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

Specific early electroencephalogram for the diagnosis of sporadic Creutzfeldt-Jakob disease

An early diagnosis is required for intervention in prion disease cases. To elucidate the specificity of early electroencephalography discharges in cases of sporadic Creutzfeldt-Jakob disease, we analysed epileptiform discharges through electroencephalography. Nine patients with methionine/methionine type 1/classic sporadic Creutzfeldt-Jakob disease and 20 patients with status epilepticus were included. Generalized periodic discharges, lateralized periodic discharges, and central sagittal sporadic epileptiform discharges were evaluated. Central sagittal sporadic epileptiform discharges were defined as nonrhythmic and nonperiodic waveforms showing generalized spike-and-wave complexes and/or sharp waves predominantly in the central sagittal region. In the sporadic Creutzfeldt-Jakob disease group, central sagittal sporadic epileptiform discharges, lateralized periodic discharges, and generalized periodic discharges were observed in five (55.6%), one (11.1%), and eight (88.9%) patients, respectively, with an average duration from onset to the appearance of the discharges of 1.6, 1.0, and 2.44 months, respectively. In the status epilepticus group, these discharges were detected in one (5.0%), six (30.0%), and six (30.0%) patients, respectively. The incorporation of central sagittal sporadic epileptiform discharges and lateralized periodic discharges into the World Health Organization diagnostic criteria, alongside generalized periodic discharges, significantly shortened the average lapse from symptom onset to sporadic Creutzfeldt-Jakob disease diagnosis (2.06 months vs. 2.44 months; p = 0.02). Central sagittal sporadic epileptiform discharges emerge as promising biomarkers for distinguishing sporadic Creutzfeldt-Jakob disease from status epilepticus, and together with lateralized periodic discharges provide an opportunity for early diagnosis of sporadic Creutzfeldt-Jakob disease.

Screening of toxic-metabolic encephalopathy with and without epileptic seizure with density spectral array

OBJECTIVE

Although toxic metabolic encephalopathy (TME) is clinically common, distinguishing between TME with/without epileptic findings remains challenging. We examined the efficacy of density spectral array (DSA), a form of power-spectrum electroencephalography (EEG) screening tool, for clinicians not specializing in EEG interpretation to make this distinction.

METHODS

Among 346 patients with suspected TME who underwent EEG for acute impaired consciousness (2012-2023), 149 were ultimately diagnosed with TME (mean age 68.9 ± 13.3 years) were enrolled. Using EEG data, we operationally classified DSAs based on frequency changes, as follows: 1) flame or cyclic (presence of temporal frequency change), 2) band (presence of continuous alpha-range activity), 3) gradation (alpha to delta-range activity), and 4) other patterns. The inter-rater agreement rate for DSA pattern assignment was evaluated in a double-blind manner to confirm the reasonableness of the classification. Additionally, we evaluated the sensitivity and specificity of each DSA pattern at determining the ultimate diagnostic outcomes (TME alone or TME with epileptic findings).

RESULTS

TME alone and TME with epileptic findings were 136 and 13, respectively. The inter-rater agreement for DSA classification was high among clinicians (κ = 0.72-0.92). The flame or cyclic pattern exhibited high specificity (97.1 %), but low sensitivity (23.1 %) for the diagnosis of TME with epileptic findings. Conversely, the band and gradation patterns showed a high specificity (76.9-84.6 %) for the diagnosis of TME alone.

CONCLUSIONS

Overall, our DSA classification demonstrated a high inter-rater agreement rate, indicating utility as a simple yet specific tool for distinguishing TME with and without epileptic findings.

Acute Symptomatic Seizures During CAR T-Cell Therapy for Hematologic Malignancies: Tri-Site Mayo Clinic Experience

BACKGROUND AND OBJECTIVES

Chimeric antigen receptor T-cell (CAR T-cell) therapy is associated with neurotoxicity, which may include acute symptomatic seizures (ASySs). Specific risk factors and short-term and long-term outcomes of ASyS associated with CAR T-cell therapy have not been well investigated.

METHODS

This retrospective cohort study evaluated incidence and risk factors for ASyS during CAR T-cell therapy. We included patients treated at Mayo Clinic in Minnesota, Florida, and Arizona who underwent CAR T-cell therapy for hematologic malignancies from October 2019 to November 2023. Pretreatment demographics, clinical information, type of CAR T-cell therapy, neuroimaging, laboratories during treatment, and clinical features during admission were analyzed. Data on treatment and prevalence of seizures, EEG, and survival at the last follow-up were assessed. T-tests and nonparametric testing were performed on categorical and continuous data, respectively. Multivariable analysis was also performed.

RESULTS

We included 180 patients (mean age 62.3 years, 57.2% women) with 8 (4.4%) developing ASyS at a mean of 8.0 ± 5.3 days after therapy. Earlier onset of cytotoxic release syndrome (odds ratio [OR] 1.81, 95% CI 0.62-2.99, p = 0.007), higher grade immune effector cell-associated neurotoxicity syndrome (ICANS) (OR -1.43, 95% CI -1.86 to -1.00, p < 0.001), focal neurologic deficits (OR 7.15, 95% CI 1.60-32.14, p = 0.007), and cefepime (OR 0.58, 95% CI 0.51-0.65, p = 0.022) exposure were significantly associated with a higher risk of ASyS. A multivariable model accounting for age and sex fit best using the lowest minimum immune effector cell encephalopathy score and highest ICANS grade (R2 = 0.555, χ2 = 28.507, p < 0.001). ASyS was associated with death at the last follow-up (OR 0.48, 95% CI 0.41-0.56, p = 0.007), although short-term outcomes were not affected by ASyS. Nonprotocolized antiseizure medication (ASM) prophylaxis did not affect ASyS incidence.

DISCUSSION

This study suggests a low risk of ASyS because of CAR T-cell therapy, with certain risk factors that may be predictive of ASyS and lack of a definitive and direct association of ASyS with outcomes. The current approach to ASM prophylaxis should be reconsidered when ICANS is encountered. This study is limited by its retrospective nature and the use of ASM prophylaxis in all patients with ICANS, which requires further study to assess its necessity.

Developing an Electroencephalogram-based Model to Predict Awakening after Cardiac Arrest Using Partial Processing with the BIS Engine

BACKGROUND

Accurate prognostication in comatose survivors of cardiac arrest is a challenging and high-stakes endeavor. The authors sought to determine whether internal electroencephalogram (EEG) subparameters extracted by the BIS monitor (Medtronic, USA), a device commonly used to estimate depth of anesthesia intraoperatively, could be repurposed to predict recovery of consciousness after cardiac arrest.

METHODS

In this retrospective cohort study, a three-layer neural network was trained to predict recovery of consciousness to the point of command following versus not based on 48 h of continuous EEG recordings in 315 comatose patients admitted to a single U.S. academic medical center after cardiac arrest (derivation cohort, n = 181; validation cohort, n = 134). Continuous EEGs were partially processed into subparameters using virtualized emulation of the BIS Engine ( i.e. , the internal software of the BIS monitor) applied to signals from the frontotemporal leads of the standard 10-20 EEG montage. The model was trained on hourly averaged measurements of these internal subparameters. This model's performance was compared to the modified Westhall qualitative EEG scoring framework.

RESULTS

Maximum prognostic accuracy in the derivation cohort was achieved using a network trained on only four BIS subparameters (inverse burst suppression ratio, mean spectral power density, gamma power, and theta/delta power). In a held-out sample of 134 patients, the model outperformed current state-of-the-art qualitative EEG assessment techniques at predicting recovery of consciousness (area under the receiver operating characteristics curve, 0.86; accuracy, 0.87; sensitivity, 0.83; specificity, 0.88; positive predictive value, 0.71; negative predictive value, 0.94). Gamma band power has not been previously reported as a correlate of recovery potential after cardiac arrest.

CONCLUSIONS

In patients comatose after cardiac arrest, four EEG features calculated internally by the BIS Engine were repurposed by a compact neural network to achieve a prognostic accuracy superior to the current clinical qualitative accepted standard, with high sensitivity for recovery. These features hold promise for assessing patients after cardiac arrest.

Altered neural avalanche spreading in people with drug-resistant epilepsy✰

OBJECTIVE

To characterize a peculiar "EEG endophenotype" of drug-resistant epilepsy (DRE) through the graph theory characterization of avalanche spatiotemporal spreading properties.

METHODS

We performed avalanche analysis and computed avalanche transition matrices (ATMs) on 19-channel scalp EEG of 120 people with epilepsy (60 DRE and 60 non-DRE) who assumed two anti-seizure medications, comparing such results with a group of 40 healthy subjects (HS). Network topologies of ATMs were characterized through graph theory metrics. We performed an analysis of variance to compare aperiodic metrics between HS, DRE and non-DRE. Logistic regression was performed to test and compare the ability of graph theory metrics on ATM and clinical features to correctly discriminate the PwE group according to the clinical outcome (DRE or non-DRE).

RESULTS

DRE exhibited a peculiar altered avalanche spreading as proved by the higher mean betweenness centrality, the longer characteristic path length and the lower small-world index (more regular and less plastic network topology) of ATMs than non-DRE and HS (p-values from <0.001 to 0.05). Graph metrics on ATMs significantly improved the yield of detecting DRE and contributed the most to the model accuracy (0.83) than clinical features. Resting-state EEG activity of HS and PwE did not deviate from the characteristics of a system operating at criticality.

CONCLUSIONS

ATMs detect alterations of resting-state networks peculiar to the DRE condition.

SIGNIFICANCE

These findings could open new scenarios for the future identification of promising biomarkers of DRE through scalp EEG.

EEG as a predictive biomarker of neurotoxicity in anti-CD19 CAR T-cell therapy

OBJECTIVE

Immune effector cell-associated neurotoxicity syndrome (ICANS) is a potentially fatal complication of CD19-directed CAR T-cell therapy. The aim of this study was to investigate the role of EEG as a predictive biomarker of ICANS.

METHODS

In this prospective, monocentric, cohort study, consecutive refractory B-cell non-Hodgkin lymphoma patients undergoing CAR T-cell therapy had EEG assessments at fixed time points pre- and post-infusion. The risk of ICANS was evaluated according to EEG findings detected qualitatively, using a grading scale ranging from 0 (normal) to 3 (severely abnormal), and quantitatively, using power spectral and connectivity measures.

RESULTS

307 EEGs from 68 patients have been qualitatively evaluated, of whom 238 were eligible for quantitative analysis. Neurotoxicity manifested in 22/68 (32.4%) patients. Pre-infusion EEG abnormalities (grade 1 and 2) were qualitatively detected in 8/68 (11.7%) patients, emerging as a risk factor for ICANS [HR 5.8 (95%CI 2.6-12.9)]. Quantitative analysis of pre-infusion EEGs did not yield significative results. Post-infusion qualitative EEG abnormalities were associated to a higher risk of ICANS development [HR 11.6 (4.4-30.5) for grade 2; HR 9.7 (2.6-36.6) for grade 3]. Concerning the quantitative analysis, in post-infusion EEGs higher theta energy [HR 1.10 (1.03-1.16)] and delta + theta/alfa ratio [HR 1.37 (1.11-1.67)] were associated to higher risk of ICANS, while higher beta energy resulted protective [HR 0.91 (0.85-0.97)].

