Long-term outcome and prognosis of patients with emergent periodic lateralized epileptiform discharges (ePLEDs)

Periodic discharges and status epilepticus: A critical reappraisal

OBJECTIVE

Periodic Discharges (PDs) in Status Epilepticus (SE) are historically related to negative outcome, and the Epidemiology-based Mortality Score in SE (EMSE) identifies PDs as an EEG feature associated with unfavorable prognosis. However, supportive evidence is conflicting. This study aims to evaluate the prognostic significance of interictal PDs during and following SE.

METHODS

All 2020-2023 non-hypoxic-ischemic SE patients with available EEG during SE were retrospectively assessed. Interictal PDs during SE (SE-PDs) and PDs occurring 24-72 h after SE resolution (post-SE-PDs) were examined. In-hospital death was defined as the primary outcome.

RESULTS

189 SE patients were finally included. SE-PDs were not related to outcome, while post-SE-PDs were related to poor prognosis confirmed after multiple regression analysis. EMSE global AUC was 0.751 (95%CI:0.680-0.823) and for EMSE-64 cutoff sensitivity was 0.85, specificity 0.52, accuracy 63%. We recalculated EMSE score including only post-SE-PDs. Modified EMSE (mEMSE) global AUC was 0.803 (95%CI:0.734-0.872) and for mEMSE-64 cutoff sensitivity was 0.84, specificity 0.68, accuracy 73%.

CONCLUSION

Interictal PDs during SE were not related to outcome whereas PDs persisting or appearing > 24 h after SE resolution were strongly associated to unfavorable prognosis. EMSE performed well in our cohort but considering only post-SE-PDs raised specificity and accuracy for mEMSE64 cutoff.

SIGNIFICANCE

This study supports the utility of differentiating between interictal PDs during and after SE for prognostic assessment.

Periodic Discharges in Critically Ill Children: Predictors and Outcome

OBJECTIVES

We aimed to identify clinical and EEG monitoring characteristics associated with generalized, lateralized, and bilateral-independent periodic discharges (GPDs, LPDs, and BIPDs) and to determine which patterns were associated with outcomes in critically ill children.

METHODS

We performed a prospective observational study of consecutive critically ill children undergoing continuous EEG monitoring, including standardized scoring of GPDs, LPDs, and BIPDs. We identified variables associated with GPDs, LPDs, and BIPDs and assessed whether each pattern was associated with hospital discharge outcomes including the Glasgow Outcome Scale-Extended Pediatric version (GOS-E-Peds), Pediatric Cerebral Performance Category (PCPC), and mortality.

RESULTS

PDs occurred in 7% (91/1,399) of subjects. Multivariable logistic regression indicated that patients with coma (odds ratio [OR], 3.45; 95% confidence interval [CI]: 1.55, 7.68) and abnormal EEG background category (OR, 6.85; 95% CI: 3.37, 13.94) were at increased risk for GPDs. GPDs were associated with mortality (OR, 3.34; 95% CI: 1.24, 9.02) but not unfavorable GOS-E-Peds (OR, 1.93; 95% CI: 0.88, 4.23) or PCPC (OR, 1.64; 95% CI: 0.75, 3.58). Patients with acute nonstructural encephalopathy did not experience LPDs, and LPDs were not associated with mortality or unfavorable outcomes. BIPDs were associated with mortality (OR, 3.68; 95% CI: 1.14, 11.92), unfavorable GOS-E-Peds (OR, 5.00; 95% CI: 1.39, 18.00), and unfavorable PCPC (OR, 5.96; 95% CI: 1.65, 21.46).

SIGNIFICANCE

Patients with coma or more abnormal EEG background category had an increased risk for GPDs and BIPDs, and no patients with an acute nonstructural encephalopathy experienced LPDs. GPDs were associated with mortality and BIPDs were associated with mortality and unfavorable outcomes, but LPDs were not associated with unfavorable outcomes.

