American Clinical Neurophysiology Society's Standardized Critical Care EEG Terminology: 2021 Version

First Seizures, Acute Repetitive Seizures, and Status Epilepticus

OBJECTIVE

This article provides current evidence on how and when to treat unprovoked first seizures in children and adults, guides intervention with appropriate doses and types of modern and effective therapies for acute repetitive (cluster) seizures, and reviews evidence for the diagnosis and management of established, refractory and super-refractory status epilepticus.

LATEST DEVELOPMENTS

Artificial intelligence shows promise as a clinical assistant in decision making after a first seizure. For nonanoxic convulsive refractory status epilepticus third-phase treatment, equipoise exists regarding whether it is better to add a second IV nonsedating antiseizure medication given via loading dose (eg, brivaracetam, lacosamide, levetiracetam, fosphenytoin or valproic acid) or to start an anesthetizing continuous IV infusion antiseizure medication such as ketamine, midazolam, propofol or pentobarbital.

ESSENTIAL POINTS

After a first seizure, the risk of a second seizure is about 36% at 2 years and 46% after 5 years. The risk is doubled in the presence of EEG epileptiform discharges, a brain imaging abnormality, a nocturnal first seizure, or prior brain trauma. For acute repetitive seizures, providers should give a proper dose of benzodiazepines based on the patient's weight and needs. First-phase treatment for convulsive established status epilepticus is the immediate administration of full doses of benzodiazepines. Second-phase treatment for convulsive established status epilepticus is a full loading dose of IV fosphenytoin, levetiracetam, valproic acid, or if necessary, phenobarbital.

Late-Onset Findings During Extended EEG Monitoring Are Rare in Critically Ill Children

PURPOSE

Electrographic seizures (ES) are common in critically ill children undergoing continuous EEG (CEEG) monitoring, and previous studies have aimed to target limited CEEG resources to children at highest risk of ES. However, previous studies have relied on observational data in which the duration of CEEG was clinically determined. Thus, the incidence of late occurring ES is unknown. The authors aimed to assess the incidence of ES for 24 hours after discontinuation of clinically indicated CEEG.

METHODS

This was a single-center prospective study of nonconsecutive children with acute encephalopathy in the pediatric intensive care unit who underwent 24 hours of extended research EEG after the end of clinical CEEG. The authors assessed whether there were new findings that affected clinical management during the extended research EEG, including new-onset ES.

RESULTS

Sixty-three subjects underwent extended research EEG. The median duration of the extended research EEG was 24.3 hours (interquartile range 24.0-25.3). Three subjects (5%) had an EEG change during the extended research EEG that resulted in a change in clinical management, including an increase in ES frequency, differential diagnosis of an event, and new interictal epileptiform discharges. No subjects had new-onset ES during the extended research EEG.

CONCLUSIONS

No subjects experienced new-onset ES during the 24-hour extended research EEG period. This finding supports observational data that patients with late-onset ES are rare and suggests that ES prediction models derived from observational data are likely not substantially underrepresenting the incidence of late-onset ES after discontinuation of clinically indicated CEEG.

Defining neonatal status epilepticus: A scoping review from the ILAE neonatal task force

OBJECTIVE

To review the available literature concerning the definition of neonatal status epilepticus (SE) and/or seizure burden.

METHODS

The International League Against Epilepsy Neonatal Task Force performed a scoping review of the definitions of neonatal SE. Following a systematic literature review, articles were screened and data were abstracted regarding: (1) article characteristics (author identification, publication year, journal name, digital object identifier, title, objective, and study design); (2) cohort characteristics (sample size, gestational age, seizure etiology); (3) definition of SE and/or seizure burden; and (4) the method used to identify and classify SE, including routine EEG (EEG), continuous EEG monitoring (cEEG), amplitude-integrated EEG (aEEG), or clinical features.

RESULTS

The scoping review yielded 44 articles containing a definition of neonatal SE. Studies mainly included infants with hypoxic-ischemic encephalopathy or neonates considered at risk for seizures. SE identification and classification most often relied on cEEG. The majority of studies based the definition of SE on seizure duration, including summed duration of seizures comprising ≥50% of any 1-h epoch, recurrent seizures for >50% of the total recording time, or either electrographic seizures lasting >30 min and/or repeated electrographic seizures totaling >50% in any 1-h period. Seizure burden was reported in 20 studies, and the most commonly used approach assessed total seizure burden, defined as total duration of EEG seizures in minutes. Sixteen studies assessed the relationship between seizure burden and outcomes, and most identified a significant association between higher seizure burden and unfavorable outcomes.

SIGNIFICANCE

This scoping review demonstrates a substantial variation in neonatal SE definitions across the literature. The most common definitions were based around a 30-min seizure duration criterion, but evidence was insufficient to support that 30 min was a cutoff defining prolonged seizures or that seizures exceeding this burden were more likely to be pharmacoresistant or associated with worse outcomes. As a next step, the Neonatal Task Force intends to develop a standardized approach to assessing and describing neonatal seizure burden and defining neonatal SE.

PLAIN LANGUAGE SUMMARY

Prolonged seizures are a neurologic emergency, if untreated, can lead to permanent injury or death. In adults and children, seizures lasting longer than 30 min are believed to cause brain damage. However, it is not clear if this definition can be applied to neonates. The International League Against Epilepsy Neonatal Taskforce performed a scoping literature review which identified 44 articles containing a definition of neonatal status epilepticus. In this article, the authors reviewed the current used definitions for prolonged seizures in neonates to establish a relationship between seizure duration and neurological outcome. As a next step, the Neonatal Task Force intends to develop a standardized approach to assessing and describing neonatal seizure burden and defining neonatal SE.

Early initiation of intravenous cyclophosphamide and one-year outcome in super-refractory cryptogenic-new onset refractory status epilepticus

To explore the potential efficacy of early initiation of intravenous cyclophosphamide (IVCPA), we reviewed consecutive four cases of super-refractory cryptogenic-new onset refractory status epilepticus (C-NORSE) between 2015 and 2023. We compared functional outcomes at 3 months and 1 year after the onset between patients who received IVCPA within 20 days (early-treated) and those who received it later (late-treated). All patients (median age: 43 years) had a prodromal fever. Brain MRI revealed symmetrically increased FLAIR signals in the medial temporal lobes of all patients. Despite initiating antiseizure medications (ASMs) and first-line immunotherapy (intravenous-methylprednisolone and immunoglobulins) within a median of 3 days from onset, SE persisted >5 days. The diagnosis of C-NORSE was suggested based on a high C-NORSE score (6/6). Thus, all patients received IVCPA a median of 15.5 days after seizure onset (three within 20 days and one at 31 days). One of the three early-treated patients also received tocilizumab. Early-treated patients exhibited shorter sedation periods (median 29 vs. 75 days) and better 1 year functional status (mRS 1-2 vs. mRS 4) compared to the late-treated patient. Early initiation of IVCPA and/or tocilizumab, along with ASMs, may contribute to a better one-year functional status in super-refractory C-NORSE patients. PLAIN LANGUAGE SUMMARY: This study demonstrates the potential efficacy of early administration of intravenous cyclophosphamide on one-year functional status in patients with super-refractory cryptogenic-new onset refractory status epilepticus. "Early-treated patients" who received it within 20 days of seizure onset achieved a good one-year functional status. The "late-treated patient" (Case 4) who received it later did not achieve a good functional status. Early initiation of cyclophosphamide, along with antiseizure medications, may contribute to a better one-year functional status in this population.

EEG in Epilepsy

OBJECTIVE

The purpose of this article is to review the fundamentals and limitations of EEG, guide the selection of EEG type to answer clinical questions, and provide instruction on the interpretation of results within the patient's clinical context.

LATEST DEVELOPMENTS

EEG is the single most useful ancillary test to support the clinical diagnosis of epilepsy, but if used incorrectly it can cause great harm. Misapplication of EEG findings can lead to misdiagnosis and long-term mental and physical health sequelae. Although all neurologists may not have sufficient training for independent EEG interpretation, most should be able to review and apply the findings from the report accurately to guide patient care. Longer-term EEGs with similar recording electrodes tend to have higher diagnostic yields. Common EEG findings are described in this article, along with diagnostic limitations of some classically described patterns. There is an updated definition for an epileptiform discharge, along with a consensus on EEG patterns in the critically ill.

ESSENTIAL POINTS

EEG continues to be the most useful ancillary test to assist in the diagnosis of epilepsy. Its application requires proper understanding of its limitations and variability of testing results.

