Which EEG patterns in coma are nonconvulsive status epilepticus?

Nonconvulsive status epilepticus (NCSE) is common in patients with coma with a prevalence between 5% and 48%. Patients in deep coma may exhibit epileptiform EEG patterns, such as generalized periodic spikes, and there is an ongoing debate about the relationship of these patterns and NCSE. The purposes of this review are (i) to discuss the various EEG patterns found in coma, its fluctuations, and transitions and (ii) to propose modified criteria for NCSE in coma.Classical coma patterns such as diffuse polymorphic delta activity, spindle coma, alpha/theta coma, low output voltage, or burst suppression do not reflect NCSE. Any ictal patterns with a typical spatiotemporal evolution or epileptiform discharges faster than 2.5 Hz in a comatose patient reflect nonconvulsive seizures or NCSE and should be treated. Generalized periodic diacharges or lateralized periodic discharges (GPDs/LPDs) with a frequency of less than 2.5 Hz or rhythmic discharges (RDs) faster than 0.5 Hz are the borderland of NCSE in coma. In these cases, at least one of the additional criteria is needed to diagnose NCSE (a) subtle clinical ictal phenomena, (b) typical spatiotemporal evolution, or (c) response to antiepileptic drug treatment. There is currently no consensus about how long these patterns must be present to qualify for NCSE, and the distinction from nonconvulsive seizures in patients with critical illness or in comatose patients seems arbitrary.The Salzburg Consensus Criteria for NCSE [1] have been modified according to the Standardized Terminology of the American Clinical Neurophysiology Society [2] and validated in three different cohorts, with a sensitivity of 97.2%, a specificity of 95.9%, and a diagnostic accuracy of 96.3% in patients with clinical signs of NCSE. Their diagnostic utility in different cohorts with patients in deep coma has to be studied in the future.This article is part of a Special Issue entitled “Status Epilepticus”.     

Diagnosing nonconvulsive status epilepticus: Defining electroencephalographic and clinical response to diagnostic intravenous antiseizure medication trials

Objective

The Salzburg criteria for nonconvulsive status epilepticus (NCSE) and the American Clinical Neurophysiology Society (ACNS) Standardized Critical Care EEG Terminology 2021 include a diagnostic trial with intravenous (IV) antiseizure medications (ASMs) to assess electroencephalographic (EEG) and clinical response as a diagnostic criterion for definite NCSE and possible NCSE. However, how to perform this diagnostic test and assessing the EEG and clinical responses have not been operationally defined.

Methods

We performed a Delphi process involving six experts to standardize the diagnostic administration of IV ASM and propose operational criteria for EEG and clinical response.

Results

Either benzodiazepines (BZDs) or non-BZD ASMs can be used as first choice for a diagnostic IV ASM trial. However, non-BZDs should be considered in patients who already have impaired alertness or are at risk of respiratory depression. Levetiracetam, valproate, lacosamide, brivaracetam, or (if the only feasible drug) fosphenytoin or phenobarbital were deemed appropriate for a diagnostic IV trial. The starting dose should be approximately two thirds to three quarters of the full loading dose recommended for treatment of status epilepticus, with an additional smaller dose if needed. ASMs should be administered during EEG recording under supervision. A monitoring time of at least 15 min is recommended. If there is no response, a second trial with another non-BDZ or BDZs may be considered. A positive EEG response is defined as the resolution of the ictal–interictal continuum pattern for at least three times the longest previously observed spontaneous interval of resolution (if any), but minimum of one continuous minute. For a clinical response, physicians should use a standardized examination before and after IV ASM administration. We suggest a definite time-locked improvement in a focal deficit or at least one-step improvement on a new dedicated one-domain 10-level NCSE response scale.

Significance

The proposed standardized approach of a diagnostic IV ASM trial further refines the ACNS and Salzburg diagnostic criteria for NCSE.     