Dural arteriovenous fistula presenting with recurrent focal status epilepticus and lateralised periodic epileptiform discharges

BACKGROUND

Dural arteriovenous fistulae (dAVF) are relatively infrequently encountered, and status epilepticus (SE) and lateralised periodic discharges (LPDs) on electroencephalography (EEG) have only rarely been associated with these arteriovenous malformations.

METHODS

We present a patient with recurrent presentations with focal SE, aphasia and other focal deficits of cortical function and ictal and peri-ictal LPDs on serial EEG, who was shown to have a left hemispheric dAVF associated with left transverse and sigmoid sinus thrombosis. Seizures proved refractory to four anti-seizure medications but became more amenable to control after successful embolisation of the dAVF, with subsequent resolution of the focal cortical deficits. We discuss the co-occurrence of SE and LPDs with dAVF and review previously reported cases with this rare association.

CONCLUSIONS

Our report supports a causative relationship between dAVF and focal SE, manifesting as ictal LPDs on EEG, and highlights the importance of active dAVF management in achieving seizure control. The relatively good patient outcome contrasts to the few similar case reports. Whilst rare, it is important to consider dAVF as a potentially treatable condition underlying new-onset seizures, including SE.

Clinical Correlates of Electroencephalographic Patterns in Critically Ill Patients

OBJECTIVE

The objective of this study was to determine the frequency and clinical correlates of different electroencephalographic patterns and their association with clinical outcomes in critically ill patients.

SUBJECTS AND METHODS

This retrospective cross-sectional study was performed in the Neurology Department of King Fahd Hospital of the University, Kingdom of Saudi Arabia and involved a review and analysis of medical records pertaining to 179 intensive care unit patients who underwent electroencephalography (EEG) in the June to November 2018 period.

RESULTS

Among the different etiologies, presence of spike and wave or sharp wave (SWs) was associated with encephalitis (P = .01) and large artery stroke (P = .01), whereas markedly attenuated EEG activity (p = .04) and burst suppression (P = .01) were associated with large artery stroke and hypoxic ischemic encephalopathy (HIE), respectively. Generalized theta activity (P = .01) was significantly found in patients of septic encephalopathy, while generalized delta activity (P = .02) and asymmetrical background (P = .04) were significantly associated with traumatic brain injury. Presence of periodic discharges in EEG was significantly associated with more adverse clinical outcomes (P = .001), whereas rhythmic delta activity (RDA) (P = .03), persistent focal slow wave activity (P = .01), and asymmetric background (P = .002) were found in patients who were discharged from hospital with sequelae of current illness.

CONCLUSION

Certain EEG patterns are associated with particular underlying etiologies like SWs for encephalitis, markedly attenuated EEG activity and burst suppression with large artery stroke and HIE, respectively. Whereas few EEG patterns, including periodic discharges, RDA, persistent focal slow wave activity have some prognostic value in critically ill patients. However, they cannot be used as markers for prognostic assessment of patients without considering other clinical and diagnostic variables. Further larger prospective studies with continuous EEG monitoring with control of confounding factors are needed.

Predictors of outcome in super refractory status epilepticus

PURPOSE

We conducted this study to determine the clinical, electrophysiological and radiological predictors of outcome in Super Refractory Status Epilepticus (SRSE).

METHODS

Data of patients treated for SRSE between January 2000 and November 2019, archived prospectively in our SE registry were analyzed. Functional outcome was measured by Glasgow outcome score (GOS) at the time of hospital discharge and was divided into: good i.e. GOS ≥ 3 and bad outcome i.e. GOS < 3. The predictors of outcome were determined using appropriate statistical tests by univariate and multivariate analysis, p < 0.05 was considered as statistically significant.