CONCLUSIONS

Our study establishes EEG as a predictive tool for identifying patients at risk for ICANS before CAR T-cell infusion, who may benefit from prophylactic treatments, and anticipating ICANS onset following infusion, enabling early intervention.

Association of the Timing and Type of Acute Symptomatic Seizures With Poststroke Epilepsy and Mortality

BACKGROUND

Acute symptomatic seizures (ASyS) increase the risk of epilepsy and mortality after a stroke. The impact of the timing and type of ASyS remains unclear.

METHODS

This multicenter cohort study included data from 9 centers between 2002 and 2018, with a final analysis in February 2024. The study included 4552 adults (2005 female; median age, 73 years) with ischemic stroke and no seizure history. Seizures were classified using International League Against Epilepsy definitions. We examined ASyS occurring within seven days after stroke. The main outcomes were all-cause mortality and epilepsy. Validation of the updated SeLECT score (SeLECT-ASyS) was performed in 3 independent cohorts (Switzerland, Argentina, and Japan) collected between 2012 and 2024, including 74 adults with ASyS.

RESULTS

The 10-year risk of poststroke epilepsy ranged from 41% to 94%, and mortality from 36% to 100%, depending on ASyS type and timing. ASyS on stroke onset day had a higher epilepsy risk (adjusted hazard ratio [aHR], 2.3 [95% CI, 1.3-4.0]; P=0.003) compared with later ASyS. Status epilepticus had the highest epilepsy risk (aHR, 9.6 [95% CI, 3.5-26.7]; P<0.001), followed by focal to bilateral tonic-clonic seizures (aHR, 3.4 [95% CI, 1.9-6.3]; P<0.001). Mortality was higher in those with ASyS presenting as focal to bilateral tonic-clonic seizures on day 0 (aHR, 2.8 [95% CI, 1.4-5.6]; P=0.004) and status epilepticus (aHR, 14.2 [95% CI, 3.5-58.8]; P<0.001). The updated SeLECT-ASyS model, available as an application, outperformed a previous model in the derivation cohort (concordance statistics, 0.68 versus 0.58; P=0.02) and in the validation cohort (0.70 versus 0.50; P=0.18).

CONCLUSIONS

ASyS timing and type significantly affect epilepsy and mortality risk after stroke, improving epilepsy prediction and guiding patient counseling.

Features affecting treatment decisions and outcome in refractory status epilepticus

OBJECTIVE

Refractory status epilepticus (RSE) is associated with worse outcomes than responsive established status epilepticus (SE). Guidelines recommend that refractory convulsive SE should be treated with continuous intravenous anesthetic drugs (CIVADs). Many cases of nonconvulsive SE are not reated with CIVADs, and the use of anesthesia might be associated with increased mortality. The factors leading to the decision to use anesthesia and how these might affect outcome are still largely unknown. Our goal was to identify features of refractory SE associated with treatment choices and outcome.

METHODS

A single-center, retrospective study was conducted of all consecutive patients with RSE admitted to a tertiary center between January 2015 and December 2020. We collected demographic and clinical variables at SE onset and at time of third-line treatment, including ictal burden during the hour preceding the administration of the third-line treatment. The primary outcome measure was the decision to use CIVADs as third-line treatment. Secondary outcome measures were in-hospital mortality and functional outcome at discharge.

RESULTS

One hundred sixty-one RSE episodes were included. Of these, 29 (18%) received CIVADs as third-line treatment and 61 (38%) died. The type of third-line treatment was not associated with mortality. CIVADs were more likely to be used with higher ictal burden, fewer comorbidities, a lower Glasgow Coma Scale (GCS) score at time of third-line administration, and in the absence of history of epilepsy (odds ratio [OR] = 1.03, .76, .66, and .25, respectively). Multivariable analyses also identified comorbidities, an acute etiology, and lower GCS score at time of third-line administration as risk factors of mortality (OR = 1.43, .09-.28, and .80, respectively). Ictal burden was not associated with outcome.

SIGNIFICANCE

Ictal burden, semiology, and consciousness at time of third-line treatment are associated with the decision to use CIVADs in SE. Semiology and consciousness at time of third-line treatment are also associated with mortality.

Management and Outcomes in Confirmed or Suspected Acute Symptomatic Seizure: Role of Structured Outpatient Care

OBJECTIVE

Post-discharge management and outcomes of acute symptomatic seizures (ASyS) remain underexplored. We analyzed post-discharge ASM management and outcomes in ASyS patients undergoing continuous EEG (cEEG), including the role of outpatient care through a post-acute symptomatic seizure (PASS) clinic.

METHODS

We performed a single-center, retrospective study of adults without epilepsy discharged on ASMs due to witnessed or suspected ASyS in 2019. A cause-specific cumulative distribution function was used to estimate outcome probabilities, and cause-specific Cox proportional hazards models examined factors influencing the first ASM discontinuation, subsequent unprovoked seizure, and death.

RESULTS

The study evaluated 307 patients [mean 61.6 years; 51.8% females], 60.2% with confirmed ASyS [144 (46.9%) clinical ASyS; 41 (13.4%) with electrographic ASyS only]. During median 14-month follow-up, 31.9% discontinued ASM, 18.6% experienced unprovoked seizure, and 38.4% died. Based on cumulative incidence function, ASM discontinuation, unprovoked seizure, and death at 12 months occurred in 26.2%, 14.1%, and 29.3% of patients, respectively. 59.6% of alive patients without unprovoked seizures were taking ASMs. Clinical ASyS (HR 0.48; 95% CI 0.31, 0.76), electrographic ASyS only (HR 0.37; 0.17, 0.82), and acute epileptiform abnormalities (HR 0.48; 0.27, 0.84) were associated with lower ASM discontinuation. Unprovoked seizures were associated with epileptiform outpatient EEG (HR 5.40; 2.62, 11.12). PASS clinic patients discontinued ASMs 74% faster (HR 1.74; 1.12, 2.71), with 88% lower risk of unprovoked seizures (HR 0.12; 0.04, 0.34).

INTERPRETATION

Outpatient ASM overuse in ASyS patients is common. Outpatient epileptiform abnormalities may predict unprovoked seizures. Structured outpatient care, such as PASS clinics, facilitates faster yet safer ASM discontinuation.

Association of Time to Continuous EEG Initiation With Outcomes in Critically Ill Patients

PURPOSE

Continuous electroencephalography (cEEG) is used in the critical care setting for seizure detection and treatment, sedation management, and ischemia detection. Further evidence is needed to support whether early cEEG use can improve outcomes. We examined whether time from admission to cEEG initiation affects outcomes.

METHODS

This is a single-center cohort study of critically ill adults (age > 18 years) who underwent cEEG monitoring within 7 days of admission from January to December 2019. Patients with anoxic brain injury were excluded. Time (hours) from admission to cEEG was recorded. Outcomes were in-hospital mortality and poor discharge modified Rankin Score (4-6). Results are reported as median [quartile range] and odds ratio (OR) [confidence intervals, CI].

RESULTS

In total, 464 patients met eligibility. Median time to cEEG was 23 hours [13, 52]. On multivariable analysis, increasing time to cEEG was associated with discharge mortality (OR, 1.006 [CI, 1.0002-1.013], 0.1%/hour [CI, 0.02-0.2]) and poor outcome (OR, 1.013 [CI, 1.005-1.020], 0.2%/hour [CI, 0.07-0.3]). Median time to cEEG initiation in patients with clinical concern for seizures/status at presentation (n = 121) was 12 hours [6, 17] and in patients without clinical concern for seizures at presentation (n = 343) was 31 hours [18, 66]. In patients without clinical concern for seizures/status epilepticus at presentation, time to cEEG continued to be associated with mortality (OR, 1.007 [CI, 1.001-1.014)] and poor outcome (OR, 1.012 [CI, 1.003-1.021]).

CONCLUSIONS

Increasing time to cEEG initiation was associated with higher mortality and worse outcomes. We hypothesize earlier cEEG results in timely interventions including treatment escalation and de-escalation that may improve outcomes.

Predicting Intraoperative Burst Suppression Using Preoperative EEG and Patient Characteristics

Burst suppression (BS) is an electroencephalogram (EEG) pattern observed in patients undergoing general anesthesia. The occurrence of BS is associated with adverse outcomes such as postoperative delirium, extended recovery time, and increased postoperative mortality. The detection and prediction of BS can help expedite the evaluation of patient conditions, optimize anesthesia administration, and improve patient safety. This study explores the potential for automatic BS detection using intraoperative EEG and BS prediction using preoperative EEG signals and patient characteristics. A dataset comprising 287 patients who underwent carotid endarterectomy procedures at Maastricht University Medical Center+ was analyzed. An EEG toolbox developed by T. Zhan at the Massachusetts Institute of Technology was utilized for the automatic detection/annotation of BS, while five machine learning classifiers were employed to predict BS occurrence using preoperative data. Based on the 160 patients manually annotated by EEG experts (regarding the presence or absence of BS), the automatic detection tool demonstrated an accuracy of 0.75. For the BS prediction task, an initial subset of 120 patients was evaluated, showing modest performance, with the K-nearest neighbors ([Formula: see text]) classifier achieving the best results, with an accuracy of 0.72. Subsequent experiments indicated that increasing the number of patients (by using Zhan's Toolbox to annotate the unlabeled instances), applying SMOTE to balance the training set, and enriching the feature set was beneficial. The final experiment demonstrated a significant improvement, with Random Forest and Gradient Boosting outperforming other classifiers, achieving an accuracy of 0.86 and ROC-AUC of 0.94. Patient characteristics, including type of anesthetic agents, symptoms, age, mean absolute delta power, mean absolute theta power, and cognitive impairment, were identified by an xAI method as important features potentially indicating the predisposition to experience BS.

Multimodal assessment of favorable neurological outcome using NSE levels and kinetics, EEG and SSEP in comatose patients after cardiac arrest

BACKGROUND

Prognostic markers of good neurological outcome after cardiac arrest (CA) remain limited. We aimed to evaluate the prognostic value of neuron-specific enolase (NSE), electroencephalogram (EEG) and somatosensory evoked potentials (SSEP) in predicting good outcome, assessed separately and in combination.

METHODS

A retrospective study was conducted in a tertiary CA center, using a prospective registry. We included all patients comatose after discontinuation of sedation and with one EEG and NSE blood measurement at 24, 48 or/and 72 h after CA. The primary outcome was favorable neurological outcome at three months, a Cerebral Performance Categories (CPC) scale 1-2 defining a good outcome.

