Malignant EEG Patterns Research Articles

EEG for good outcome prediction after cardiac arrest: A multicentre cohort study

AimAssess the prognostic ability of a non-highly malignant and reactive EEG to predict good outcome after cardiac arrest (CA). MethodsProspective observational multicentre substudy of the “Targeted Hypothermia versus Targeted Normothermia after Out-of-hospital Cardiac Arrest Trial”, also known as the TTM2-trial. Presence or absence of highly malignant EEG patterns and EEG reactivity to external stimuli were prospectively assessed and reported by the trial sites. Highly malignant patterns were defined as burst-suppression or suppression with or without superimposed periodic discharges. Multimodal prognostication was performed 96 h after CA. Good outcome at 6 months was defined as a modified Rankin Scale score of 0–3. Results873 comatose patients at 59 sites had an EEG assessment during the hospital stay. Of these, 283 (32%) had good outcome. EEG was recorded at a median of 69 h (IQR 47–91) after CA. Absence of highly malignant EEG patterns was seen in 543 patients of whom 255 (29% of the cohort) had preserved EEG reactivity. A non-highly malignant and reactive EEG had 56% (CI 50–61) sensitivity and 83% (CI 80–86) specificity to predict good outcome. Presence of EEG reactivity contributed (p < 0.001) to the specificity of EEG to predict good outcome compared to only assessing background pattern without taking reactivity into account. ConclusionNearly one-third of comatose patients resuscitated after CA had a non-highly malignant and reactive EEG that was associated with a good long-term outcome. Reactivity testing should be routinely performed since preserved EEG reactivity contributed to prognostic performance.

The predictive value of highly malignant EEG patterns after cardiac arrest: evaluation of the ERC-ESICM recommendations

PurposeThe 2021 guidelines endorsed by the European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) recommend using highly malignant electroencephalogram (EEG) patterns (HMEP; suppression or burst-suppression) at > 24 h after cardiac arrest (CA) in combination with at least one other concordant predictor to prognosticate poor neurological outcome. We evaluated the prognostic accuracy of HMEP in a large multicentre cohort and investigated the added value of absent EEG reactivity.MethodsThis is a pre-planned prognostic substudy of the Targeted Temperature Management trial 2. The presence of HMEP and background reactivity to external stimuli on EEG recorded > 24 h after CA was prospectively reported. Poor outcome was measured at 6 months and defined as a modified Rankin Scale score of 4–6. Prognostication was multimodal, and withdrawal of life-sustaining therapy (WLST) was not allowed before 96 h after CA.Results845 patients at 59 sites were included. Of these, 579 (69%) had poor outcome, including 304 (36%) with WLST due to poor neurological prognosis. EEG was recorded at a median of 71 h (interquartile range [IQR] 52–93) after CA. HMEP at > 24 h from CA had 50% [95% confidence interval [CI] 46–54] sensitivity and 93% [90–96] specificity to predict poor outcome. Specificity was similar (93%) in 541 patients without WLST. When HMEP were unreactive, specificity improved to 97% [94–99] (p = 0.008).ConclusionThe specificity of the ERC-ESICM-recommended EEG patterns for predicting poor outcome after CA exceeds 90% but is lower than in previous studies, suggesting that large-scale implementation may reduce their accuracy. Combining HMEP with an unreactive EEG background significantly improved specificity. As in other prognostication studies, a self-fulfilling prophecy bias may have contributed to observed results.

Use of Prognostication Instruments in Prognostication Procedures of Postanoxic Coma Patients over Time: A Retrospective Study.

