most antiepileptic drugs for established, refractory, and super-refractory SE. Limiting the methodologic heterogeneity across studies is required and high-class randomized, controlled trials to inform clinicians about the best treatment in established and refractory status are needed.

Which EEG patterns in coma are nonconvulsive status epilepticus?

Nonconvulsive status epilepticus (NCSE) is common in patients with coma with a prevalence between 5% and 48%. Patients in deep coma may exhibit epileptiform EEG patterns, such as generalized periodic spikes, and there is an ongoing debate about the relationship of these patterns and NCSE. The purposes of this review are (i) to discuss the various EEG patterns found in coma, its fluctuations, and transitions and (ii) to propose modified criteria for NCSE in coma. Classical coma patterns such as diffuse polymorphic delta activity, spindle coma, alpha/theta coma, low output voltage, or burst suppression do not reflect NCSE. Any ictal patterns with a typical spatiotemporal evolution or epileptiform discharges faster than 2.5 Hz in a comatose patient reflect nonconvulsive seizures or NCSE and should be treated. Generalized periodic diacharges or lateralized periodic discharges (GPDs/LPDs) with a frequency of less than 2.5 Hz or rhythmic discharges (RDs) faster than 0.5 Hz are the borderland of NCSE in coma. In these cases, at least one of the additional criteria is needed to diagnose NCSE (a) subtle clinical ictal phenomena, (b) typical spatiotemporal evolution, or (c) response to antiepileptic drug treatment. There is currently no consensus about how long these patterns must be present to qualify for NCSE, and the distinction from nonconvulsive seizures in patients with critical illness or in comatose patients seems arbitrary. The Salzburg Consensus Criteria for NCSE [1] have been modified according to the Standardized Terminology of the American Clinical Neurophysiology Society [2] and validated in three different cohorts, with a sensitivity of 97.2%, a specificity of 95.9%, and a diagnostic accuracy of 96.3% in patients with clinical signs of NCSE. Their diagnostic utility in different cohorts with patients in deep coma has to be studied in the future. This article is part of a Special Issue entitled "Status Epilepticus".

Nonconvulsive status epilepticus disguising as hepatic encephalopathy

Nonconvulsive status epilepticus has become an important issue in modern neurology and epileptology. This is based on difficulty in definitively elucidating the condition and its various clinical phenomena and on our inadequate insight into the intrinsic pathophysiological processes. Despite nonconvulsive status epilepticus being a situation that requires immediate treatment, this disorder may not be appreciated as the cause of mental status impairment. Although the pathophysiology of nonconvulsive status epilepticus remains unknown, this disorder is thought to lead to neuronal damage, so its identification and treatment are important. Nonconvulsive status epilepticus should be considered in the differential diagnosis of patients with liver cirrhosis presenting an altered mental status. We report a case of a 52-year-old male with liver cirrhosis presenting an altered mental status. He was initially diagnosed with hepatic encephalopathy but ultimately diagnosed with nonconvulsive status epilepticus by electroencephalogram.

A Wavelet-Statistical Features Approach for Nonconvulsive Seizure Detection

The detection of nonconvulsive seizures (NCSz) is a challenge because of the lack of physical symptoms, which may delay the diagnosis of the disease. Many researchers have reported automatic detection of seizures. However, few investigators have concentrated on detection of NCSz. This article proposes a method for reliable detection of NCSz. The electroencephalography (EEG) signal is usually contaminated by various nonstationary noises. Signal denoising is an important preprocessing step in the analysis of such signals. In this study, a new wavelet-based denoising approach using cubical thresholding has been proposed to reduce noise from the EEG signal prior to analysis. Three statistical features were extracted from wavelet frequency bands, encompassing the frequency range of 0 to 8, 8 to 16, 16 to 32, and 0 to 32 Hz. Extracted features were used to train linear classifier to discriminate between normal and seizure EEGs. The performance of the method was tested on a database of nine patients with 24 seizures in 80 hours of EEG recording. All the seizures were successfully detected, and false positive rate was found to be 0.7 per hour.

MiR-134 blockade prevents status epilepticus like-activity and is neuroprotective in cultured hippocampal neurons

Status epilepticus (SE) is a life-threatening neurological disorder associated with significant morbidity and mortality. MicroRNAs (miRNAs) are small, non-coding RNAs that act post-transcriptionally modulating messenger RNA (mRNA) translation or stability which may have important roles in the pathogenesis of epilepsy. It has been reported that silencing microRNA-134 in vivo has significant neuroprotective and prolonged seizure-suppressive effects. However, the mechanism by which miR-134 inhibition suppressed seizures and whether miR-134 inhibition works in an in vitro model of SE, is unknown. Compared to a complex in vivo system, in vitro models of SE-like electrographic activity can be powerful tools to study this miRNA. Using a cell culture model of low Mg(2+) treatment of rat hippocampal neurons, we found SE-like electrographic activity increased expression of miR-134. Inhibiting expression of miR-134 using an inhibitor lentivirus with two miR-134 binding sites reduced SE-like electrographic activity in the hippocampal neurons and reduced neuronal death. This study provides direct evidence that inhibition of miR-134 can block status epilepticus-like discharges and is neuroprotective in hippocampal neuronal cultures and implies that inhibiting miR-134 may be a potential candidate for the clinical treatment of SE.

Mechanisms of levetiracetam in the control of status epilepticus and epilepsy

Status epilepticus (SE) is a major clinical emergency that is associated with high mortality and morbidity. SE causes significant neuronal injury and survivors are at a greater risk of developing acquired epilepsy and other neurological morbidities, including depression and cognitive deficits. Benzodiazepines and some anticonvulsant agents are drugs of choice for initial SE management. Despite their effectiveness, over 40% of SE cases are refractory to the initial treatment with two or more medications. Thus, there is an unmet need of developing newer anti-SE drugs. Levetiracetam (LEV) is a widely prescribed anti-epileptic drug that has been reported to be used in SE cases, especially in benzodiazepine-resistant SE or where phenytoin cannot be used due to allergic side-effects. Levetiracetam’s non-classical anti-epileptic mechanisms of action, favorable pharmacokinetic profile, general lack of central depressant effects, and lower incidence of drug interactions contribute to its use in SE management. This review will focus on LEV’s unique mechanism of action that makes it a viable candidate for SE treatment.