Salzburg Consensus Criteria for Non-Convulsive Status Epilepticus – approach to clinical application

BackgroundSalzburg Consensus Criteria for diagnosis of Non-Convulsive Status Epilepticus (SCNC) were proposed at the 4th London–Innsbruck Colloquium on status epilepticus in Salzburg (2013).MethodsWe retrospectively analyzed the EEGs of 50 consecutive nonhypoxic patients with diagnoses of nonconvulsive status epilepticus (NCSE) at discharge and 50 consecutive controls with abnormal EEGs in a large university hospital in Austria. We implemented the American Clinical Neurophysiology Society's Standardized Critical Care EEG Terminology, 2012 version (ACNS criteria) to increase the test performance of SCNC. In patients without preexisting epileptic encephalopathy, the following criteria were applied: (1) more than 25 epileptiform discharges (ED) per 10-second epoch, i.e., > 2.5/s and (2) patients with EDs ≤ 2.5/s or rhythmic delta/theta activity (RDT) exceeding 0.5/s AND at least one of the additional criteria: (2a) clinical and EEG improvements from antiepileptic drugs (AEDs), (2b) subtle clinical phenomena, or (2c) typical spatiotemporal evolution. In case of fluctuation without evolution or EEG improvement without clinical improvement, “possible NCSE” was diagnosed. For identification of RDT, the following criteria were compared: (test condition A) continuous delta–theta activity without further rules, (B) ACNS criterion for rhythmic delta activity (RDA), and (C) ACNS criteria for RDA and fluctuation.ResultsFalse positive rate in controls dropped from 28% (condition A) to 2% (B) (p = 0.00039) and finally to 0% (C) (p = 0.000042). Application of test condition C in the group with NCSE gives one false negative (2%). Various EEG patterns were found in patients with NCSE: (1) 8.2%, (2a) 2%, (2b) 12.2%, and (2c) 32.7%. Possible NCSE was diagnosed based on fluctuations in 57.1% and EEG improvement without clinical improvement in 14.2%.ConclusionThe modified SCNC with refined definitions including the ACNS terminology leads to clinically relevant and statistically significant reduction of false positive diagnoses of NCSE and to minimal loss in sensitivity.This article is part of a Special Issue entitled “Status Epilepticus”.     

Uso de la electroencefalografía urgente por el neurólogo de guardia: utilidad en el diagnóstico del estatus epiléptico no convulsivo

Introduction

We aim to describe the use of emergency electroencephalogram (EmEEG) by the on-call neurologist when nonconvulsive status epilepticus (NCSE) is suspected, and in other indications, in a tertiary hospital.

The yield of routine electroencephalography in the detection of incidental nonconvulsive status epilepticus – A prospective study

ObjectiveDiagnosis of NCSE is challenging, because the clinical presentation ranges from minimally altered mental status to coma without tonic–clonic activity. According to the largest retrospective study to date the incidence of NCSE is about 0.2%.MethodsWe prospectively investigated electroencephalography (EEG) recordings of 2514 consecutive patients that were referred to the Electrophysiology Unit of Department of Neurology, Vienna General Hospital between November 2009 and February 2011 (i.e. 16 months).ResultsThe incidence of NCSE in our study population was 0.8%, i.e. the EEG of 19 patients fulfilled the criteria of NCSE. In 53% of these patients the NCSE was not suspected by treating physicians. A severely reduced level of consciousness was found in 78% of patients with a suspected NCSE and in 30% of patients with an unsuspected NCSE, although the results were not statistically significant (p = 0.081). The delay between the admission to the hospital and diagnosis ranged between 0 and 51 days.ConclusionsNCSE was an unsuspected finding in more than half of the patients. Consciousness was severely impaired in only one third of these patients.SignificanceThese results highlight the importance of urgent EEG for the diagnosis of NCSE in patients even without significant impairment of consciousness.     

Optimized set of criteria for defining interictal epileptiform EEG discharges

ObjectiveTo find and validate the optimal combination of criteria that define interictal epileptiform EEG discharges (IEDs). Our target was a specificity over 95%, to avoid over-reading in clinical EEG.MethodsWe constructed 63 combinations of the six criteria from the operational definition of IEDs, recently issued in the EEG-glossary of the International Federation of Clinical Neurophysiology (IFCN). The diagnostic gold standard was derived from video-EEG recordings. In a testing EEG dataset from 100 patients, we selected the best performing combinations of criteria and then we validated them in an independent dataset from 70 patients. We compared their performance with subjective, expert-scorings and we determined inter-rater agreement (IRA).ResultsWithout using criteria, the specificity of expert-scorings was lower than the pre-defined threshold (86%). The best performing combination of criteria was the following: waves with spiky morphology, followed by a slow-afterwave and voltage map suggesting a source in the brain. In the validation dataset this achieved a specificity of 97% and a sensitivity of 89%. IRA was substantial.ConclusionsThe optimized set of criteria for defining IEDs has high accuracy and IRA.SignificanceUsing these criteria will contribute to decreasing over-reading of EEG and avoid misdiagnosis of epilepsy.     

