Incidence of recurrent seizures following hospital discharge in patients with LPDs (PLEDs) and nonconvulsive seizures recorded on continuous EEG in the critical care setting

PurposeContinuous EEG (cEEG) has helped to identify nonconvulsive seizures (NCS) and nonconvulsive status epilepticus (NCSE) along with lateralized periodic patterns (LPDs or PLEDs) in ICU patients with much higher frequency than previously appreciated, but understanding their implications may be more complex. The aim of this study was to investigate the incidence of recurrent seizures after hospital discharge and their associated factors in patients with PLEDs and NCS in the critical care setting.MethodsAfter IRB approval, we used our EEG reporting database to find 200 consecutive patients who had PLEDs and/or NCSs on cEEG. Patients with less than 3 months of follow-up were excluded. Remaining patients were divided into three groups: PLEDs + Seizure (NCS/NCSE), PLEDs only, and Seizures (NCS/NCSE) only. Medical records were reviewed to gather demographical and clinical details. Univariate data analysis was done using JMP 9.0 (Marlow, Buckinghamshire, UK).ResultsThere were 51 patients in ‘PLEDs + Seizure’ group, 45 in ‘PLEDs only’ group, and 22 in ‘Seizure only’ group. Ischemic stroke, hemorrhage, and tumors were the top three etiologies. Nearly 47% of our study population had postdischarge seizures during a mean follow-up period of 11.9 (+/− 6) months. We found that 24.4% of patients in the PLEDs only group had seizures after discharge, which increased to 60.7% if they had seizures as well during their ICU stay. Slightly more than 52% of patients had a postdischarge EEG, of which, 59% was in the form of inpatient cEEG during a rehospitalization, accounting for 30.5% of the total study population. It was an indicator of high readmission rates in this population.ConclusionAlmost every other patient with PLEDs and/or NCS on cEEG had seizures after ICU discharge. A quarter of patients on cEEG in the ICU with PLEDs alone had seizures after discharge, and after excluding prior epilepsy, 17% of patients with PLEDs had seizures on follow-up. This was dramatically increased with the recording of PLEDs with NCS, with 60% of patients having seizures after discharge from the ICU and 48% of patients after excluding prior epilepsy. Patients with NCS on cEEG alone had 63% chance of seizure recurrence that dropped to 38% with exclusion of prior epilepsy. Future studies are needed to define the postdischarge outcomes including seizure recurrence in this patient population.This article is part of a Special Issue entitled “Status Epilepticus”.     

Continuous EEG monitoring in the evaluation of non-convulsive seizures and status epilepticus

Non-convulsive seizures (NCSzs) and non-convulsive status epilepticus (NCSE) occur in a substantial proportion of patients with acute brain injury. These acute seizure disorders are often unrecognized and under-diagnosed. Seizure semiology of NCSz is too subtle clinically to be noticed. Most often, mental status impairment is the presenting feature. Changes in the functions of the thalamo-cortical system in patients with impaired consciousness can be detected by continuous EEG (cEEG) monitoring. cEEG monitoring allows detection of the changes at a reversible stage, often when there are no clinical indications of such phenomena. In addition EEG provides reasonable spatial resolution and excellent temporal resolution. This makes cEEG an excellent method for supplementing single or serial recordings in the detection of NCSzs and NCSE. Recent advances in digital EEG have made cEEG monitoring in the neurological intensive care unit (NICU) technically feasible. Current evidence suggests that the common clinical denominator associated with electrographic seizures or NCSzs is mental status impairment. In NCSE, the duration of ictal activity and the time of delay to diagnosis are independent predictors of poor outcome. It will be prudent to do cEEG monitoring in any patient with impaired consciousness either in the setting of acute brain injury or with no clear explanation to detect NCSzs/NCSE. Early recognition and timely intervention is likely to be associated with good outcomes.     

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.     

Feasibility of online seizure detection with continuous EEG monitoring in the intensive care unit

IntroductionContinuous EEG (cEEG) is of great interest in view of the reported high prevalence of non-convulsive seizures on intensive care units (ICUs). Here, we describe our experiences applying a seizure warning system using cEEG monitoring.MethodsFifty comatose ICU patients were included prospectively and monitored. Twenty-eight patients had post-anoxic encephalopathy (PAE) and 22 had focal brain lesions. A measure of neuronal interactions, synchronization likelihood, was calculated online over 10 s EEG epochs and instances when the synchronization likelihood exceeded a threshold where marked as seizures.ResultsFive patients developed seizures. Our method detected seizures in three patients, in the other patients seizures were missed because of they were non-convulsive and had a focal character. The average false positive rate was 0.676/h.DiscussionThis is our first attempt to implement online seizure detection in the ICU. Despite problems with artifacts and that we missed focally oriented seizures, we succeeded in monitoring patients online. Given the relatively high occurrence of seizures, online seizure detection with cEEG merits further development for use in ICUs.     

