Multimodal Approach to Decision to Treat Critically Ill Patients With Periodic or Rhythmic Patterns Using an Ictal-Interictal Continuum Spectral Severity Score

Ictal-Interictal Continuum in the Pediatric Intensive Care Unit

BACKGROUND

The ictal-interictal continuum (IIC) consists of several electroencephalogram (EEG) patterns that are common in critically ill adults. Studies focused on the IIC are limited in critically ill children and have focused primarily on associations with electrographic seizures (ESs). We report the incidence of the IIC in the pediatric intensive care unit (PICU). We then compare IIC patterns to rhythmic and periodic patterns (RPP) not meeting IIC criteria looking for associations with acute cerebral abnormalities, ES, and in-hospital mortality.

METHODS

This was a retrospective review of prospectively collected data for patients admitted to the PICU at Children's National Hospital from July 2021 to January 2023 with continuous EEG. We excluded patients with known epilepsy and cerebral injury prior to presentation. All patients were screened for RPP. The American Clinical Neurophysiology Society standardized Critical Care EEG terminology for the IIC was applied to each RPP. Associations between IIC and RPP not meeting IIC criteria, with clinical and EEG variables, were calculated using odds ratios (ORs).

RESULTS

Of 201 patients, 21% (42/201) had RPP and 12% (24/201) met IIC criteria. Among patients with an IIC pattern, the median age was 3.4 years (interquartile range (IQR) 0.6-12 years). Sixty-seven percent (16/24) of patients met a single IIC criterion, whereas the remainder met two criteria. ESs were identified in 83% (20/24) of patients and cerebral injury was identified in 96% (23/24) of patients with IIC patterns. When comparing patients with IIC patterns with those with RPP not qualifying as an IIC pattern, both patterns were associated with acute cerebral abnormalities (IIC OR 26 [95% confidence interval {CI} 3.4-197], p = 0.0016 vs. RPP OR 3.5 [95% CI 1.1-11], p = 0.03), however, only the IIC was associated with ES (OR 121 [95% CI 33-451], p < 0.0001) versus RPP (OR 1.3 [0.4-5], p = 0.7).

CONCLUSIONS

Rhythmic and periodic patterns and subsequently the IIC are commonly seen in the PICU and carry a high association with cerebral injury. Additionally, the IIC, seen in more than 10% of critically ill children, is associated with ES. The independent impact of RPP and IIC patterns on secondary brain injury and need for treatment of these patterns independent of ES requires further study.

A study on the clinical and electrographic profile of Nonconvulsive Status Epilepticus (NCSE) in comatose ICU patients using portable electroencephalography (EEG)

Background

Coma is one of the frequently encountered clinical conditions in any intensive care unit (ICU), which is responsible for considerable morbidity and mortality. Therefore, this study was designed to look at the clinical and EEG profile of Nonconvulsive Status Epilepticus (NCSE) in comatose ICU patients using portable electroencephalography (EEG).

Methods

In all 102 patients of unresponsive coma (GCS ≤ 8), who remained in poor sensorium despite 48 h of optimum treatment in ICU, were included in the study. All patients underwent 1 h of electroencephalography (EEG) monitoring with a portable EEG machine. All EEGs were screened according to Salzburg Consensus Criteria (SCC) for Nonconvulsive Status Epilepticus (NCSE). Patients with evidence of NCSE were administered parenteral Antiepileptic Drugs (AED). A repeat EEG was done after 24 h of baseline to ascertain the effect of AED. The primary outcome was the recognition of patients with NCSE on the basis of established EEG criteria. The secondary outcome measure was the Glasgow outcome scale (GOS) at the time of discharge.

