Clinical and Electroencephalographic Predictors of Seizures and Status Epilepticus in 12,450 Critically Ill Adults: A Retrospective Cohort Study.

OBJECTIVES: Status epilepticus (SE) is associated with significantly higher morbidity and mortality than isolated seizures. Our objective was to identify clinical diagnoses and rhythmic and periodic electroencephalogram patterns (RPPs) associated with SE and seizures. DESIGN: Retrospective cohort study. SETTING: Tertiary-care hospitals. SUBJECTS: Twelve thousand four hundred fifty adult hospitalized patients undergoing continuous electroencephalogram (cEEG) monitoring in selected participating sites in the Critical Care EEG Monitoring Research Consortium database (February 2013 to June 2021). INTERVENTIONS: Not applicable. MEASUREMENTS AND MAIN RESULTS: We defined an ordinal outcome in the first 72 hours of cEEG: no seizures, isolated seizures without SE, or SE (with or without isolated seizures). Composite groups included isolated seizures or SE (AnySz) and no seizure or isolated seizures. In this cohort (mean age: 60 ± 17 yr), 1,226 patients (9.8%) had AnySz and 439 patients (3.5%) had SE. In a multivariate model, factors independently associated with SE were cardiac arrest (9.2% with SE; adjusted odds ratio, 8.8 [6.3-12.1]), clinical seizures before cEEG (5.7%; 3.3 [2.5-4.3]), brain neoplasms (3.2%; 1.6 [1.0-2.6]), lateralized periodic discharges (LPDs) (15.4%; 7.3 [5.7-9.4]), brief potentially ictal rhythmic discharges (BIRDs) (22.5%; 3.8 [2.6-5.5]), and generalized periodic discharges (GPDs) (7.2%; 2.4 [1.7-3.3]). All above variables and lateralized rhythmic delta activity (LRDA) were also associated with AnySz. Factors disproportionately increasing odds of SE over isolated seizures were cardiac arrest (7.3 [4.4-12.1]), clinical seizures (1.7 [1.3-2.4]), GPDs (2.3 [1.4-3.5]), and LPDs (1.4 [1.0-1.9]). LRDA had lower odds of SE compared with isolated seizures (0.5 [0.3-0.9]). RPP modifiers did not improve SE prediction beyond RPPs presence/absence ( p = 0.8). CONCLUSIONS: Using the largest existing cEEG database, we identified specific predictors of SE (cardiac arrest, clinical seizures prior to cEEG, brain neoplasms, LPDs, GPDs, and BIRDs) and seizures (all previous and LRDA). These findings could be used to tailor cEEG monitoring for critically ill patients.

Electroencephalography as a Biomarker of Prognosis in Acute Brain Injury.

Electroencephalography (EEG) is a noninvasive tool that allows the monitoring of cerebral brain function in critically ill patients, aiding with diagnosis, management, and prognostication. Specific EEG features have shown utility in the prediction of outcomes in critically ill patients with status epilepticus, acute brain injury (ischemic stroke, intracranial hemorrhage, subarachnoid hemorrhage, and traumatic brain injury), anoxic brain injury, and toxic-metabolic encephalopathy. Studies have also found an association between particular EEG patterns and long-term functional and cognitive outcomes as well as prediction of recovery of consciousness following acute brain injury. This review summarizes these findings and demonstrates the value of utilizing EEG findings in the determination of prognosis.

Stigma and functional neurological disorder: a research agenda targeting the clinical encounter.

Stigma against patients with functional neurological disorder (FND) presents obstacles to diagnosis, treatment, and research. The lack of biomarkers and the potential for symptoms to be misunderstood, invalidated, or dismissed can leave patients, families, and healthcare professionals at a loss. Stigma exacerbates suffering and unmet needs of patients and families, and can result in poor clinical management and prolonged, repetitive use of healthcare resources. Our current understanding of stigma in FND comes from surveys documenting frustration experienced by providers and distressing healthcare interactions experienced by patients. However, little is known about the origins of FND stigma, its prevalence across different healthcare contexts, its impact on patient health outcomes, and optimal methods for reduction. In this paper, we set forth a research agenda directed at better understanding the prevalence and context of stigma, clarifying its impact on patients and providers, and promoting best practices for stigma reduction.