RESULTS

Between January 2017 and April 2024, 215 patients were included. Participants were 63 years old (IQR [52-73]), and 73% were male. At 3 months, 54 patients (25.1%) had a good outcome. Compared to the poor outcome group, NSE blood levels were significantly lower in the good outcome group at 24 h (39 IQR[27-45] vs 54 IQR[37-82]µg/L, p < 0.001), 48 h (26 [18-43] vs 107 [54-227]µg/L, p < 0.001) and 72 h (20 µg/L IQR [15-30] vs 184 µg/l IQR [60-300], p < 0,001). Normal NSE (i.e., < 17 µg/L) at 24 h was highly predictive of good outcome, with a predictive positive value (PPV) of 71% despite a sensitivity (Se) of 9%. The best cut-off values for NSE at 24, 48 and 72 h were below 45.5, 51.5 and 41.5 µg/L, yielding PPV of 64%, 80% and 83% and sensitivities of 74%, 93% and 90%, respectively. A decreasing trend in NSE levels between 24 and 72 h was also highly predictive of good outcome (PPV 82%, Se 81%). A benign EEG pattern was more frequently observed in the good outcome group (87.1 vs 14.9%, p < 0.001) and predicted a good outcome with a PPV of 72% and a Se of 94%. Regarding SSEPs, a bilateral N20-baseline amplitude > 0.85 µV was predictive of good outcome (PPV 75%, Se 100%). The combination of NSE < 51.5 µg/l at 48 h, a decreasing NSE trend between 24 and 72 h and a benign EEG showed the best predictive value (PPV 96%, Se 76%).

CONCLUSION

In comatose patients after CA, a low NSE levels at 24, 48 h or 72 h, a decreasing trend in NSE over time, a benign EEG and a high N20 amplitude are robust markers of favorable outcome, reducing prognosis uncertainty.

Neural correlates of β-lactam exposure in intensive care unit patients: an observational, prospective cohort study

BACKGROUND

β-lactam-induced neurotoxicity in critical care patients can compromise clinical outcomes. Despite the growing use of therapeutic drug monitoring (TDM) for β-lactams, clear toxicity thresholds remain undefined, leaving clinicians uncertain about dosing adjustments when adverse effects occur. Identifying a relevant and easily detectable neurophysiological biomarker for β-lactam exposure would improve monitoring and prevent serious complications.

METHODS

In a prospective multicenter, non-interventional study, we analyzed electroencephalographic (EEG) signals of 56 patients hospitalized in intensive care units (ICUs) receiving continuous infusions of five β-lactams (meropenem, piperacillin/tazobactam, cefepime, cefotaxime, or ceftazidime). We applied a time frequency decomposition on these EEG data to investigate quantitatively the power of neural dynamics across frequencies ranging from 1 to 45 Hz. We used a multivariate pattern decoding method to correlate the β-lactam exposure and Sepsis-related Organ Failure Assessment (SOFA) scores with the neural activity.

RESULTS

β-lactam exposure correlated with increased β-low γ neural dynamics (20-40 Hz) (p < 0.001, FDR corrected), independent of other clinical factors or medications. β-neural activity was most pronounced in central electrodes (C3: r = 0.20, p < 0.01; C4: r = 0.26, p < 0.01) and the right frontal electrode (Fp2: r = 0.12, p = 0.02). Lower θ-α activity (3.5-5 Hz and 12-18 Hz) was associated with higher SOFA scores (p < 0.001, FDR corrected). No significant correlations were observed between other drugs (opioids, anti-seizure medications, and psychotropics) and β or θ-α dynamics.

CONCLUSIONS

These results suggest that β neural dynamics represent a potential biomarker for β-lactam exposure in ICU patients. They highlight the potential of quantitative EEG and advanced multivariate decoding methods to identify subtle neurophysiological features that are otherwise difficult to detect.

TRIAL REGISTRATION

ClinicalTrials.gov ID NCT03339869. Registered 14 September 2017.

Cathodal weak direct current decreases epileptic excitability with reduced neuronal activity and enhanced delta oscillations

Seizures are manifestations of hyperexcitability in the brain. Non-invasive weak current stimulation, delivered through cathodal transcranial direct current stimulation (ctDCS), has emerged to treat refractory epilepsy and seizures, although the cellular-to-populational electrophysiological mechanisms remain unclear. Using the ctDCS in vivo model, we investigate how neural excitability is modulated through weak direct currents by analysing the local field potential (LFP) and extracellular unit spike recordings before, during and after ctDCS versus sham stimulation. In rats with kainic acid (KA)-induced acute hippocampal seizures, ctDCS reduced seizure excitability by decreasing the number and amplitude of epileptic spikes in LFP and enhancing delta (δ) power. We identified unit spikes of putative excitatory neurons in CA1 stratum pyramidale based on waveform sorting and validated via optogenetic inhibitions which increased aberrantly in seizure animals. Notably, cathodal stimulation significantly reduced these unit spikes, whereas anodal stimulation exhibited the opposite effect, showing polarity-specific and current strength-dependent responses. The reduced unit spikes after ctDCS coupled to δ oscillations with an increased coupling strength. These effects occurred during stimulation and lasted 90 min post-stimulation, accompanied by inhibitory short-term synaptic plasticity changes shown in paired-pulse stimulation after ctDCS. Consistently, neuronal activations measured by c-Fos significantly decreased after ctDCS, particularly in CaMKII+-excitatory neurons while increased in GAD+-inhibitory neurons. In conclusion, epileptic excitability was alleviated with cathodal weak direct current stimulation by diminishing excitatory neuronal activity and enhancing endogenous δ oscillations through strengthened coupling between unit spikes and δ waves, along with inhibitory plasticity changes, highlighting the potential implications to treat brain disorders characterized by hyperexcitability. KEY POINTS: Electric fields generated by transcranial weak electric current stimulation were measured at CA1, showing polarity-specific and current strength-dependent modulation of unit spike activity. Polyspike epileptiform discharges were observed in rats with kainic acid (KA)-induced hippocampal seizures. Cathodal transcranial direct current stimulation (ctDCS) reduced the number and amplitude of the epileptic spikes in local field potentials (LFPs) while increased δ oscillations. Neuronal unit spikes aberrantly increased in seizures and coupled with epileptiform discharges. ctDCS reduced excitatory neuronal firings at CA1 and strengthened the coupling between unit spikes and δ waves. Neuronal activations, measured by c-Fos, decreased in CaMKII+-excitatory neurons while increased in GAD+-inhibitory neurons after ctDCS. These effects on LFP and unit spikes lasted up to 90 min post-stimulation. Inhibitory short-term plasticity changes detected through paired-pulse stimulation underpin the enduring effects of ctDCS on seizures.

Robust EEG Characteristics for Predicting Neurological Recovery from Coma After Cardiac Arrest

OBJECTIVE

Clinically, patients in a coma after cardiac arrest are given the prognosis of "neurological recovery" to minimize discrepancies in opinions and reduce judgment errors. This study aimed to analyze the background patterns of electroencephalogram (EEG) signals from such patients to identify the key indicators for assessing the prognosis after coma.

APPROACH

Standard machine learning models were applied sequentially as feature selectors and filters. CatBoost demonstrated superior performance as a classification method compared to other approaches. In addition, Shapley additive explanation (SHAP) values were utilized to rank and analyze the importance of the features.

RESULTS

Our results indicated that the three different EEG features helped achieve a fivefold cross-validation receiver-operating characteristic (ROC) of 0.87. Our evaluation revealed that functional connectivity features contribute the most to classification at 70%. Among these, low-frequency long-distance functional connectivity (45%) was associated with a poor prognosis, whereas high-frequency short-distance functional connectivity (25%) was linked with a good prognosis. Burst suppression ratio is 20%, concentrated in the left frontal-temporal and right occipital-temporal regions at high thresholds (10/15 mV), demonstrating its strong discriminative power.

SIGNIFICANCE

Our research identifies key electroencephalographic (EEG) biomarkers, including low-frequency connectivity and burst suppression thresholds, to improve early and objective prognosis assessments. By integrating machine learning (ML) algorithms, such as Gradient Boosting Models and Support Vector Machines, with SHAP-based feature visualization, robust screening methods were applied to ensure the reliability of predictions. These findings provide a clinically actionable framework for advancing neurological prognosis and optimizing patient care.

Psychiatric comorbidities predict seizure recurrence in newly treated adults with epilepsy

OBJECTIVE

At least 30 % to 40 % of patients newly treated for epilepsy experience further seizures despite initiation of appropriate antiseizure medication (ASM) treatment. This study aimed to identify clinically useful predictors of seizure recurrence in newly treated adults with epilepsy which would have major clinical benefits.

METHODS

This work is a prospective cohort study conducted in Northeast China between June 2017 and May 2022. At enrolment, we collected information about demographics, clinical characteristics, and psychiatric comorbidities in newly treated adults with epilepsy. All patients were followed for 12 months for further seizures. Predictors of seizure recurrence were identified using logistic regression analyses.

RESULTS

A total of 836 newly treated adults with epilepsy were included in the final analysis. During follow-up, 362 (43.3 %) patients experienced at least one seizure recurrence, and 474 (56.7 %) entered seizure remission. Multivariable analysis showed that the odds of patients with depression having seizure recurrence were 1.74 times greater than those of patients without depression (Adjusted OR 1.74, 95 % CI 1.21-2.51). Similarly, the odds of patients with anxiety having seizure recurrence were 1.69 times greater than those of patients without anxiety (Adjusted OR 1.69, 95 % CI 1.21-2.37). Other Predictors of seizure recurrence included >5 seizures prior to treatment, brain MRI lesion, EEG epileptiform discharges.

CONCLUSION

We found that psychiatric comorbidities at baseline increase the risk of seizure recurrence in newly treated adults with epilepsy. Future studies are required to clarify the mechanisms underlying the links among psychiatric comorbidities and epilepsy. Furthermore, our findings might inform prospective studies investigating whether psychiatric treatment reduces the risk of seizure recurrence in these patients.

Synchronicity of pyramidal neurones in the neocortex dominates isoflurane-induced burst suppression in mice

BACKGROUND

Anaesthesia-induced burst suppression signifies profound cerebral inactivation. Although considerable efforts have been directed towards elucidating the electroencephalographic manifestation of burst suppression, the neuronal underpinnings that give rise to isoflurane-induced burst suppression are unclear.

METHODS

Electroencephalography combined with micro-endoscopic calcium imaging was used to investigate the neural mechanisms of isoflurane-induced burst suppression. Synchronous activities of pyramidal neurones in the auditory cortex and medial prefrontal cortex and inhibitory neurones in the auditory cortex (including parvalbumin [PV], somatostatin [SST], and vasoactive intestinal peptide [Vip]) and subcortical regions (including the medial geniculate body, locus coeruleus, and thalamic reticular nucleus) were recorded during isoflurane anaesthesia. In addition, the effects of chemogenetic manipulation inhibitory neurones in the auditory cortex on isoflurane-induced burst suppression were studied.