Results

Out of 102 cases enrolled, 12 (11.8%) cases were detected to have NCSE on portable EEG. The mean age of patients with NCSE was 52.2 years. In terms of gender distribution, 2/12 (17%) were female, and 10/12 (83%) were male (M: F = 5:1). Median GCS was 6 (range 3-8). Looking at CNS infections, 4/12 (33.3%) had evidence of some form of CNS infection in the NCSE group, compared to 16/90 (18%) in the group without NCSE. This difference was statistically significant (P-value < 0.05). The EEG recordings of patients with NCSE showed dynamicity with fluctuating rhythms and ictal-EEG patterns associated with spatiotemporal evolution. All twelve cases showed reversal of EEG changes with AED administration. In 5 out of 12, transient improvement in GCS (>2 points) after administration of AED' was noted with good clinical outcomes (GOS 5). In five of these 12 cases, death was the final outcome (GOS 1).

Conclusions

NSCE should be considered in the differential diagnosis of all unresponsive comatose ICU patients. In resource-limited settings, where continuous EEG monitoring may not be feasible, bedside portable EEG testing can be used to diagnose patients with NCSE. Treating NCSE reverses epileptiform EEG changes and improves clinical outcomes in a subset of comatose ICU patients.

Electrographic Seizures in the Critically Ill

Identifying and treating critically ill patients with seizures can be challenging. In this article, the authors review the available data on patient populations at risk, seizure prognostication with tools such as 2HELPS2B, electrographic seizures and the various ictal-interictal continuum patterns with their latest definitions and associated risks, ancillary testing such as imaging studies, serum biomarkers, and invasive multimodal monitoring. They also illustrate 5 different patient scenarios, their treatment and outcomes, and propose recommendations for targeted treatment of electrographic seizures in critically ill patients.

Hyperperfusion Tmax mapping for nonconvulsive status epilepticus in the acute setting: A pilot case-control study

OBJECTIVE

Nonconvulsive status epilepticus (NCSE) is misdiagnosed in >50% of cases in the emergency department. Computed tomographic perfusion (CTP) has been implemented in the hyperacute setting to detect seizure-induced hyperperfusion. However, the diagnostic value of CTP is limited by the lack of thresholds for hyperperfusion and high interrater variability. This pilot case-control study aims at identifying the diagnostic value of reverse Tmax (rTmax) in differentiating NCSE from acute ischemic stroke in the hyperacute setting.

METHODS

We enrolled patients with NCSE (Salzburg criteria-based diagnosis) and stroke cases 1:1 matched for clinical features and time of presentation. CTP standard maps (mean transit time [MTT]-cerebral blood volume-cerebral blood flow [CBF]) and rTmax maps were elaborated and rated by two experts in CTP blinded to the final diagnosis. Hyperperfusion was adjudicated for standard CTP maps as an increase in CBF and a decrease in MTT, and for rTmax as the presence of a black area on 3-, 2-, and 1-s threshold maps. Cronbach alpha was used for interrater agreement; receiver operating curve analysis was run to measure accuracy with area under the curve.

RESULTS

Overall, 34 patients were included (17 NCSE, 17 stroke; time from onset to imaging = 2 h for both groups). People with NCSE were older and more frequently had a history of epilepsy. NCSE patients had hyperperfusion on rTmax maps in 11 of 17 cases versus zero of 17 in stroke. Intra- and interrater reliability was higher for rTmax than for standard CTP maps (κ = 1 vs. κ = .6). rTmax was 82% (95%CI = 67-97%) accurate in predicting NCSE versus stroke in the hyperacute setting. Agreement between neuroimaging and electroencephalography (EEG) was limited at a hemispheric level for standard CTP maps, whereas rTMax had agreement with EEG largely reaching the sublobar level.

SIGNIFICANCE

rTmax mapping might represent a reliable tool to spot NCSE-induced hyperperfusion with a threshold-based reproducible approach. Further studies are needed for validation and implementation in the differential diagnosis of focal neurological deficit in the hyperacute setting.