Continuous EEG predictors of outcome in patients with altered sensorium

PurposeTo evaluate EEG predictors of outcome in patients with altered sensorium suspected to have seizure and to assess whether short term EEG is as effective as long term continuous EEG (cEEG) in predicting the outcome of patients with altered sensorium due to neurological causes.MethodsWe identified 99 consecutive critically ill patients with altered sensorium in whom nonconvulsive seizures were suspected. They underwent cEEG. Functional outcome was assessed with the modified Rankin Scale (mRS) at 4 weeks, discharge or death. We compared efficacy of short term EEG and long term continuous EEG in recording the abnormal patterns on EEG. Logistic regression analysis was performed to identify EEG findings associated with poor outcome, defined as mRS 4–6 (dead or moderately to severely disabled).ResultsPoor outcome was associated with nonconvulsive seizures (NCS), nonconvulsive status epilepticus (NCSE), periodic lateralized epileptiform discharges (PLEDS), PLEDS plus, generalized periodic epileptiform discharges (GPEDS) and abnormal EEG background. Short term EEG can detect seizure activity and other electrographic markers of poor outcome but the values are statistically insignificant.ConclusioncEEG monitoring provides independent prognostic information in patients with altered sensorium and suspected seizures. Unfavorable findings include nonconvulsive seizures, periodic epileptiform discharges and abnormal background. Short term EEG is ineffective in detecting seizures on EEG in patients with altered sensorium and should not be used as substitute for Long term EEG     

Use of EEG Monitoring and Management of Non-Convulsive Seizures in Critically Ill Patients: A Survey of Neurologists

Background  

Continuous EEG monitoring (cEEG) of critically ill patients is frequently utilized to detect non-convulsive seizures (NCS) and status epilepticus (NCSE). The indications for cEEG, as well as when and how to treat NCS, remain unclear. We aimed to describe the current practice of cEEG in critically ill patients to define areas of uncertainty that could aid in designing future research.     

Epileptic activity in neurological deterioration after ischemic stroke,a continuous EEG study

ObjectiveDespite improvement in acute stroke care, almost 40% of patients with ischemic stroke present neurological deterioration. Neurological deterioration is associated with higher death and dependency rates. Neurological deterioration mechanisms are unknown, and half of neurological deterioration remains unexplained. We postulate that a substantial proportion of neurological deterioration in ischemic stroke is associated with periodic discharges/non-convulsive seizures that negatively impact the recovery of ischemic stroke and worsen symptoms.MethodsRetrospective review of 24 h continuous EEG monitoring (cEEG) performed for neurological deterioration in the stroke unit of a tertiary academic centre.ResultsEighty-one patients were included. cEEG detected epileptic activities in 44% of cases (Non-convulsive seizures/non-convulsive status epilepticus: 10/81 (12%), periodic discharges: 17/81 (21%) and sporadic epileptiform discharges in 14/81 (17%)). The proportion of patients who did not receive recanalization therapy was significantly higher in the NCSE/NCSz/PDs group than in the group devoid of NCSE/NCSz/PDs: 17/22 (77%) vs 13/59 (22%); p < 0,001. Treatment of Non-convulsive seizures /non-convulsive status epilepticus and periodic discharges was followed by EEG improvement in respectively 7/8 and 10/16 of treated patients.ConclusionsNon-convulsive seizures /non-convulsive status epilepticus /periodic discharges are associated to neurological deterioration after ischemic stroke.SignificanceTreatment of Non-convulsive seizures /non-convulsive status epilepticus and periodic discharges, if such patterns are detected, could help prevent adverse metabolic consequences of epileptic activities on ischemic brain tissue.     