Nonkonvulsiver Status epilepticus

Background

Nonconvulsive status epilepticus (NCSE) is associated with a poor outcome and is furthermore a diagnostic challenge in routine clinical work.

Objective

Several sets of diagnostic criteria exist. What is the difference between them and which ones have been evaluated? Which concept can be recommended in the light of current knowledge?

Material and methods

A survey on the current literature is provided and a structured approach for diagnosing NCSE is given.

Results

Only one study on evaluation of the diagnostic criteria for NCSE exists, i.?e. the “Salzburg criteria for NCSE”, which were investigated retrospectively in a multicenter study. The diagnosis of NCSE is based on clinical and EEG data. The additional implementation of paraclinical information, such as cerebral imaging, emergency and toxicology laboratories is mandatory.

Conclusion

Currently available criteria enable efficient and effective management of the majority of patients suspected of having NCSE; however, in individual cases it has to be taken into consideration that the criteria can be falsely positive or falsely negative.

     

Diagnostic accuracy of microEEG: A miniature,wireless EEG device

Measuring the diagnostic accuracy (DA) of an EEG device is unconventional and complicated by imperfect interrater reliability. We sought to compare the DA of a miniature, wireless, battery-powered EEG device (“microEEG”) to a reference EEG machine in emergency department (ED) patients with altered mental status (AMS). Two hundred twenty-five ED patients with AMS underwent 3 EEGs. Two EEGs, EEG1 (Nicolet Monitor, “reference”) and EEG2 (microEEG) were recorded simultaneously with EEG cup electrodes using a signal splitter. The remaining study, EEG3, was recorded with microEEG using an electrode cap immediately before or after EEG1/EEG2. The official EEG1 interpretation was considered the gold standard (EEG1-GS). EEG1, 2, and 3 were de-identified and blindly interpreted by two independent readers. A generalized mixed linear model was used to estimate the sensitivity and specificity of these interpretations relative to EEG1-GS and to compute a diagnostic odds ratio (DOR). Seventy-nine percent of EEG1-GS were abnormal. Neither the DOR nor the κ_f representing interrater reliabilities differed significantly between EEG1, EEG2, and EEG3. The mean setup time was 27 min for EEG1/EEG2 and 12 min for EEG3. The mean electrode impedance of EEG3 recordings was 12.6 kΩ (SD: 31.9 kΩ). The diagnostic accuracy of microEEG was comparable to that of the reference system and was not reduced when the EEG electrodes had high and unbalanced impedances. A common practice with many scientific instruments, measurement of EEG device DA provides an independent and quantitative assessment of device performance.     

Low frequency nonevolving generalized periodic epileptiform discharges and the borderland of hypoxic nonconvulsive status epilepticus in comatose patients after cardiac arrest

To explore the EEG boundary of nonconvulsive status epilepticus (NCSE) and the concept of “possible NCSE”, we studied 14 consecutive patients with ≤ 2-Hz nonevolving periodic generalized epileptiform discharges (GPDs) in their first EEG after out of hospital cardiac arrest (OHCA). The pattern was associated with myoclonus in 11 patients. EG reactivity to antiseizure drugs (benzodiazepines and propofol), but without clinical improvement, was noted in 8 patients, satisfying the diagnostic criteria of “possible NCSE”. Resolution of GPDs and emergence of physiological rhythms in follow-up EEGs and/or subsequent clinical improvement were noted in 6 of them, strongly suggesting that the initial slow nonevolving GPD pattern reflected NCSE significantly contributing to their coma. Background rhythms from 10 to 90% of the periods between GPDs were noted in 9 patients and appeared to correlate with reactivity of the GPD pattern to antiseizure drugs when 20% or more. Ten patients died, and four were discharged to longer care rehabilitation centers. Although based on few observations, preliminary evidence appears to indicate that in this context, nonevolving GPD frequencies as low as 0.8 Hz can reflect clinically significant NCSE and, therefore, warrant appropriate testing for possible reactivity. There is also some preliminary indication that background rhythms may be another important diagnostic and, perhaps, prognostic indicator, but this needs to be tested in large prospective studies.This article is part of a Special Issue entitled “Status Epilepticus”.     

