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.

OBJECTIVE:Previously proposed "synchronous EEG patterns" predict poor outcome within 24 h after cardiac arrest (CA). We investigate the prognostic performance of these early EEG predictors in addition to the late EEG predictors (>24 h) recommended in the European post-resuscitation guidelines. METHODS:Observational substudy of the TTM2-trial including consecutive comatose resuscitated patients. Continuous EEG-monitoring (cEEG) was blindly assessed using the American Clinical Neurophysiology Societýs standardised EEG terminology and categorised into early EEG predictors (burst-suppression with identical or highly epileptiform bursts, or suppression with generalised periodic discharges) and late EEG predictors (heterogenous burst-suppression or suppression). Poor outcome was defined as modified Rankin Scale 4-6 at six months. RESULTS:Of 191 included patients, 53 % had poor outcome. Early EEG predictors had 100 %[CI 96-100] specificity at all time-points and maximal sensitivity 30 %[CI 21-40] before 24 h. Late EEG predictors had 100 %[CI 96-100] specificity beyond 24 h with maximal sensitivity 32 %[CI 21-43]. Using both early and late EEG predictors, and gradually adding cEEG-information from consecutive time-epochs, sensitivity increased to 49 %[CI 39-59] up to 36 h after CA (p = 0.001). A continuous background within 12 h predicted good outcome (sensitivity 61 %[CI 50-71]; specificity 87 %[CI 79-93]). CONCLUSION:Searching for both early EEG predictors (e.g. identical burst-suppression) and late EEG predictors (e.g. heterogenous burst-suppression > 24 h) significantly improved sensitivity of poor outcome prediction without false positive survivors in this cohort. A self-fulfilling prophecy may have affected our results. cEEG during the first two days after CA identified half of the patients with a long-term poor outcome and half of the patients with a good outcome.

Background and Objectives EEG is widely used for prediction of neurologic outcome after cardiac arrest. To better understand the relationship between EEG and neuronal injury, we explored the association between EEG and neurofilament light (NfL) as a marker of neuroaxonal injury, evaluated whether highly malignant EEG patterns are reflected by high NfL levels, and explored the association of EEG backgrounds and EEG discharges with NfL. Methods We performed a post hoc analysis of the Target Temperature Management After Out-of-Hospital Cardiac Arrest trial. Routine EEGs were prospectively performed after the temperature intervention >= 36 hours postarrest. Patients who awoke or died prior to 36 hours postarrest were excluded. EEG experts blinded to clinical information classified EEG background, amount of discharges, and highly malignant EEG patterns according to the standardized American Clinical Neurophysiology Society terminology. Prospectively collected serum samples were analyzed for NfL after trial completion. The highest available concentration at 48 or 72 hours postarrest was used. Results A total of 262/939 patients with EEG and NfL data were included. Patients with highly malignant EEG patterns had 2.9 times higher NfL levels than patients with malignant patterns and NfL levels were 13 times higher in patients with malignant patterns than those with benign patterns (95% CI 1.4-6.1 and 6.5-26.2, respectively; effect size 0.47; p < 0.001). Both background and the amount of discharges were independently strongly associated with NfL levels (p < 0.001). The EEG background had a stronger association with NfL levels than EEG discharges (R-2 = 0.30 and R-2 = 0.10, respectively). NfL levels in patients with a continuous background were lower than for any other background (95% CI for discontinuous, burst-suppression, and suppression, respectively: 2.26-18.06, 3.91-41.71, and 5.74-41.74; effect size 0.30; p < 0.001 for all). NfL levels did not differ between suppression and burst suppression. Superimposed discharges were only associated with higher NfL levels if the EEG background was continuous. Discussion Benign, malignant, and highly malignant EEG patterns reflect the extent of brain injury as measured by NfL in serum. The extent of brain injury is more strongly related to the EEG background than superimposed discharges. Combining EEG and NfL may be useful to better identify patients misclassified by single methods.