Prediction of rhythmic and periodic EEG patterns and seizures on continuous EEG with early epileptiform discharges

BackgroundContinuous EEG (cEEG) is necessary to document nonconvulsive seizures (NCS), nonconvulsive status epilepticus (NCSE), as well as rhythmic and periodic EEG patterns of ‘ictal–interictal uncertainty’ (RPPIIU) including periodic discharges, rhythmic delta activity, and spike-and-wave complexes in neurological intensive care patients. However, cEEG is associated with significant recording and analysis efforts. Therefore, predictors from short-term routine EEG with a reasonably high yield are urgently needed in order to select patients for evaluation with cEEG.ObjectiveThe aim of this study was to assess the prognostic significance of early epileptiform discharges (i.e., within the first 30 min of EEG recording) on the following: (1) incidence of ictal EEG patterns and RPPIIU on subsequent cEEG, (2) occurrence of acute convulsive seizures during the ICU stay, and (3) functional outcome after 6 months of follow-up.MethodsWe conducted a separate analysis of the first 30 min and the remaining segments of prospective cEEG recordings according to the ACNS Standardized Critical Care EEG Terminology as well as NCS criteria and review of clinical data of 32 neurological critical care patients.ResultsIn 17 patients with epileptiform discharges within the first 30 min of EEG (group 1), electrographic seizures were observed in 23.5% (n = 4), rhythmic or periodic EEG patterns of ‘ictal–interictal uncertainty’ in 64.7% (n = 11), and neither electrographic seizures nor RPPIIU in 11.8% (n = 2). In 15 patients with no epileptiform discharges in the first 30 min of EEG (group 2), no electrographic seizures were recorded on subsequent cEEG, RPPIIU were seen in 26.7% (n = 4), and neither electrographic seizures nor RPPIIU in 73.3% (n = 11). The incidence of EEG patterns on cEEG was significantly different between the two groups (p = 0.008). Patients with early epileptiform discharges developed acute seizures more frequently than patients without early epileptiform discharges (p = 0.009). Finally, functional outcome six months after discharge was significantly worse in patients with early epileptiform discharges (p = 0.01).ConclusionsEpileptiform discharges within the first 30 min of EEG recording are predictive for the occurrence of ictal EEG patterns and for RPPIIU on subsequent cEEG, for acute convulsive seizures during the ICU stay, and for a worse functional outcome after 6 months of follow-up.This article is part of a Special Issue entitled Status Epilepticus.     

Kontinuierliches EEG zum Monitoring auf der neurologischen Intensivstation Neue Einsatzmöglichkeiten und Nutzen für therapeutische Entscheidungen

Fifteen patients at our neurological intensive care unit were monitored with continuous EEG (cEEG: 10 channels EEG and ECG) for a total of 109 days. Primary indications for monitoring were nonconvulsive seizures in patients with altered consciousness (AC, n = 9) and control of therapy in generalized/partial status epilepticus (SE, n = 5). The cEEG findings influenced therapeutic management of patients in almost 50% of monitoring days (50/109), with decisive decisions (changes in medication) being made in 31/109 days. In 5/9 patients with AC, cEEG revealed findings that could not be demonstrated in previous EEG recordings. Identification of repetitive, nonepileptic, involuntary movements was guided by cEEG in four patients. Aside from the established application of cEEG monitoring in SE, the usefulness of clarifying the differential diagnosis in patients with AC was demonstrated particularly by the finding of nonconvulsive seizures in three patients. In two of these, intermittent EEG recordings did not demonstrate the seizures.     

Stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs): a common EEG phenomenon in the critically ill

PURPOSE: To describe an underrecognized EEG phenomenon in critically ill patients undergoing continuous EEG monitoring (cEEG). We named these EEG patterns stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs). METHODS: We reviewed 150 consecutive patients undergoing cEEG during a 9-month period and compared those with and without SIRPIDs. SIRPIDs were defined as periodic, rhythmic, or ictal-appearing discharges that were consistently induced by alerting stimuli. RESULTS: We identified 33 patients with SIRPIDs (22%). SIRPID patterns included periodic epileptiform discharges in 21 patients (nine lateralized) and rhythmic patterns with evolution that fulfilled criteria for ictal discharges in 18 patients (12 unilateral). Eight patients had prior epilepsy; 24 had acute brain injury. Half the patients (17 of 33) had seizures, clinical or subclinical, during the acute illness in addition to SIRPIDs, and half (16 of 33) did not. No significant difference was found in the incidence of clinical seizures in patients with SIRPIDs (30%) compared with those without (45%). Clinical status epilepticus was more common in patients with focal (43%) or ictal-appearing (33%) SIRPIDs than in those without SIRPIDs (17%). CONCLUSIONS: Rhythmic, periodic, or ictal-appearing EEG patterns are commonly elicited by stimulation in critically ill, encephalopathic patients. Recording video, documenting patient stimulation, or repetitively examining patients during cEEG is necessary to recognize these patterns and to differentiate SIRPIDs from spontaneous seizures. Further research is necessary to determine the pathophysiologic, prognostic, and therapeutic significance of SIRPIDs.     

