Inter-observer variability of the EEG diagnosis of seizures in comatose patients

ObjectiveTo assess the inter-observer agreement of the electroencephalogram (EEG) diagnosis of (non-convulsive) seizures in comatose patients.Design/setting/patientsNine clinicians with different levels of experience in clinical neurophysiology were asked to evaluate in a strictly controlled way 90 epochs (10 s each) of 30 EEG’s of 23 comatose patients admitted to the intensive care unit (ICU). For each EEG clinicians had to decide whether there was an electrographic seizure or not. Furthermore, Young’s EEG criteria for (non-convulsive) seizures were scored in detail for all EEG’s. Agreement was determined by calculating kappa values.ResultsThe inter-observer agreement of an EEG diagnosis of seizure was limited. The overall kappa score for the five experienced raters was 0.5, and the kappa score for less experienced raters was 0.29. Kappa values for the individual Young’s criteria were highly variable, indicating discrepancies in the interpretation of specific phenomena. Especially, some types of periodic discharges gave rise to different interpretations.ConclusionsThe EEG diagnosis of (non-convulsive) seizures in ICU patients is not very reliable, even when strict criteria such as proposed by Young are applied. There is a need for less ambiguous EEG criteria for (non-convulsive) seizures and status epilepticus.     

Pentobarbital treatment of refractory status epilepticus

We studied nine patients with status epilepticus refractory to standard therapy. In all patients so treated, IV pentobarbital terminated seizure activity. Mortality was high (77%) in those treated, but was attributed to underlying pathology and possibly to duration of status epilepticus. Pentobarbital therapy should be initiated within 0 to 2 hours after onset of seizures, with continuous EEG monitoring in an intensive care unit.     

Management of patients with status epilepticus treated at a pediatric intensive care unit in Turkey

We investigated the etiology, treatment, and prognosis of patients treated for status epilepticus at a pediatric intensive care unit. Medical records of 89 patients admitted to a pediatric intensive care unit with status epilepticus were reviewed retrospectively. Patients ranged in age from 2 months to 18 years (mean age ± S.D., 4.7 ± 3.8 years). Seizure etiologies comprised remote symptomatic in 47 (52.7%), febrile in 15 (16.9%), acute symptomatic in 12 (13.5%), and unknown in 15 (16.9%). Seizure durations ranged from 30-60 minutes in 58 patients, whereas 31 manifested refractory seizures longer than 60 minutes. Seizure control was achieved within 30 minutes in 55 patients, from 30-60 minutes in 19, and after 60 minutes in 15. Rectal diazepam was administered to 38 (42.7%) patients before admission to the hospital. Length of intensive care unit stay increased with increasing seizure duration (P < 0.05). The total mortality rate was 3.4%. This lower mortality rate may be considered evidence of the effectiveness and reliability of the status epilepticus treatment protocol in our pediatric intensive care unit. Prehospital rectal diazepam administration and the treatment of brain edema in the intensive care unit may be useful in the management of patients with status epilepticus.     

The EEG of status epilepticus.

SUMMARY: Gastaut noted that there are as many forms of status epilepticus (SE) as there are seizure types. The pleomorphic EEG patterns reflect this wide variety of clinical types. The different electroclinical types of status epilepticus share EEG characteristics including rhythmic activity, epileptiform discharges, and often a waxing and waning evolution. Gray zones of interpretation exist in the form of runs of epileptiform periodic discharges, typically of lower frequency, and lesser temporal variability. In diagnosing SE, clinical correlation and response to parenteral anti-epileptic drugs (AEDs) are of particular importance. Accurate diagnosis of electroclinical SE type is essential, because it determines prognosis and dictates the intensity of therapeutic management. Some patients with benign forms of SE may benefit from nonparenteral treatment, and be followed up clinically and by spot EEGs. Conversely, intensive care unit management with anesthesia and continuous monitoring, and parenteral AEDs may be required for refractory convulsive SE.     