Refractory and Super-Refractory Status Epilepticus: Therapeutic Options and Prognosis

In patients with status epilepticus (SE), the underlying biologic background represents the main prognostic variable. A swift application of a treatment protocol is recommended, including adequate doses of a benzodiazepine followed by an intravenous anti-seizure medicine. If refractory SE arises, general anesthetics should be used in generalized convulsive and non-convulsive SE in coma, while further non-sedating anti-seizure medications attempts are warranted in patients with focal forms. Ketogenic diet and/or ketamine in patients with super-refractory SE, and immunologic treatments for those with new-onset refractory SE/febrile-induced refractory epilepsy syndrome should be considered early. Pharmacologic treatment of SE after cardiac arrest should be oriented by the results of multimodal prognostication.

Prediction of good neurological outcome after return of circulation following paediatric cardiac arrest: A systematic review and meta-analysis

AIM

To evaluate the ability of blood-biomarkers, clinical examination, electrophysiology, or neuroimaging, assessed within 14 days from return of circulation to predict good neurological outcome in children following out- or in-hospital cardiac arrest.

METHODS

Medline, EMBASE and Cochrane Trials databases were searched (2010-2023). Sensitivity and false positive rates (FPR) for good neurological outcome (defined as either 'no, mild, moderate disability or minimal change from baseline') in paediatric survivors were calculated for each predictor. Risk of bias was assessed using the QUIPS tool.

RESULTS

Thirty-five studies (2974 children) were included. The presence of any of the following had a FPR < 30% for predicting good neurological outcome with moderate (50-75%) or high (>75%) sensitivity: bilateral reactive pupillary light response within 12 h; motor component ≥ 4 on the Glasgow Coma Scale score at 6 h; bilateral somatosensory evoked potentials at 24-72 h; sleep spindles, and continuous cortical activity on electroencephalography within 24 h; or a normal brain MRI at 4-6d. Early (≤12 h) normal lactate levels (<2mmol/L) or normal s100b, NSE or MBP levels predicted good neurological outcome with FPR rate < 30% and low (<50%) sensitivity. All studies had moderate to high risk of bias with timing of measurement, definition of test, use of multi-modal tests, or outcome assessment heterogeneity.

CONCLUSIONS

Clinical examination, electrophysiology, neuroimaging or blood-biomarkers as individual tests can predict good neurological outcome after cardiac arrest in children. However, evidence is often low quality and studies are heterogeneous. Use of a standardised, multimodal, prognostic algorithm should be studied and is likely of added value over single modality testing.

Evaluating the Impact of Point-of-Care Electroencephalography on Length of Stay in the Intensive Care Unit: Subanalysis of the SAFER-EEG Trial

BACKGROUND

Electroencephalography (EEG) is needed to diagnose nonconvulsive seizures. Prolonged nonconvulsive seizures are associated with neuronal injuries and deleterious clinical outcomes. However, it is uncertain whether the rapid identification of these seizures using point-of-care EEG (POC-EEG) can have a positive impact on clinical outcomes.

METHODS

In a retrospective subanalysis of the recently completed multicenter Seizure Assessment and Forecasting with Efficient Rapid-EEG (SAFER-EEG) trial, we compared intensive care unit (ICU) length of stay (LOS), unfavorable functional outcome (modified Rankin Scale score ≥ 4), and time to EEG between adult patients receiving a US Food and Drug Administration-cleared POC-EEG (Ceribell, Inc.) and those receiving conventional EEG (conv-EEG). Patient records from January 2018 to June 2022 at three different academic centers were reviewed, focusing on EEG timing and clinical outcomes. Propensity score matching was applied using key clinical covariates to control for confounders. Medians and interquartile ranges (IQRs) were calculated for descriptive statistics. Nonparametric tests (Mann-Whitney U-test) were used for the continuous variables, and the χ2 test was used for the proportions.

RESULTS

A total of 283 ICU patients (62 conv-EEG, 221 POC-EEG) were included. The two populations were matched using demographic and clinical characteristics. We found that the ICU LOS was significantly shorter in the POC-EEG cohort compared to the conv-EEG cohort (3.9 [IQR 1.9-8.8] vs. 8.0 [IQR 3.0-16.0] days, p = 0.003). Moreover, modified Rankin Scale functional outcomes were also different between the two EEG cohorts (p = 0.047).

CONCLUSIONS

This study reveals a significant association between early POC-EEG detection of nonconvulsive seizures and decreased ICU LOS. The POC-EEG differed from conv-EEG, demonstrating better functional outcomes compared with the latter in a matched analysis. These findings corroborate previous research advocating the benefit of early diagnosis of nonconvulsive seizure. The causal relationship between the type of EEG and metrics of interest, such as ICU LOS and functional/clinical outcomes, needs to be confirmed in future prospective randomized studies.

The electroencephalogram in the diagnosis and classification of status epilepticus: a practical guide

Status epilepticus is a serious neurological emergency requiring swift recognition and treatment. Presentations with prominent motor features are easily recognised but it can be challenging to diagnose those with subtle or no motor features. Electroencephalogram (EEG) remains indispensable in diagnosing, classifying, monitoring and prognosticating of status epilepticus. There are several separate classification systems for seizures, epilepsy and status epilepticus, incorporating clinical features, causes and EEG correlates. This review focuses on using EEG in status epilepticus and provides a practical approach to diagnosis and classification aligning with the current International League Against Epilepsy and American Clinical Neurophysiology Society definitions.

[Case of ictal aphasia and post-ictal aphasia due to focal epilepsy associated with cerebral hemorrhage]

The patient was a 69-year-old right-handed woman. She had sensory aphasia, and the brain MRI revealed a subacute phase hemorrhage in the left subcortical temporal lobe. We speculated that the patient had post-ictal aphasia due to symptomatic epileptic seizures associated with cerebral hemorrhage. Seven months later, she was readmitted to the hospital with sensory aphasia; however, this time, the brain MRI FLAIR demonstrated high signal in the left medial temporal lobe and thalamic pillow. Furthermore, the electroencephalogram showed periodic discharges focused on the left temporal region. 123I-IMP SPECT of cerebral blood flow indicated a cluster within the medial left temporal lobe. Aphasia associated with nonconvulsive seizures was considered. Sudden onset sensory aphasia should be differentiated from ictal and post-ictal aphasias.

Accuracy of a Rapid-Response EEG's Automated Seizure-Burden Estimator: AccuRASE Study

BACKGROUND AND OBJECTIVES

The use of rapid response EEG (rr-EEG) has recently expanded in limited-resource settings and as a supplement to conventional EEG to rapidly detect and treat nonconvulsive status epilepticus. The study objective was to test the accuracy of an rr-EEG's automated seizure burden estimator (ASBE).

METHODS

This is a retrospective observational study using multiple blinded reviewers. All consecutive clinical rr-EEG procedures performed between November 2019 and February 2021 at Yale New Haven Hospital, one affiliated community hospital, and one affiliated inner-city regional hospital were included. Three reviewers blindly reviewed each EEG. The reference standard was 2/3 agreement. The co-primary outcome measures were the negative predictive value (NPV) of the ASBE for the detection of electrographic status epilepticus (ESE) or possible ESE (ESE/pESE) (to be used as a screening method to exclude ESE without the need for urgent expert review) and the positive predictive value (PPV, to be used for immediate treatment without requiring urgent expert review). These were assessed using a variety of seizure burden cutoffs determined by the algorithm (>1%, >10%, >20%, >50%, and >90%).

RESULTS

In the first 2 hours, a >10% burden cutoff detected 86% (95% CI 42%-100%) of studies with ESE alone and 88% (68%-97%) with ESE/pESE; this >10% cutoff had a NPV of 99% (97%-100%) for ESE and 98% (95%-100%) for ESE/pESE. The specificity at this threshold was 79% (73%-84%) for ESE and 84% (79%-89%) for ESE/pESE, but the PPV was low at 11% (4%-23%) for ESE and 39% (26%-53%) for ESE/pESE. A >90% burden cutoff was 97% (94%-99%) specific for detecting ESE (PPV 33% [7%-70%]) and 99% (97%-100%) specific for detecting ESE/pESE [PPV 78% (40%-97%)], although the sensitivity dropped significantly to 29% (13%-51%) for ESE/pESE and 43% (10%-82%) for ESE at the >90% threshold.

DISCUSSION

The ASBE has high specificity at >90% seizure burden threshold for detecting ESE and ESE/pESE, with good PPV for ESE/pESE, though with only low-to-moderate sensitivity; at this threshold, it can be used to help triage patients for immediate treatment/transfer, urgent expert review, and additional CEEG. A >10% threshold has a high sensitivity, detecting approximately 85% of patients with ESE; at this lower cutoff, it can be used as a screening tool to exclude ESE with >95% NPV.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that ASBE software can reliably exclude ESE (98% negative predictive value using a <10% burden cutoff) without expert review in most patients requiring rapid response EEG.

Ketamine Versus Midazolam as the First-Line Continuous Infusion for Status Epilepticus in Children with Cardiac Disease

BACKGROUND

The treatment of status epilepticus (SE) in children with cardiac disease is challenging given their often-tenuous hemodynamic state. We aim to determine whether ketamine is safe and effective in children with cardiac disease as the first-line continuous infusion for the treatment of refractory SE (RSE) and to compare ketamine to midazolam for the treatment of RSE in this population.