Many survivors of cardiovascular arrest remain in a postanoxic coma. The neurologist's task is to provide the most accurate assessment of the patient's neurologic prognosis through a multimodal approach of clinical and technical tests. The aim of this study is to analyze differences and developments in the concept of neurological prognosis assessment and in-hospital outcome of patients over a five year-period. This retrospective observational study included 227 patients with postanoxic coma treated in the medical intensive care unit of the University Hospital, Mannheim from January 2016 to May 2021. We retrospectively analyzed patient characteristics, post-cardiac arrest care, and the use of clinical and technical tests for neurological prognosis assessment and patient outcome. Over the observation period, 215 patients received a completed neurological prognosis assessment. Regarding the multimodal prognostic assessment, patients with poor prognosis (54%) received significantly fewer diagnostic modalities than patients with very likely poor (20.5%), indeterminate (24.2%), or good prognosis (1.4%; p = 0.001). The update of the DGN guidelines in 2017 had no effect on the number of performed prognostic parameters per patient. The finding of bilaterally absent pupillary light reflexes or severe anoxic injury on CT contributed most to a poor prognosis category (OR 8.38, 95%CI 4.01-7.51 and 12.93, 95%CI 5.55-30.13, respectively), whereas a malignant EEG pattern and NSE > 90 µg/L at 72 h resulted in the lowest OR (5.11, 95%CI 2.32-11.25, and 5.89, 95%CI 3.14-11.06, respectively) for a poor prognosis category. Assessment of baseline NSE significantly increased over the years (OR 1.76, 95%CI 1.4-2.22, p < 0.001), and assessment of follow-up NSE at 72 h trended to increase (OR 1.19, 95%CI 0.99-1.43, p = 0.06). In-hospital mortality was high (82.8%), remained unchanged over the observation period, and corresponded to the number of patients in whom life-sustaining measures were discontinued. Among comatose survivors of cardiac arrest, the prognosis remains poor. Prognostication of a poor outcome led nearly exclusively to withdrawal of care. Prognostic modalities varied considerably with regard to their contribution to a poor prognosis category. Increasing enforcement of a standardized prognosis assessment and standardized evaluation of diagnostic modalities are needed to avoid false-positive prognostication of poor outcomes.

Epileptiform patterns predicting unfavorable outcome in postanoxic patients: A matter of time?

ObjectiveHistorically, epileptiform malignant EEG patterns (EMPs) have been considered to anticipate an unfavorable outcome, but an increasing amount of evidence suggests that they are not always or invariably associated with poor prognosis. We evaluated the prognostic significance of an EMP onset in two different timeframes in comatose patients after cardiac arrest (CA): early-EMPs and late-EMPs, respectively. MethodsWe included all comatose post-CA survivors admitted to our intensive care unit (ICU) between 2016 and 2018 who underwent at least two 30-minute EEGs, collected at T0 (12–36 h after CA) and T1 (36–72 h after CA). All EEGs recordings were re-analyzed following the 2021 ACNS terminology by two senior EEG specialists, blinded to outcome. Malignant EEGs with abundant sporadic spikes/sharp waves, rhythmic and periodic patterns, or electrographic seizure/status epilepticus, were included in the EMP definition. The primary outcome was the cerebral performance category (CPC) score at 6 months, dichotomized as good (CPC 1–2) or poor (CPC 3–5) outcome. ResultsA total of 58 patients and 116 EEG recording were included in the study. Poor outcome was seen in 28 (48%) patients. In contrast to late-EMPs, early-EMPs were associated with a poor outcome (p = 0.037), persisting after multiple regression analysis. Moreover, a multivariate binomial model coupling the timing of EMP onset with other EEG predictors such as T1 reactivity and T1 normal voltage background can predict outcome in the presence of an otherwise non-specific malignant EEG pattern with quite high specificity (82%) and moderate sensitivity (77%). ConclusionsThe prognostic significance of EMPs seems strongly time-dependent and only their early-onset may be associated with an unfavorable outcome. The time of onset of EMP combined with other EEG features could aid in defining prognosis in patients with intermediate EEG patterns.