EEG in Creutzfeldt-Jakob disease.

Electroecenphalography (EEG) is an integral part of the diagnostic process in patients with Creutzfeldt-Jakob disease (CJD). The EEG has therefore been included in the World Health Organisation diagnostic classification criteria of CJD. In sporadic CJD (sCJD), the EEG exhibits characteristic changes depending on the stage of the disease, ranging from nonspecific findings such as diffuse slowing and frontal rhythmic delta activity (FIRDA) in early stages to disease-typical periodic sharp wave complexes (PSWC) in middle and late stages to areactive coma traces or even alpha coma in preterminal EEG recordings. PSWC, either lateralized (in earlier stages) or generalized, occur in about two-thirds of patients with sCJD, with a positive predictive value of 95%. PSWC occur in patients with methionine homozygosity and methionine/valine heterozygosity but only rarely in patients with valine homozygosity at codon 129 of the prion protein gene. PSWC tend to disappear during sleep and may be attenuated by sedative medication and external stimulation. Seizures are an uncommon finding, occurring in less than 15% of patients with sCJD. In patients with iatrogenic CJD, PSWC usually present with more regional EEG findings corresponding to the site of inoculation of the transmissible agent. In genetic CJD, PSWC in its typical form are uncommon, occurring in about 10%. No PSWC occur in EEG recordings of patients with variant CJD.     

Continuous video-EEG monitoring increases detection rate of nonconvulsive status epilepticus in the ICU

Purpose: Status epilepticus (SE) is an important neurologic emergency requiring treatment on an intensive care unit (ICU). Although convulsive SE is self‐evident, the diagnosis of nonconvulsive SE (NCSE) depends on electroencephalography (EEG) confirmation. Previous work showed that 82% of patients with SE had NCSE in our ICU. We hypothesize that continuous video‐EEG monitoring (CVEM) may increase the diagnostic yield in patients with SE, especially NCSE, and leave fewer patients undiagnosed. Methods: We retrospectively assessed the EEG reports of 537 patients with suspected SE during three comparable 9‐month periods, two groups before (groups 1 and 2) and one (group 3) after CVEM introduction. Differences in monthly rates of SE between groups were assessed using the Mann‐Whitney U‐test. Key Findings: The rates of diagnosis increased significantly after implementation of CVEM (p = 0.0546). There was no significant difference in monthly rates of NCSE diagnosis between groups 2 and 1 (difference = 0.78 new diagnosis/month; p = 0.374). Differences between groups 3 and 2 (2.89; p = 0.0173), between groups 3 and 1 (3.67; p = 0.006) and between group 3 and pooled groups 1 and 2 (3.28; p = 0.002) were statistically significant. Significance: Frequency of NCSE diagnosis increased significantly after implementation of CVEM and was higher than the increment of performed investigations alone. Such an effect may result from the combination of longer observation periods during CVEM, greater and permanent availability of EEG recordings, and heightened awareness of NCSE. Future studies may corroborate improvement of diagnosis and outcomes in patients with disorders of consciousness by CVEM.     

Diagnostic accuracy of EEG changes during carotid endarterectomy in predicting perioperative strokes