Electrophysiologic Monitoring in Acute Brain Injury

To determine the optimal use and indications of electroencephalography (EEG) in critical care management of acute brain injury (ABI). An electronic literature search was conducted for articles in English describing electrophysiological monitoring in ABI from January 1990 to August 2013. A total of 165 studies were included. EEG is a useful monitor for seizure and ischemia detection. There is a well-described role for EEG in convulsive status epilepticus and cardiac arrest (CA). Data suggest EEG should be considered in all patients with ABI and unexplained and persistent altered consciousness and in comatose intensive care unit (ICU) patients without an acute primary brain condition who have an unexplained impairment of mental status. There remain uncertainties about certain technical details, e.g., the minimum duration of EEG studies, the montage, and electrodes. Data obtained from both EEG and EP studies may help estimate prognosis in ABI patients, particularly following CA and traumatic brain injury. Data supporting these recommendations is sparse, and high quality studies are needed. EEG is used to monitor and detect seizures and ischemia in ICU patients and indications for EEG are clear for certain disease states, however, uncertainty remains on other applications.     

Treatment of status epilepticus]

Status epilepticus (SE) is a condition requiring emergency care. There are convulsive SE, non-convulsive SE including complex partial status and absence status, non-convulsive electric SE and pseudostatus epilepticus, although convulsive SE is the most common. Diagnosis of status epilepticus of complex partial seizures (CPS) and absence seizures was significantly delayed because delays in seeking medical attention were common. The seizures were generalized convulsive SE in 84% and CPS status in 16%, and the overall mortality rate was 15% in 41 SE patients of our study. EEG monitoring is important to make or exclude the diagnosis of SE. Diazepam is the first choice medication and effective in the management of SE, and lately, lorazepam, midazolam, propofol and pentobarbital etc as emergency therapy. Phenytoin is also considered first-line agent in the emergency management of SE. Repetitive transcranial magnetic stimulation (rTMS) led to a prolonged latency for seizure induction after an intraperitoneal injection of pentylenetetrazol (PTZ) and effectively prevented the development of status epilepticus of PTZ-induced convulsions in the rats. Our data suggest that rTMS has suppressive effects on the neuronal excitability in rats. These effects are anticonvulsive and suggest the possibility of therapeutic use of rTMS in the patients with refractory seizures.     

Digital video-electroencephalographic monitoring in the neurological-neurosurgical intensive care unit: clinical features and outcome

BACKGROUND: Prolonged electroencephalographic (EEG) recordings in the neurological-neurosurgical intensive care unit (NICU) may be performed in patients with status epilepticus, repetitive seizure activity, or an encephalopathy with or without seizures. The electroclinical correlation and neurological outcome of patients undergoing digital video-EEG monitoring (DVEEG) in the NICU has not been determined. OBJECTIVES: To evaluate the clinical utility and prognostic importance of the DVEEG in the NICU. METHODS: We retrospectively evaluated 105 patients who underwent DVEEG in the NICU at the Mayo Clinic, Rochester, Minn, between January 1, 1994, and July 31, 2001. All patients had a routine EEG recording performed prior to DVEEG. RESULTS: The mean age of the patients at the time of the DVEEG was 54 years (age range, 16-88 years). The mean duration of the DVEEG was 2.9 days (range, 1-17 days). Forty-four patients (42%) had a severe encephalopathy (Glasgow Coma Scale score, <8) at the time of the DVEEG. Forty-five patients (42.8%) had generalized convulsive status epilepticus, 19 patients (18.1%) had nonconvulsive status epilepticus, and 7 patients (6.7%) had epilepsia partialis continua. The mean duration of follow-up was 7 months (range, 1-54 months). The outcome in 84 patients included death in 38 patients, severe neurological deficits, that is, bed bound and needs support for activities of daily living, in 6 patients, and a vegetative state in 3 patients. Fifteen individuals had no neurological impairment during follow-up. Refractory status epilepticus (P<.003), hypoxic-ischemic encephalopathy (P<.004), and multiple cerebral infarcts (P<.003) were the factors associated with increased mortality in univariate analysis. With multivariate logistic regression analysis only the presence of multiple strokes (P<.03; odds ratio, 5.62) was predictive of mortality. CONCLUSIONS: Continuous EEG monitoring is essential in the diagnosis and treatment of refractory status epilepticus or an encephalopathy with seizures in the NICU. A minority of these patients, however, experienced a favorable neurological outcome.     