RESULTS

Isoflurane-induced burst suppression was highly correlated with the synchronous activities of excitatory neurones in the cortex (∼65% positively and ∼20% negatively correlated neurones). Conversely, a minimal or absent correlation was observed with the neuronal synchrony of inhibitory interneurones and with neuronal activities within subcortical areas. Only activation or inhibition of PV neurones, but not SST or Vip neurones, decreased (P<0.0001) or increased (P<0.0001) isoflurane-induced neuronal synchrony.

CONCLUSIONS

Isoflurane-induced burst suppression might be primarily driven by the synchronous activities of excitatory pyramidal neurones in the cortex, which could be bidirectionally regulated by manipulating the activity of inhibitory PV interneurones. Our findings provide new insights into the neuronal mechanisms underlying burst suppression.

Long-Term Seizure Outcomes in Autoimmune Encephalitis

Introduction

Seizures are common in autoimmune encephalitis (AE), but identifying patients at risk of chronic epilepsy in the post-acute phase remains challenging. This study aims to identify risk factors of treatment-resistant postencephalitic epilepsy.

Methods

This retrospective cohort study included patients with AE who experienced new-onset seizures within one year of symptom onset from two tertiary care centers in New York. EEG findings were analyzed separately based on whether the EEG recording was obtained in the acute (<3 months from symptom onset) or subacute phase. A multivariate logistic regression model was used to identify independent predictors of postencephalitic epilepsy.

Results

Eighty-nine patients were included (median age: 33 years). Neural antibodies were present in 73% of patients (NMDAR: 35, LGI1: 19, GAD65: 9, Hu: 1, AGNA-1: 1). Over a median follow-up of 4.9 years, 29.2% developed treatment-resistant postencephalitic epilepsy. Independent predictors of postencephalitic epilepsy included focal slowing on acute EEG (OR 0.15, CI 0.02-0.90), interictal epileptiform discharges (IEDs) or periodic discharges (PDs) on subacute EEG (OR 20.01, CI 1.94-206.44), and cell surface antibodies (OR 0.21, CI 0.05-0.89). Immunotherapy within three months of onset was associated with decreased epilepsy development in patients with neural antibodies (OR 4.16, CI 1.11-16.30).

Conclusions

Nearly one-third of patients with AE and acute seizures developed treatment-resistant postencephalitic epilepsy, with significant predictors including absence of focal slowing on acute EEG, presence of IEDs and PDs on subacute EEG, absence of cell surface antibodies, and absence of early immunotherapy treatment of patients with positive neural antibodies.

Investigation of lateralized periodic discharge features associated with epileptogenesis

OBJECTIVE

To identify factors, especially the electrographic features, that predispose patients with lateralized periodic discharges (LPDs) to epilepsy development.

METHODS

We included adults, without epilepsy history, who had LPDs on continuous EEG (cEEG) monitoring during hospitalization. We characterized LPDs based on American Clinical Neurophysiology Society rhythmic and periodic pattern modifiers. The outcome variable was epilepsy development as defined by clinical seizure after discharge. We used a Cox regression model to calculate adjusted hazard ratios (aHR) for epilepsy development.

RESULTS

Of 174 patients, 52 (30 %) developed epilepsy during a median follow-up time of 15.0 (IQR 62.1) months. We found that an LPD-plus pattern was associated with an increased risk of epilepsy development during the follow-up period [aHR 2.67 (95 %CI 1.26-5.64)]. We also found that LPD frequency ≥ 1.5 Hz was associated with an increased risk of epilepsy development during the first year of follow-up [aHR 2.27 (95 %CI 1.02-5.05)].

CONCLUSIONS

Among patients with LPDs, the presence of a plus pattern and discharge frequency ≥ 1.5 Hz are both independently associated with more than two-times increased risk of epilepsy development.

SIGNIFICANCE

Identification of EEG-based predictors of epileptogenesis in patients with LPDs can help early identification of patients at higher risk for future seizures and help tailor their management.

Seizure Characteristics and EEG Features in Intoxication Type and Energy Deficiency Neurometabolic Disorders in the Pediatric Intensive Care Unit: Single-Center Experience Over 10 Years

BACKGROUND

Acute metabolic crises in inborn errors of metabolism (such as urea cycle disorders, organic acidemia, maple syrup urine disease, and mitochondrial disorders) are neurological emergencies requiring management in the pediatric intensive care unit (PICU). There is a paucity of data pertaining to electroencephalograms (EEG) characteristics in this cohort. We hypothesized that the incidence of background abnormalities and seizures in this cohort would be high. Neuromonitoring data from our center's PICU over 10 years are presented in this article.

METHODS

Data were collected by retrospective chart review for patients with the aforementioned disorders who were admitted to the PICU at our institution because of metabolic/neurologic symptoms from 2008 to 2018. Descriptive statistics (χ2 test or Fisher's exact test) were used to study the association between EEG parameters and outcomes.

RESULTS

Our cohort included 40 unique patients (8 with urea cycle disorder, 7 with organic acidemia, 3 with maple syrup urine disease, and 22 with mitochondrial disease) with 153 admissions. Presenting symptoms included altered mentation (36%), seizures (41%), focal weakness (5%), and emesis (28%). Continuous EEG was ordered in 34% (n = 52) of admissions. Twenty-three admissions were complicated by seizures, including eight manifesting as status epilepticus (seven nonconvulsive and one convulsive). Asymmetry and focal slowing on EEG were associated with seizures. Moderate background slowing or worse was noted in 75% of EEGs. Among those patients monitored on EEG, 4 (8%) died, 3 (6%) experienced a worsening of their Pediatric Cerebral Performance Category (PCPC) score as compared to admission, and 44 (86%) had no change (or improvement) in their PCPC score during admission.

CONCLUSIONS

This study shows a high incidence of clinical and subclinical seizures during metabolic crisis in patients with inborn errors of metabolism. EEG background features were associated with risk of seizures as well as discharge outcomes. This is the largest study to date to investigate EEG features and risk of seizures in patients with neurometabolic disorders admitted to the PICU. These data may be used to inform neuromonitoring protocols to improve mortality and morbidity in inborn errors of metabolism.

Predictors of status epilepticus among older adults - a prospective real-world study

Data on status epilepticus (SE) in older inpatients is limited.

AIM

To assess SE characteristics and etiologies, and identify risk factors for SE in a cohort of hospitalized patients.

METHODS

We selected patients aged ≥ 60 years with late-onset seizures from a tertiary center. We analyzed demographics, clinical characteristics, etiology of seizures, neurological diseases, and comorbidities. We performed the Kaplan-Meier analysis to examine acute symptomatic and unprovoked seizures and multivariate logistic regression to identify risk factors for SE.

RESULTS

We enrolled 236 patients (mean age: 77.1 ± 9.7 years [SD]) with acute symptomatic seizures, unprovoked seizures and both. SE occurred in 61 (25.8 %) patients. The mean age at the first-ever seizure was 76.5 ± 9.8 years. Females comprised 62.3 % of the patients in the SE group. Convulsive SE was the most common presentation (80.3 %). Cerebrovascular disorders were the most common etiology (27.9 %) among patients with SE. The likelihood of SE occurring was similar between patients with acute symptomatic seizures alone or in combination with unprovoked seizures (118/50 %), and those with unprovoked seizures (118/50 %). Dyslipidemia negatively correlated with SE (OR 0.45 [95 % CI, 0.24-0.85]; p = 0.014), perhaps due to statin use. Psychiatric disorders (OR 2.76 [95 % CI, 1.45-5.24]; p = 0.002;), sepsis (OR 2.33 [95 % CI, 1.13-4.79]; p = 0.021), and congestive heart failure (OR 2.95 [95 % CI,1.07-8.12]; p = 0.036) were risk factors for SE.

CONCLUSION

We identified older inpatients who developed SE, their characteristics, and the risk factors for developing SE.

Indications for continuous electroencephalography and frequency of electrographic seizure detection in a pediatric and neonatal cardiovascular intensive care unit

OBJECTIVE

Seizures are a recognized complication of critical cardiovascular illness in infants and children. We assessed the diagnostic yield of continuous video-electroencephalography (cEEG) in a pediatric and neonatal cardiovascular intensive care unit (CVICU) by the symptoms and risk factors prompting cEEG evaluation.

METHODS

This retrospective case series included all consecutive cEEGs in patients ≤21 years old performed in one CVICU over 38 months. cEEG indications were categorized as (1) index symptoms of concern and/or (2) clinical risk factors. Index symptoms were divided into (1) vital sign symptoms (i.e., heart rate, blood pressure, oxygen, respiration, or temperature) and (2) non-vital sign symptoms (i.e., mental status, abnormal movements, eye findings, weakness, or failed extubation). Indications for cEEG were extracted by manual chart review. The presence of seizures was established electrographically from neurophysiologist reports.

RESULTS

There were 605 cEEGs from 411 patients. The median study was 26 h (25%-75%, interquartile range = 20-41 h). Seizures were detected in 57 of 605 (9%) cEEGs overall; in 34 of 356 (10%) cEEGs obtained for risk factors alone (odds ratio [OR] = 1.03, 95% confidence interval [CI] = .60-1.82, p = .90), 0 of 104 (0%) for isolated vital sign changes (p < .001), 10 of 101 (10%) for symptoms not involving vital signs (OR = 1.06, 95% CI = .52-2.09, p = .88), and in 13 of 44 (30%) for both vital sign and non-vital sign symptoms (OR = 4.93, 95% CI = 2.45-9.77, p < .001). On univariate analysis, symptoms involving gaze deviation, abnormal limb movements, or intermittent oxygen desaturation, and the risk factors of preexisting epilepsy, recent neurosurgery, acute stroke, and cardiac air embolism were associated with seizures (p < .05).

SIGNIFICANCE

There were zero electrographic seizures in cEEGs obtained for isolated vital sign changes, whereas cEEGs obtained for the combination of vital sign changes and other non-vital sign symptoms were five times more likely to detect electrographic seizures than cEEGs obtained based on risk factors alone.

Predictors of Recovering Full Consciousness: Results From a Prospective Multisite Italian Study

BACKGROUND

Improving prognostication in patients with a prolonged disorder of consciousness (pDoC) is among the most challenging issues in neurorehabilitation. The aim of this Italian multisite prospective longitudinal study was to identify valuable predictors of the complete recovery of consciousness (emergence from Minimally Conscious State, eMCS) at 3 months (T1) from the admission in intensive rehabilitation units (IRUs) in pDoC (T0).

METHODS

Patients with Unresponsive Wakefulness Syndrome (UWS) or MCS admitted within 3 months of injury to 4 Italian IRUs were included. Demographic, clinical, and neurophysiological data were collected at T0, and a clinical diagnosis of consciousness (UWS, MCS-, MCS+) was established at T0 and T1 using the Coma Recovery Scale-Revised (CRS-R).