The 30 day stroke rate following carotid endarterectomy (CEA) ranges between 2–6%. Such periprocedural strokes are associated with a three-fold increased risk of mortality. Our primary aim was to determine the diagnostic accuracy of electroencephalogram (EEG) in predicting perioperative strokes through meta-analysis of existing literature. An extensive search for relevant literature was undertaken using PubMed and Web of Science databases. Studies were included after screening using predetermined criteria. Data was extracted and analyzed. Summary sensitivity, specificity and diagnostic odds ratio were obtained. Subgroup analysis of studies using eight or more EEG channels was done. Perioperative stroke rate for the cohort of 8765 patients was 1.75%. Pooled sensitivity and specificity of EEG changes in predicting these strokes were 52% (95% confidence interval [CI], 43–61%) and 84% (95% CI, 81–86%) respectively. Summary estimates of the subgroup were similar. The diagnostic odds ratio was 5.85 (95% CI, 3.71–9.22). For the observed stroke rate, the positive likelihood ratio was 3.25 while the negative predictive value was 98.99%. According to these results, patients with perioperative strokes have six times greater odds of experiencing an intraoperative change in EEG during CEA. EEG monitoring was found to be highly specific in predicting perioperative strokes after CEA.     

Usefulness of the Neurobehavioral Cognitive Status Examination in the hospitalized elderly.

A prospective pilot study compared the Neurobehavioral Cognitive Status Examination (NCSE) to the Folstein Mini-Mental State Examination (MMSE) to determine the usefulness of the NCSE as a cognitive screen in a geriatric inpatient population. All patients directly admitted to the geriatric evaluation and treatment unit (GETU) of a university teaching hospital over a two-and-a-half-month period were eligible for the study, in which 42% participated. Within 72 hours of admission, patients were given the MMSE and the NCSE in a nonrandom order by a trained psychologist and a structured interview by a psychiatrist. The ability of the NCSE to detect global cognitive impairment was compared to the MMSE and psychiatrist's assessment. Differences in sensitivity were examined by discordant pair analysis. The psychiatrist's determination of the presence of cognitive impairment was used as the criterion standard. Comparisons of the MMSE and NCSE, respectively, revealed the following: sensitivity 83% versus 100%; specificity 78% versus 11%; positive predictive value 83% versus 43%; and negative predictive value 78% versus 100%. Seven patients who were cognitively impaired by the NCSE were not impaired by the MMSE (p less than 0.05 by discordant pair analysis). The time of administration for the two tests was significantly shorter for the MMSE (14.75 +/- 5.7 minutes) than for the NCSE (38.9 +/- 12.9 minutes). The NCSE was found to be more sensitive than the MMSE in detecting cognitive impairment among geriatric inpatients, but its specificity and positive predictive values were lower. Beyond this pilot study, additional work examining the utility of the NCSE in other geriatric settings and for different purposes (e.g., as part of comprehensive assessment) needs to be performed.     

Forehead EEG electrode set versus full-head scalp EEG in 100 patients with altered mental state

BackgroundAcute EEG is vastly underutilized in acute neurological settings. The most common reason for this is simply the fact that acute EEG is not available when needed or getting EEG is delayed as it requires trained technicians and equipment to be properly recorded. We have recently described a handy disposable forehead EEG electrode set that is suitable for acute emergency EEG recordings. The specific objective in this study was to assess the forehead electrode's utility when the clinical demand was to exclude SE.Patients and methodsOne hundred consecutive acute neurological patients (53 women, 47 men, age: 18–90 years) with unexplained altered mental state were studied with acute emergency EEG to rule out SE. Electroencephalographic recordings were obtained simultaneously with forehead EEG electrode and routine 10–20 system full-head scalp electrodes to clarify the clinical usefulness of forehead EEG electrode in this setting. Electroencephalographic recordings were interpreted blindly by three experienced clinical neurophysiologists first only based on forehead EEG and then by full-head EEG.ResultsNinety-six out of the 100 patients did not show EEG evidence of SE. There was 100% agreement with forehead and routine EEG. Four out of the 100 patients showed EEG evidence of SE in routine EEG, with 50% agreement between different electrode types. The forehead EEG missed two cases because the EEG findings supporting SE were restricted to the posterior parts of the brain.Major conclusionsWith a forehead EEG set, the sensitivity of detecting NCSE was 50%. There were no false positive cases yielding a specificity of 100%. Patients with AMS can benefit from forehead EEG recording in prehospital, hospital, and ICU settings. Since EEG recording can be started within a few minutes with the forehead EEG set, it will significantly reduce the delay in treatment of SE.This article is part of a Special Issue entitled "Status Epilepticus".     