METHODS

This is a single-center retrospective cohort study of pediatric patients with cardiac disease and RSE admitted to the cardiac intensive care unit at a tertiary children's hospital between January 1, 2017 and June 30, 2023. Consecutive patients < 18 years of age who had electroencephalogram-confirmed RSE treated with a continuous infusion of ketamine and/or midazolam were included. Clinical variables were extracted from the electronic medical record, and descriptive statistics were used.

RESULTS

Thirty-four patients with cardiac disease and RSE were treated with a continuous infusion: 15 were treated with ketamine first, and 19 were treated with midazolam first. An equivalent number of patients in both groups required a single infusion for seizure cessation (11 [73%] in the ketamine group and 12 [63%] in the midazolam group; p = 0.72). The median time from seizure onset to seizure cessation, time from seizure onset to initiation of a continuous infusion, time from initiation of a continuous infusion to seizure cessation, infusion duration, and recurrence of seizures during weaning of the continuous infusion were comparable between groups. There was no difference between groups in the proportion of patients who experienced potential adverse events attributable to their continuous infusion.

CONCLUSIONS

This retrospective cohort study provides evidence that ketamine may be as effective as midazolam as the first-line continuous infusion for RSE in children with cardiac disease. This study also provides preliminary evidence of safety in this population, at least in comparison to midazolam.

Effects of a Gluten-Free Diet on Brain Bioelectrical Activity and Neurological Symptoms in Children with Celiac Disease: A Study Using EEG Assessment

Celiac disease (CeD), also known as gluten enteropathy, is an immune-mediated inflammatory enteropathy triggered by intolerance to gluten. It presents with a spectrum of symptoms, including both gastrointestinal and extraintestinal manifestations, as well as neurological symptoms. A review of the literature indicates that 10-22% of patients with CeD present with neurological symptoms. The objective of this study is to assess the influence of a gluten-free diet (GFD) on brain bioelectrical activity and neurological symptoms in children with CeD. Methods: The study was conducted using a multidisciplinary approach, encompassing a comprehensive array of clinical data gathered alongside laboratory test results, questionnaires, and electroencephalogram (EEG) assessments. The study population included 85 children: 18 newly diagnosed cases of CeD patients (NDC), subsequently reassessed after 6 months on a GFD as a celiac disease on diet (CDD); 27 CeD patients on a GFD for over 12 months (CDD2); and 40 healthy individuals in the comparison group (CG). Results: It was observed that over half of the NDC group exhibited neurological symptoms, particularly headaches. Following a six-month period on a GFD, there was a notable reduction in symptom severity. In comparison to the CG, the NDC patient group exhibited a higher prevalence of abnormalities in EEG recordings (p = 0.032), including focal sharp waves or slow waves. Conclusions: The results demonstrate that a GFD has a positive impact on the neurological condition of children with CeD. The clinical improvements correspond with EEG normalization, which supports the hypothesis that dietary intervention plays a role in mitigating CeD-associated neurological dysfunction.

Personalized neuron-specific enolase level based on EEG pattern for prediction of poor outcome after cardiac arrest

BACKGROUND

After cardiac arrest (CA), the European recommendations suggest to use a neuron-specific enolase (NSE) level > 60 µg/L at 48-72 h to predict poor outcome. However, the prognostic performance of NSE can vary depending on electroencephalogram (EEG). The objective was to determine whether the NSE threshold which predicts poor outcome varies according to EEG patterns and the effect of electrographic seizures on NSE level.

METHODS

A retrospective study was conducted in a tertiary CA center, using a prospective registry of 155 adult patients comatose 72 h after CA. EEG patterns were classified according to the Westhall classification (benign, malignant or highly malignant). Neurological outcome was evaluated using the CPC scale at 3 months (CPC 3-5 defining a poor outcome).

RESULTS

Participants were 64 years old (IQR [53; 72,5]), and 74% were male. 83% were out-of-hospital CA and 48% were initial shockable rhythm. Electrographic seizures were observed in 5% and 8% of good and poor outcome patients, respectively (p = 0.50). NSE blood levels were significantly lower in the good outcome (median 20 µg/L IQR [15; 30]) compared to poor outcome group (median 110 µg/l IQR [49;308], p < 0,001). Benign EEG was associated with lower level of NSE compared to malignant and highly malignant patterns (p < 0.001). The NSE level was not significantly increased in patients with seizures as compared with malignant patterns (p = 0.15). In patients with a malignant EEG, a NSE > 45.2 µg/L was predictive of unfavorable outcome with 100% specificity and a higher sensitivity (70.8%) compared to the recommended NSE cut-off of 60 µg/l (Se = 66%). Combined to electrographic seizures, a NSE > 53.5 µg/L predicts poor outcome with 100% specificity and a higher sensitivity (77.7%) compared to the recommended cut-off (Se = 66.6%). Combined to a benign EEG, a NSE level > 78.2 µg/L was highly predictive of a poor outcome with a higher specificity (Sp = 100%) compared to the recommended cut-off (Sp = 94%).

CONCLUSION

In comatose patients after AC, a personalized approach of NSE according to EEG pattern could improve the specificity and sensitivity of this biomarker for poor outcome prediction. Compared to others malignant EEG, no significant difference of NSE level was observed in case of electrographic seizures.

Adherence to Recommendations and Yield of Critical Care EEG Monitoring: A Prospective Multicentric Study

PURPOSE

The American Clinical Neurophysiology Society has provided a set of recommendations on the use of critical care EEG monitoring (CEEG). However, these recommendations have not been prospectively validated. We aimed to assess the adherence to the American Clinical Neurophysiology Society recommendations for obtaining CEEG for different indications and the yield of obtained CEEG according to these different indications.

METHODS

This was a multicenter prospective observational study of critically ill adult patients between April 01, 2022, and June 22, 2022, in two academic medical centers and a large teaching hospital. Indications for CEEG, according to the American Clinical Neurophysiology Society recommendations, were determined based on clinical data at the time of discharge from the intensive care unit. The use of CEEG and detection of electrographic seizures were retrieved from the EEG databases.

RESULTS

A total of 600 patients were enrolled in this study. The primary admission diagnoses were medical (49%), surgical (30%), or neurologic/neurosurgical (21%). Approximately 60% of patients had an altered mental status. A few (6%) patients had a preceding clinical seizure, and 1% had generalized convulsive status epilepticus. Indications were identified in 226 admissions. Of these patients, 88 (39%) underwent CEEG. In addition, 12 patients underwent CEEG without clear indications. Of the 100 patients, 33 (33%) had electrographic seizures. Adherence to recommendations and yields was highest for refractory status epilepticus, altered mental status after any clinical seizure, and acute brain injury. Adherence and yield varied the most and were inversely correlated in the group of patients without acute brain injury, suggesting that additional clinical factors may have contributed to patient selection.

CONCLUSIONS

Patients meeting American Clinical Neurophysiology Society indications and receiving CEEG had a high seizure risk. Emerging CEEG programs should focus on epilepsy-related and neurologic diagnosis. Although recommendations effectively identify groups of patients with a high seizure risk, additional clinical factors might further help select candidates in the low-risk group.

Seizures and status epilepticus in anti-NMDA receptor encephalitis

BACKGROUND

Seizures, including status epilepticus (SE), are common in anti-NMDA receptor encephalitis (NMDARE). We aimed to describe clinical and electrographic features of patients with seizures with NMDARE, determine factors associated with SE, and describe long-term seizure outcomes.

METHODS

We retrospectively identified patients with seizures in the setting of NMDARE treated at inpatient Mayo Clinic sites during the acute phase of encephalitis between October 2008 and March 2023. Seizure semiology, clinical symptoms, electrographic features, neuroimaging, treatment course, complications, and outcome were abstracted. We compared clinical features between patients with and without SE.

RESULTS

We identified 29 patients with seizures during acute NMDARE. Temporal onset was the most common EEG localization (n = 14, 48.3%). Subclinical seizures were recorded in 15 (51.7%). Twelve (41.4%) patients had SE, which was associated with temporal T2-signal hyperintensity, seizures with unilateral clonic and/or tonic movements, multiple seizure foci on EEG, temporal and midline/central onset seizures, higher acute CASE scores, intensive care unit (ICU) admission, longer length of hospitalization, and need for post-hospitalization rehabilitation. One patient (3.4%) died during the acute encephalitis. One patient (3.4%) developed chronic epilepsy. The remaining patients were seizure-free at the last follow-up (median 23 months, range 2-163 months). SE was not associated with differences in outcome at last follow-up.

DISCUSSION

Seizures in NMDARE are frequently temporal onset. SE is common and associated with higher likelihood of ICU level care, longer hospitalization, and higher need for post-hospital rehabilitation. Despite the significant short-term impact of SE, long-term outcome was not affected, and seizure prognosis was favorable.