Objective: EEG is commonly used to predict prognosis in post anoxic coma. We investigated if stimulus-induced rhythmic, periodic or ictal discharges (SIRPIDs) add prognostic information after cardiac arrest. Methods: In the multicenter Targeted Temperature Management trial, routine-EEGs were prospectively recorded after rewarming (>= 36 h). Presence and subtype of SIRPIDs and main EEG-pattern (benign, malignant, highly malignant) were retrospectively reported according to a standardised classification. Patients were followed up after 180 days. Poor outcome was defined as severe neurological disability or death (Cerebral Performance Category 3-5). Results: Of 142 patients, 71% had poor outcome and 14% had SIRPIDs. There was no significant difference in outcome between patients with and without SIRPIDs, even when subgrouped according to underlying main EEG-pattern. Comparing subtypes of SIRPIDs, 82% of patients with stimulus-induced periodic discharges had poor outcome compared to 44% of patients with stimulus-induced rhythmic delta activity, but the difference was not significant. Conclusions: In EEGs performed >36 h after cardiac arrest, SIRPIDs cannot be used to reliably predict poor outcome. Whether certain subtypes of SIRPIDs indicate worse prognosis needs further investigation. Significance: Categorising the main EEG-pattern has important prognostic implications, but assessment of late appearing SIRPIDs does not seem to add prognostic information. (C) 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V.

Purpose To assess the performance of a 4-step algorithm for neurological prognostication after cardiac arrest recommended by the European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM). Methods Retrospective descriptive analysis with data from the Target Temperature Management (TTM) Trial. Associations between predicted and actual neurological outcome were investigated for each step of the algorithm with results from clinical neurological examinations, neuroradiology (CT or MRI), neurophysiology (EEG and SSEP) and serum neuron-specific enolase. Patients examined with Glasgow Coma Scale Motor Score (GCS-M) on day 4 (72–96 h) post-arrest and available 6-month outcome were included. Poor outcome was defined as Cerebral Performance Category 3–5. Variations of the ERC/ESICM algorithm were explored within the same cohort. Results The ERC/ESICM algorithm identified poor outcome patients with 38.7% sensitivity (95% CI 33.1–44.7) and 100% specificity (95% CI 98.8–100) in a cohort of 585 patients. An alternative cut-off for serum neuron-specific enolase, an alternative EEG-classification and variations of the GCS-M had minor effects on the sensitivity without causing false positive predictions. The highest overall sensitivity, 42.5% (95% CI 36.7–48.5), was achieved when prognosticating patients irrespective of GCS-M score, with 100% specificity (95% CI 98.8–100) remaining. Conclusion The ERC/ESICM algorithm and all exploratory multimodal variations thereof investigated in this study predicted poor outcome without false positive predictions and with sensitivities 34.6–42.5%. Our results should be validated prospectively, preferably in patients where withdrawal of life-sustaining therapy is uncommon to exclude any confounding from self-fulfilling prophecies.

Objective: To study if comatose cardiac arrest patients can be assessed with a reduced number of EEG electrodes. Methods: 110 routine EEGs from 67 consecutive patients, including both hypothermic and normothermic EEGs were retrospectively assessed by three blinded EEG-experts using two different electrode montages. A standard 19-electrode-montage was compared to the reduced version of the same EEGs, down-sampled to six electrodes (F3, T3, P3, F4, T4, P4). We used intra-rater and inter-observer statistics to assess the reliability of the reduced montage for background features and discharges. Results: The reduced montage had almost perfect performance for background continuity (kappa 0.80-0.88), including identification of highly malignant backgrounds (burst-suppression/suppression) (kappa 0.85-0.94) and benign backgrounds (continuous/nearly continuous) (kappa 0.85-0.91). We found substantial performance for identifying rhythmic/periodic discharges (kappa 0.79-0.86). The reduced montage had high accuracy for assessment of both highly malignant (sensitivity 91-95%, specificity 94-99%) and benign (sensitivity 89-98%, specificity 91-96%) backgrounds, and periodic/rhythmic patterns (sensitivity 79-100%, specificity 89-99%), compared to the full montage. The inter-observer variability was not increased by the reduced montage. Conclusion: Reduced EEG had high performance for classifying important background and discharge patterns in this post cardiac arrest cohort. Significance: Our results support the use of reduced EEG-montage for monitoring comatose cardiac arrest patients. (C) 2020 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The authors regret that the line “Unequivocal seizures or status epilepticus” was missing under the definition of “Malignant rhythmic or periodic features” in Supplementary Table S1 of the above article. The authors would like to apologise for any inconvenience caused.