Diagnostic value of periodic complexes in Creutzfeldt-Jakob disease

In 1996, our group published objective electroencephalogram (EEG) criteria to define periodic sharp-wave complexes (PSWCs) suggestive for Creutzfeldt-Jakob disease (CJD). These criteria have since then been strictly applied in all cases reported to us as possible CJD in the course of the German CJD surveillance study. Furthermore, EEG analysis of the records was performed without any additional information on complementary clinical and laboratory data. In this study, we investigated sensitivity, specificity, and the predictive values of these EEG criteria exclusively in cases in which autopsy confirmed (n=150) or excluded (n=56) CJD. EEG criteria were positive in 64% (n=96) of the CJD cases and falsely positive in 9% (n=5) of other dementias. The resulting figures for sensitivity, specificity, and positive and negative predictive values were 64%, 91%, 95%, and 49%, respectively. In the falsely positive cases, Alzheimer's disease (n=4) and vascular dementia (n=1) were the underlying diseases. However, only in one of these five cases both clinical and EEG data would have led to the false-positive result to diagnose probable CJD. These data prove the high diagnostic value of our objective EEG criteria in CJD.     

The influence of the abundance and morphology of epileptiform discharges on diagnostic accuracy: How many spikes you need to spot in an EEG

ObjectiveThe operational definition of interictal epileptiform discharges (IEDs) of the International Federation of Clinical Neurophysiology (IFCN) described six morphological criteria. Our objective was to assess the impact of pattern-repetition in the EEG-recording, on the diagnostic accuracy of using the IFCN criteria. For clinical implementation, specificity over 95% was set as target.MethodsInterictal EEG-recordings of 20-minutes, containing sharp-transients, from 60 patients (30 with epilepsy and 30 with non-epileptic paroxysmal events) were evaluated by three experts, who first marked IEDs solely based on expert opinion, and then, independently from the first session evaluated the presence of the IFCN criteria for each sharp-transient. The gold standard was derived from long-term video-EEG recordings of the patientś habitual paroxysmal episodes.ResultsPresence of at least one discharge fulfilling five criteria provided a specificity of 100% (sensitivity: 70%). For discharges fulfilling fewer criteria, a higher number of discharges was needed to keep the specificity over 95% (5 discharges, when only 3 criteria were fulfilled). A sequential combination of these sets of criteria and thresholds provided a specificity of 97% and sensitivity of 80%.ConclusionsPattern-repetition and IED morphology influence diagnostic accuracy.SignificanceSystematic application of these criteria will improve quality of clinical EEG interpretation.     

Non-convulsive status epilepticus: usefulness of clinical features in selecting patients for urgent EEG

BACKGROUND: Non-convulsive status epilepticus (NCSE) is status epilepticus without obvious tonic-clonic activity. Patients with NCSE have altered mental state. An EEG is needed to confirm the diagnosis, but obtaining an EEG on every patient with altered mental state is not practical. OBJECTIVE: To determine whether clinical features could be used to predict which patients were more likely to be in NCSE and thus in need of an urgent EEG. METHODS: Over a six month period, all patients for whom an urgent EEG was ordered to identify NCSE were enrolled. Neurology residents examined the patients and filled out a questionnaire without knowledge of the EEG results. The patients were divided into two groups, NCSE and non-NCSE, depending on the EEG result. The clinical features were compared between the two groups. The sensitivity and specificity of the features were calculated. RESULTS: 48 patients were enrolled, 12 in NCSE and 36 not in NCSE. Remote risk factors for seizures, severely impaired mental state, and ocular movement abnormalities were seen significantly more often in the NCSE group. The combined sensitivity of remote risk factors for seizures and ocular movement abnormalities was 100%. CONCLUSIONS: There are certain clinical features that are more likely to be present in patients in NCSE compared with other types of encephalopathy. Either remote risk factors for seizures or ocular movement abnormalities were seen in all patients in NCSE. These features may be used to select which patients should have an urgent EEG.     