RESULTS

Of the 384 patients with status epilepticus (SE) identified during the study, 28 (8%) were diagnosed as SRSE and were included in the final analysis. Acute symptomatic SE comprising 15 (53.6%) patients was the most common etiology of SRSE. Thirteen patients (three patients with viral encephalitis and 10 patients with clinically possible autoimmune encephalitis) had New Onset Refractory Status Epilepticus (NORSE) like clinical presentation.12 patients (42.9%) had good outcome and 16 patients (57.1%) had bad outcome. Multivariate logistic regression analysis showed that independent predictors of poor outcome were: duration of ICU stay (p < 0.001); EEG findings such as non-convulsive SE in coma (0.032), spontaneous burst suppression (0.001) and postictal diffuse attenuation (<0.001); delay in starting anesthesia (0.002); and delay in starting immunotherapy in NORSE due to autoimmune encephalitis (0.002).

CONCLUSION

We could determine independent therapeutic and electrophysiological prognostic factors for SRSE. Early initiation of treatment and stringent management of these factors especially in an younger age-group, aided by continuous EEG monitoring and a thorough etiological work-up can result in good outcomes in more than one-third of cases.

Neuroimaging Correlates of Lateralized Rhythmic Delta Activity, Lateralized Periodic Discharges, and Generalized Rhythmic Delta Activity on EEG in Critically Ill Patients

PURPOSE

The neuroimaging correlates of lateralized rhythmic delta activity (LRDA) are not well defined, and imaging findings between different epileptiform patterns have seldom been compared directly.

METHODS

Patients were retrospectively selected from a critical care EEG database between December 2014 and December 2017. Patients were included if they had greater than 6 hours of continuous EEG that contained LRDA, lateralized periodic discharges LPDs), or generalized rhythmic delta activity (GRDA) and had an MRI within 48 hours of the EEG. Clinical, EEG, and MRI characteristics were collected and compared.

RESULTS

All the following results showed statistical significance between the groups: Patients with GRDA were more likely to have a normal MRI (LRDA, 0%; LPDs, 0.8%; GRDA, 17.3%), although the majority were abnormal. In patients with LRDA and LPDs, the MRI abnormalities were much more likely lateralized to one side, whereas in those with GRDA, they were more likely to have bilateral or multifocal abnormalities. Across all groups most abnormalities were acute, although this proportion was higher in patients with LRDA and LPDs compared with that in those with GRDA (LRDA, 91.3%; LPDs, 86.0%; GRDA, 70.4%). An MRI abnormality that was concordant with the side of LRDA was present in 66.3%, with 17.3% having discordant findings. These were similar in patients with LPDs (concordant 67.4%; discordant 11.6%).

CONCLUSIONS

Patients with LRDA had a similarly high rate of acute focal abnormalities ipsilateral to the EEG pattern compared with those with LPDs. Patients with GRDA were more likely to have a normal MRI, but the majority of patients with GRDA still had acute focal findings.

[Electroencephalography in acute stroke]

OBJECTIVE

To determine the incidence of non-convulsive status epilepticus, epileptiform activity, rhythmic and periodic patterns in patients with acute stroke.

MATERIAL AND METHOD

An analysis of electroencephalography (EEG) in 86 stroke patients in the neurointensive care unit of the tertiary medical center was performed. Criteria for starting EEG recording were epileptic seizures or clinical suspicion of uncontrolled epileptic status. The ictal-interictal continuum biomarkers and the diagnostic value of EEG for prediction of survival and recovery were assessed.

RESULTS

Pathological changes on EEG were recorded in 84% of patients. These patients showed the absence of the dominant occipital rhythm (66%) and hemispheric slowing (42%). Diffuse slowing below the theta range was observed in 41% of patients. EEG reactivity was absent in 20%. Sporadic epileptiform discharges were recorded in 36% of patients and rhythmic and periodic patterns in 26%. Reliable predictors of the unfavorable outcome were the absence of dominant occipital rhythm, lack of reactivity, and low amplitude of the background EEG. No association between the recording of epileptiform activity and the probability of death was shown.