A long‐term follow‐up study of Dravet syndrome up to adulthood

Purpose : We intended to elucidate the whole clinical course of Dravet syndrome (DS) comprehensively, from infancy through adulthood. Methods : Subjects were 31 patients with DS (14 with typical DS, and 17 with borderline DS) who were followed from childhood to at least 18 years of age. Their seizures, abilities, and electroencephalography (EEG) findings were investigated and statistically analyzed. Results : The clinical findings of the patients with typical DS and those with borderline DS became largely similar in adolescence and adulthood. Seizures were intractable in childhood in all patients, but suppressed in five (16.1%) during follow‐up. Thirty‐five (87.5%) of the 40 apparently generalized convulsive seizures that were captured by ictal EEG recording at 7 years of age or later were of focal origin. The seizure‐free outcomes were significantly correlated with the experience of <3 episodes of convulsive status epilepticus, and also with disappearance of spikes on the follow‐up EEGs. Mental outcomes involving less severe intellectual disability were correlated with the presence of occipital alpha rhythms in the background activity of the follow‐up EEGs. Mean age at the recording of the follow‐up EEGs was 23.8 years. Discussion : Prevention of the occurrence of convulsive status epilepticus was indicated to be critically important for the improvement of seizure prognosis in DS.     

Alzheimer's disease underlies some cases of complex partial status epilepticus.

Alzheimer's disease is a known risk factor for seizures, and age older than 60 years is a recognized risk factor for poor outcome from convulsive and nonconvulsive status epilepticus. The authors suspect that there may be a causal relationship between dementia pathology and the development and maintenance of refractory seizures. They report two selected patients with complex partial status epilepticus whose presentation and clinical course provide partial support for this hypothesis. Their methods include case reports with clinical, EEG, imaging, and pathologic correlations. The patients were 70 and 85 years of age. Both had central and peripheral brain atrophy on imaging studies (with some regions that were affected more than others), left temporal seizure foci corresponding to areas of greatest cortical atrophy, and early presentation with inhibitory epileptic symptoms (aphasia), with evolution to complex partial status epilepticus. Pathologic confirmation of Alzheimer's disease was obtained in one patient who had not been diagnosed previously. It involved maximally the cortex underlying the seizure focus. A diagnosis of probable Alzheimer's disease was established in the other patient. Alzheimer's disease may be causal in some cases of complex partial status epilepticus. Additional observations in support of this hypothesis are needed.     

儿科重症监护病房惊厥性癫痫持续状态患儿预后影响因素分析

目的 探讨儿科重症监护病房(PICU)中惊厥性癫痫持续状态患儿预后的影响因素.方法 收集2016年6月至2020年6月期间在开封市中心医院儿科PICU住院治疗的惊厥性癫痫持续状态患儿96例的临床资料,采用END-IT评价患儿预后情况,分为预后不良组及预后良好组,整理并记录患儿的性别、年龄、病因、抽搐史、全面性发作、生长...     

Hierarchy of Seizure States in the Electrogenic Limbic Status Epilepticus Model: Behavioral and Electrographic Observations of Initial States and Temporal Progression

Repeated electrical stimulation was delivered to the amygdala in a paradigm of electrogenic limbic status epilepticus induction in rats. We observed four distinct initial behavioral states associated with prolonged spiking, comprising an ordered hierarchy of severity: immobile, exploratory, minor convulsive, and clonic convulsive. The EEG and behavioral topography of the initial prolonged seizure state behaviorally and electrographically resembled the acute seizures that occurred earlier during induction. Onset of status epilepticus on limbic induction appears to represent not a new type of seizure activity, but instead the extended version of repeated brief limbic-onset seizures as seizure-terminating mechanisms gradually become ineffective. These prolonged seizure states can therefore be used to study the anatomy and mechanisms of brief limbic seizures. We also examined the temporal progression of amygdala-induced prolonged-seizure states. At one end of the severity spectrum, immobile-associated spiking was prone to terminate early, within 90 min, accompanied by normalization of behavior. At the other end of the spectrum, clonic convulsive status epilepticus slowly decreased in behavioral severity together with a change in EEG from fast to slow spiking. Exploratory status epilepticus was characterized by incessant explorationlike behavior that could last hours and was associated with slow periodic spike-complexes on EEG. The long-term course consisted either of slow devolution, with eventual cessation of spiking, or of spontaneous late ascension to convulsive status. Prolonged-seizure states may thus be considered to fall not only within an anatomic/behavioral hierarchy of severity, but also within a temporal physiologic progression.     