Randomized trial of lacosamide versus fosphenytoin for nonconvulsive seizures.

OBJECTIVE: The optimal treatment of nonconvulsive seizures in critically ill patients is uncertain. We evaluated the comparative effectiveness of the antiseizure drugs lacosamide (LCM) and fosphenytoin (fPHT) in this population. METHODS: The TRENdS (Treatment of Recurrent Electrographic Nonconvulsive Seizures) study was a noninferiority, prospective, multicenter, randomized treatment trial of patients diagnosed with nonconvulsive seizures (NCSs) by continuous electroencephalography (cEEG). Treatment was randomized to intravenous (IV) LCM 400mg or IV fPHT 20mg phenytoin equivalents/kg. The primary endpoint was absence of electrographic seizures for 24 hours as determined by 1 blinded EEG reviewer. The frequency with which NCS control was achieved in each arm was compared, and the 90% confidence interval (CI) was determined. Noninferiority of LCM to fPHT was to be concluded if the lower bound of the CI for relative risk was >0.8. RESULTS: Seventy-four subjects were enrolled (37 LCM, 37 fPHT) between August 21, 2012 and December 20, 2013. The mean age was 63.6 years; 38 were women. Seizures were controlled in 19 of 30 (63.3%) subjects in the LCM arm and 16 of 32 (50%) subjects in the fPHT arm. LCM was noninferior to fPHT (p = 0.02), with a risk ratio of 1.27 (90% CI = 0.88-1.83). Treatment emergent adverse events (TEAEs) were similar in both arms, occurring in 9 of 35 (25.7%) LCM and 9 of 37 (24.3%) fPHT subjects (p = 1.0). INTERPRETATION: LCM was noninferior to fPHT in controlling NCS, and TEAEs were comparable. LCM can be considered an alternative to fPHT in the treatment of NCSs detected on cEEG. Ann Neurol 2018;83:1174-1185.

A standardized diagnostic approach and ongoing feedback improves outcome in psychogenic nonepileptic seizures.

INTRODUCTION: Psychogenic nonepileptic seizures (PNES) are episodic alterations in behavior presumed to reflect a physical manifestation of underlying psychological distress. Standardized treatment approaches for PNES care are lacking. We evaluated common approaches to PNES management that do not require significant commitment of time and resources. METHODOLOGY: Patients with PNES established with video-EEG monitoring were randomized to one of the following three groups: 1) PNES diagnosis delivered per the discretion of the attending physician with advice to seek mental health assistance in the community (n=12), 2) scripted PNES diagnosis provided and inpatient psychiatry consult obtained (n=10), and 3) weekly follow-up phone calls made in addition to scripted diagnosis and inpatient psychiatry consultation (n=15). Reduction in event frequency measured at 8weeks following hospital discharge represented the primary outcome variable. Secondary variables analyzed included exploration of change in self-reported mood, quality of life, and healthcare utilization. RESULTS: No significant improvements were noted in patients simply given a PNES diagnosis and advised to seek outside care on any measure. In contrast, patients receiving a scripted diagnosis and psychiatric consultation demonstrated decreased PNES frequency accompanied by improved quality of life (QOL). Patients also receiving weekly phone calls not only demonstrated decreased PNES frequency and improvements in QOL but also exhibited improved mood. DISCUSSION: These findings demonstrate that providing diagnostic information regarding PNES is insufficient by itself to meaningfully affect patient outcome. Structured feedback and psychiatric consultation appeared adequate to significantly reduce PNES frequency and improve aspects of quality of life, while the addition of a weekly phone contact also led to improved mood.

Randomized double-blind comparison of cognitive and EEG effects of lacosamide and carbamazepine.