Seizure aggravation by ampicillin/sulbactam in an elderly patient with status epilepticus

BACKGROUND

Ampicillin/sulbactam (ABPC/ SBT) is one of the most common β-lactam antibiotics for patients with status epilepticus complicated with aspiration pneumonia. It is known that β-lactam antibiotics such as penicillin aggravate epileptic seizures or status epilepticus. Here, we investigated whether ABPC/SBT aggravates seizures using electroencephalography (EEG) monitoring.

CASE PRESENTATION

An 84-year-old male with status epilepticus who presented with a new onset of clonic seizures mainly of his left side and underwent continuous video EEG was analyzed. He had been suffering from severe ulcerative colitis and infectious enteritis, delirium, atrial fibrillation and deep venous thrombosis. His cerebrospinal fluid analysis was unremarkable. Four days after starting levetiracetam, he had a cluster of seizures with impaired consciousness, consistent with status epilepticus. We started fosphenytoin and phenobarbital. We also administered ABPC/SBT twice a day, ten times in total, for aspiration pneumonia while monitoring the patient. He died twelve days after the seizure onset. We analyzed the number and duration of seizures in two hours before and after starting ABPC/SBT for each administration using EEG with trendgraph. After administration of ABPC/SBT, number of seizures significantly increased from 3.2 ± 4.7 to 7.3 ± 9.7 (mean ± SD, p = 0.047, Wilcoxson's signed-rank test) per 2 h. Duration of seizures showed a tendency of increase from 199 ± 275 to 406 ± 536 s (p = 0.079).

CONCLUSIONS

In this elderly male patient with status epilepticus, administration of ABPC/SBT aggravated his seizures. EEG monitoring using a trendgraph is useful for evaluation of seizure severity and for analysis of causative factors.

Treatment of convulsive status epilepticus in Brazil: a review

Status epilepticus (SE) is the most severe presentation of epilepsy. Currently, SE is defined according to 2 sequential time frames: time 1, after which it is unlikely that the seizure will resolve spontaneously, therefore requiring the initiation of therapy; and time 2, when long-term consequences become more likely. For convulsive SE, these time frames are well defined: 5 minutes for time 1 and 30 minutes for time 2. "Time is brain" in the treatment of SE, as delays in diagnosis and treatment are associated with worse outcomes. After clinical stabilization, the first step is the administration of intravenous (IV) benzodiazepines. Rapid initiation of treatment and use of appropriate dosing are more important than the selection of a specific benzodiazepine. Following this, treatment continues with the use of an IV antiseizure medication (ASM). In Brazil, the recommended options available are phenytoin and levetiracetam. Status epilepticus is considered refractory to treatment if seizures persist after the administration of benzodiazepines and IV ASM. The cornerstone of this stage is the induction of therapeutic coma using IV anesthetic drugs (IVADs), although evidence is limited regarding the choice among midazolam, propofol, or barbiturates. Super-refractory SE is defined when seizures persist despite continuous infusion of IVADs or recur after these drugs are tapered. There is very limited data regarding the treatment of super-refractory SE. In the absence of randomized controlled trials, treatment should be guided by the physician's experience, clinical judgment, and established therapeutic options from previous reports.

Correlation Between Quantitative Background Suppression on EEG and Serum NSE in Patients With Hypoxic-ischemic Encephalopathy

PURPOSE

We evaluated the correlation between quantitative background activities on electroencephalography (EEG) and serum neuron specific enolase (NSE) in patients with hypoxic-ischemic encephalopathy as well as a diagnostic value of prognostication.

METHODS

This retrospective cohort study enrolled patients with return of spontaneous circulation after cardiac arrest from March 2010 to March 2020. The inclusion criteria were (1) older than the age of 16 years and (2) patients who had both EEG and NSE. The median time for EEG and NSE were 3 days (interquartile range 2-5 days) and 3 days (interquartile range 2-4 days), respectively. The quantification of background activity was conducted with the suppression ratio (SR). We used a machine learning (eXtreme Gradient Boosting algorithm) to evaluate whether the SR could improve the accuracy of prognostication.

RESULTS

We enrolled 151 patients. The receiver operating characteristic analysis revealed a cut-off value of serum NSE and the SR for poor outcome, serum NSE (>31.9 μg/L, area under curve [AUC] = 0.88), and the SR (>21.5%, AUC = 0.75 in the right hemisphere, >34.4%, AUC = 0.76 in the left hemisphere). There was a significant positive correlation between the severity of SR and the level of NSE ( ρ = 0.57, p < 0.0001 for the right hemisphere, ρ = 0.58, p < 0.0001 for the left hemisphere). The SR showed an excellent diagnostic value for predicting poor outcome (93% specificity, 60% sensitivity in the right hemisphere and 93% specificity, 58% sensitivity in the left hemisphere). With machine learning analysis, there was an increment in distinguishing the neurological outcome by adding SR on clinical factors.

CONCLUSIONS

The SR showed a positive correlation with the level of serum NSE. The diagnostic value of the SR for predicting poor outcome was excellent, suggesting that it can be a possible biomarker for neuroprognostication in patients with hypoxic-ischemic encephalopathy.

Using artificial intelligence to optimize anti-seizure treatment and EEG-guided decisions in severe brain injury

Electroencephalography (EEG) is invaluable in the management of acute neurological emergencies. Characteristic EEG changes have been identified in diverse neurologic conditions including stroke, trauma, and anoxia, and the increased utilization of continuous EEG (cEEG) has identified potentially harmful activity even in patients without overt clinical signs or neurologic diagnoses. Manual annotation by expert neurophysiologists is a major resource limitation in investigating the prognostic and therapeutic implications of these EEG patterns and in expanding EEG use to a broader set of patients who are likely to benefit. Artificial intelligence (AI) has already demonstrated clinical success in guiding cEEG allocation for patients at risk for seizures, and its potential uses in neurocritical care are expanding alongside improvements in AI itself. We review both current clinical uses of AI for EEG-guided management as well as ongoing research directions in automated seizure and ischemia detection, neurologic prognostication, and guidance of medical and surgical treatment.

Hypoalbuminemia in status epilepticus is a biomarker of short- and long-term mortality: A 9-year cohort study

BACKGROUND

Outcome prediction in Status epilepticus (SE) aids in clinical decision-making, yet existing scores have limitations due to SE heterogeneity. Serum albumin is emerging as a readily available prognostic biomarker in various clinical conditions. This study evaluates hypoalbuminemia in predicting short- and long-term mortality.

METHODS

Observational cohort study including non-hypoxic SE adult patients admitted to the University Hospital of Geneva (Switzerland) between 2015 and 2023. Primary outcomes were in-hospital and 6-month mortality.

RESULTS

Four hundred and ninety-six patients were included, 46 (9.3%) died in hospital; 6-month outcome was available for 364 patients, 86 (23.6%) were not alive at follow-up. Hypoalbuminemia was associated with older age and patients' comorbidities. Binomial regression showed an independent correlation between hypoalbuminemia and short- (p = 0.005, OR = 3.35, 95% CI = 1.43-7.86) and long-term mortality (p = 0.001, OR = 3.59,95% CI = 1.75-7.35). The Status Epilepticus Severity Score (STESS) had an overall AUC of 0.754 (95% CI = 0.656-0.836) for predicting in-hospital mortality and of 0.684 (95% CI = 0.613-0.755) for 6-month mortality. Through an exploratory analysis, we replaced age with hypoalbuminemia in the STESS, creating the Albumin-STESS (A-STESS) score (0-6). The global A-STESS AUC significantly improved for both in-hospital (0.837, 95% CI = 0.760-0.916, p = 0.002) and 6-month (0.739, 95% CI = 0.688-0.826; p = 0.033) mortality prediction. A-STESS-3 cutoff demonstrated a strong sensitivity-specificity balance for both in-hospital (sensitivity = 0.88, specificity = 0.68, accuracy = 0.70) and 6-month (sensitivity = 0.67, specificity = 0.73, accuracy = 0.72) mortality.

CONCLUSIONS

Hypoalbuminemia is an easily measurable biomarker reflecting the overall patient's condition and is independently related to short- and long-term SE mortality. Integrating hypoalbuminemia into the STESS (A-STESS) significantly enhances mortality prediction. Future studies are needed to externally validate the A-STESS and evaluate the benefits of albumin supplementation in SE patient prognosis.