RESULTS

One hundred forty-three patients were initially included and 131 completed follow-ups at T1: (76 males; median age: 69 years [IQR = 23]; VS/UWS: 51, MCS-: 29, MCS+: 51; etiology: 33 traumatic, 14 anoxic, 24 ischemic, 55 hemorrhagic, 5 other; median time post-injury: 40 days [IQR = 23]). At T1, 77 patients were eMCS, and 10 improved their clinical diagnosis. Among the clinical and neurophysiological independent variables, a higher CRS-R visual sub-score and the presence of EEG reactivity to eye opening at T0 were the best independent predictors of eMCS. Out of 77 eMCS, 18 reached a moderate disability (Glasgow Outcome Scale Extended-GOSE > 4), while the others persisted with a severe disability (GOS-E ≤ 4).

CONCLUSIONS

A multimodal assessment can help identify patients who achieve functionally relevant improvements and thus better support clinicians when communicating with caregivers.

TRIAL REGISTRATION

ClinicalTrials.gov registration number: NCT04495192.

Management of severe acute encephalopathy in the ICU: an expert consensus statement from the french society of intensive care medicine

INTRODUCTION

Acute encephalopathy in the ICU poses significant diagnostic, therapeutic, and prognostic challenges. Standardized expert guidelines on acute encephalopathy are needed to improve diagnostic methods, therapeutic decisions, and prognostication.

METHODS

The experts conducted a review of the literature, analysed it according to the GRADE (Grading of Recommendation, Assessment, Development and Evaluation) methodology and made proposals for guidelines, which were rated by other experts. Only expert opinions with strong agreement were selected.

RESULTS

The synthesis of expert work and the application of the GRADE method resulted in 39 recommendations. Among the 39 formalized recommendations, 1 had a high level of evidence (GRADE 1 +) and 10 had a low level of evidence (GRADE 2 + or 2-). These recommendations describe indication for ICU admission, use of clinical scores and EEG for diagnosis, detection of complications, and prognostication. The remaining 28 recommendations were based on expert consensus. These recomandations describe common indications for blood and CSF studies, neuroimaging, use of neuromonitoring, and provide guidelines for management in the acute phase.

CONCLUSION

This expert consensus statement aims to provide a structured framework to enhance the consistency and quality of care for ICU patients presenting with acute encephalopathy. By integrating high-quality evidence with expert opinion, it offers a pragmatic approach to addressing the complex nature of acute encephalopathy in the ICU, promoting best practices in patient care and facilitating future research in the field.

Periodic discharges in portable EEG of critically ill patients with altered mentation; an alerting and alarming phenomena with helpful clues

INTRODUCTION

Periodic discharges (PDs) in critically ill patients with altered mental status (CIPAMS) have important implications. This study aimed to describe different characteristics of PDs in CIPAMS using routine electroencephalogram.

METHODS

This retrospective study was carried out at King Fahd University Hospital. The EEG recordings of CIPAMS reporting PDs were reviewed. All patients had at least 30 min of portable EEG recording (pEEG). Patients were dichotomized into two groups according to PDs. Clinical and radiological variables between the two groups were compared using Chi-square tests and Odds ratio. P value < 0.05 was considered statistically significant.

RESULTS

The electronic charts of 295 consecutive CIPAMS were reviewed. PDs, detected in 21% of the patients, were significantly more frequent in women as compared to men (OR = 1.71,CI = 1.09-2.67,P = 0.01). The mean (SD) age of the patients was significantly higher in the group having PDs than without (P = 0.01). LPDs were detected in 41, and GPDs in 17 patients. Chronic neurological illness, encephalitis, and brain tumor had a significant association with LPDs, whereas metabolic derangement and Creutzfeldt-Jakob disease with GPDs. The frequency and peri-ictal features were important determinants of non-convulsive seizure (NCS). Overall, PDs were associated with an increased likelihood of unfavorable outcomes and mortality.

Neurological Injury in Comatose Patients Following Substance-Use-Related Out-of-Hospital Cardiac Arrest: A Retrospective Cohort Study in a Safety Net Hospital

BACKGROUND

Substance-use-related cardiac arrest (SURCA) is a public health crisis, contributing to high mortality and severe neurological disability, particularly affecting young adults. This study aims to characterize the demographic and multimodal neurological prognostication features of patients with SURCA.

METHODS

This retrospective study included patients with out-of-hospital cardiac arrest who presented to an urban academic safety net hospital between July 2016 and April 2022 and were comatose on admission. Patients with SURCA were identified through toxicology screening. Data on demographics, cardiac arrest characteristics, and multimodal neurological prognostication were collected. Poor neurological outcome was defined as a Cerebral Performance Category score of 3-5 at hospital discharge. Logistic regression was used to identify factors associated with poor neurological outcomes.

RESULTS

Among 253 patients, 99 (39%) were classified as having SURCA, with 67 testing positive for stimulants and 56 testing positive for opioids. Patients with SURCA were younger (49 vs. 66 years, p < 0.001), less likely to have a witnessed cardiac arrest (56% vs. 71%, p = 0.01), and more likely to present with nonshockable rhythms (88% vs. 73%, p < 0.001). Electroencephalogram (EEG) monitoring in the SURCA cohort revealed a higher incidence of generalized periodic discharges (54% vs. 35%, p = 0.02) and electrographic seizures (28% vs. 13%, p = 0.02). Outcomes were similar between SURCA and non-SURCA groups; 86% of patients with SURCA had poor neurological outcomes, with 67% not surviving to discharge, compared to 88% and 69% of patients with non-SURCA, respectively. Nonshockable rhythms and older age were associated with poor neurological outcomes, but SURCA was not.

CONCLUSIONS

SURCA is common and is frequently associated with poor neurological outcomes despite affecting younger patients. A higher incidence of seizures and generalized periodic discharges on EEG was observed with SURCA; therefore, validation of this finding in larger multicenter cohorts is warranted. Public health interventions to improve bystander resuscitation education in populations at risk for SURCA may improve outcomes in this vulnerable population.

Fatigue, sleep quality, depression symptoms, and antiseizure medication resistance in patients with newly diagnosed epilepsy

Background

Complaints of fatigue and poor sleep quality are common in patients with epilepsy. Fatigue may precipitate seizures, and patients with poor sleep quality have higher frequency of seizures and are more likely to have symptoms of depression.

Objectives

This study aims to determine the association of baseline fatigue and sleep quality with antiseizure medication (ASM) resistance in patients with newly diagnosed epilepsy (PWNDE). We also evaluate whether the association is mediated by depression symptoms.

Methods

We performed a prospective cohort study of PWNDE at comprehensive epilepsy center in Northeast China between June 2020 and May 2024. Fatigue, sleep quality, and depression symptoms were assessed at baseline. All patients were followed for 24 months for ASM-resistant epilepsy. Cox proportional hazard regression models were used to estimate the hazard ratios (HRs) of ASM resistance. Models fitted with restricted cubic spline were performed to test for linear and nonlinear shapes of each association. Mediation analysis was used to estimate the mediating effects of depression severity on association between fatigue, sleep quality, and ASM resistance.

Results

A total of 189 patients (59 ASM-resistant cases and 130 ASM-responsive controls) were included in the final analysis. Baseline fatigue (HR, 1.98; 95% confidence interval (CI), 1.094-3.583, p = 0.024) and poor sleep quality (HR, 2.193; 95% CI, 1.29-3.729, p = 0.004) were associated with an increased hazard of ASM resistance in PWNDE after full adjustments. There exists a nonlinear association between Fatigue Severity Scale score and the hazard of ASM resistance (P for nonlinear = 0.012). Depression severity partly mediated the effect of fatigue and sleep quality on ASM resistance, with mediated proportions of 18.5% for the fatigue and 23.7% for the sleep quality.

Conclusion

Baseline fatigue and poor sleep quality were associated with an increased risk of ASM resistance. The association between fatigue, sleep quality, and ASM resistance were partly mediated by depression severity. These findings emphasize that patients with ASM-resistant epilepsy are more likely to have fatigue, depression, and poor sleep quality at baseline and this may be unrelated to ASM intake.

Electrographic and Clinical Determinants of Good Outcome After Postanoxic Status Epilepticus

BACKGROUND AND OBJECTIVES

Postanoxic electrographic status epilepticus (PSE) affects up to a third of all comatose patients after cardiac arrest (CA) and is associated with high mortality. Late PSE onset (>24 hours), from a restored continuous background pattern, and absence of established indicators of poor outcome at multimodal prognostication are described in survivors. We aimed to determine the increase in probability of good long-term outcome after PSE in patients presenting with this favorable PSE profile compared with all patients with PSE.

METHODS

This is a prospective observational substudy of the international Targeted Hypothermia vs Targeted Normothermia After Out-of-Hospital Cardiac Arrest trial (TTM2-trial, 2017-2020) including adult comatose patients resuscitated from CA with continuous EEG (cEEG) monitoring. EEG background pattern and type of PSE were determined using standardized EEG terminology of the American Clinical Neurophysiology Society, blinded to clinical data. On day 4, multimodal prognostication was performed according to the European postresuscitation guidelines. Good outcome was defined as a modified Rankin Scale score of 0-3 at 6 months. Detailed follow-up was performed at 6 and 24 months.

RESULTS

A total of 191 patients were monitored with cEEG, of whom 52 (27%) developed possible or definite PSE at a median of 42 hours [IQR 32-46] after CA. The median age was 70 (IQR 63-77) years, and 35% were female. Favorable PSE profile was present in 20 patients (38%), of whom 12 patients (60%) survived until 6 months and 8 (40%) had good outcome; thus, the probability of good outcome increased 2.7 times. All patients lacking a favorable PSE profile had poor outcome. All patients with good outcome obeyed commands within the first 7 days. At 24 months, all 12 survivors were still alive and 7 had good functional outcome. Detailed follow-up at 24 months showed that most had only mild cognitive impairment and overall life satisfaction was similar to the general population.

DISCUSSION

PSE is compatible with good outcome when onset is late and from a continuous background and no established indicators of poor outcome are present. One-third of patients with PSE had favorable PSE profile, of whom well over a third eventually had good outcome and showed improved level of consciousness within the first week.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT02908308.

Sleep spindles as a predictor of cognitive motor dissociation and recovery of consciousness after acute brain injury

Cognitive motor dissociation (CMD) can improve the accuracy to predict recovery of behaviorally unresponsive patients with acute brain injury, but acquisition and analysis of task-based electroencephalography (EEG) are technically challenging. N2 sleep patterns, such as sleep spindles on EEG, have been associated with good outcomes, rely on similar thalamocortical networks as consciousness and could provide less technically challenging complementary outcome predictors. In this prospective observational cohort study of 226 acutely brain injured patients, well-formed sleep spindles (WFSS) were more likely present in those with CMD than in those without CMD, often preceding the detection of CMD. WFSS were associated with a shorter time to recovery of consciousness, and both CMD and WFSS independently predicted recovery of independence, controlling for age, admission neurological status and injury type. WFSS are seen in approximately every third behaviorally unresponsive patient after acute brain injury, frequently precede detection of CMD and are a promising complementary predictor for recovery of consciousness and functional independence.