CONCLUSION

The most useful EEG biomarkers for predicting survival are amplitude, dominant frequency of background EEG activity and reactivity to external stimulus. Sporadic epileptiform discharges, rhythmic, and periodic patterns are not mandatory associated with a negative prognosis in stroke patients.

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.

The Ictal-Interictal Continuum: To Treat or Not to Treat (and How)?

Continuous electroencephalography (cEEG) monitoring is becoming increasingly used in neurologic and non-neurologic intensive care units (ICUs). Non-convulsive seizures (NCSz) and periodic discharges (PDs) are commonly seen in critically ill patients. Some of these PD patterns, also known as the ictal-interictal continuum (IIC), are associated with an increased risk of seizures and poor outcome. However, we do not fully understand the significance of these periodic patterns and the decision of how aggressively to treat remains controversial. IIC patterns are associated with pathophysiologic changes that closely resemble those of seizures. Here we make the argument that, rather than feature description on EEG, associated changes in brain physiology should dictate management choices.

Approach to Managing Periodic Discharges

Use of continuous EEG monitoring in the intensive care unit setting has increased detection of not only subclinical seizures, but also patterns of discharges that have epileptiform features and periodicity yet do not meet the criteria for seizures. These periodic discharges present a clinical challenge: some patterns may reflect brain injury that has already occurred, although there is evidence that some periodic discharges represent an ongoing process causing additional brain injury and necessitate treatment. Herein, we review the available data regarding the clinical significance of different categories of periodic discharges, specifically those that have features physiologically similar to seizures. We propose a stepwise approach to assessment and management of periodic discharges and lay out the general paradigm of (1) clinical assessment including benzodiazepine trial, (2) EEG assessment, with a focus on discharge frequency, and (3) integration of adjunctive data such as neuroimaging and metabolic data when available. A flowchart is provided to simplify and summarize this approach. The goal of this approach is to treat patterns associated with increased risk of seizures and/or additional brain injury, while avoiding unnecessary interventions.

Definition and Classification of Periodic and Rhythmic Patterns

The growing use of continuous video-EEG recording in the inpatient setting, in particular in patients with varying degrees of encephalopathy, has yielded a window to the brain with an excellent temporal resolution. This increasingly available tool has become more than an instrument to detect nonconvulsive seizures (its primary use), and clinical indications span from ischemia detection in acute brain injuries, neuroprognostication of comatose patients, to monitoring the degree of encephalopathy. In this context, abnormal findings such as periodic discharges and rhythmic delta activity were increasingly recognized; however, significant subjectivity remained in the interpretation of these findings pertaining to key features regarding their spatial involvement, prevalence of occurrence, duration, associated morphologic features, and behavior. In 2005, the American Clinical Neurophysiology Society proposed standardized definitions and classification of electroencephalographic rhythmic and periodic patterns. This was subsequently revised in 2011 and in 2012 and is now being used by centers worldwide, with the final version published in early 2013 as an official guideline of the ACNS. The resulting uniform terminology has allowed for significant advances in the understanding of the pathophysiology, epileptogenic potential, and overall clinical implication of these patterns. Investigators across multiple institutions are now able to collaborate while exploring diagnostic and therapeutic algorithms to these patterns, an effort that may soon provide definitive evidence guiding treating clinicians on the management of these patients.

Lateralized Periodic Discharges: A Literature Review

The purpose of this article is to provide a comprehensive review of the literature about a particular EEG pattern, lateralized periodic discharges (LPDs), or periodic lateralized epileptiform discharges (PLEDs). The review will discuss the history and terminology of LPDs and provide a detailed summary of the etiologies, pathophysiology, clinical symptoms, and imaging studies related to LPDs. Current controversies about the association of LPDs with seizures and their management will be reviewed. Finally, some unanswered questions and suggestions for future research on LPDs will be discussed.