A Current-Based EEG Amplifier and Validation With a Saline Phantom and an SSVEP Paradigm

OBJECTIVE

This work describes current-mode electroencephalography amplifiers to record the electrical activity of the tangentially oriented cells. Electroencephalography (EEG) measures the summed electrical activity from pyramidal cells in the brain by using non-invasive electrodes placed on the scalp. Traditional, voltage-based measurements are done with differential amplifiers. Depending on the location of the electrodes used for the differential measurement, EEG can estimate electrical activity from radially (common or average reference) or tangentially (bipolar derivation) oriented neurons. A limitation of the bipolar derivation is that when the electrodes are too close together, the conductive solution used to improve electrode-skin impedance can short-circuit the electrodes. Magnetoencephalography (MEG) also enables measurements from tangentially oriented cells without concerns about short-circuiting the electrodes. However, MEG is a more expensive, and a less available technology. Measuring from both radial and tangential cells can improve the resolution to localize the origin of brain activity; this could be extremely useful for diagnoses and treatment of several neurological disorders.

METHODS

Circuit design from previous implementations was improved and the device was compared to a voltage-based (vEEG) amplifier in a saline phantom and in humans with a steady state visually evoked potentials paradigm.

RESULTS

The current-based (cEEG) amplifier satisfied suggested electrical parameters for EEG amplifiers and exhibited higher sensitivity to tangential dipoles in the phantom study. It measured brain activity using the same scalp electrodes as vEEG amplifiers with comparable performance.

CONCLUSION

current-based EEG amplifiers can be comparable to traditional voltage-based amplifiers and offer complementary information.

Time is brain: detection of nonconvulsive seizures and status epilepticus during acute stroke evaluation using point-of-care electroencephalography

OBJECTIVES

Seizures are both a common mimic and a potential complication of acute stroke. Although EEG can be helpful to evaluate this differential diagnosis, conventional EEG infrastructure is resource-intensive and unable to provide timely monitoring to match the emergent context of a stroke code. We aimed to evaluate the real-world use and utility of a point-of-care EEG device as an adjunct to acute stroke evaluation.

MATERIALS AND METHODS

We performed a retrospective observational cohort study at a tertiary care community teaching hospital by identifying patients who underwent point-of-care EEG monitoring using Rapid Response EEG system (Ceribell Inc., Sunnyvale, CA) during stroke code evaluation of acute neurological deficits during the study period from January 1, 2020 to December 31, 2020. We assessed the frequency of seizures and highly epileptiform patterns among patients with either confirmed strokes or stroke mimics.

RESULTS

Point-of-care EEG monitoring was used in the wake of a stroke code in 70 patients. Of these, neuroimaging and clinical information resulted in a diagnosis of stroke in 38 patients (28 ischemic, 6 hemorrhagic, 4 transient ischemic attack; median NIHSS score of 6.5 [IQR 2.0-12.0]) and absence of any stroke in 32 patients. Point-of-care EEG detected seizures and highly epileptiform patterns in 6 (15.8 %) stroke patients and 11 (34.4 %) stroke-mimic patients, including 2 patients with persistent expressive aphasia due to repeated focal seizures.

CONCLUSIONS

Point-of-care EEG has utility for detecting nonconvulsive seizures in patients undergoing acute stroke evaluations.

Evaluating the late seizures of acute encephalopathy with biphasic seizures and late reduced diffusion via monitoring using continuous electroencephalogram

BACKGROUND

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) causes clustered seizures (late seizures; LS) 3-7 days after early seizure (ES); however, few reports provide continuous electroencephalogram (C-EEG) monitoring details. This study aimed to evaluate the initial/last detection date of LS using C-EEG and determine whether LS EEG features correlate with neurological sequelae.

MATERIALS AND METHODS

We analyzed 28 patients diagnosed with AESD who underwent C-EEG monitoring between 2015 and 2020. Multiple pediatric neurologists and epileptologists evaluated the LS detection timing, duration, and severity. Based on the evaluated data, we compared the clinical characteristics and LS-induced neurological sequelae between the ESEEG+LS (initiated C-EEG immediately after ES) and LSEEG+LS (initiated C-EEG after LS confirmation) groups. Additionally, we compared LS clinical characteristics and severity between severe and non-severe groups for 15 patients (baseline Pediatric Cerebral Performance Category Scale score <3).

RESULTS

LS was detected in 17 of 28 patients. The earliest and latest LS detection dates were 2 and 11 days, respectively, and the longest LS duration was 7 days (median, 0.6 days). Regarding neurological sequelae, the LS duration was markedly longer in the severe group than that in the non-severe group during the distant period. However, LS severity was not associated with neurological sequelae.

CONCLUSION

This study highlights the importance of C-EEG as it could aid in the early detection of LS. Neurological sequelae correlated with LS duration but not severity.

Prognostic Value of Signal Abnormalities on Brain MRI in Post-Anoxic Super-Refractory Status Epilepticus: A Single-Center Retrospective Study

BACKGROUND

Epileptiform activity, including status epilepticus (SE), occurs in up to one-third of comatose survivors of cardiac arrest and may predict poor outcome. The relationship between SE and hypoxic-ischemic brain injury (HIBI) is not established.

METHODS

This is a single-center retrospective study on consecutive patients with post-anoxic super-refractory SE. HIBI was graded as non-widespread (group 1) or widespread (group 2) by qualitative analysis of DWI/ADC and T2w-FLAIR. Between-group differences in the rate of poor neurological outcome at 6 months (primary outcome), SE resolution and consciousness recovery before discharge, and mortality at 6 months (secondary outcomes) were investigated.

RESULTS

From January 2011 to February 2023, 40 patients were included. HIBI was widespread in 45% of patients and non-widespread in 55%. The rate of poor neurological outcome at 6 months was 27% in group 1 and 83% in group 2 (OR 12.8, CI 95% [2.5-64.3], p = 0.002). The rate of consciousness recovery before discharge was 73% in group 1 versus 22% in group 2 (OR 8.8, CI 95% [1.9-40.3], p = 0.005). SE resolved in 95% of patients in group 1 versus 67% in group 2 (OR 10.5, CI 95% [1.1-97.9], p = 0.039). Mortality rate at 6 months was 27% in group 1 versus 50% in group 2 (OR 0.4, CI 95% [0.1-1.9], p = 0.303).

CONCLUSION

Patients with widespread HIBI had higher odds of poor outcome at 6 months, lower probability of SE resolution and of consciousness recovery before discharge compared to those with non-widespread HIBI. Mortality at 6 months did not differ significantly between the two groups.

Cyclic Alternating Patterns of Encephalopathy (CAPE) in Acute Brain Injury Through a Quantitative Electroencephalogram (QEEG) Perspective: A Case Series

Continuous EEG (cEEG) is a non-invasive bedside tool used to detect causative or contributory conditions of the encephalopathic state. By continuously recording electrical brain activity, it provides insights into background patterns, seizures, and dynamic cerebral activity, thereby aiding in the management of critically ill patients with acute brain injury. The term 'cyclic alternating pattern of encephalopathy' (CAPE) was recently introduced to describe alternating changes in brain electrical activity observed on EEG in critically ill patients. CAPE is characterized by electrocerebral background pattern shifts lasting at least ten seconds and repeating regularly for a minimum of six cycles. Quantitative EEG (QEEG) facilitates the interpretation of extensive cEEG datasets by applying mathematical algorithms to transform raw EEG data into time-compressed, frequency- or amplitude-based visualizations. Through Fourier analysis, QEEG decomposes the EEG signals, plotting the amplitude of different frequency bands over time, enabling easier identification of state changes such as CAPE across extended periods. This case series highlights four critically ill patients exhibiting CAPE on cEEG, with corresponding findings illustrated via QEEG. These cases demonstrate that QEEG effectively identifies CAPE by detecting changes in spectral power density and rhythmicity across distinct states. Adjusting the temporal resolution on QEEG enhances the visibility of CAPE patterns, facilitating their recognition.

A scientific approach to diagnosis of disorders of consciousness

Disorder of consciousness (DoC) are the shared clinical manifestation of severe brain injuries resulting from a variety of etiologies. The nosology of DoC, as well as the armamentarium of methods available to diagnose it, has rapidly evolved. As a result, the diagnosis of DoC is complex and dynamic. We offer an evidence-based approach to DoC diagnosis, highlighting the challenges and pitfalls therein. Accordingly, we summarize the contemporary taxonomy of DoC and its development. We discuss the standardized behavioral diagnostic tools that form the foundation of DoC diagnosis, the evidence for their use, and their limitations. We also highlight recent advances in functional MRI (fMRI) and electroencephalography (EEG) techniques to increase the sensitivity and specificity of DoC diagnosis. We discuss the concept of covert consciousness (i.e., cognitive motor dissociation) as a discrete diagnostic category of DoC, as well as its diagnostic implications. Finally, we underscore issues of neuroethics and equity raised by contemporary models of DoC.

Electrographic Seizures and Predictors of Epilepsy after Pediatric Arteriovenous Malformation Rupture

OBJECTIVES

To assess clinical and electroencephalogram (EEG) predictors of epilepsy and to describe the percentage of electrographic seizures and development of epilepsy among patients with spontaneous intracerebral hemorrhage (ICH) due to arteriovenous malformation (AVM) rupture.