Use of intrathecal rituximab in autoimmune epilepsy: A retrospective study

BACKGROUND

Autoimmune encephalitis (AE) is a significant challenge in neurological practice, often proving refractory to conventional treatments. It typically manifests with recurrent seizures or status epilepticus, necessitating early diagnosis and tailored therapy for optimal outcomes. Early institution of effective treatment has been reported to reduce the mortality and morbidity associated with this condition. A subpopulation presenting with acute seizures due to autoimmune encephalitis later develop chronic epilepsy, which can be refractory to conventional modes of treatments. In addition, there is a group of chronic epilepsy patients who did not have acute symptomatic seizures who have autoimmune antibodies suggesting an immunological origin of their seizures. This study aims at evaluating the use of rituximab administered intrathecally, for treating these patients, taking pharmacodynamic properties into account.

MATERIALS AND METHODS

We retrospectively evaluated the efficacy and safety of intrathecal rituximab (ITR) in 15 patients with autoimmune-related epilepsy (9 of them with acute presentation with seizures and 6 with chronic intractable epilepsy). The nature of these seizures, laboratory findings, imaging and EEG findings were compared over the course of treatment and follow up.

RESULTS

No significant long term side effects related to administration of ITR were noted in the 15 patients reported in this series. Improvement was noted in seizure control in the majority of the patients, especially in the acute presentation category, although definitive conclusions about efficacy could not be made since these patients were also receiving additional modes of therapies. Better seizure control was noted in all patients in 12 months follow up.

CONCLUSIONS

Our findings underscore the safety of intrathecal rituximab in treating autoimmune-related status epilepticus and refractory epilepsy related to autoimmune etiology.

Myoclonic status epilepticus with dystonia-like symptoms in patients with dementia: Report of two cases

We report cases of two elderly women with dementia who presented with a new-onset seizure disorder characterized by subtle, rhythmic muscular contractions involving the buccolingual region and the four limbs, persistent jaw opening, and abnormal cervical posture that mimicked myoclonus-dystonia syndrome and oromandibular dystonia. The symptoms lasted several minutes to a few hours. Video-polygraphic recordings revealed an electromyographic (EMG) pattern of brief, shock-like muscular contractions consistent with myoclonus that correlated with a high-amplitude (70-90 µV), 11-14 Hertz, bilaterally symmetric electroencephalographic (EEG) rhythm over the frontocentral regions. A time-locked relationship between the frontocentral EEG activity and the EMG myoclonic potentials demonstrated the cortical origin of myoclonus and therefore the epileptic nature of the disorder, whereas the oromandibular and cervical dystonic-like postures suggested the pathogenic involvement of subcortical structures. The intravenous administration of diazepam suppressed the clinical symptoms and the EEG-EMG correlate of myoclonus. The clinical and neurophysiological findings illustrate a form of myoclonic status epilepticus (SE) with dystonia-like symptoms resulting from the functional involvement of cortical and subcortical structures. The manifestation of subtle, rhythmic myoclonus and dystonic-like postures in patients with atypical EEG patterns of SE may require challenging differential diagnoses with myoclonus-dystonia syndrome and oromandibular dystonia.

Temporal Lobe Epilepsy Perturbs the Brain-Wide Excitation-Inhibition Balance: Associations with Microcircuit Organization, Clinical Parameters, and Cognitive Dysfunction

Excitation-inhibition (E/I) imbalance is theorized as a key mechanism in the pathophysiology of epilepsy, with ample research focusing on elucidating its cellular manifestations. However, few studies investigate E/I imbalance at the macroscale, whole-brain level, and its microcircuit-level mechanisms and clinical significance remain incompletely understood. Here, the Hurst exponent, an index of the E/I ratio, is computed from resting-state fMRI time series, and microcircuit parameters are simulated using biophysical models. A broad decrease in the Hurst exponent is observed in pharmaco-resistant temporal lobe epilepsy (TLE), suggesting more excitable network dynamics. Connectome decoders point to temporolimbic and frontocentral cortices as plausible network epicenters of E/I imbalance. Furthermore, computational simulations reveal that enhancing cortical excitability in TLE reflects atypical increases in recurrent connection strength of local neuronal ensembles. Mixed cross-sectional and longitudinal analyses show stronger E/I ratio elevation in patients with longer disease duration, more frequent electroclinical seizures as well as interictal epileptic spikes, and worse cognitive functioning. Hurst exponent-informed classifiers discriminate patients from healthy controls with high accuracy (72.4% [57.5%-82.5%]). Replicated in an independent dataset, this work provides in vivo evidence of a macroscale shift in E/I balance in TLE patients and points to progressive functional imbalances that relate to cognitive decline.

Yield in routine electroencephalography in adults with newly diagnosed epilepsy at a third-level epilepsy center in South Korea

PURPOSE

In people with epilepsy (PWE), the yield of interictal epileptiform discharges in electroencephalography (EEG) is an important determinant of good clinical practice. This study sought to investigate routine EEGs in adults with newly diagnosed epilepsy at a third-level epilepsy center in South Korea and assess the factors affecting yield.

METHODS

Electronic medical records and 2,584 EEGs from 339 PWE were retrospectively reviewed from July to December 2023. Overall and cumulative yields, yield-increasing predictive factors, routine EEG natural sleep state, and yield changes before and after medical treatment were investigated.

RESULTS

For the first EEG, the yield was 31.6 %, while the initial two and three consecutive EEGs had cumulative yields of 44.0 % and 49.6 %, respectively. Yield-increasing predictive factors included age ≤16 years at seizure onset, idiopathic generalized epilepsy, gender (female), and drug-resistant epilepsy. Of the PWE, approximately 90 % experienced natural sleep during routine EEG recordings, and the duration of sleep stage N2 was proven to be a yield-increasing predictive factor. Yield change before and after medical treatment was statistically significant.

CONCLUSIONS

At our center, among adults with newly diagnosed epilepsy, the yield from initial EEGs was comparable to that reported by some previous studies. Our results suggest that for epilepsy diagnosis, if necessary, repeated EEGs should be performed with sleep EEG before starting medical treatment for cost-effectiveness. After medical treatment, care should be taken not to underestimate the likelihood of false negatives in the EEG.

Myoclonus After Cardiac Arrest did not Correlate with Cortical Response on Somatosensory Evoked Potentials

PurposeMyoclonus after anoxic brain injury is a marker of significant cerebral injury. Absent cortical signal (N20) on somatosensory evoked potentials (SSEPs) after cardiac arrest is a reliable predictor of poor neurological recovery when combined with an overall clinical picture consistent with severe widespread neurological injury. We evaluated a clinical question of if SSEP result could be predicted from other clinical and neurodiagnostic testing results in patients with post-anoxic myoclonus.MethodsRetrospective chart review of all adult patients with post-cardiac arrest myoclonus who underwent both electroencephalographic (EEG) monitoring and SSEPs for neuroprognostication. Myoclonus was categorized as "non-myoclonic movements," "myoclonus not captured on EEG," "myoclonus without EEG correlate," "myoclonus with EEG correlate," and "status myoclonus." SSEP results were categorized as all absent, all present, N18 and N20 absent bilaterally, and N20 only absent bilaterally. Cox proportional hazards with censoring was used to evaluate the association of myoclonus category, SSEP results, and confounding factors with survival.ResultsIn 56 patients, median time from arrest to either confirmed death or last follow up was 9 days. The category of myoclonus was not associated with SSEP result or length of survival. Absence of N20 s or N18 s was associated with shorter survival (N20 hazard ratio [HR] 4.4, p = 0.0014; N18 HR 5.5, p < 0.00001).ConclusionsCategory of myoclonus did not reliably predict SSEP result. SSEP result was correlated with outcome consistently, but goals of care transitioned to comfort measures only in all patients with present peripheral potentials and either absent N20 s only or absence of N18 s and N20 s. Our results suggest that SSEPs may retain prognostic value in patients with post-anoxic myoclonus.

Electroencephalographic (EEG) Stages in Patients With Cerebral Edema Following Cardiac Arrest

ObjectiveTo describe electroencephalographic (EEG) changes in pediatric patients with cerebral edema after cardiac arrest.MethodsA retrospective study of patients admitted to the pediatric intensive care unit from July 2021 to January 2023. We included patients with cardiac arrest and changes in EEG background with clinical changes and/or neuroimaging consistent with cerebral edema. We excluded patients with electrographic seizures. We applied American Clinical Neurophysiology Society standardized critical care EEG terminology to classify EEG background, noting timing of the change in background classification. Clinical variables included age, sex, and neuroimaging findings and were described with descriptive statistics.ResultsNine patients met inclusion criteria, with median age 24 months (interquartile range 21-49), and 89% were male. There were 5 common EEG stages: stage 1, burst suppression/burst attenuation; stage 2, continuous/discontinuous ± multifocal sporadic epileptiform discharges ± rhythmic or periodic patterns; stage 3, discontinuous/burst suppression/burst attenuation ± rhythmic or periodic patterns; stage 4, gradual voltage suppression; and stage 5, diffuse suppression. The ranges for each stage were as follows: stage 1, 2-10 hours; stage 2, 2.5-15.5 hours; stage 3, 0.5-6.24 hours; and stage 4, 0.5-11 hours. We could not calculate the duration of stage 5 given no uniform time to EEG discontinuation. One patient had a clinical change in stage 3. Remaining patients presented with fixed and dilated pupils with global anoxic injury.ConclusionsEEG stages of cerebral edema have not been described after pediatric cardiac arrest. These stages may be relevant to other patient populations. Early stages may be a therapeutic target for intracranial pressure-lowering medications and/or neuroprotective strategies to minimize sequalae of cerebral edema.

Ictal-interictal continuum following coil embolization of cerebral aneurysms

PURPOSE

The ictal-interictal continuum (IIC) has been reported in various clinical conditions, but its relationship with intravascular treatments remains poorly understood. This study reports three cases of IIC following coil embolization (CE) of cerebral aneurysms and evaluates associated outcomes.

METHODS

A retrospective review of medical records from May 2018 to May 2024 was conducted, focusing on patients with reduced consciousness after CE. IIC was diagnosed based on EEG patterns following the guidelines of the American Clinical Neurophysiology Society. Factors related to outcomes, including IIC development, were analyzed using a multivariable linear regression model with robust standard errors.

RESULTS

Of 30 patients who underwent continuous (3-hour) EEG monitoring post-coiling, three exhibited IIC patterns characterized by lateralized epileptic activity ipsilateral to the coiling site. One patient also displayed repeated electrographic seizures associated with subtle motor phenomena. EEG abnormalities resolved immediately after intravenous benzodiazepines, but coma persisted. Full recovery of consciousness occurred approximately one week after benzodiazepines withdrawal. Adjusting for other risk factors, patients with IIC had a mean Glasgow Coma Scale score 3.13 points higher at 14 days compared to those without IIC (95 % CI, 0.43∼5.84; p = 0.025). Durations of ICU stay (95 %CI, -6.30-8.27; p = 0.782) and total hospital stay (95 %CI, -43.15∼20.79; p = 0.477) were comparable between groups.