Electrographic and Clinical Natural History of Lateralized Periodic Discharges

PURPOSE

The long-term electrographic features of lateralized periodic discharges (LPD) and their impact on clinical management are unclear. The authors investigated routine EEGs (rEEG) to analyze the delayed natural history of LPDs, and studied the clinical care of these patients.

METHODS

After IRB approval, the prospectively maintained continuous EEG (cEEG) database was searched to identify patients fulfilling the following criteria: LPDs on cEEG, age ≥18 years, no epilepsy history, and rEEG completed within 1 to 12 months of hospital discharge. Their rEEGs were reviewed followed by clinical data extraction. Appropriate statistical tools were used for data analysis.

RESULTS

Thirty-nine patients (20 females) with a mean age of 63.3 ± 16.8 years at the time of cEEG fulfilled the study criteria. Thirty-three (85%) had associated electrographic seizures. rEEG was performed 4.7 ± 3.5 months after cEEG. Seven (18%) patients had interictal epileptiform discharges (IEDs) on the rEEG. The LPDs on cEEG of these patients were more often continuous, with an amplitude >2 times their background compared with 10 (26%) patients with normal rEEGs findings. After a mean follow-up of 19.8 ± 9.9 months, 11 (31%) patients developed epilepsy, but only 3 had IEDs on their rEEG. Majority (86%) of patients were on AEDs at the time of last follow-up.

CONCLUSIONS

LPDs lead to markers of epileptogenicity in around 18% of patients. One-third of the study population developed epilepsy. rEEG findings were not found to be good indicators of epilepsy development in our small, retrospective study limited by its sampling bias. Indiscriminate, long-term use of AEDs in these patients is a concerning finding.

Lateralized periodic discharges associated with status epilepticus in the first year after stroke

Backgrand. Lateralized periodic discharges (LPDs) are infrequent electroencephalograph (EEG) findings, and may present in ictal or interictal form. They are regarded as potential electrophysiologic signs of convulsive or nonconvulsive status epilepticus (NCSE). We report four patients who presented with NCSE and one who presented with convulsive status epilepticus in the postictal period, characterized by LPDs in EEG recordings in the first year after stroke.

Material and methods. We prospectively evaluated patients who clinically presented with status epilepticus associated LPDs between March 2014 and March 2015. We investigated patients that presented with a new stroke occurrence. We excluded the other LPD etiologies. EEG studies of five patients (two men) who were admitted to our emergency unit with confusion, three of whom had visual symptoms; four were treated for NCSE as diagnosed with LPDs. The fifth patient had convulsive status epilepticus with LPD in the postictal period.

Results and Discussion. None of the five patients, who were aged between 68 and 92 years, showed any etiologic factor other than a history of cerebrovascular disease (CVD). Magnetic resonance imaging studies of the patients revealed old infarcts and transitional diffusion restrictions. The clinical and EEG findings decreased substantially upon antiepileptic drug treatment. Herein, we illustrate the first patient who had confusion, visual hallucinations, and ictal and interictal LPD in her consecutive EEGs.

Conclusions. CVDs may pave the way for LPDs in patients with a history of stroke because CVDs cause structural brain damage. Patients who present with a similar clinical profile and imaging signs of stroke should be checked for NCSE, particularly in the presence of LPDs in EEGs.

Generalized periodic discharges: Pathophysiology and clinical considerations

Generalized periodic discharges (GPDs) are commonly encountered in metabolic encephalopathy and cerebral hypoxia/ischemia. The clinical significance of this EEG pattern is indistinct, and it is unclear whether treatment with antiepileptic drugs is beneficial. In this study, we discuss potential pathophysiological mechanisms. Based on the literature, supplemented with simulations in a minimal computational model, we conclude that selective synaptic failure or neuronal damage of inhibitory interneurons, leading to disinhibition of excitatory pyramidal cells, presumably plays a critical role. Reversibility probably depends on the potential for functional recovery of these interneurons. Whether antiepileptic drugs are helpful for regaining function is unclear. This article is part of a Special Issue entitled "Status Epilepticus".