Persistent Nonconvulsive Status Epilepticus After the Control of Convulsive Status Epilepticus

Summary: Purpose: Convulsive status epilepticus (CSE) is a major medical and neurological emergency that is associated with significant morbidity and mortality. Despite this high morbidity and mortality, most acute care facilities in the United States cannot evaluate patients with EEG monitoring during or immediately after SE. The present study was initiated to determine whether control of CSE by standard treatment protocols was sufficient to terminate electrographic seizures. Methods: One hundred sixty-four prospective patients were evaluated at the Medical College of Virginia/VCU Status Epilepticus Program. Continuous EEG monitoring was performed for a minimum of 24 h after clinical control of CSE. SE and seizure types were defined as described previously. A standardized data form entry system was compiled for each patient and used to evaluate the data collected. Results: After CSE was controlled, continuous EEG monitoring demonstrated that 52% of the patients had no after-SE ictal discharges (ASIDS) and manifested EEG patterns of generalized slowing, attenuation, periodic lateralizing epileptiform discharges (PLEDS), focal slowing, and/or burst suppression. The remaining 48% demonstrated persistent electrographic seizures. More than 14% of the patients manifested nonconvulsive SE (NCSE) predominantly of the complex partial NCSE seizure (CPS) type (2). These patients were comatose and showed no overt clinical signs of convulsive activity. Clinical detection of NCSE in these patients would not have been possible with routine neurological evaluations without use of EEG monitoring. The clinical presentation, mortality, morbidity, and demographic information on this population are reported. Conclusions: Our results demonstrate that EEG monitoring after treatment of CSE is essential to recognition of persistent electrographic seizures and NCSE unresponsive to routine therapeutic management of CSE. These findings also suggest that EEG monitoring immediately after control of CSE is an important diagnostic test to guide treatment plans and to evaluate prognosis in the management of SE.     

Nonconvulsive seizures: developing a rational approach to the diagnosis and management in the critically ill population.

Originally described in patients with chronic epilepsy, nonconvulsive seizures (NCSs) are being recognized with increasing frequency, both in ambulatory patients with cognitive change, and even more so in the critically ill. In fact, the majority of seizures that occur in the critically ill are nonconvulsive and can only be diagnosed with EEG monitoring. The semiology of NCSs and the associated EEG findings are quite variable. There are a number of periodic, rhythmic or stimulation-related EEG patterns in the critically ill of unclear significance and even less clear treatment implications. The field struggles to develop useful diagnostic criteria for NCSs, to standardize nomenclature for the numerous equivocal patterns, and to devise studies that will help determine which patterns should be treated and how aggressively. This review surveys the evidence for and against NCSs causing neuronal injury, and attempts to develop a rational approach to the diagnosis and management of these seizures, particularly in the encephalopathic population.     

Continuous electroencephalogram monitoring in critically ill patients

The past few years have witnessed remarkable advances in continuous EEG monitoring (cEEG). The indications and applications for cEEG are broadening, including detection of nonconvulsive seizures, spell characterization, and prognostication. Seizures are common in the critically ill, are usually nonconvulsive, and can easily be missed without cEEG. Interpretation and clinical management of the complex periodic and rhythmic EEG patterns commonly identified in these patients require further study. With the use of quantitative analysis techniques, cEEG can detect cerebral ischemia very early, before permanent neuronal injury occurs. This article reviews the indications and recent advances in cEEG in critically ill patients. Continuous brain monitoring with cEEG is rapidly becoming the standard of care in critically ill patients with neurologic impairment.     

Continuous EEG monitoring in patients with subarachnoid hemorrhage.

Patients with subarachnoid hemorrhage (SAH) are at risk for seizures and delayed cerebral ischemia, both of which can be detected with continuous EEG monitoring (cEEG). Ischemia can be detected with EEG at a reversible stage. CEEG may be most useful in patients with poor grade SAH, as the neurological exam is of limited utility in these stuporous or comatose patients. Seizures have been detected in 19% of SAH patients undergoing cEEG, with the vast majority (95%) of these seizures being nonconvulsive and without any detectable clinical correlate. Applying quantitative analysis to the cEEG (relative alpha variability, post-stimulation alpha/delta ratio) allows reliable detection of ischemia from vasospasm, with EEG changes often preceding changes in the clinical exam and other non-continuous monitoring techniques by up to two days. In patients at risk for developing vasospasm, cEEG monitoring, preferably with quantitative EEG analysis, should be started as early as possible and carried out for up to 14 days after the SAH. CEEG findings may lead to therapeutic (e.g., antiepileptic medication, hypertensive therapy, angioplasty) or additional diagnostic interventions such as angiography, CT or MRI.     