CONCLUSIONS

This study highlights IIC as a potential complication of CE. The development of postoperative IIC does not necessarily correlate with worse outcomes.

Rhythmic EEG patterns: The oldest idea in the EEG world, but without an obvious definition

The word "rhythmic" was quickly introduced in the vocabulary of the electroencephalographers with the discovery of the alpha rhythm and typical discharges of spike-and-waves at 3 Hz in childhood absence epilepsy, but without any definition until recently. In its last revision (2017), the International Federation of Clinical Neurophysiology proposed a specific definition. The word "rhythmic" is "applied to regular waves occurring at a constant period and of relatively uniform morphology." Unfortunately, there is a serious problem of ambiguity as this definition exactly corresponds in science to the definition of a periodic function (periodic waveform). This definition of regular patterns at constant intervals (constant period) can be applied to physiological rhythms such as alpha and mu rhythms but also to unusual rhythms such as rhythmic theta bursts of drowsiness. It can also be used to describe EEG patterns, such as frontal/temporal/occipital intermittent rhythmic activities or generalized rhythmic delta activities. Except with typical absence seizures, this definition cannot be used to describe most epileptic seizures and absence status epilepticus. Identifying 'periodic' versus 'rhythmic' features is crucial when analyzing an EEG in critically ill patients. The importance lies in a balanced approach that frequently promotes an interpretation of an acute encephalopathy when referring to diffuse periodic EEG patterns, and status epilepticus for unreactive bilateral rhythmic patterns. To include seizures and status epilepticus in the definition of rhythmic patterns, we suggest a more "dynamic" approach in addition to the regular waves at constant intervals without interdischarge intervals between waveforms. For the observed rhythmic patterns, we propose: repetition of consecutive waves with, in case of a variation in the pattern, a dynamic approach to these waveforms. Dynamic means spatiotemporal evolution of the patterns.

Alpha-band activity in density spectral array predictive for neurological outcome in patients with hypoxic-ischemic encephalopathy

BACKGROUND

In patients with hypoxic-ischemic encephalopathy (HIE), EEG is used to predict outcomes. However, a clear threshold for EEG findings associated with favorable outcomes remains unestablished. This study evaluates the predictive value of density spectral array (DSA)-based background activity in HIE patients.

METHODS

Forty-four consecutive HIE patients with disturbance of consciousness (2010-2023) were retrospectively assessed and categorized into highly malignant, malignant, or benign EEG patterns according to the conventional EEG classification. The presence of alpha-band activity, defined as an increase in alpha (or theta) frequency band power visible in the DSA, was also assessed. The relationship among conventional EEG classification, alpha-band activity, and neurological outcomes was evaluated.

RESULTS

All patients with highly malignant EEG lacked alpha-band activity and experienced poor outcomes, whereas those with less severe patterns occasionally exhibited alpha-band activity (14 % in the malignant vs. 60 % in the benign, p = 0.021), and demonstrated various outcomes. Recovery of consciousness until discharge was more prominent in patients with alpha-band activity compared to those without (100 % vs. 39 %, p < 0.001).

CONCLUSIONS

DSA-based evaluations provide a simple and valuable tool for predicting favorable neurological outcomes.

Cortical hemodynamics of electrographic status epilepticus in the critically ill

OBJECTIVES

The pathophysiological mechanisms of status epilepticus (SE) underlying potential brain injury remain largely unclear. This study aims to employ functional near-infrared spectroscopy (fNIRS) combined with video-electroencephalography (vEEG) to monitor brain hemodynamics continuously and non-invasively in critically ill adult patients experiencing electrographic SE. Our primary focus is to investigate neurovascular coupling and cerebrovascular changes associated with seizures, particularly during recurring and/or prolonged episodes.

METHODS

Eleven critically ill adult patients underwent simultaneous vEEG-fNIRS with large cortical coverage. Data from seven patients with identified electrographic SE were analyzed. The timing of recorded seizures was marked using standardized critical care EEG terminology. A general linear model was employed to extract the hemodynamic response to seizures from the fNIRS recordings. Linear mixed-effects models were utilized to correlate hemodynamic responses with seizure characteristics.

RESULTS

A total of >200 h of monitoring and >1000 seizures were recorded. In most patients, an increase in oxyhemoglobin (HbO) and a decrease in deoxyhemoglobin (HbR) were observed during shorter-duration seizures. Although a similar response could also be seen initially for longer-duration seizures, this hemodynamic change was often followed by a progressive decline in HbO concentration and an increase in HbR. At the systemic level, no significant difference in peripheral oxygenation occurred during seizures, and only small changes in mean arterial blood pressure and heart rate occurred in four and two patients, respectively.

SIGNIFICANCE

We demonstrate the feasibility of using multichannel vEEG-fNIRS to measure the hemodynamic changes associated with electrographic seizures in critically ill adult patients. Our findings suggest that disrupted neurovascular coupling is more prevalent during prolonged seizures compared to recurrent short-duration seizures. This research provides valuable insights into the dynamic interplay between neuronal activity and hemodynamics during critical care seizures.

Allopregnanolone as an Adjunct Therapy to Midazolam is More Effective Than Midazolam Alone in Suppressing Soman-Induced Status Epilepticus in Male Rats

AIMS

Humans and animals acutely intoxicated with the organophosphate soman can develop sustained status epilepticus (SE) that rapidly becomes refractory to benzodiazepines. We compared the antiseizure efficacy of midazolam, a current standard of care treatment for OP-induced SE, versus combined therapy with midazolam and allopregnanolone (ALLO) in a rat model of soman-induced SE.

METHODS

Soman-intoxicated male rats with robust seizure behavior and high-amplitude electroencephalographic (EEG) activity were administered midazolam (0.65 mg, i.m.) 20 min after seizure initiation and 10 min later either a second dose of midazolam or ALLO (12 or 24 mg/kg, i.m.). Seizure behavior and EEG were monitored for 4 h after treatment. Brains were collected at the end of the monitoring period for histological analyses.

RESULTS

Animals receiving 2 doses of midazolam exhibited persistent SE. Sequential dosing with midazolam followed by ALLO suppressed electrographic seizure activity. The combination therapy also significantly reduced soman-induced neurodegeneration and neuroinflammation compared to 2 doses of midazolam. High but not low dose ALLO was associated with transitory and reversible respiratory compromise during the 1 h period after dosing.

CONCLUSIONS

Treatment with midazolam followed by ALLO was more effective than 2 doses of midazolam in suppressing benzodiazepine-refractory, soman-induced SE, and in mitigating its acute neuropathological consequences.

Refuting a Temporal Correlation: Interictal Epileptic Discharges Do Not Preferentially Occur During Respiratory Events in Patients With Sleep-Related Breathing Disorder and Epilepsy

The bidirectional interaction between sleep and epilepsy is well known. In particular, it has been established that sleep apnea can worsen epilepsy, whereas sleep apnea (SA) treatment has a beneficial effect on seizure control. However, the exact mechanisms whereby SA promotes epileptic seizures are unknown. We set out to examine whether interictal epileptic discharges (IED), one of the hallmarks of epilepsy, occur predominantly during respiratory events (RE, apnea or hypopnea) or desaturations in patients with obstructive SA (OSA) and epilepsy. Adult patients (> 18) who underwent a video-polysomnography at the Bern University Hospital between 2012 and 2020 with an apnea-hypopnea-index (AHI) ≥ 10/h and IED were included in this retrospective study. IED density (per hour) was computed during and outside RE and oxygen desaturations (3%) using the AASM criteria and an extended definition. A total of 27 patients (9 females) met the inclusion criteria. The median age was 49 years and the median AHI was 17.4/h. There was no statistically significant difference in IED density in phases of sleep with RE compared to sleep without (median 3.6 [IQR 0.2-8.0] vs. 6.3 [3.7-19.7], p = 0.055). In the extended definition of RE, IED density was significantly lower during RE: 2.6 [0.3-6.6] versus 6.7 [3.9-20.5], p = 0.017. Desaturations were similarly associated with lower IED density in both analyses: 2.2 [0-7.4] versus 6.4 [3.4-18.4], p = 0.009 and 2.6 [0-6.7] versus 6.8 [3.4-18.5], p = 0.012. Our study shows that the influence of OSA on epileptic activity is probably indirect and does not result solely from immediate hypoxemia.

Continuous Electroencephalography in Acute Liver Failure: Findings and Prognostic Value

BACKGROUND

Neurologic complications contribute significantly to morbidity and mortality in acute liver failure (ALF). However, clinical assessment of neurologic function in this population is often challenging. Continuous electroencephalography (cEEG) is a low-risk, noninvasive diagnostic tool that can monitor real-time cerebral function. We aimed to investigate cEEG findings and prognostic significance of specific EEG features in a cohort of strictly defined patients with ALF.

METHODS

This was a retrospective, single-center study of adult patients with ALF who underwent cEEG monitoring for at least 6 h between 2013 and 2022. Clinical, laboratory, imaging, and treatment characteristics were evaluated. cEEG variables included background continuity, background frequency, the presence of sporadic epileptiform discharges, rhythmic or periodic patterns, and electrographic or electroclinical seizures. The primary outcome was mortality or transition to end-of-life care during the index admission.

RESULTS

A total of 32 patients with ALF were included. 56.3% of patients had rhythmic or periodic patterns, of which the majority were generalized periodic discharges (37.5%). 12.5% of patients had sporadic epileptiform discharges, and 6.3% of patients demonstrated electrographic or clinical seizures. Eighteen (56.3%) patients died or were transitioned to end-of-life care during the index admission. Worsening background continuity or frequency over the course of the cEEG recording was significantly associated with poor outcome (p = 0.001, p = 0.007, respectively), with a 100% mortality rate in patients demonstrating these EEG trends. A worst recorded continuity of suppression, attenuation, and burst-suppression was also associated with poor outcome (p = 0.012). The presence of rhythmic or periodic patterns, sporadic epileptiform discharges, or seizures was not predictive of outcome.

CONCLUSIONS

Worsening cEEG background continuity or frequency is associated with poor outcome in adults with ALF. cEEG may contribute useful prognostic information in these patients, in conjunction with other laboratory and clinical markers of disease severity.

New-onset prolonged psychosis from non-convulsive status epilepticus

The most common ictal psychiatric symptom is fear, followed by ictal depression, and least commonly ictal psychosis. A 44-year-old man with poststroke focal epilepsy developed new-onset behavioural change, disorientation, hallucinations and delusions, persisting for several months before medical evaluation. He was agitated, disorientated, with impaired memory and disorganised thinking, but had no minor epileptic motor signs. His EEG showed electroclinical status epilepticus. His psychotic symptoms persisted despite seizure control and required antipsychotic treatment. Ictal psychosis is rare but clinicians should suspect this in people with epilepsy with new-onset behavioural change. Rarely, it can persist for months, sometimes needing antipsychotic treatment.