Continuous EEG of memories of Near-death and mystical experiences: Preliminary research

We recently recorded, processed, and published brain activity by quantitative electroencephalography (QEEG) and quantitative electroencephalography (QEEGt), comparing separate subjects remembering their near-death experience (NDE) and mystical experience. Our studies refer to a mystical experience as a spiritual contemplative experience (SCE). We found neural and Greyson Scale (GS) correlations between them. This study is a real-time enhancement of that study using the emerging technology of continuous EEG monitoring (CEEG), which intensive care unit (ICU) professionals use to identify malignant EEG patterns quickly and provide care effectively. EEG monitoring encompasses a wide range of technical and clinical issues in successfully monitoring critically ill patients to detect significant changes in cerebral function and prevent serious neuronal injury over time. Because the brain undergoes continuous and dynamic changes, CEEG was considered an important method for real-time monitoring of functional brain changes while remembering near-death experiences (NDE) and spiritual contemplative experience (SCE). The CEEG envelope showed an incremental amplitude coinciding with NDE and SCE remembering the time, but an increase of amplitude was greater for SCE. CEEG also demonstrated a greater amplitude in frontal lobes for SCE. Statistical increments of absolute power for alpha and gamma bands were demonstrated during both NDE and SCE. We conclude that CEEG is a useful method for continuously assessing dynamic changes while remembering NDE and SCE.

Association Between EEG Patterns and Serum Neurofilament Light After Cardiac Arrest: A Post Hoc Analysis of the TTM Trial.

Background and ObjectivesEEG 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.MethodsWe 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.ResultsA 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 (R2 = 0.30 and R2 = 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.DiscussionBenign, 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.Trial Registration InformationClinicalTrials.gov NCT01020916.

Neurological Prognostication After Hypoglycemic Coma: Role of Clinical and EEG Findings.

Hypoglycemic coma (HC) is an uncommon but severe clinical condition associated with poor neurological outcome. There is a dearth of robust neurological prognostic factors after HC. On the other hand, there is an increasing body of literature on reliable prognostic markers in the postanoxic coma, a similar-albeit not identical-situation. The objective of this study was thus to investigate the use and predictive value of these markers in HC. We conducted a retrospective, multicenter, cohort study within five centers of the Critical Care EEG Monitoring Research Consortium. We queried our electroencephalography (EEG) databases to identify all patients undergoing continuous EEG monitoring after admission to an intensive care unit with HC (defined as Glasgow Coma Scale < 8 on admission and a first blood glucose level < 50mg/dL or not documented but in an obvious clinical context) between 01/01/2010 and 12/31/2020. We studied the association of findings at neurological examination (Glasgow Coma Scale motor subscale, pupillary light and corneal reflexes) and at continuous EEG monitoring(highly malignant patterns, reactivity, periodic discharges, seizures) with best neurological outcome within 3months after hospital discharge, defined by the Cerebral Performance Category as favorable (1-3: recovery of consciousness) versus unfavorable (4-5: lack of recovery of consciousness). We identified 60 patients (30 [50%] women; age 62 [51-72] years). Thirty-one and 29 patients had a favorable and unfavorable outcome, respectively. The presence of pupillary reflexes (24 [100%] vs. 17 [81%]; p value 0.04) and a motor subscore > 2 (22 [92%] vs. 12 [63%]; p value 0.03) at 48-72h were associated with a favorable outcome. A highly malignant EEG pattern was observed in 7 of 29 (24%) patients with unfavorable outcome versus 0 of 31 (0%) with favorable outcome, whereas the presence of EEG reactivity was observed in 28 of 31 (90%) patients with favorable outcome versus 13 of 29 (45%) with unfavorable outcome (p < 0.001 for comparison of all background categories). This preliminary study suggests that highly malignant EEG patterns might be reliable prognostic markers of unfavorable outcome after HC. Other EEG findings, including lack of EEG reactivity and seizures and clinical findings appear less accurate. These findings should be replicated in a larger multicenter prospective study.

HP35: Takotsubo cardiomyopathy complicated with non-convulsive status epilepticus