STUDY DESIGN

Retrospective review of patients admitted to the pediatric intensive care unit with ICH secondary to AVM rupture over 11 years. Clinical variables were collected by review of the electronic medical record. Seizures were described as acute symptomatic (7 days after AVM rupture), subacute (7-30 days after AVM rupture) and remote (greater than 30 days after AVM rupture). Outcome metrics included mortality, and the development of epilepsy post discharge. Descriptive statistics were used.

RESULTS

Forty-three patients met inclusion criteria with a median age of 12.2 years (IQR 7.3-14.8) and 49% (21/43) were female. Sixteen percent (7/43) presented with a clinical seizure prior to EEG placement. EEG was performed in 62% (27/43) of patients; one had electrographic status epilepticus without clinical signs. Sixteen percent (7/43) of patients were diagnosed with epilepsy, with a median time to diagnosis of 1.34 years (IQR 0.55-2.07) after AVM rupture. One-year epilepsy-free survival was 84% (95% CI 70%-98%) and 2-year epilepsy-free survival was 79% (95% CI 63%-95%) Remote seizures were associated with epilepsy (P < .001), but acute symptomatic seizures were not (P = .16).

CONCLUSIONS

EEG-confirmed seizures are uncommon in patients with ICH secondary to AVM rupture; however, when identified, the seizure burden appears to be high. Patients with seizures 30 days after AVM rupture are more likely to develop epilepsy.

Lateralized Rhythmic Delta Activity and Lateralized Periodic Discharges in Critically Ill Pediatric Patients

PURPOSE

To evaluate the clinical and electrographic characteristics of critically ill pediatric patients with lateralized rhythmic delta activity (LRDA) and compare them with patients with lateralized periodic discharges (LPDs).

METHODS

This was a retrospective study examining consecutive critically ill pediatric patients (1 month-18 years) with LRDA or LPDs monitored on continuous electroencephalography. Clinical, radiologic, and electrographic characteristics; disease severity; and acute sequelae were compared between the two groups.

RESULTS

Of 668 pediatric patients monitored on continuous electroencephalography during the study period, 12 (1.79%) patients had LRDA and 15 (2.24%) had LPDs. The underlying etiologies were heterogeneous with no difference in the acuity of brain MRI changes between both groups. Lateralized rhythmic delta activity and LPDs were concordant with the side of MRI abnormality in most patients [85.7% (LRDA) and 83.3% (LPD)]. There was no difference in the measures of disease severity between both groups. Seizures were frequent in both groups (42% in the LRDA group and 73% in the LPD group). Patients in the LPD group had a trend toward requiring a greater number of antiseizure medications for seizure control (median of 4 vs. 2 in the LRDA group, p = 0.09), particularly those patients with LPDs qualifying as ictal-interictal continuum compared with those without ictal-interictal continuum ( p = 0.02).

CONCLUSIONS

Lateralized rhythmic delta activity and LPDs are uncommon EEG findings in the pediatric population. Seizures occur commonly in patients with these patterns. Seizures in patients with LPDs, especially those qualifying as ictal-interictal continuum, showed a trend toward being more refractory. Larger studies are needed in the future to further evaluate these findings.

Stimulus-induced rotary saturation imaging of visually evoked response: A pilot study

Spin-lock (SL) pulses have been proposed to directly detect neuronal activity otherwise inaccessible through standard functional magnetic resonance imaging. However, the practical limits of this technique remain unexplored. Key challenges in SL-based detection include ultra-weak signal variations, sensitivity to magnetic field inhomogeneities, and potential contamination from blood oxygen level-dependent effects, all of which hinder the reliable isolation of neuronal signals. This pilot study evaluates the performance of the stimulus-induced rotary saturation (SIRS) technique to map visual stimulation response in the human cortex. A rotary echo spin-lock (RESL) preparation followed by a 2D echo planar imaging readout was used to investigate 12 healthy subjects at rest and during continuous exposure to 8 Hz flickering light. The SL amplitude was fixed to the target neuroelectric oscillations at that frequency. The signal variance was used as contrast metric, and two alternative post-processing pipelines (regression-filtering-rectification and normalized subtraction) were statistically evaluated. Higher variance in the SL signal was detected in four of the 12 subjects. Although group-level analysis indicated activation in the occipital pole, analysis of variance revealed that this difference was not statistically significant, highlighting the need for comparable control measures and more robust preparations. Further optimization in sensitivity and robustness is required to noninvasively detect physiological neuroelectric activity in the human brain.

Electrographic Seizure Characteristics and Electrographic Status Epilepticus Prediction

PURPOSE

We aimed to characterize electrographic seizures (ES) and electrographic status epilepticus (ESE) and determine whether a model predicting ESE exclusively could effectively guide continuous EEG monitoring (CEEG) utilization in critically ill children.

METHODS

This was a prospective observational study of consecutive critically ill children with encephalopathy who underwent CEEG. We used descriptive statistics to characterize ES and ESE, and we developed a model for ESE prediction.

RESULTS

ES occurred in 25% of 1,399 subjects. Among subjects with ES, 23% had ESE, including 37% with continuous seizures lasting >30 minutes and 63% with recurrent seizures totaling 30 minutes within a 1-hour epoch. The median onset of ES and ESE occurred 1.8 and 0.18 hours after CEEG initiation, respectively. The optimal model for ESE prediction yielded an area under the receiver operating characteristic curves of 0.81. A cutoff selected to emphasize sensitivity (91%) yielded specificity of 56%. Given the 6% ESE incidence, positive predictive value was 11% and negative predictive value was 99%. If the model were applied to our cohort, then 53% of patients would not undergo CEEG and 8% of patients experiencing ESE would not be identified.

CONCLUSIONS

ESE was common, but most patients with ESE had recurrent brief seizures rather than long individual seizures. A model predicting ESE might only slightly improve CEEG utilization over models aiming to identify patients at risk for ES but would fail to identify some patients with ESE. Models identifying ES might be more advantageous for preventing ES from evolving into ESE.

Potential role of electroencephalographic monitoring for diagnosis and treatment of local anesthetic systemic toxicity during general anesthesia: a case report

BACKGROUND

Local anesthetic systemic toxicity (LAST) is a rare but potentially life-threatening complication. Under general anesthesia, neurological signs are often masked, delaying diagnosis and increasing the risk of sudden cardiovascular collapse. Therefore, early detection methods are critically needed.

CASE PRESENTATION

A 48-year-old male patient (height: 182 cm, weight: 98 kg) underwent resection of a mediastinal goiter. He received 10 mL of 4% lidocaine for topical airway anesthesia and 20 mL of 1% lidocaine with 1:100,000 epinephrine for chest wall anesthesia. Thirty minutes after airway anesthesia, continuous theta waves appeared on the frontal electroencephalogram (EEG), which were enhanced following chest wall anesthesia. These waves transitioned into a repeating pattern and evolved into sharp periodic discharges. After administering 150 mL of 20% lipid emulsion, the EEG normalized.

CONCLUSIONS

This case highlights that EEG monitoring during general anesthesia may facilitate the early detection of LAST and provide real-time feedback on treatment efficacy.

Prediction of Survival After Pediatric Cardiac Arrest Using Quantitative EEG and Machine Learning Techniques

BACKGROUND AND OBJECTIVES

Early neuroprognostication in children with reduced consciousness after cardiac arrest (CA) is a major clinical challenge. EEG is frequently used for neuroprognostication in adults, but has not been sufficiently validated for this indication in children. Using machine learning techniques, we studied the predictive value of quantitative EEG (qEEG) features for survival 12 months after CA, based on EEG recordings obtained 24 hours after CA in children. The results were confirmed through visual analysis of EEG background patterns.

METHODS

This is a retrospective single-center study including children (0-17 years) with CA, who were subsequently admitted to the pediatric intensive care unit (PICU) of a tertiary care hospital between 2012 and 2021 after return of circulation (ROC) and were monitored using EEG at 24 hours after ROC. Signal features were extracted from a 30-minute EEG segment 24 hours after CA and used to train a random forest model. The background pattern from the same EEG fragment was visually classified. The primary outcome was survival or death 12 months after CA. Analysis of the prognostic accuracy of the model included calculation of receiver-operating characteristic and predictive values. Feature contribution to the model was analyzed using Shapley values.

RESULTS

Eighty-six children were included (in-hospital CA 27%, out-of-hospital CA 73%). The median age at CA was 2.6 years; 53 (62%) were male. Mortality at 12 months was 56%; main causes of death on the PICU were withdrawal of life-sustaining therapies because of poor neurologic prognosis (52%) and brain death (31%). The random forest model was able to predict death at 12 months with an accuracy of 0.77 and positive predictive value of 1.0. Continuity and amplitude of the EEG signal were the signal parameters most contributing to the model classification. Visual analysis showed that no patients with a background pattern other than continuous with amplitudes exceeding 20 μV were alive after 12 months.