Factors associated with the use of anesthetic drug infusion in patients with status epilepticus and their relation to outcome: a prospective study

Status epilepticus (SE) is one of the most dreadful neurological emergencies; unfortunately, studies targeting SE are still inadequate. This study aims to identify factors associated with the use of CIVAD in patients presenting with status epilepticus and detect those impact the clinical outcome. A prospective study involving 144 episodes of SE in 144 patients. Patients were categorized according to whether or not they received CIVAD. Subjects underwent clinical assessment, brain imaging, and EEG. The consciousness level was assessed using the Glasgow coma scale (GCS) and the Full outline of responsiveness (FOUR) scale. SE severity score (STESS) and Epidemiology-based mortality score (EMSE) were used as scales for outcome prediction. Continuous IV anesthetic drug infusion was initiated in 36% of patients (+ CIVAD). Such groups showed a significantly worse initial level of consciousness (< 0.001), an unstable course of seizure evolution (0.009), and all of them showed abnormal EEG patterns. A significantly higher number of patients (+ CIVAD) developed complications (< 0.001), had higher outcome prediction scores (< 0.001), and mortality rates (< 0.001) compared to those who did not need CIVAD (- CIVAD). Mortality was associated with acute symptomatic etiology and higher total doses of propofol. Among the study population, mortality among patients who received CIVAD was associated with acute symptomatic SE and prolonged propofol infusion rather than any clinical parameters or predictor scores.

Management of Status Epilepticus, Refractory Status Epilepticus, and Super-refractory Status Epilepticus

PURPOSE OF REVIEW

Status epilepticus is a serious condition caused by disorders and diseases that affect the central nervous system. In status epilepticus, hypersynchronous epileptic activity lasts longer than the usual duration of isolated self-limited seizures (time t1), which causes neuronal damage or alteration of neuronal networks at a certain time point (time t2), depending on the type of and duration of status epilepticus. The successful management of status epilepticus includes both the early termination of seizure activity and the earliest possible identification of a causative etiology, which may require independent acute treatment. In nonconvulsive status epilepticus, patients present only with subtle clinical signs or even without any visible clinical manifestations. In these cases, EEG allows for the assessment of cerebral function and identification of patterns in need of urgent treatment.

RECENT FINDINGS

In 2015, the International League Against Epilepsy proposed a new definition and classification of status epilepticus, encompassing four axes: symptomatology, etiology, EEG, and age. Various validation studies determined the practical usefulness of EEG criteria to identify nonconvulsive status epilepticus. The American Clinical Neurophysiology Society has incorporated these criteria into their most recent critical care EEG terminology in 2021. Etiology, age, symptomatology, and the metabolic demand associated with an increasing duration of status epilepticus are the most important determinants of prognosis. The consequences of status epilepticus can be visualized in vivo by MRI studies.

SUMMARY

The current knowledge about status epilepticus allows for a more reliable diagnosis, earlier treatment, and improved cerebral imaging of its consequences. Outcome prediction is a soft tool for estimating the need for intensive care resources.

Functional neuroimaging in nonepileptiform electroencephalographic patterns in status epilepticus

BACKGROUND

The diagnosis of nonconvulsive status epilepticus (NCSE) in patients with nonepileptiform EEG patterns remains a challenge.

OBJECTIVE

To evaluate the usefulness of single photon emission computerized tomography (SPECT) and its quantification (QtSPECT) in the diagnosis of NCSE.

METHODS

We retrospectively reviewed patients admitted with clinical suspicion of NCSE who underwent an HMPAO-SPECT simultaneously with scalp EEG showing nonepileptiform patterns, in a 5-year period. After a complete diagnostic workup, treatment, and clinical evolution, disregarding the SPECT results, patients were classified into confirmed NCSE (n = 11) and non-NCSE (n = 8). Then, we compared the EEG and SPECT results in both groups.

RESULTS

Lateralized rhythmic delta activity (LRDA) was predominant in the NCSE group (45.4%, p = .045), while lateralized irregular slowing was observed equally in both groups. Patients with NCSE showed significant hyperperfusion compared with non-NCSE patients (p = .026). QtSPECT correctly classified 91% of patients in NCSE and 75% patients with non-NCSE (p = .006).

CONCLUSIONS

Regional cerebral blood flow measured with SPECT could be useful in the diagnosis of NCSE in cases of an EEG pattern with lateralized slow activity and high clinical suspicion.