Takotsubo cardiomyopathy (TTC) is a cardiac condition that causes an unexpected waning of the heart occurring during a stressful emotional event and potentially leading to acute heart failure [Ghadri J 2018]. TTC can be associated with various complications including cardiogenic shock, life-threatening arrhythmias and cardiac arrest [Templin C 2015]. Here we present a case of a young woman with TTC complicating with cardiac arrest and non-convulsive status epilepticus and a good neurological outcome Case report: A 38-years-old woman with unremarkable past medical history, after a strong emotional distress presented acute chest pain, dyspnea, and loss of consciousness with perioral cyanosis and noisy breathing. Cardiopulmonary resuscitation was immediately initiated, which continued for 50 minutes until the appearance of the sinus rhythm on the ECG. Dilated apex and mid-ventricular segment akinesis were recorded on echocardiography. Brain CT was unremarkable. Continuous video-EEG monitoring showed malignant EEG patterns, firstly, suppressed and non-reactive background, followed 24h later by frontally predominant generalized spike and spike-wave discharges. Administration of diazepam 20 mg did not modify her clinical and EEG state, while infusion of phenobarbital 1200 mg [20mg/kg] resulted in significant EEG improvement. Under combined antiepileptic medication (i.e., valproate 500 mg bid and levetiracetam 750 mg bid, her EEG and clinical status improved in few days. Conclusion: Although non-convulsive status epilepticus after cardiac arrest is associated with poor outcome, our patient survived, with a Cerebral Performance Category score of 2. Good recovery in this case might be related to young age, reversible cardiomyopathy, and timely management of complications.

Background frequency can enhance the prognostication power of EEG patterns categories in comatose cardiac arrest survivors: a prospective, multicenter, observational cohort study

BackgroundWe assessed the prognostic accuracy of the standardized electroencephalography (EEG) patterns (“highly malignant,” “malignant,” and “benign”) according to the EEG timing (early vs. late) and investigated the EEG features to enhance the predictive power for poor neurologic outcome at 1 month after cardiac arrest.MethodsThis prospective, multicenter, observational, cohort study using data from Korean Hypothermia Network prospective registry included adult patients with out-of-hospital cardiac arrest (OHCA) treated with targeted temperature management (TTM) and underwent standard EEG within 7 days after cardiac arrest from 14 university-affiliated teaching hospitals in South Korea between October 2015 and December 2018. Early EEG was defined as EEG performed within 72 h after cardiac arrest. The primary outcome was poor neurological outcome (Cerebral Performance Category score 3–5) at 1 month.ResultsAmong 489 comatose OHCA survivors with a median EEG time of 46.6 h, the “highly malignant” pattern (40.7%) was most prevalent, followed by the “benign” (33.9%) and “malignant” (25.4%) patterns. All patients with the highly malignant EEG pattern had poor neurologic outcomes, with 100% specificity in both groups but 59.3% and 56.1% sensitivity in the early and late EEG groups, respectively. However, for patients with “malignant” patterns, 84.8% sensitivity, 77.0% specificity, and 89.5% positive predictive value for poor neurologic outcome were observed. Only 3.5% (9/256) of patients with background EEG frequency of predominant delta waves or undetermined had good neurologic survival. The combination of “highly malignant” or “malignant” EEG pattern with background frequency of delta waves or undetermined increased specificity and positive predictive value, respectively, to up to 98.0% and 98.7%.ConclusionsThe “highly malignant” patterns predicted poor neurologic outcome with a high specificity regardless of EEG measurement time. The assessment of predominant background frequency in addition to EEG patterns can increase the prognostic value of OHCA survivors.Trial registration KORHN-PRO, NCT02827422. Registered 11 September 2016—Retrospectively registered.

Assessing neurological prognosis in post-cardiac arrest patients from short vs plain text EEG reports: A survey among intensive care clinicians

BackgroundElectroencephalography (EEG) patterns are predictive of neurological prognosis in comatose survivors from cardiac arrest but intensive care clinicians are dependent of neurophysiologist reports to identify specific patterns. We hypothesized that the proportion of correct assessment of neurological prognosis would be higher from short statements confirming specific EEG patterns compared with descriptive plain text reports. MethodsVolunteering intensive care clinicians at two university hospitals were asked to assess the neurological prognosis of a fictional patient with high neuron specific enolase. They were presented with 17 authentic plain text reports and three short statements, confirming whether a “highly malignant”, “malignant” or “benign” EEG pattern was present. Primary outcome was the proportion of clinicians who correctly identified poor neurological prognosis from reports consistent with highly malignant EEG patterns. Secondary outcomes were how the prognosis was assessed from reports consistent with malignant and benign patterns. ResultsOut of 57 participants, poor prognosis was correctly identified by 61% from plain text reports and by 93% from the short statement “highly malignant” EEG patterns. Unaffected prognosis was correctly identified by 28% from plain text reports and by 40% from the short statement “malignant” patterns. Good prognosis was correctly identified by 64% from plain text reports and by 93% from the short statement “benign” pattern. ConclusionStandardized short statement, “highly malignant EEG pattern present”, as compared to plain text EEG descriptions in neurophysiologist reports, is associated with more accurate identification of poor neurological prognosis in comatose survivors of cardiac arrest.