Background Continuous EEG‐monitoring (cEEG) in the ICU is recommended to assess prognosis and detect seizures after cardiac arrest but implementation is often limited by the lack of EEG‐technicians and experts. The aim of the study was to assess ICU physicians ability to perform preliminary interpretations of a simplified cEEG in the post cardiac arrest setting. Methods Five ICU physicians received training in interpretation of simplified cEEG ‐ total training duration 1 day. The ICU physicians then interpreted 71 simplified cEEG recordings from 37 comatose survivors of cardiac arrest. The cEEG included amplitude‐integrated EEG trends and two channels with original EEG‐signals. Basic EEG background patterns and presence of epileptiform discharges or seizure activity were assessed on 5‐grade rank‐ordered scales based on standardized EEG terminology. An EEG‐expert was used as reference. Results There was substantial agreement (κ 0.69) for EEG background patterns and moderate agreement (κ 0.43) for epileptiform discharges between ICU physicians and the EEG‐expert. Sensitivity for detecting seizure activity by ICU physicians was limited (50%), but with high specificity (87%). Conclusions After cardiac arrest, preliminary bedside interpretations of simplified cEEGs by trained ICU physicians may allow earlier detection of clinically relevant cEEG changes, prompting changes in patient management as well as additional evaluation by an EEG‐expert. This strategy requires awareness of limitations of both the simplified electrode montage and the cEEG interpretations performed by ICU physicians. cEEG evaluation by an expert should not be delayed.

Introduction: Multimodal neurological prognostication is recommended for comatose patients after cardiac arrest. The absence of cortical N20-potentials in a somatosensory evoked potential (SSEP) examination reliably predicts poor outcome, but presence of N20-potentials have limited prognostic value. A benign routine electroencephalogram (EEG) may identify patients with a favourable prognosis who are likely to have present N20-potentials. Objective: To investigate whether a routine EEG can identify patients where SSEP is unnecessary to perform. Methods: In a multi-centre trial, comatose patients after cardiac arrest were randomised to a controlled temperature of 33 degrees C or 36 degrees C. A routine EEG was protocolised and SSEP performed at the clinicians' discretion, both during normothermic conditions. EEGs were categorised into benign, malignant or highly malignant based on standardised terminology. A benign EEG was defined as a continuous normal-voltage background without abundant discharges. The N20-potentials were reported as absent (bilaterally) or present (bilaterally or unilaterally). Results: Both EEG and SSEP were performed in 161 patients. EEG was performed before SSEP in 60%, A benign EEG was seen in 29 patients and 100% (CI 88-100%) had present N20-potentials. For the 69 patients with a malignant EEG and the 63 patients with a highly malignant EEG, 67% (CI 55-77%) and 44% (CI 33-57%) had present N20-potentials, respectively. Conclusions: All patients with a benign EEG had present N20-potentials, suggesting that SSEP may be omitted in these patients to save resources. SSEP is useful in patients with a malignant or highly malignant EEG since these patterns are associated with both present and absent N20-potentials.