The Use of Continuous EEG Monitoring in Intensive Care Units in The Netherlands: A National Survey

Background

Currently, continuous electroencephalographic monitoring (cEEG) is the only available diagnostic tool for continuous monitoring of brain function in intensive care unit (ICU) patients. Yet, the exact relevance of routinely applied ICU cEEG remains unclear, and information on the implementation of cEEG, especially in Europe, is scarce. This study explores current practices of cEEG in adult Dutch ICU departments focusing on organizational and operational factors, development over time and factors perceived relevant for abstaining its use.

Methods

A national survey on cEEG in adults among the neurology and adult intensive care departments of all Dutch hospitals (n?=?82) was performed.

Results

The overall institutional response rate was 78%. ICU cEEG is increasingly used in the Netherlands (in 37% of all hospitals in 2016 versus in 21% in 2008). Currently in 88% of university, 55% of teaching and 14% of general hospitals use ICU cEEG. Reasons for not performing cEEG are diverse, including perceived non-feasibility and lack of data on the effect of cEEG use on patient outcome. Mostly, ICU cEEG is used for non-convulsive seizures or status epilepticus and prognostication. However, cEEG is never or rarely used for monitoring cerebral ischemia and raised intracranial pressure in traumatic brain injury. Review and reporting practices differ considerably between hospitals. Nearly all hospitals perform non-continuous review of cEEG traces. Methods for moving toward continuous review of cEEG traces are available but infrequently used in practice.

Conclusions

cEEG is increasingly used in Dutch ICUs. However, cEEG practices vastly differ between hospitals. Future research should focus on uniform cEEG practices including unambiguous EEG interpretation to facilitate collaborative research on cEEG, aiming to provide improved standard patient care and robust data on the impact of cEEG use on patient outcome.

     

Continuous EEG Monitoring in the Intensive Care Unit

In the past 15 years, the increased availability and use of continuous electroencephalography (cEEG) in critically ill patients has substantially changed our understanding of the injured brain. We have become increasingly aware that electrographic seizures in this population may have only subtle or no clinical signs and that cEEG greatly increases the likelihood of detecting these seizures. This review highlights the rationale behind using cEEG rather than routine EEG for detection of nonconvulsive seizures and nonconvulsive status epilepticus in critically ill patients and defines which patients are at greatest risk. It also describes other applications of cEEG in the intensive care unit and how it may play an important role in monitoring brain function.     

Nonconvulsive status epilepticus in a neurological intensive care unit: profile in a developing country

PURPOSE: Nonconvulsive status epilepticus (NCSE) is an under-recognized cause of altered mental status. There are hardly any reported data on NCSE in developing countries. MATERIAL AND METHODS: Prospectively 210 consecutive patients with altered mental status admitted to neurological intensive care unit (NICU) of a tertiary care center in south India were studied for the frequency of NCSE. All patients were evaluated initially with 60-min emergent EEG (EmEEG) and subsequently by continuous EEG (cEEG) monitoring. RESULTS: Of the 210 with altered mental status admitted to NICU, the diagnosis of NCSE was established in 22 (10.5%) patients, in 12 (55%) patients with 60-min EmEEG and in 10 (45%) after cEEG monitoring for 12 to 48 hours. Of the 22 patients with NCSE, 32% had subtle motor phenomena, these were not an initial presenting features, but were apparent during cEEG recording. Acute medical or neurologic etiology was the risk factor in 68% of patients. Central nervous system (CNS) infections and cortical sino-venous thrombosis (CSVT), respectively, accounted for 23% and 14% of the etiologies. Intravenous midazolam terminated NCSE in 19 patients and valproate in 2. Of the 15 patients with acute symptomatic NCSE, 4 (18%) had poor prognosis (3 deaths and one persistent vegetative state). The etiological risk factors in the 9 (41%) patients with excellent outcome included epilepsy (3), remote symptomatic (2), cryptogenic (1), and metabolic and drugs (3). CONCLUSIONS: The frequency of NCSE in the current study was comparable with those in prior reports from developed countries. CNS infections accounted for about a fifth of the etiology. Outcome was excellent in patients with nonacute symptomatic NCSE. Initial 60-min EmEEG may be performed in establishing the diagnosis of NCSE, but almost half of patients with NCSE will be missed with this approach.     