Differential effectiveness of antiepileptic drugs (AEDs) is more commonly determined by tolerability than efficacy. Cognitive effects of AEDs can adversely affect tolerability and quality of life. This study evaluated cognitive and EEG effects of lacosamide (LCM) compared with carbamazepine immediate-release (CBZ-IR). A randomized, double-blind, double-dummy, two-period crossover, fixed-dose study in healthy subjects compared neuropsychological and EEG effects of LCM (150mg, b.i.d.) and CBZ-IR (200mg, t.i.d.). Testing was conducted at screening, predrug baseline, the end of each treatment period (3-week titration; 3-week maintenance), and the end of each washout period (4weeks after treatment). A composite Z-score was derived for the primary outcome variable (computerized cognitive tests and traditional neuropsychological measures) and separately for the EEG measures. Other variables included individual computer, neuropsychological, and EEG scores and adverse events (AEs). Subjects included 60 healthy adults (57% female; mean age: 34.4years [SD: 10.5]); 44 completed both treatments; 41 were per protocol subjects. Carbamazepine immediate-release had worse scores compared with LCM for the primary composite neuropsychological outcome (mean difference=0.33 [SD: 1.36], p=0.011) and for the composite EEG score (mean difference=0.92 [SD: 1.77], p=0.003). Secondary analyses across the individual variables revealed that CBZ-IR was statistically worse than LCM on 36% (4/11) of the neuropsychological tests (computerized and noncomputerized) and 0% of the four EEG measures; none favored CBZ-IR. Drug-related AEs occurred more with CBZ-IR (49%) than LCM (22%). Lacosamide had fewer untoward neuropsychological and EEG effects and fewer AEs and AE-related discontinuations than CBZ-IR in healthy subjects. Lacosamide exhibits a favorable cognitive profile.

Interrater agreement for Critical Care EEG Terminology.

OBJECTIVE: The interpretation of critical care electroencephalography (EEG) studies is challenging because of the presence of many periodic and rhythmic patterns of uncertain clinical significance. Defining the clinical significance of these patterns requires standardized terminology with high interrater agreement (IRA). We sought to evaluate IRA for the final, published American Clinical Neurophysiology Society (ACNS)-approved version of the critical care EEG terminology (2012 version). Our evaluation included terms not assessed previously and incorporated raters with a broad range of EEG reading experience. METHODS: After reviewing a set of training slides, 49 readers independently completed a Web-based test consisting of 11 identical questions for each of 37 EEG samples (407 questions). Questions assessed whether a pattern was an electrographic seizure; pattern location (main term 1), pattern type (main term 2); and presence and classification of eight other key features ("plus" modifiers, sharpness, absolute and relative amplitude, frequency, number of phases, fluctuation/evolution, and the presence of "triphasic" morphology). RESULTS: IRA statistics (κ values) were almost perfect (90-100%) for seizures, main terms 1 and 2, the +S modifier (superimposed spikes/sharp waves or sharply contoured rhythmic delta activity), sharpness, absolute amplitude, frequency, and number of phases. Agreement was substantial for the +F (superimposed fast activity) and +R (superimposed rhythmic delta activity) modifiers (66% and 67%, respectively), moderate for triphasic morphology (58%), and fair for evolution (21%). SIGNIFICANCE: IRA for most terms in the ACNS critical care EEG terminology is high. These terms are suitable for multicenter research on the clinical significance of critical care EEG patterns. A PowerPoint slide summarizing this article is available for download in the Supporting Information section http://dx.doi.org/10.1111/epi.12653/supinfo.

Continuous EEG monitoring: a survey of neurophysiologists and neurointensivists.

OBJECTIVE: Continuous EEG monitoring (cEEG) of critically ill adults is being used with increasing frequency, and practice guidelines on indications for cEEG monitoring have recently been published. However, data describing the current practice of cEEG in critically ill adults is limited. We aimed to describe the current practice of cEEG monitoring in adults in the United States. METHODS: A survey assessing cEEG indications and procedures was sent to one intensivist and one neurophysiologist responsible for intensive care unit (ICU) cEEG at 151 institutions in the United States. At some institutions only one physician could be identified. RESULTS: One hundred thirty-seven physicians from 97 institutions completed the survey. Continuous EEG is utilized by nearly all respondents to detect nonconvulsive seizures (NCS) in patients with altered mental status following clinical seizures, intra cerebral hemorrhage (ICH), traumatic brain injury, and cardiac arrest, as well as to characterize abnormal movements suspected to be seizures. The majority of physicians monitor comatose patients for 24-48 h. In an ideal situation with unlimited resources, 18% of respondents would increase cEEG duration. Eighty-six percent of institutions have an on-call EEG technologist available 24/7 for new patient hookups, but only 26% have technologists available 24/7 in-house. There is substantial variability in who reviews EEG and how frequently it is reviewed as well as use of quantitative EEG. SIGNIFICANCE: Although there is general agreement regarding the indications for ICU cEEG, there is substantial interinstitutional variability in how the procedure is performed.