DISCUSSION

Both qEEG and visual EEG background classification for registrations obtained 24 hours after ROC form a strong predictor of nonsurvival 12 months after CA in children.

Complex auditory regularity processing across levels of consciousness in coma: Stage 1 Registered Report

A key question for the scientific study of consciousness is whether it is possible to identify specific features in brain activity that are uniquely linked to conscious experience. This question has important implications for the development of markers to detect covert consciousness in unresponsive patients. In this regard, many studies have focused on investigating the neural response to complex auditory regularities. One noteworthy example is the local global paradigm, which allows for the investigation of auditory regularity encoding at the 'global' level, based on the repetition of groups of sounds. The inference of global regularities is thought to depend on conscious access to such complex auditory stimuli as mostly shown in chronic stages of disorders of consciousness patients. However, whether global regularity encoding can identify covert consciousness along the consciousness spectrum including earlier stages of these disorders remains controversial. Here, we aim to fill this gap by investigating whether the inference of global auditory regularities can occur in acute coma, in the absence of consciousness, and how this may be modulated by the severity of the patients' clinical condition and consciousness level measured using the Full Outline of UnResponsiveness (FOUR) score. We will acquire 63-channel continuous electroencephalography to measure the neural response to global auditory regularity in comatose patients (N = 30) during the first day after cardiac arrest, when patients are unconscious, sedated and under normothermia, and during the second day (with reduced or absent sedation and body temperature control). We hypothesize that global regularity encoding will persist in the absence of consciousness independent of patient outcome, observed as above chance decoding of the neural response to global regularities using multivariate decoding analyses. We further hypothesize that decoding performance will positively correlate with the FOUR score, which indexes consciousness level, and typically improves between the first and second day after coma onset following cardiac arrest in patients with favourable outcome. In an exploratory analysis, we will also evaluate whether global regularity encoding may be influenced by the patients' clinical management, specifically sedation, also shown to affect global deviance detection. Our results will shed light on the neurophysiological correlates of complex auditory regularity processing in unconscious patients and on the link to residual levels of consciousness during the underexplored state of coma upon the first days after cardiac arrest.

Electroencephalography (EEG) for Neurological Prognostication in Post-Anoxic Coma Following Cardiac Arrest and Its Relationship to Outcome

BACKGROUND/OBJECTIVES

Cardiac arrest may cause significant hypoxic-ischemic injury leading to coma, seizures, myoclonic jerks, or status epilepticus. Mortality is high, but accurate prognostication is challenging. A multimodal approach is employed, in which electroencephalography (EEG) forms a key part with several recognised patterns of prognostic significance.

METHODS

In this retrospective study, clinical and qualitative features of the EEG of patients admitted to the Intensive Care Unit (ICU) at Kingston General Hospital following cardiac arrest from 2017 to 2020 were reviewed. The study included 81 adult patients (≥18 years). Outcome was assessed using the Cerebral Performance Category (CPC) as 1-2 (favourable) or 3-5 (unfavourable). EEG patterns were divided into groups within the highly malignant, malignant and benign patterns described in the literature.

RESULTS

There were a wide range of causes and 22% had a favourable outcome. Highly malignant, malignant and benign patterns were associated with survival in 0%, 70% and 100%, respectively, and favourable outcomes in 0%, 48% and 100%. All patients with seizures died, and 94% with myoclonus had unfavourable outcomes. In contrast, EEG reactivity and improvement on follow-up EEG were associated with a favourable outcome.

CONCLUSIONS

Highly malignant EEG, seizures and myoclonus were associated with unfavourable outcomes, while patients with malignant EEG had better outcomes.

Sensitivity of detecting interictal epileptiform activity using rapid reduced montage EEG

OBJECTIVE

Rapid EEG devices (REDs) have demonstrated substantial benefit regarding reduced time to performance of study and diagnosis in cases where urgent EEG is needed to evaluate patients for potentially revealing nonconvulsive status epilepticus and seizures. However, urgent EEG is also important in identifying cases regarding the need for initiation of antiseizure medication as well as triaging the use of continuous EEG monitoring. Some forms of REDs have a reduced montage (RRME) with electrode derivations that are one-half of standard recordings. This could impact spatial resolution and therefore potentially limit recovery of epileptiform abnormalities.

METHODS

In this study we evaluated the use of the Ceribell® rapid response EEG system and compared it to conventional video EEG (CvEEG). After applying inclusion and exclusion criteria, a total of 20 subjects were included in our analysis.

RESULTS

RRME was highly sensitive in detecting abundant and periodic discharges (p = 0.013) as well as discharges with a broad spatial distribution on CvEEG (p = 0.039). Sensitivity for detecting less prevalent discharges or those with more restricted spatial distribution was lower.

SIGNIFICANCE

Given the possibility of less frequent and more restricted epileptiform discharges eluding detection on RRME, we propose a protocol for the approach of using RRME and when to consider CvEEG when RRME is negative for epileptiform activity and highlight that urgent CvEEG may still be warranted following RRME.

Improving Electroencephalography Screening via an Online Module for Neurology Trainees: A Multicenter Study

PURPOSE

To investigate the utility of a 15-minute online module to improve the self-confidence and knowledge of neurology trainees when screening an EEG.

METHODS

We developed a fast, convenient, and accessible 15-minute online module to teach basic concepts of EEG screening using a five-step approach. To assess the efficacy of the module among neurology trainees, three surveys were developed. The EEG module and surveys were distributed to neurology trainees at multiple institutions in the United States. Associations between continuous variables were evaluated using t-test and ANOVA test.

RESULTS

A total of 199 residents from 7 different adult neurology residency programs participated in the study. We obtained a response rate of 38% (76/199) for EEG survey 1 and 25% (49/199) for the demographic survey, among junior and senior residents; 22 senior residents completed EEG survey 2. The online EEG module improved confidence when interpreting an EEG among junior residents (1.67 vs. 2.56, p < 0.0001). Senior residents improved their EEG survey score after completing the online module (53.9 vs. 68.6%, p < 0.001). Most of the trainees would recommend the online module to other trainees (93.9%) and would consider including it in an introductory course (93.9%).

CONCLUSIONS

A brief and accessible online EEG module was easily implemented as an early introduction to EEG screening for junior neurology trainees and to improve EEG screening skills for senior trainees. These findings clarify specific areas where EEG learning may be optimized and reinforce the importance of implementing innovative curricula that are accessible and efficient for all neurology trainees.

2024 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

This is the eighth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations; a more comprehensive review was done in 2020. This latest summary addresses the most recent published resuscitation evidence reviewed by the International Liaison Committee on Resuscitation task force science experts. Members from 6 International Liaison Committee on Resuscitation task forces have assessed, discussed, and debated the quality of the evidence, using Grading of Recommendations Assessment, Development, and Evaluation criteria, and their statements include consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections. In addition, the task forces list priority knowledge gaps for further research.

Optimizing brain protection after cardiac arrest: advanced strategies and best practices

Cardiac arrest (CA) is associated with high incidence and mortality rates. Among patients who survive the acute phase, brain injury stands out as a primary cause of death or disability. Effective intensive care management, including targeted temperature management, seizure treatment and maintenance of normal physiological parameters, plays a crucial role in improving survival and neurological outcomes. Current guidelines advocate for neuroprotective strategies to mitigate secondary brain injury following CA, although certain treatments remain subjects of debate. Clinical examination and neuroimaging studies, both invasive and non-invasive neuromonitoring methods and serum biomarkers are valuable tools for predicting outcomes in comatose resuscitated patients. Neuromonitoring, in particular, provides vital insights for identifying complications, personalizing treatment approaches and forecasting prognosis in patients with brain injury post-CA. In this review, we offer an overview of advanced strategies and best practices aimed at optimizing brain protection after CA.

Commentary on stimulus-induced arousal with transient electroencephalographic improvement distinguishes nonictal from ictal generalized periodic discharges

Here we critique recent arguments proposing to distinguish ictal from non-ictal generalized periodic discharges (GPDs) based on etiology and stimulation response, arguing that these are unreliable. We advocate for an empirical approach to GPDs: describe objectively, interpret through medication trials, and base further treatment on response. We call for evidence-based approaches considering meaningful clinical outcomes.

The role of genetic testing in adult patients with unexplained epilepsy

OBJECTIVE

Genetic causes are often overlooked in patients with epilepsy of unknown etiology, particularly in adults. We aimed to evaluate clinical features of genetic epilepsy and the utility of genetic testing.

METHODS

We retrospectively screened consecutive unrelated adult epilepsy patients at an epilepsy clinic from April 2022 to May 2023. Patients with unknown etiology or special brain lesions were classified as unexplained epilepsy. In them, patients with young-onset seizures or family history of seizures who were recommended for and ultimately underwent genetic testing using either panel next-generation sequencing (NGS) or whole-exome sequencing (WES) were enrolled. A definite or probable genetic diagnosis was established through genotype-phenotype correlation. We compared the demographic characteristics between genetic epilepsy and other etiologies.