Characteristics and outcome in an Egyptian Cohort with status epilepticus

OBJECTIVES

Status epilepticus (SE) is an important cause of mortality worldwide. Information regarding associations of mortality outcome in Egypt is limited. The main objective of this study was to describe the clinical characteristics and factors associated with mortality of patients with SE admitted to Cairo University Hospitals.

METHODS

A prospective observational hospital-based study was conducted from January 2017 to June 2018. Patients with SE aged ≥12 years old were followed with documentation of outcome on discharge as survival versus death.

RESULTS

The study cohort included 144 SE patients. The majority of episodes (96.5%) were with prominent motor features, while nonconvulsive SE occurred in 3.5%. There was a clear semiology evolution in 22.9% of episodes, 56.3% had unchanging semiology (e.g., just convulsive or just nonconvulsive) and the semiology evolution could not be discerned in 20.8%. In relation to treatment, the majority of cases were responsive (46.5%), whereas 43.1% were refractory and only 10.4% were super-refractory SE. Apart from seven patients who were referred to other hospitals, 99 patients survived whereas 38 (26.4%) died. After regression analysis, only absence of a history of epilepsy, semiology evolution and mechanical ventilator use were associated with mortality increasing its odds by 3.7, 5, 111 times, respectively.

CONCLUSION

Absence of a history of epilepsy, SE semiology evolution, and mechanical ventilator use was found to be associated with mortality outcome among Egyptian patients with SE.

Clinical phenotypes within nonconvulsive status epilepticus

The study aimed to identify distinct phenotypes within nonconvulsive status epilepticus (NCSE). Consecutive episodes of NCSE in patients at least 14 years old were included. The level of consciousness was assessed through the Glasgow Coma Scale (GCS). Etiology of NCSE was defined as symptomatic (acute, remote, progressive) or unknown. Electroencephalographic (EEG) recordings were searched for lateralized periodic discharges (LPDs), generalized sharply and/or triphasic periodic potentials (GPDs), and spontaneous burst suppression (BS). According to treatment response, NCSE was classified as responsive, refractory, or superrefractory. Average linkage hierarchical cluster analysis was performed with Pearson correlation as similarity measure. Two hundred twenty‐nine episodes of NCSE were included. Three clusters were identified. The first cluster linked GCS score 3–8, presence of spontaneous BS on EEG, acute symptomatic etiology, and treatment superrefractoriness. The second cluster gathered GCS score 9–12, presence of LPDs or GPDs on EEG, unknown etiology, and treatment refractoriness. The third cluster associated GCS score 13–15, absence of LPDs, GPDs, and spontaneous BS on EEG, and progressive and remote symptomatic etiology with treatment responsiveness. Phenotyping the heterogeneity of NCSE into electroclinical clusters can contribute to understanding correlations between pathologic and clinical domains, assessing the intrinsic severity of NCSE episodes, and estimating the likelihood of treatment responsiveness.

A Theoretical Paradigm for Evaluating Risk-Benefit of Status Epilepticus Treatment

Aggressive treatment of status epilepticus with anesthetic drugs can provide rapid seizure control, but it might lead to serious medical complications and worse outcomes. Using a decision analysis approach, this concise review provides a framework for individualized decision making about aggressive and nonaggressive treatment in status epilepticus. The authors propose and review the most relevant parameters guiding the risk-benefit analysis of treatment aggressiveness in status epilepticus and present real-world-based case examples to illustrate how these tools could be used at the bedside and serve to guide future research in refractory status epilepticus treatment.

Monitoring the Burden of Seizures and Highly Epileptiform Patterns in Critical Care with a Novel Machine Learning Method

INTRODUCTION

Current electroencephalography (EEG) practice relies on interpretation by expert neurologists, which introduces diagnostic and therapeutic delays that can impact patients' clinical outcomes. As EEG practice expands, these experts are becoming increasingly limited resources. A highly sensitive and specific automated seizure detection system would streamline practice and expedite appropriate management for patients with possible nonconvulsive seizures. We aimed to test the performance of a recently FDA-cleared machine learning method (Claritγ, Ceribell Inc.) that measures the burden of seizure activity in real time and generates bedside alerts for possible status epilepticus (SE).