Retrospective Visual and Quantitative Assessment of Burst Suppression With and Without Identical Bursts in Patients After Cardiac Arrest

BACKGROUND

The objective of this study was to assess the prognostic significance of identical bursts (IBs) in cardiac arrest survivors with burst suppression on continuous electroencephalogram (cEEG) monitoring. Burst suppression with IBs is associated with poor neurological outcomes and mortality.

METHODS

We conducted a retrospective analysis of cardiac arrest survivors admitted to a US academic medical center between 2013 and 2021 who had an EEG background of burst suppression. EEG and clinical features were extracted from our institutional review board-approved repositories. EEG features were qualitatively and quantitatively rated at 0, 12, 24, 48, and 72 h following initiation of monitoring. Qualitative visual assessment occurred, blinded to all clinical features, including outcomes, and in accordance with the current American Clinical Neurophysiology Society definition. Quantitative assessment involved manual marking of 50 consecutive pairs of bursts and interburst intervals (IBIs) for analysis. Similarity of bursts/IBIs were assessed with correlation coefficients. The primary clinical outcome was survival to hospital discharge. Comparisons were performed between groups, and a multivariate model was generated for significant variables.

RESULTS

Of 593 cardiac arrest patients, 203 (34.2%) had burst suppression. Thirty-one (15.3%) patients with burst suppression survived. IBs were detected in 80 patients (39.4% of burst suppression). No patient with qualitatively identified IBs had a good neurological outcome (76 deceased, 4 in a state of unresponsive wakefulness). Whereas 11 of 123 (8.9%) with burst suppression without IB had Cerebral Performance Category scores of 1-2. Quantitative analysis of 268 instances of burst suppression demonstrated that mortality was associated with longer bursts, longer IBIs, and higher burst correlation coefficients (i.e., bursts that were more similar to each other) only when allowing analysis of the first 2 s of bursts. Binary logistic regression showed that the only independent EEG predictor of mortality was the burst correlation coefficient measured over 2 s (adjusted odds ratio 4.82 [95% confidence interval 1.21-8.42], p = 0.009).

CONCLUSIONS

Using a single-center US cohort, IBs within 72 h post cardiac arrest were strongly associated with poor outcomes. Quantitative analysis revealed that including the first 2 s of the bursts was superior to limiting the analysis to 0.5-1 s.

Epileptic activity on foramen ovale electrodes is associated with sleep and tau pathology in Alzheimer's disease

Both sleep alterations and epileptiform activity are associated with the accumulation of amyloid-β and tau pathology and are currently investigated for potential therapeutic interventions in Alzheimer's disease. However, a bidirectional intertwining relationship between sleep and neuronal hyperexcitability might modulate the effects of Alzheimer's disease pathology on the corresponding associations. To investigate this, we performed multiple day simultaneous foramen ovale (FO) plus scalp EEG and polysomnography recordings and acquired 18F-MK6240 tau PET-MR in three patients in the prodromal stage of Alzheimer's disease and in two patients with mild and moderate dementia due to Alzheimer's disease, respectively. As an eligibility criterion for the present study, subjects either had a history of a recent seizure (n = 2) or subclinical epileptiform activity (SEA) on a previous scalp EEG taken in a research context (n = 3). The 18F-MK6240 standard uptake value ratio (SUVR) and asymmetry index (AI) were calculated in a priori-defined volumes of interest. Linear mixed-effects models were used to study associations between interictal epileptiform discharges (IEDs), polysomnography parameters and 18F-MK6240 SUVR. Epileptiform activity was bilateral but asymmetrically present on FO electrodes in all patients and ≥95% of IEDs were not visible on scalp EEG. In one patient, two focal seizures were detected on FO electrodes, both without visual scalp EEG correlate. We observed lateralized periodic discharges, brief potentially ictal rhythmic discharges and lateralized rhythmic delta activity on FO electrodes in four patients. Unlike scalp EEG, intracranial electrodes showed a lateralization of epileptiform activity. Although the amount of IEDs on intracranial electrodes was not associated to the 18F-MK6240 SUVR binding in different volumes of interest, there was a congruent asymmetry of the 18F-MK6240 binding towards the most epileptic hemisphere for the mesial (P = 0.007) and lateral temporal cortex (P = 0.006). IEDs on intracranial electrodes were most abundant during slow wave sleep (SWS) (92/h) and non-REM sleep 2 (N2, 81/h), followed by non-REM sleep 1 (N1, 33/h) and least frequent during wakefulness (17/h) and REM sleep (9/h). The extent of IEDs during sleep was not reflected in the relative time in each sleep stage spent [REM% (P = 0.415), N1% (P = 0.668), N2% (P = 0.442), SWS% (P = 0.988)], and not associated with the arousal index (P = 0.317), apnoea-hypopnoea index (P = 0.846) or oxygen desaturation index (P = 0.746). Together, our observations suggest a multi-directional interaction between sleep, epileptiform activity and tau pathology in Alzheimer's disease.

Prolonged Monitoring of Brain Electrical Activity in the Intensive Care Unit

Electroencephalography (EEG) has been used to assess brain electrical activity for over a century. More recently, technological advancements allowed EEG to be a widely available and powerful tool in the intensive care unit (ICU), where patients at risk for cerebral dysfunction and brain injury can be monitored in a continuous, real-time manner. In the last 2 decades, several organizations established guidelines for continuous EEG monitoring in the ICU, defining critical care EEG terminology and technical standards for technicians, machines, and electroencephalographers. This article provides an overview of the current role of continuous EEG monitoring in the ICU.

Infantile epileptic spasms syndrome: When spasms come out of the blue

BACKGROUND

This study evaluates the electroclinical features of infantile epileptic spasms syndrome (IESS) suddenly appearing in previously normal patients, aiming to describe clinical outcomes and independent predictors.

METHOD

We retrospectively selected a homogeneous group of patients with IESS from two Italian centers. All patients had normal development prior to IESS onset and a follow-up period lasting at least one year. Patients with clinically relevant risk factors, other seizure types, brain structural abnormalities or known genetic diseases were excluded. The BASED score was used to standardize interictal EEG patterns.

RESULTS

Forty-three patients were enrolled, with a median age at IESS onset of 6 months; median follow-up was 43 months. At onset, 65.11 % exhibited mild behavioral changes, including irritability and poor social smile. At firstEEG, epileptic encephalopathy (EE) was prevalent during wakefulness (69.76 %; median BASED score 4) and sleep (81.40 %; median BASED score 5). Within 15 days of treatment, 83.72 % achieved seizure freedom, primarily with ACTH depot (90.70 %). After six months, all patients were seizure- and EE-free. At the last follow-up, 81.40 % had normal cognitive functioning; in the remaining, specific neurodevelopmental disorders, predominantly involving language were reported. No statistically significant differences were found in the electroclinical presentation and neuropsychological outcome.

CONCLUSION

We describe a subgroup of IESS patients with prompt response to treatment, long-term seizure freedom, and absence of severe neurodevelopmental impact. Our data suggest that within the IESS spectrum, there is a distinctive subgroup with global favorable outcome. Key clinical features predictors of good outcome could include normal development prior to IESS and early response to treatment.

The value of electroencephalography features in the prognostic evaluation of large hemispheric infarction patients at different time intervals

BACKGROUND

Large Hemispheric Infarction (LHI) is a devastating disease with high mortality. This study aimed to use electroencephalography (EEG) to evaluate the death risk of LHI patients and identify suitable evaluation time.

METHODS

This study retrospectively collected clinical and EEG data from 73 LHI patients, dividing them into death and survival group at discharge. EEG data was classified as 1-5 days and 6-14 days after onset according to the time intervals of cerebral edema. Regression and receiver operator characteristic curve (ROC) analysis were applied to explore the impact of temporal changes in various EEG and clinical features on death.

RESULTS

The areas under ROC curve (AUC) of death prediction for non-α frequency on non-infarct side at 6-14 days after onset was significantly higher than that at 1-5 days (p = 0.004). And there was no significant difference between the AUC of seizure activity for death prediction at 1-5 days and 6-14 days (p = 0.418). Multivariate regression analysis revealed that non-α frequency on non-infarct side and seizure activity at 6-14 days after onset were the independent risk factors for the death of LHI patients. Additionally, above two EEG features significantly improved the death predictive efficacy of clinical features in LHI patients with the integrated discrimination improvement index (IDI) of 0.174 (p = 0.015) and the net reclassification improvement (NRI) of 1.314 (p<0.001).

CONCLUSIONS

Non-α frequency on non-infarct side and seizure activity were reliable indicators for death prediction. 6-14 days after onset was the better time window for death evaluation of LHI patients through EEG.

Myoclonus After Cardiac Arrest: Need for Standardization-A Systematic Review and Research Proposal on Terminology

OBJECTIVES

Although myoclonus less than or equal to 72 hours after cardiac arrest (CA) is often viewed as a single entity, there is considerable heterogeneity in its clinical and electrophysiology characteristics, and its strength of association with outcome. We reviewed definitions, electroencephalogram, and outcome of myoclonus post-CA to assess the need for consensus and the potential role of electroencephalogram for further research.

DATA SOURCES

PubMed, Embase, and Cochrane databases.

STUDY SELECTION

English-language adult (≥ 18 yr) studies from 1966 to May 31, 2024, reporting myoclonus, myoclonic status/status myoclonus (MyS/SM), myoclonic status epilepticus (MSE), and/or early Lance-Adams Syndrome (eLAS) less than or equal to 72 hours post-CA. All study designs were independently screened by two authors.

DATA EXTRACTION

Data on patients presenting myoclonus, MyS/SM, MSE, and eLAS less than or equal to 72 hours post-CA, along with their definitions, electroencephalogram, and outcomes were extracted. The Newcastle-Ottawa Scale and Cochrane-Risk-of-Bias Assessment tool were used to evaluate study quality (PROSPERO n.CRD42023438107).

DATA SYNTHESIS

Of 585 identified articles, 119 met the inclusion criteria, revealing substantial heterogeneity in definitions, electroencephalogram, and outcomes. Among 3881 patients, myoclonus was reported in 2659, MyS/SM in 883, MSE in 569, and eLAS in 40. Among patients with a defined outcome, a Cerebral Performance Category (CPC) scale of 1-2 was reported in 9.8% of patients with myoclonus, 5.8% with MyS/SM, 5.7% with MSE, and 82.0% with eLAS. Electroencephalogram was recorded in 2714 patients (69.9%). CPC of 1-2 was observed in 1.6% of patients with suppression/suppression burst (SB)/unreactive (U) electroencephalogram, 11.3% with non-SB/U electroencephalogram and status epilepticus (SE), and 22.3% with non-SB/U electroencephalogram without SE.

CONCLUSIONS

Heterogeneity in definitions resulted in weak associations with outcomes. We propose to investigate myoclonus by including related electroencephalogram patterns: myoclonus associated with suppression/SB background electroencephalogram, myoclonus with nonsuppression/SB background but SE-electroencephalogram, and myoclonus with nonsuppression/SB background without SE-electroencephalogram. This pragmatic research approach should be validated in future studies.