Neurological Prognostication Using Raw EEG Patterns and Spectrograms of Frontal EEG in Cardiac Arrest Patients.

We investigated which raw EEG and spectrogram patterns in frontal EEG predict poor neurological outcomes in patients with hypoxic ischemic encephalopathy after cardiac arrest. This multicenter, prospective, observational study included 52 patients with anoxic brain injury after cardiac arrest. Raw EEGs and spectrograms (color density spectral arrays) measured with hardwired frontal EEG monitoring were used to predict poor prognosis. Neurological variables upon admission, raw EEG patterns, including highly malignant and malignant EEG patterns, and changes in frequency and amplitude from color density spectral arrays were investigated. All patients exhibiting highly malignant EEG patterns died, and malignant EEG patterns were significant predictors of poor prognosis as the area under the receiver operating characteristic curve was 0.83 to 0.86. Irregular high-voltage waves in the high-frequency beta band in continuous background EEGs were associated with poor prognosis ( P = 0.022). Malignant EEG patterns including high-voltage and high-frequency beta waves were significantly stronger predictors of poor prognosis than the absence of ventricular fibrillation and pupil reflex, delayed length of anoxic time, and lower Glasgow coma scale score (odds ratio, 9; P = 0.035). Compared with prognostication using malignant EEG patterns alone, the area under the receiver operating characteristic curve of results incorporating high-voltage and high-frequency beta waves was 0.84 (vs. 0.83) at day 1, 0.88 (vs. 0.85) at day 2, 0.92 (vs. 0.86) at day 3, and 0.99 (vs. 0.86) at day 4. Frontal EEG monitoring is useful for predicting poor neurological outcomes. Brain function monitoring using both raw EEG patterns and color density spectral arrays is more helpful for predicting poor prognosis than raw EEG alone.

Prognostic significance of specific EEG patterns after cardiac arrest in a Lisbon Cohort

ObjectiveTo evaluate if EEG patterns considered highly malignant are reliable predictors not only of poor neurological outcome but also reliable predictors of death. MethodsRetrospectively, EEGs from Cardiac Arrest (CA) patients of two teaching hospitals in Lisbon were classified into 3 groups: highly malignant, malignant, and benign groups. Outcome was assessed at 6 months after CA by CPC (Cerebral Performance Categories) scale. We evaluated the accuracy of these patterns to predict poor neurological outcome and death. ResultsWe included 106 patients for analysis. All patients with a highly malignant EEG (n = 37) presented a poor neurological outcome. Those patterns were also associated with death. Malignant EEG patterns were not associated with poor neurological outcome. Benign EEG patterns were associated with good neurological recovery (p < 0.0001). ConclusionHighly malignant EEG patterns were strongly associated with poor neurological outcome and can be considered to be predictors of death. SignificanceThis study increased the knowledge about the value of EEG as a tool in outcome prediction of patients after cardiac arrest.

RETRACTED: Neurological outcome of postanoxic refractory status epilepticus after aggressive treatment