Nonconvulsive status epilepticus in patients with brain tumors

PurposeThe prevalence of nonconvulsive status epilepticus (NCSE) in brain tumor patients is unknown. Since NCSE has been associated with significant mortality and morbidity, early identification is essential. This study describes the clinical and EEG characteristics, treatment, and outcome in brain tumor patients with NCSE.MethodAll patients admitted to Mount Sinai Hospital from 2009 to 2012 with an ICD-9 brain tumor code were cross-referenced with the epilepsy department's database. EEGs from matching patients were reviewed for NCSE. Relevant information from the medical records of the patients with NCSE was extracted.Results1101 brain tumor patients were identified, of which 259 (24%) had an EEG and 24 (2%) had NCSE. The vast majority of seizures captured were subclinical with 13 patients (54%) having only subclinical seizures. Treatment resolved the NCSE in 22 patients (92%) with accompanying clinical improvement in 18 (75%) of those patients. Tumor recurrence or progression on MRI was associated with decreased 2-month survival (75% mortality, p = 0.035) compared to stable tumors (20% mortality). Patients with metastatic disease had median survival from tumor diagnosis of 1.2 months.ConclusionNCSE in brain tumor patients may be under diagnosed due to the frequent lack of outward manifestations and highly treatable with improvement in the majority of patients. NCSE patients with progressing brain lesions, tumor recurrence, or metastatic disease are at serious risk of mortality within 2 months. Continuous EEG monitoring in brain tumor patients with recent clinical seizures and/or a depressed level of consciousness may be critical in providing appropriate care.     

EEG autoregressive modeling analysis: A diagnostic tool for patients with epilepsy without epileptiform discharges

ObjectiveNumerous types of nonepileptic paroxysmal events, such as syncopes and psychogenic nonepileptic seizures, may imitate epileptic seizures and lead to diagnostic difficulty. Such misdiagnoses may lead to inappropriate treatment in patients that can considerably affect their lives. Electroencephalogram (EEG) is a commonly used tool in assisting diagnosis of epilepsy. Although the appearance of epileptiform discharges (EDs) in EEG recordings is specific for epilepsy diagnosis, only 25%–56% of patients with epilepsy show EDs in their first EEG examination.MethodsIn this study, we developed an autoregressive (AR) model prediction error–based EEG classification method to distinguish EEG signals between controls and patients with epilepsy without EDs. Twenty-three patients with generalized epilepsy without EDs in their EEG recordings and 23 age-matched controls were enrolled. Their EEG recordings were classified using AR model prediction error–based EEG features.ResultsAmong different classification methods, XGBoost achieved the highest performance in terms of accuracy and true positive rate. The results showed that the accuracy, area under the curve, true positive rate, and true negative rate were 85.17%, 87.54%, 89.98%, and 81.81%, respectively.ConclusionsOur proposed method can help neurologists in the early diagnosis of epilepsy in patients without EDs and might help in differentiating between nonepileptic paroxysmal events and epilepsy.SignificanceEEG AR model prediction errors could be used as an alternative diagnostic marker of epilepsy.     

Diagnostic accuracy of various EEG changes during carotid endarterectomy to detect 30-day perioperative stroke: A systematic review

ObjectivesWe assessed whether significant intraoperative electroencephalography (EEG) changes have predictive value for perioperative stroke within 30 days after carotid endarterectomy (CEA) procedures for carotid stenosis (CS) patients. We also assessed the diagnostic accuracy of various EEG changes in predicting perioperative stroke.MethodsWe searched databases for reports with outcomes of CS patients who underwent CEA with intraoperative EEG monitoring. We calculated the sensitivity, specificity, and diagnostic odds ratio (DOR) of EEG changes for predicting perioperative stroke. Sensitivity and specificity were presented with forest plots and a summary receiver operating characteristic (ROC) curve.ResultsThe meta-analysis included 10,672 patients. Intraoperative EEG changes predicted 30-day stroke with a sensitivity of 46% (95% CI, 38–54%) and specificity of 86% (95% CI, 83–88%). The estimated DOR was 5.79 (95% CI, 3.86–8.69). The estimated DOR for reversible and irreversible EEG changes were 8.25 (95% CI, 3.34–20.34) and 70.84 (95% CI, 36.01–139.37), respectively.ConclusionIntraoperative EEG changes have high specificity but modest sensitivity for predicting perioperative stroke following CEA. Patients with irreversible EEG changes are at high risk for perioperative stroke.SignificanceIntraoperative EEG changes can help surgeons predict the risk of perioperative stroke for CS patients following CEA.