METHODS

We retrospectively identified adult patients (n = 353) who underwent evaluation of possible seizures with Rapid Response EEG system (Rapid-EEG, Ceribell Inc.). Automated detection of seizure activity and seizure burden throughout a recording (calculated as the percentage of ten-second epochs with seizure activity in any 5-min EEG segment) was performed with Claritγ, and various thresholds of seizure burden were tested (≥ 10% indicating ≥ 30 s of seizure activity in the last 5 min, ≥ 50% indicating ≥ 2.5 min of seizure activity, and ≥ 90% indicating ≥ 4.5 min of seizure activity and triggering a SE alert). The sensitivity and specificity of Claritγ's real-time seizure burden measurements and SE alerts were compared to the majority consensus of at least two expert neurologists.

RESULTS

Majority consensus of neurologists labeled the 353 EEGs as normal or slow activity (n = 249), highly epileptiform patterns (HEP, n = 87), or seizures [n = 17, nine longer than 5 min (e.g., SE), and eight shorter than 5 min]. The algorithm generated a SE alert (≥ 90% seizure burden) with 100% sensitivity and 93% specificity. The sensitivity and specificity of various thresholds for seizure burden during EEG recordings for detecting patients with seizures were 100% and 82% for ≥ 50% seizure burden and 88% and 60% for ≥ 10% seizure burden. Of the 179 EEG recordings in which the algorithm detected no seizures, seizures were identified by the expert reviewers in only two cases, indicating a negative predictive value of 99%.

DISCUSSION

Claritγ detected SE events with high sensitivity and specificity, and it demonstrated a high negative predictive value for distinguishing nonepileptiform activity from seizure and highly epileptiform activity.

CONCLUSIONS

Ruling out seizures accurately in a large proportion of cases can help prevent unnecessary or aggressive over-treatment in critical care settings, where empiric treatment with antiseizure medications is currently prevalent. Claritγ's high sensitivity for SE and high negative predictive value for cases without epileptiform activity make it a useful tool for triaging treatment and the need for urgent neurological consultation.

Electrographic seizures and ictal-interictal continuum (IIC) patterns in critically ill patients

Critical care long-term continuous electroencephalogram (cEEG) monitoring has expanded dramatically in the last several decades spurned by technological advances in EEG digitalization and several key clinical findings: 1-Seizures are relatively common in the critically ill-large recent observational studies suggest that around 20% of critically ill patients placed on cEEG have seizures. 2-The majority (~75%) of patients who have seizures have exclusively "electrographic seizures", that is, they have no overt ictal clinical signs. Along with the discovery of the unexpectedly high incidence of seizures was the high prevalence of EEG patterns that share some common features with archetypical electrographic seizures but are not uniformly considered to be "ictal". These EEG patterns include lateralized periodic discharges (LPDs) and generalized periodic discharges (GPDs)-patterns that at times exhibit ictal-like behavior and at other times behave more like an interictal finding. Dr. Hirsch and colleagues proposed a conceptual framework to describe this spectrum of patterns called the ictal-interictal continuum (IIC). In the following years, investigators began to answer some of the key pragmatic clinical concerns such as which patients are at risk of seizures and what is the optimal duration of cEEG use. At the same time, investigators have begun probing the core questions for critical care EEG-what is the underlying pathophysiology of these patterns, at what point do these patterns cause secondary brain injury, what are the optimal treatment strategies, and how do these patterns affect clinical outcomes such as neurological disability and the development of epilepsy. In this review, we cover recent advancements in both practical concerns regarding cEEG use, current treatment strategies, and review the evidence associating IIC/seizures with poor clinical outcomes.

Bedside interpretation of simplified continuous EEG after cardiac arrest

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.