Predictors of nonconvulsive seizures among critically ill children

Purpose: Continuous electroencephalography (EEG) monitoring is a valuable tool for the detection of seizures among critically ill children, in particular when these seizures occur without clinical signs: termed nonconvulsive seizures. Continuous EEG monitoring is a limited resource in many centers. We sought to identify which critically ill children most frequently experience nonconvulsive seizures, and thus may particularly benefit from continuous EEG monitoring. Methods: Single‐center review was undertaken of consecutive diagnostic continuous EEG (cEEG) recordings performed in our pediatric and neonatal intensive care units (ICUs). We examined the indications for monitoring, the clinical characteristics of monitored patients, the occurrence and timing of seizures, and clinical and EEG characteristics associated with nonconvulsive seizures. Key Findings: One hundred twenty‐one patients underwent diagnostic continuous EEG monitoring, for a mean duration of 26 h. Seizures were detected in 32% of these patients, of which 90% experienced some nonconvulsive seizures, and 72% experienced exclusively nonconvulsive seizures. Patients with nonconvulsive seizures had significantly greater odds of having acute epilepsy, acute structural brain injury, prior in‐hospital convulsive seizures, and the presence of interictal epileptiform abnormalities on EEG. Significance: Seizures are common among critically ill children undergoing diagnostic cEEG monitoring. The great majority of these seizures are nonconvulsive, requiring EEG for their detection. Predictors of nonconvulsive seizures include acute epilepsy, acute structural brain injury, prior in‐hospital convulsive seizures, and interictal epileptiform abnormalities on EEG. These findings can help inform future allocation of limited cEEG monitoring resources to those patients at greatest risk for nonconvulsive seizures.     

Diagnosis of nonconvulsive status epilepticus (NCSE) in adults with altered mental status: clinico-electroencephalographic considerations

The high incidence of nonconvulsive status epilepticus (NCSE) and difficulties encountered in rapid diagnosis have only recently become apparent and most neurophysiology textbooks have yet to fully address this topic. There is an immediate need to provide neurologists, neurology residents, and electroneurodiagnostic technologists with information to assist them in achieving early, accurate diagnosis of NCSE in patients they encounter on a daily basis. Instead of attempting to write a comprehensive review of the topic, we examined over 90 NCSE publications since 1972 and focused our efforts on extracting and summarizing those EEG and clinical considerations we found most useful for accurate diagnosis of NCSE in an adult population. The wide overlap between the clinical symptoms of NCSE and many other disorders causing change in mental status limits the usefulness of clinical measures for diagnosis. Those clinical parameters which have some utility are outlined. EEG testing and accurate interpretation is needed to identify NCSE in most instances. EEG patterns of NCSE are detailed and examples provided in order of progressive complexity. Timely treatment reduces patient risk for morbidity attributed to NCSE. Electroneurodiagnostic technologists who learn to recognize the entire spectrum of NCSE EEG patterns are better able to alert electroencephalographers to EEGs likely needing expedited review. This may facilitate early diagnosis if electroencephalographers determine that NCSE is indeed present. Electroencephalographers correlate the EEG pattern, clinical activity, and other diagnostic information to provide the treating medical doctors with an interpretation and recommendation in a timely manner. Lastly, EEG and clinical checklists and an algorithm which uses benzodiazepine response in conjunction with continuous EEG monitoring are provided to help reduce uncertainty in interpretation of equivocal EEG patterns of NCSE.     

Continuous EEG monitoring in the intensive care unit

It is now feasible and desirable to continuously monitor brain function with EEG in critically ill patients. Nonconvulsive seizures are more common than previously recognized and may contribute to impaired mental status and brain injury. Alerting stimuli commonly elicit periodic or ictal-appearing EEG patterns. Cerebral ischemia can be detected at a reversible stage with continuous EEG monitoring (cEEG). With the current availability of treatments for acute ischemia, this early detection has great potential for the prevention of stroke, but is only now beginning to be utilized for this purpose. The intensive care unit poses many technical difficulties for EEG acquisition, and artifact recognition is more important than ever. Recording synchronized video with EEG is essential for maximizing the efficiency and accuracy of cEEG interpretation, and quantitative EEG analysis can be quite helpful. The role of the EEG technologist is particularly important in these patients to aid in recognizing and minimizing artifact, to enhance communication between electroencephalographers and clinicians, to assess the effect of alerting stimuli, and to note possible subtle clinical correlates of electrographic seizures.