Refractory and super-refractory status epilepticus--an update.

Status epilepticus is a medical emergency with a high mortality. Early recognition and initiation of treatment leads to a better response and may improve outcomes. Refractory status epilepticus is defined as recurrent seizure activity despite two appropriately selected and dosed antiepileptic drugs including a benzodiazepine. The term "super-refractory status epilepticus" was introduced during the London-Innsbruck Colloquium on status epilepticus in 2011 and refers to status epilepticus that continues or recurs 24 h or more after the initiation of treatment with anesthetic antiepileptic drugs. This includes cases in which seizure control is attained after induction of anesthesia but recurs on weaning the patient off the anesthetic agent. This article reviews the approach to refractory status epilepticus and super-refractory status epilepticus, including management as well as common pathophysiological causes of these entities.

Management of status epilepticus in pregnancy: a clinician survey.

BACKGROUND: Status epilepticus in pregnancy (SEP) is rare and life-threatening for both mother and fetus. There are well-established guidelines for the management of women with epilepsy during pregnancy; however, there is little evidence guiding the management of SEP, leading to uncertainty among treating physicians. Therefore, this survey aims to investigate the real-world practices of physicians treating SEP to explore management approaches for improvements in care. METHODS: An anonymous, electronic survey was created and distributed to neurointensivists and neurologists between September and December 2021. RESULTS: One hundred physicians initiated the survey and 95 completed it in full: 87 (87%, 87/100) identified neurology as their primary specialty, 31 had subspecialty training in neurocritical care, and 48 had subspecialty training in epilepsy and/or clinical neurophysiology. Over half of the survey respondents (67%, 67/100) reported having participated in the management of SEP, with 48.9% (49/98) having done so in the past year. Most survey respondents (73%, 73/100) reported that their management approach to SEP is different than that of non-pregnant patients. Survey respondents were more likely to involve epilepsy consultants when treating SEP (58.5%, 58/99) and the vast majority involved Obstetrics/Maternal Fetal Medicine consultants (90.8%, 89/98). Survey respondents showed a clear preference for levetiracetam (89.7%, 87/97) in the treatment of benzodiazepine refractory status epilepticus followed by lacosamide (61%, 60/98) if an additional second line agent was needed. Valproate and phenobarbital were unlikely to be used. There was less agreement for the management of refractory and super-refractory SEP. CONCLUSIONS: Levetiracetam is the most frequently used anti-seizure medication (ASM) for benzodiazepine-refractory SEP. Survey participants tended to manage SEP differently than in non-pregnant patients including greater involvement of interdisciplinary teams as well as avoidance of ASMs associated with known teratogenicity.

Intravenous ketamine for the treatment of refractory status epilepticus: a retrospective multicenter study.

PURPOSE: To examine patterns of use, efficacy, and safety of intravenous ketamine for the treatment of refractory status epilepticus (RSE). METHODS: Multicenter retrospective review of medical records and electroencephalography (EEG) reports in 10 academic medical centers in North America and Europe, including 58 subjects, representing 60 episodes of RSE that were identified between 1999 and 2012. Seven episodes occurred after anoxic brain injury. KEY FINDINGS: Permanent control of RSE was achieved in 57% (34 of 60) of episodes. Ketamine was felt to have contributed to permanent control ("possible" or "likely" responses) in 32% (19 of 60) including seven (12%) in which ketamine was the last drug added (likely responses). Four of the seven likely responses, but none of the 12 possible ones, occurred in patients with postanoxic brain injury. No likely responses were observed when infusion rates were lower than 0.9 mg/kg/h, when ketamine was introduced at least 8 days after SE onset, or after failure of seven or more drugs. Ketamine was discontinued due to possible adverse events in five patients. Complications were mostly attributed to concurrent drugs, especially other anesthetics. Mortality rate was 43% (26 of 60), but was lower when SE was controlled within 24 h of ketamine initiation (16% vs. 56%, p = 0.0047). SIGNIFICANCE: Ketamine appears to be a relatively effective and safe drug for the treatment of RSE. This retrospective series provides preliminary data on effective dose and appropriate time of intervention to aid in the design of a prospective trial to further define the role of ketamine in the treatment of RSE.