Refractory status epilepticus (RSE) occurs in up to 30% of patients following resuscitation after cardiac arrest. The impact of aggressive treatment of postanoxic RSE on long-term neurological outcome remains uncertain. We investigated neurological outcome of cardiac arrest patients with RSE treated with a standardized aggressive protocol with antiepileptic drugs and anesthetics, compared with patients with other electroencephalographic (EEG) patterns. A prospective cohort of 166 consecutive patients with cardiac arrest in coma was stratified according to four independent EEG patterns (benign; RSE; generalized periodic discharges (GPDs); malignant nonepileptiform) and multimodal prognostic indicators. Primary outcomes were survival and cerebral performance category (CPC) at 6 months. Refractory status epilepticus occurred in 36 patients (21.7%) and was treated with an aggressive standardized protocol as long as multimodal prognostic indicators were not unfavorable. Refractory status epilepticus started after 3 ± 2.3 days after cardiac arrest and lasted 4.7 ± 4.3 days. A benign electroencephalographic patterns was recorded in 76 patients (45.8%), a periodic pattern (GPDs) in 13 patients (7.8%), and a malignant nonepileptiform EEG pattern in 41 patients (24.7%). The four EEG patterns were highly associated with different prognostic indicators (low flow time, clinical motor seizures, N20 responses, neuron-specific enolase (NSE), neuroimaging). Survival and good neurological outcome (CPC 1 or 2) at 6 months were 72.4% and 71.1% for benign EEG pattern, 54.3% and 44.4% for RSE, 15.4% and 0% for GPDs, and 2.4% and 0% for malignant nonepileptiform EEG pattern, respectively. Aggressive and prolonged treatment of RSE may be justified in cardiac arrest patients with favorable multimodal prognostic indicators.This article is part of the Special Issue “Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures"

Good Outcome in Cardiac Arrest Patients in Refractory Status Epilepticus: A Result of Aggressive Treatment or EEG Reclassification.

Neurologic outcome of postanoxic refractory status epilepticus after aggressive treatment. Beretta S, Coppo A, Bianchi E, et al. Neurology. 2018;91(23):e2153-e2162. doi:10.1212/WNL.0000000000006615. Epub October 31, 2018.Objective:To investigate neurologic outcome of patients with cardiac arrest with refractory status epilepticus (RSE) treated with a standardized aggressive protocol with antiepileptic drugs and anesthetics compared to patients with other electroencephalogram (EEG) patterns.Methods:In the prospective cohort study, 166 consecutive patients with cardiac arrest in coma were stratified according to 4 independent EEG patterns (benign, RSE, generalized periodic discharges [GPDs], malignant nonepileptiform) and multimodal prognostic indicators. Primary outcomes were survival and cerebral performance category (CPC) at 6 months.Results:The RSE occurred in 36 (21.7%) patients and was treated with an aggressive standardized protocol as long as multimodal prognostic indicators were not unfavorable. The RSE started 3 ± 2.3 days after cardiac arrest and lasted 4.7 ± 4.3 days. A benign EEG pattern was recorded in 76 (45.8%) patients, a periodic pattern (GPDs) was seen in 13 (7.8%) patients, and a malignant nonepileptiform EEG pattern was recorded in 41 (24.7%) patients. The 4 EEG patterns were highly associated with different prognostic indicators (low-flow time, clinical motor seizures, N20 responses, neuron-specific enolase, neuroimaging). Survival and good neurologic outcome (CPC 1 or 2) at 6 months were 72.4% and 71.1% for benign EEG pattern, 54.3% and 44.4% for RSE, 15.4% and 0% for GPDs, and 2.4% and 0% for malignant nonepileptiform EEG pattern, respectively.Conclusions:Aggressive and prolonged treatment of RSE may be justified in patients with cardiac arrest with favorable multimodal prognostic indicators.

Neurologic outcome of postanoxic refractory status epilepticus after aggressive treatment.