RESULTS

Of the 374 adult epilepsy patients, 258 were classified as unexplained epilepsy, 129 were suspected of having genetic epilepsy due to young-onset seizures or a positive family history, 33 underwent genetic testing; 13 harbored variants classified as pathogenic, and 6 reached a definite genetic diagnosis, resulting in a yield of 18%. Among the 27 patients without a definite genetic diagnosis, 7 had a nongenetic structural etiology. Patients with genetic etiology exhibited greater multisystem involvement particularly multiple structural anomalies and early childhood-onset seizures, but wasn't directly correlated with young-onset seizures or a positive family history. The diagnostic yield was comparable between panel NGS and WES.

SIGNIFICANCE

In adult patients with unexplained epilepsy, genetic epilepsy is more associated with multisystem involvement and multiple structural anomalies but not family history of seizures or young-onset seizures.

Perampanel as an Add-On Therapy in Patients with Refractory Status Epilepticus and Postanoxic Encephalopathy: A Real-Life Single-Center Retrospective Cohort Study

BACKGROUND

Data on the efficacy of perampanel in refractory status epilepticus (RSE) and postanoxic encephalopathy (PAE) are limited; its use in such conditions is currently off-label.

METHODS

We conducted a retrospective cohort study of consecutive adult patients with RSE, including PAE, exhibiting electroencephalographic patterns indicative of status epilepticus who were treated at our center (January 2018 to December 2022) with assessment of clinical and electroencephalographic outcomes.

RESULTS

Thirty-six patients were included in the study, of whom 29 had nonanoxic RSE and 7 had PAE. Within the nonanoxic RSE subgroup, 45% (13 of 29; 95% confidence interval [CI] 27-63%) of study participants were responders, 34% (10 of 29; 95% CI 17-52%) were partial responders, and 21% (6 of 29; 95% CI 6-35%) were nonresponders. In the PAE subgroup (n = 7), no patients fully responded to perampanel; 43% (3 of 7; 95% CI 6-80%) were partial responders, and 57% (4 of 7; 95% CI 20-95%) were nonresponders. Responder and nonresponder study participants exhibited overlapping baseline characteristics. No significant differences in duration of hospitalization were observed between responders and nonresponders in both subgroups. Responders in the RSE subgroup had a median discharge modified Rankin Scale score of 3 (interquartile range 3-4), and nonresponders had a median discharge modified Rankin Scale score of 5 (interquartile range 5-6).

CONCLUSIONS

Despite limitations from the retrospective design and the small population size, this study suggests that perampanel use in nonanoxic RSE appears to yield promising results at moderate doses, including a tendency toward a better functional outcome at discharge, without significant adverse effects. However, in patients with PAE, the drug seems to show suboptimal performance. Perampanel appears to have promising efficacy as an add-on therapy in nonanoxic RSE. However, in patients with PAE, its efficacy seems to be lower. Further studies are warranted to confirm these observations.

Early diagnosis of nonconvulsive status epilepticus due to lithium intoxication using 6-channel electroencephalography

INTRODUCTION

Nonconvulsive status epilepticus is a severe complication of lithium intoxication that requires prompt diagnosis and treatment. While conventional electroencephalography (EEG) remains the gold standard for diagnosis for nonconvulsive status epilepticus, its implementation in emergency settings can be challenging and time-consuming. We present a case in which simplified EEG with six electrodes enabled rapid detection and monitoring of nonconvulsive status epilepticus in lithium intoxication in the emergency setting.

CASE PRESENTATION

A 65-year-old woman with stable bipolar disorder presented to our emergency department with impaired consciousness. She had been maintained on lithium carbonate (1600 mg daily) and carbamazepine (400 mg daily) for over 10 years. Following two weeks of nausea and recent onset of agitation and slurred speech, she developed generalized convulsions. Laboratory examinations revealed elevated serum lithium (3.88 mEq/L) and acute renal dysfunction (creatinine 347.5 μmol/L). After resolving initial convulsions, a simplified sixelectrode EEG (Neurofax EEG-1250, Nihon Kohden Corporation, Tokyo, Japan), applied by an emergency physician, demonstrated generalized spike and wave patterns consistent with nonconvulsive status epilepticus. Despite initial seizure control with midazolam during intubation, continuous EEG monitoring revealed recurrent nonconvulsive status epilepticus. After hemodialysis and continued deep sedation, she was discharged on day 40 without neurological sequelae.

DISCUSSION

This case demonstrates the utility of simplified EEG in emergency settings for early detection and monitoring of nonconvulsive status epilepticus in lithium intoxication. The ability of emergency physicians to apply and interpret simplified EEG enabled timely intervention and prevention of neurological complications. While further research is needed to validate interpretation protocols by non-EEG specialists, simplified EEG shows promise as an accessible tool for rapid assessment of neurotoxicity in lithium intoxication, potentially improving patient outcomes through earlier intervention.

Comparison of Continuous Intracortical and Scalp Electroencephalography in Comatose Patients with Acute Brain Injury

BACKGROUND

Depth electroencephalography (dEEG) is a recent invasive monitoring technique used in patients with acute brain injury. This study aimed to describe in detail the clinical manifestations of nonconvulsive seizures (NCSzs) with and without a surface EEG correlate, analyze their long-standing effects, and provide data that contribute to understanding the significance of certain scalp EEG patterns observed in critically ill patients.

METHODS

We prospectively enrolled a cohort of 33 adults with severe acute brain injury admitted to the neurological intensive care unit. All of them underwent multimodal invasive monitoring, including dEEG. All patients were scanned on a 3T magnetic resonance imaging scanner at 6 months after hospital discharge, and mesial temporal atrophy (MTA) was calculated using a visual scale.

RESULTS

In 21 (65.6%) of 32 study participants, highly epileptiform intracortical patterns were observed. A total of 11 (34.3%) patients had electrographic or electroclinical seizures in the dEEG, of whom 8 had both spontaneous and stimulus-induced (SI) seizures, and 3 patients had only spontaneous intracortical seizures. An unequivocal ictal scalp correlate was observed in only 3 (27.2%) of the 11 study participants. SI-NCSzs occurred during nursing care, medical procedures, and family visits. Subtle clinical manifestations, such as restlessness, purposeless stereotyped movements of the upper limbs, ventilation disturbances, jerks, head movements, hyperextension posturing, chewing, and oroalimentary automatisms, occurred during intracortical electroclinical seizures. MTA was detected in 18 (81.8%) of the 22 patients. There were no statistically significant differences between patients with MTA with and without seizures or status epilepticus.

CONCLUSIONS

Most NCSzs in critically ill comatose patients remain undetectable on scalp EEG. SI-NCSzs frequently occur during nursing care, medical procedures, and family visits. Semiology of NCSzs included ictal minor signs and subtle symptoms, such as breathing pattern changes manifested as patient-ventilator dyssynchrony.

Utility of CT perfusion in seizures and rhythmic and periodic patterns

OBJECTIVE

CT hyper-perfusion has been reported in non-convulsive status epilepticus (NCSE), while its occurrence and relevance after single seizures or with rhythmic and periodic patterns (RPPs) that lie along the ictal-interictal continuum (IIC), remain unclear. The goal of the study is to assess the role of CT perfusion (CTP) in diagnosing patients with clinical seizures, subclinical seizures, or RPPs that lie along the IIC, to help in the clinical assessment of these entities.

METHODS

We retrospectively reviewed inpatients who underwent a CTP and an EEG within 6 h of each other. CTP and EEGs were blindly reviewed independent of electronic medical records.

RESULTS

Out of 103 patients, 15 patients (15 %) demonstrated hyper-perfusion, 40 patients (39 %) had hypo-perfusion, while 48 patients (47 %) had normal CTP. Patients with focal CTP hyperperfusion were more likely to have clinical seizures, electrographic seizures, and/or lateralized rhythmic periodic patterns (RPPs) compared to those without CTP hyperperfusion. Focal CTP hyper-perfusion had 34 % sensitivity and 96 % specificity for identifying patients with clinical seizures, and a 40 % sensitivity and 92 % specificity for identifying patients with electrographic seizures or lateralized RPP. Although the numbers were small, none of the patients with generalized periodic discharges or generalized rhythmic delta activity had CTP hyper-perfusion.

CONCLUSIONS

Focal CTP hyper-perfusion has low sensitivity but high specificity for identifying patients with seizures and lateralized RPPs, and may be considered in the clinical assessment of patients where the clinical information are unclear or insufficient.

SIGNIFICANCE

The presence of CTP hyper-perfusion should alert the physician to the possibility of an ictal related etiology accounting for the patient's symptoms.