Treatment of status epilepticus: an international survey of experts.

BACKGROUND: As part of the development of the Neurocritical Care Society (NCS) Status Epilepticus (SE) Guidelines, the NCS SE Writing Committee conducted an international survey of SE experts. METHODS: The survey consisted of three patient vignettes (case 1, an adult; case 2, an adolescent; case 3, a child) and questions regarding treatment. The questions for each case focused on initial and sequential therapy as well as when to use continuous intravenous (cIV) therapy and for what duration. Responses were obtained from 60/120 (50%) of those surveyed. RESULTS: This survey reveals that there is expert consensus for using intravenous lorazepam for the emergent (first-line) therapy of SE in children and adults. For urgent (second-line) therapy, the most common agents chosen were phenytoin/fosphenytoin, valproate sodium, and levetiracetam; these choices varied by the patient age in the case scenarios. Physicians who care for adult patients chose cIV therapy for RSE, especially midazolam and propofol, rather than a standard AED sooner than those who care for children; and in children, there is a reluctance to choose propofol. Pentobarbital was chosen later in the therapy for all ages. CONCLUSION: There is close agreement between the recently published NCS guideline for SE and this survey of experts in the treatment of SE.

Ellen R. Grass Lecture: Disparities in Access to Neurodiagnostic Testing.

Limited access to EEG services in rural areas creates health disparities in neurological care, including unnecessary transfers and delays in diagnosis and treatment. Rural facilities face several challenges to expanding EEG resources, including a lack of neurologists, technologists, EEG equipment, and adequate IT infrastructure. Potential solutions include investment in innovative technology, expansion of the workforce, and development of hub-and-spoke EEG networks. Bridging the EEG gap requires collaboration between academic and community practices to advance practical technologies, train competent personnel and develop cost-effective resource-sharing strategies.

Safety and efficacy of lacosamide in the intensive care unit.

BACKGROUND: Seizures are common in critically ill patients and can impact morbidity and mortality. Traditional anti-epileptic drugs (AEDs) in this setting are not always effective and are associated with adverse events and drug interactions. Lacosamide (LCM) is a new AED which is available in parental form although few studies have evaluated the safety and efficacy of LCM in critically ill patients. METHODS: Critically ill patients at Emory University Hospital who received LCM from April 1, 2009 to February 1, 2010 were retrospectively reviewed. Primary outcome measure was incidence and time to seizure cessation. Adverse effects were also recorded. RESULTS: LCM was administered in 24 patients including 13 episodes of refractory status epilepticus (RSE) occurring in 10 patients and for treatment of isolated seizures or following resolution of RSE in an additional 14 patients. Seizure cessation was achieved in 5/13 (38%) episodes of RSE (mean 11.2 h) while there was at least a 50% decrease in seizure frequency in 7/13 (54%). 11/14 patients (76%) who received LCM for treatment of isolated seizures or prevention of seizure recurrence remained seizure free. Three patients experienced a decline in systolic blood pressure (> 20 mmHg) while one patient experienced unexplained fever and one patient had elevation of liver function tests. CONCLUSIONS: This preliminary data suggests that LCM may be a safe and effective alternative for treatment of seizures in critically ill patients. Further prospective, randomized controlled trials are needed to confirm these findings and further explore the incidence of adverse effects.

Guidelines for the evaluation and management of status epilepticus.