The authors regret that the line “Unequivocal seizures or status epilepticus” was missing under the definition of “Malignant rhythmic or periodic features” in Supplementary Table S1 of the above article. The authors would like to apologise for any inconvenience caused. Highly malignant routine EEG predicts poor prognosis after cardiac arrest in the Target Temperature Management trialResuscitationVol. 131PreviewRoutine EEG is widely used and accessible for post arrest neuroprognostication. Recent studies, using standardised EEG terminology, have proposed highly malignant EEG patterns with promising predictive ability. Full-Text PDF

Continuous monitoring of electroencephalography (EEG), with a focus on amplitude-integrated EEG (aEEG), has been used in neonatal intensive care for decades. A number of systems have been suggested for describing and quantifying aEEG patterns. Extensive full-montage EEG monitoring is used in specialised intensive care units. The American Clinical Neurophysiology Society published recommendations for defining and reporting EEG findings in critically ill adults and infants. Swedish neonatologists and clinical neurophysiologists collaborated to optimise simplified neonatal continuous aEEG and EEG recordings based on these American documents. This paper describes the Swedish consensus document produced by those meetings.

Introduction: Routine EEG is widely used and accessible for post arrest neuroprognostication. Recent studies, using standardised EEG terminology, have proposed highly malignant EEG patterns with promising predictive ability. Objectives: To validate the performance of standardised routine EEG patterns to predict neurological outcome after cardiac arrest. Methods: In the prospective multicenter Target Temperature Management trial, comatose cardiac arrest patients were randomised to different temperature levels (950 patients, 36 sites). According to the prospective protocol a routine EEG was performed in patients who remained comatose after the 36 h temperature control intervention. EEGs were retrospectively reviewed blinded to outcome using the standardised American Clinical Neurophysiology Society terminology. Highly malignant, malignant and benign EEG patterns were correlated to poor and good outcome, defined by best achieved Cerebral Performance Category up to 180 days. Results: At 20 sites 207 patients had a routine EEG performed at median 76 h after cardiac arrest. Highly malignant patterns (suppression or burst-suppression with or without discharges) had a high specificity for poor outcome (98%, CI 92-100), but with limited sensitivity (31%, CI 24-39). Our false positive patient had a burst-suppression pattern during ongoing sedation. A benign EEG, i.e. continuous normal-voltage background without malignant features, identified patients with good outcome with 77% (CI 66-86) sensitivity and 80% (CI 73-86) specificity. Conclusion: Highly malignant routine EEG after targeted temperature management is a strong predictor of poor outcome. A benign EEG is an important indicator of a good outcome for patients remaining in coma.

Continuous monitoring of electroencephalography (EEG), with a focus on amplitude-integrated EEG (aEEG), has been used in neonatal intensive care for decades. A number of systems have been suggested for describing and quantifying aEEG patterns. Extensive full-montage EEG monitoring is used in specialised intensive care units. The American Clinical Neurophysiology Society published recommendations for defining and reporting EEG findings in critically ill adults and infants. Swedish neonatologists and clinical neurophysiologists collaborated to optimise simplified neonatal continuous aEEG and EEG recordings based on these American documents.CONCLUSION:This paper describes the Swedish consensus document produced by those meetings.

OBJECTIVE:To describe the electrophysiological characteristics and pathophysiological significance of electrographic status epilepticus (ESE) after cardiac arrest and specifically compare patients with unequivocal ESE to patients with rhythmic or periodic borderline patterns defined as possible ESE. METHODS:Retrospective cohort study of consecutive patients treated with targeted temperature management and monitored with simplified continuous EEG. Patients with ESE were identified and electrographically characterised until 72h after ESE start using the standardised terminology of the American Clinical Neurophysiology Society. RESULTS:ESE occurred in 41 of 127 patients and 22 fulfilled the criteria for unequivocal ESE, which typically appeared early and transiently. Three of the four survivors had unequivocal ESE, starting after rewarming from a continuous background. There were no differences between the groups of unequivocal ESE and possible ESE regarding outcome, neuron-specific enolase levels or prevalence of reported clinical convulsions. CONCLUSION:ESE is common after cardiac arrest. The distinction between unequivocal and possible ESE patterns was not reflected by differences in clinical features or survival. SIGNIFICANCE:A favourable outcome is seen infrequently in patients with ESE, regardless of using strict or liberal ESE definitions.