To investigate neurologic outcome of patients with cardiac arrest with refractory status epilepticus (RSE) treated with a standardized aggressive protocol with antiepileptic drugs and anesthetics compared to patients with other EEG patterns. In the prospective cohort study, 166 consecutive patients with cardiac arrest in coma were stratified according to 4 independent EEG patterns (benign, RSE, generalized periodic discharges [GPDs], malignant nonepileptiform) and multimodal prognostic indicators. Primary outcomes were survival and cerebral performance category (CPC) at 6 months. RSE occurred in 36 patients (21.7%) and was treated with an aggressive standardized protocol as long as multimodal prognostic indicators were not unfavorable. RSE started after 3 ± 2.3 days after cardiac arrest and lasted 4.7 ± 4.3 days. A benign EEG pattern was recorded in 76 patients (45.8%); a periodic pattern (GPDs) was seen in 13 patients (7.8%); and a malignant nonepileptiform EEG pattern was recorded in 41 patients (24.7%). The 4 EEG patterns were highly associated with different prognostic indicators (low-flow time, clinical motor seizures, N20 responses, neuron-specific enolase, neuroimaging). Survival and good neurologic outcome (CPC 1 or 2) at 6 months were 72.4% and 71.1% for benign EEG pattern, 54.3% and 44.4% for RSE, 15.4% and 0% for GPDs, and 2.4% and 0% for malignant nonepileptiform EEG pattern, respectively. Aggressive and prolonged treatment of RSE may be justified in patients with cardiac arrest with favorable multimodal prognostic indicators.

Highly malignant routine EEG predicts poor prognosis after cardiac arrest in the Target Temperature Management trial

IntroductionRoutine 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. ObjectivesTo validate the performance of standardised routine EEG patterns to predict neurological outcome after cardiac arrest. MethodsIn 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. ResultsAt 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. ConclusionHighly 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.

S24. The combination of electroencephalogram (EEG) and somatosensory evoked potentials (SSEP) for prognostication following anoxic brain injury – A pilot study from an Academic Hospital in Ireland

Introduction Clinical evaluation for prognosis of comatose patients following hypoxic ischaemic encephalopathy in the intensive care setting is difficult. Electroencephalogram (EEG) and somatosensory evoked potentials (SSEP) both hold value as predictive tools when assessing outcome following cardiac arrest (CA) and hypoxic brain injury. EEG may be used for diagnosis and prognostication on a poorly responsive patient following catastrophic brain injury. There is evidence that loss of EEG reactivity is a strong risk factor for mortality or poor neurological recovery following cardiac arrest, however, bilaterally absent SSEPs remain the most reliable predictor of poor outcome. SSEPs have not been widely available in Ireland as a component of neurophysiologic investigation following hypoxic ischaemic encephalopathy. The aim of this review is to assess and compare the predictive value of EEG and SSEP separately as single modality testing and then subsequently combine both tests for a multimodal approach to predict poor outcome following anoxic brain injury. Is a multimodal approach mandatory? Methods Seventeen cardiac arrest survivors were included in this review. We adopted a multimodal approach to neurophysiologic investigations in the ICU setting with prospective evaluation of patients of hypoxic ischaemic encephalopathy after CA. EEG and SSEPs were performed at normothermia. EEG background reactivity to painful stimulation was tested. Results Of the 17 patients included in the review, two survived to discharge and 15 subsequently died during hospitalisation. EEG was utilised as a marker for poor outcome combining malignant EEG patterns and absent reactivity of background rhythms. 11 out of 17 fitted into the “poor outcome” category for EEG, all of whom died. Bilateral absent N20 cortical responses were utilised for poor outcome, 9 out of 17 fitted into the “poor outcome” category, all of whom went on to die. However, there were eight patients included showing present N20s, this is not prognostic of a favourable outcome. A combination of EEG and SSEP was needed to predict outcome. The EEG showed malignant EEG patterns and unreactive background in 2 of the present N20 patients who subsequently went on to die. Conclusion The EEG represents a useful tool for prognostic assessment. Unreactive EEG background and malignant EEG patterns are incompatible with good long term recovery. In settings without access to SSEPs this can be helpful, however, a bilaterally absent somatosensory evoked potential is still the most reliable predictor for poor outcome. Throughout our review a multimodal approach is shown to be favourable when assessing Hypoxic Ischemic Encephalopathy. This approach, as described above, was necessary to predict outcome in cases where the N20 cortical response was present, thus optimising prognostic accuracy when assessing hypoxic brain injury in the ICU. Early identification of patients without the potential for recovery of brain function may result in unnecessary prolongation of medical therapy.

Treatment of Seizures and Postanoxic Status Epilepticus.