Status epilepticus (SE) treatment strategies vary substantially from one institution to another due to the lack of data to support one treatment over another. To provide guidance for the acute treatment of SE in critically ill patients, the Neurocritical Care Society organized a writing committee to evaluate the literature and develop an evidence-based and expert consensus practice guideline. Literature searches were conducted using PubMed and studies meeting the criteria established by the writing committee were evaluated. Recommendations were developed based on the literature using standardized assessment methods from the American Heart Association and Grading of Recommendations Assessment, Development, and Evaluation systems, as well as expert opinion when sufficient data were lacking.

Impact of the COVID-19 Pandemic on Continuous EEG Utilization.

PURPOSE: The coronavirus disease 2019 (COVID-19) has significantly impacted healthcare delivery and utilization. The aim of this article was to assess the impact of the COVID-19 pandemic on in-hospital continuous electroencephalography (cEEG) utilization and identify areas for process improvement. METHODS: A 38-question web-based survey was distributed to site principal investigators of the Critical Care EEG Monitoring Research Consortium, and institutional contacts for the Neurodiagnostic Credentialing and Accreditation Board. The survey addressed the following aspects of cEEG utilization: (1) general center characteristics, (2) cEEG utilization and review, (3) staffing and workflow, and (4) health impact on EEG technologists. RESULTS: The survey was open from June 12, 2020 to June 30, 2020 and distributed to 174 centers with 79 responses (45.4%). Forty centers were located in COVID-19 hotspots. Fifty-seven centers (72.1%) reported cEEG volume reduction. Centers in the Northeast were most likely to report cEEG volume reduction (odds ratio [OR] 7.19 [1.53-33.83]; P = 0.012). Additionally, centers reporting decrease in outside hospital transfers reported cEEG volume reduction; OR 21.67 [4.57-102.81]; P ≤ 0.0001. Twenty-six centers (32.91%) reported reduction in EEG technologist coverage. Eighteen centers had personal protective equipment shortages for EEG technologists. Technologists at these centers were more likely to quarantine for suspected or confirmed COVID-19; OR 3.14 [1.01-9.63]; P = 0.058. CONCLUSIONS: There has been a widespread reduction in cEEG volume during the pandemic. Given the anticipated duration of the pandemic and the importance of cEEG in managing hospitalized patients, methods to optimize use need to be prioritized to provide optimal care. Because the survey provides a cross-sectional assessment, follow-up studies can determine the long-term impact of the pandemic on cEEG utilization.

Clinical Neurophysiology Fellowship Program Directors Survey on a Standardized Fellowship Match Process: A Call for Action.

PURPOSE: To survey US Clinical Neurophysiology (CNP) fellowship program directors on the nature of CNP and related training programs, current recruitment cycle, and views for a standardized process. METHODS: A 23-question electronic survey was sent to all 93 US Accreditation Council for Graduate Medical Education-accredited CNP fellowship program directors from December 2020 to January 2021. RESULTS: The response rate was 60%. There was great variability in the number of CNP positions and CNP tracks offered. The following tracks were identified: 48% EEG dominant, 26% EMG dominant, 22% split equally between EEG and EMG, and 2% and 1% were neurophysiologic intraoperative monitoring and autonomic dominant, respectively. Of the responding institutions, 43% offered a second year of training options to CNP fellows, mainly in conjunction with Epilepsy fellowship, which was pursued by 25% of CNP fellows. Many programs indicated flexibility in their design between different CNP tracks or between CNP and other related training programs based on the available candidates. The median percentage of CNP fellowship positions filled over the last 5 years was 80%, and there was great variation in the recruitment timeline across institutions. Overall, 86% of program directors favored a universal timeline and 71% favored a formal match for CNP. The respondents were split between an independent CNP match (39%) and joining the initiatives of affiliate societies on a standardized process (61%). CONCLUSIONS: There is significant heterogeneity in the makeup of the CNP fellowship programs and the recruitment process. The majority of CNP program directors are in favor of standardization of the recruitment process.

Seizures and encephalopathy.