Background: Postanoxic electrographic status epilepticus (ESE) is considered a predictor of poor outcome in resuscitated patients after cardiac arrest (CA). Observational data suggest that a subgroup of patients may have a good outcome. This study aimed to describe the prevalence of ESE and potential clinical and electrographic prognostic markers.Methods : In this retrospective single study, we analyzed consecutive patients who suffered from CA, and who received temperature management and were monitored with simplified continuous EEG (cEEG) during a five-year period. The patients' charts and cEEG data were initially screened to identify patients with clinical seizures or ESE. The cEEG diagnosis of ESE was retrospectively reanalyzed according to strict criteria by a neurophysiologist blinded to patient outcome. The EEG background patterns prior to the onset of ESE, duration of ESE, presence of clinical seizures, and use of antiepileptic drugs were analyzed. The results of somatosensory-evoked potentials (SSEPs) and neuron specific enolase (NSE) at 48 h after CA were described in all patients with ESE. Antiepileptic treatment strategies were not protocolized. Outcome was evaluated using the Cerebral Performance Category (CPC) scale at 6 months, and good outcome was defined as CPC 1-2.Results: Of 127 patients, 41 (32%) developed ESE. Twenty-five patients had a discontinuous EEG background prior to ESE, and all died without regaining consciousness. Sixteen patients developed a continuous EEG background prior to the start of ESE, four of whom survived, three with CPC 1-2 and one with CPC 3 at 6 months. Among survivors, ESE developed at a median of 46 h after CA. All had preserved N20 peaks on SSEP and NSE values of 18-37 mu g/l.Conclusion: Electrographic status epileplicus is common among comatose patients after cardiac arrest, with few survivors. A combination of a continuous EEG background prior to ESE, preserved N20 peaks on SSEPs, and low or moderately elevated NSE levels may indicate a good outcome. (C) 2015 Elsevier Inc. All rights reserved,

In this paper, we study machine learning techniques and features of electroencephalography activity bursts for predicting outcome in extremely preterm infants. It was previously shown that the distribution of interburst interval durations predicts clinical outcome, but in previous work the information within the bursts has been neglected. In this paper, we perform exploratory analysis of feature extraction of burst characteristics and use machine learning techniques to show that such features could be used for outcome prediction. The results are promising, but further verification in larger datasets is needed to obtain conclusive results.

PURPOSE:To assess if 3T MRI can be further improved by adding surface coil imaging, in the context of detection and characterization of cerebral lesions in patients with drug-resistant epilepsy.METHODS:Twenty five patients with drug-resistant epilepsy undergoing evaluation for epilepsy surgery were examined with high resolution 3T MRI. The patients were MRI-negative (n = 15), or had unclear findings (n = 10), on previous MRI at 1.0-1.5T. Surface coils were applied over the suspected epileptogenic zone after imaging in the head coil. In MRI-negative patients, placement of the coils was defined by semiological analysis, extracranial video-EEG, and, in selected cases, subtraction ictal SPECT co-registered with MRI and PET. Coil placement was re-analyzed and graded, based on the degree of convergence between different investigational modalities.RESULTS:Surface coil MRI allowed visualization of the cortical lesions with somewhat better demarcation and detail, but did not contribute to detection of previously undiagnosed lesions and did not provide additional information regarding type of lesion. Possible epileptogenic lesions were detected on 3T MRI in 12 patients. No abnormalities were found in the remaining 13 patients. 3T MRI provided new or additional information about the cortex, compared with reports from previous 1.0-1.5T MRI in 5 patients (20%).CONCLUSION:3T MRI with high resolution is valuable for lesion detection, especially MCD, in patients with drug-resistant epilepsy. We question the additional contribution from supplementary surface coil imaging at 3T MRI.