Seizures are a common occurrence following cardiac arrest and may occur both during targeted temperature management and after rewarming. Postanoxic seizures may be nonconvulsive and very difficult to diagnose without electroencephalography (EEG) or associated with prominent myoclonus. Importantly, to date no randomized controlled trials are available to guide the management of seizures in patients with cardiac arrest. Seizure prophylaxis is not recommended, and when seizures are diagnosed they are typically treated the same as seizures in other patients with acute brain injury. Electroencephalographic abnormalities that are highly epileptiform, but do not fulfill classic seizure criteria, also known as the ictal-interictal continuum, occur frequently and there is no consensus on how to treat these. Several EEG patterns have been associated with poor outcome in retrospective studies. Increasing evidence has emerged that patients may have a favorable outcome, even with status myoclonus and malignant EEG patterns, if aggressive management is pursued.

Abstract PR117

Background & Objectives: Bilateral absence of cortical response to somatosensory evoked potentials (SSEPs) after cardiac arrest (CA)is an established marker of poor neurological outcome. However, the presence of these responses (N20PRES) has failed to reliably predict good neurological outcome. In the setting of multimodal monitoring, few data are available on the clinical characteristics of N20PRES patients with poor neurological outcome. Materials & Methods: Retrospective analysis of an institutional database (January 2010 to January 2013) including all adult patients admitted to the Intensive Care Unit (ICU) after CA and undergoing SSEPs between 48 and 72 hours after cardiac arrest. All patients underwent targeted temperature management (TTM; 32–34°C) for 24 hours. We collected the absence of pupillary reflexes, absent or posturing motor response and status myoclonus on day 2–3 and electroencephalography (EEG) data (e.g. absence of reactivity to painful stimuli; presence of a malignant pattern, such as burst-suppression or flat tracings; electroencephalographic status epilepticus) after return to normothermia. Poor neurological outcome (PNO) was defined as a Cerebral Performance Categories of 3–5 at assessed at 3 months Results: We studied 126 patients, including 81 with N20PRES; 55 had PNO. Demographics, comorbidities and CA characteristics were similar between groups except for non-cardiac origin of arrest and non-shockable rhythm which were more frequent in patients with PNO than in the others. PNO Patients with N20PRES were more likely to have absent pupillary reflexes (31% vs. 0%; p=0.003), absent or posturing motor response (51% vs. 11%; p=0.001) on day 2–3 than the other patients. They were also more likely to have a malignant EEG pattern, particularly burst suppression (18% vs. 0%; p=0.02) and a non-reactive EEG (75% vs. 27%; p<0.001). All patients with absent pupillary reflexes on day 2–3 had a PNO (p=0.003). Conclusion: In patients with preserved cortical responses to painful stimuli prognostication may be reliably guided by clinical and EEG signs. The presence of early malignant EEG patterns and the absence of pupillary reflexes on day 2–3 are associated with poor neurological outcome The use of a multimodal assessment may be helpful to guide neuroprognostication in this setting.

Interrater variability of EEG interpretation in comatose cardiac arrest patients

ObjectiveEEG is widely used to predict outcome in comatose cardiac arrest patients, but its value has been limited by lack of a uniform classification. We used the EEG terminology proposed by the American Clinical Neurophysiology Society (ACNS) to assess interrater variability in a cohort of cardiac arrest patients included in the Target Temperature Management trial. The main objective was to evaluate if malignant EEG-patterns could reliably be identified. MethodsFull-length EEGs from 103 comatose cardiac arrest patients were interpreted by four EEG-specialists with different nationalities who were blinded for patient outcome. Percent agreement and kappa (κ) for the categories in the ACNS EEG terminology and for prespecified malignant EEG-patterns were calculated. ResultsThere was substantial interrater agreement (κ 0.71) for highly malignant patterns and moderate agreement (κ 0.42) for malignant patterns. Substantial agreement was found for malignant periodic or rhythmic patterns (κ 0.72) while agreement for identifying an unreactive EEG was fair (κ 0.26). ConclusionsThe ACNS EEG terminology can be used to identify highly malignant EEG-patterns in post cardiac arrest patients in an international context with high reliability. SignificanceThe establishment of strict criteria with high transferability between interpreters will increase the usefulness of routine EEG to assess neurological prognosis after cardiac arrest.