There is a complex relationship between seizures and encephalopathy. Seizures alone without any underlying neurologic or medical illness can be the sole cause of encephalopathy. Often these patients have a history of epilepsy, in which case accurate diagnosis is straightforward. Acute neurologic conditions often contribute to encephalopathy, but also increase the risk of seizures--many of which are subclinical. In these scenarios, it can be difficult to determine whether the encephalopathy is caused by seizures, the underlying neurologic disorder, or both. In addition, systemic diseases are commonly associated with encephalopathy; they may also increase the risk of seizures, although less commonly than acute neurologic conditions, and therefore may go unrecognized. This review will examine common and uncommon causes of seizures in encephalopathic patients, typical clinical presentations as well as diagnosis and treatment.

Quantitative EEG analysis for automated detection of nonconvulsive seizures in intensive care units.

Because of increased awareness of the high prevalence of nonconvulsive seizures in critically ill patients, use of continuous EEG (cEEG) monitoring is rapidly increasing in ICUs. However, cEEG monitoring is labor intensive, and manual review and interpretation of the EEG are impractical in most ICUs. Effective methods to assist in rapid and accurate detection of nonconvulsive seizures would greatly reduce the cost of cEEG monitoring and enhance the quality of patient care. In this study, we report a preliminary investigation of a novel ICU EEG analysis and seizure detection algorithm. Twenty-four prolonged cEEG recordings were included in this study. Seizure detection sensitivity and specificity were assessed for the new algorithm and for the two commercial seizure detection software systems. The new algorithm performed with a mean sensitivity of 90.4% and a mean false detection rate of 0.066/hour. The two commercial detection products performed with low sensitivities (12.9 and 10.1%) and false detection rates of 1.036/hour and 0.013/hour, respectively. These findings suggest that the novel algorithm has potential to be the basis of clinically useful software that can assist ICU staff in timely identification of nonconvulsive seizures. This study also suggests that currently available seizure detection software does not perform sufficiently in detection of nonconvulsive seizures in critically ill patients. This article is part of a Supplemental Special Issue entitled The Future of Automated Seizure Detection and Prediction.

Continuous EEG Findings in Autoimmune Encephalitis.

PURPOSE: Autoimmune encephalitis (AE) is a cause of new-onset seizures, including new-onset refractory status epilepticus, yet there have been few studies assessing the EEG signature of AE. METHODS: Multicenter retrospective review of patients diagnosed with AE who underwent continuous EEG monitoring. RESULTS: We identified 64 patients (male, 39%; white, 49%; median age, 44 years); of whom, 43 (67%) were antibody-proven AE patients. Of the patients with confirmed antibody AE, the following were identified: N-methyl-D-aspartate receptor (n = 17, 27%), voltage-gated potassium channel (n = 16, 25%), glutamic acid decarboxylase (n = 6, 9%), and other (n = 4, 6%). The remaining patients were classified as probable antibody-negative AE (n = 11, 17%), definite limbic encephalitis (antibody-negative) (n = 2, 3%), and Hashimoto encephalopathy (n = 8, 13%). Fifty-three percent exhibited electrographic seizures. New-onset refractory status epilepticus was identified in 19% of patients. Sixty-three percent had periodic or rhythmic patterns; of which, 38% had plus modifiers. Generalized rhythmic delta activity was identified in 33% of patients. Generalized rhythmic delta activity and generalized rhythmic delta activity plus fast activity were more common in anti-N-methyl-D-aspartate AE (P = 0.0001 and 0.0003, respectively). No other periodic or rhythmic patterns exhibited AE subtype association. Forty-two percent had good outcome on discharge. Periodic or rhythmic patterns, seizures, and new-onset refractory status epilepticus conferred an increased risk of poor outcome (OR, 6.4; P = 0.0012; OR, 3; P = 0.0372; OR, 12.3; P = 0.02, respectively). CONCLUSION: Our study confirms a signature EEG pattern in anti-N-methyl-D-aspartate AE, termed extreme delta brush, identified as generalized rhythmic delta activity plus fast activity in our study. We found no other pattern association with other AE subtypes. We also found a high incidence of seizures among patients with AE. Finally, periodic or rhythmic patterns, seizures, and new-onset refractory status epilepticus conferred an increased risk of poor outcome regardless of AE subtype.