The use of levetiracetam in refractory status epilepticus.

Six patients with status epilepticus (SE) of various etiologies refractory to at least two antiepileptic drugs (AEDs) had complete cessation of their seizures following administration of oral levetiracetam (LEV). Seizure types included convulsive, focal, and nonconvulsive status epilepticus. Effective doses of levetiracetam ranged from 500 to 3000 mg/day, achieving seizure control within 12-96 h. No significant adverse events were noted. Adjunctive levetiracetam should be considered for patients with status epilepticus unresponsive to initial therapy.     

Epileptic patients who are refractory to anticonvulsant medications

To evaluate criteria that predict success or failure of currently available anticonvulsant medications, we studied 194 epileptic patients who were admitted to an intensive treatment unit. Seizures were present in the hospital in 78.3% and could not be controlled in 33.7%. Combinations of at least two of the following criteria were associated with limited treatment responses: multiple handicap (intellectual limitations or abnormal neurologic signs), different seizure types, cluster seizures, slowing of EEG background rhythms, and seizures discharges in the EEG despite adequate anticonvulsant blood levels. Presumed etiology was not associated with predictive ability. Patients who were neurologically and intellectually intact and had frequent clinical attacks, normal EEG background rhythms, and no seizure discharges usually had pseudoseizures.     

Continuous video-EEG monitoring in pediatric intensive care units

Purpose: Several studies indicate a higher occurrence than might be expected of seizures in intensive care unit patients, many of which are not clinically apparent. Few of these studies are devoted exclusively to pediatric patients. The purpose of this study is to determine the occurrence of seizures in a cohort of pediatric and neonatal intensive care unit patients. Methods: Long‐term video electroencephalography (EEG) monitoring studies performed in the pediatric and neonatal intensive care units were reviewed. Age, gender, diagnosis, EEG background, epileptiform activity, time of onset and duration of seizures, presence of electroclinical or electrographic seizures, and survival were collected. Key Findings: One hundred thirty‐eight recordings encompassing 122 patients were identified. Thirty‐four percent of the sessions identified seizures in the first 24 h (38% of the cohort experienced a seizure at some time during monitoring, which ranged from 1–22 days): 17% captured only electroclinical seizures, 49% were electrographic only, and 34% had both electroclinical and electrographic seizures. Seventy percent of those patients experiencing seizures had their first seizure within the first hour of EEG recording. Younger age and epileptiform activity (including periodic) were associated with the occurrence of seizures. Diagnoses of head trauma and status epilepticus/recent prior seizure were more likely than other at‐risk diagnoses to be associated with seizures; cardiac arrest managed with hypothermia was less likely to be associated with seizures. One‐fourth of the recordings identified nonepileptic events. Significance: Seizures occurred in one‐third of critically ill pediatric patients at risk for seizures who underwent video‐EEG monitoring, and many of these seizures did not have a clinical correlate. In those at risk for seizures in intensive care units, there should be a low threshold for obtaining long‐term monitoring.     

Treatment of status epilepticus in the adult. Retrospective analysis of 192 cases treated in intensive care units

The results of therapy have been analyzed in a series of 192 patients admitted for status epilepticus over 7 years in two intensive care units. Most (142 cases without any prior epilepsy) corresponded to secondary forms. In 2/3 of the cases, the patients were admitted because of failure of benzodiazepines and/or phenobarbitone. Sodium thiopentone achieved control of seizures in 75%; short-acting barbiturates should be especially prescribed in grand mal status with impending brain anoxia. Diphenylhydantoin would appear suitable in non-life-threatening conditions such as serial seizures or partial status. Chlormethiazole often succeeds in controlling convulsive status which has proved refractory to other treatment. Supportive management is mandatory: 52% of patients required respiratory assistance. Fatalities (36%) exclusively correspond to the underlying cerebral conditions and systemic disorders.     

Amplitude-integrated electroencephalography in patients with acute encephalopathy with refractory, repetitive partial seizures

We report amplitude-integrated EEG findings in two children with acute encephalopathy with refractory, repetitive partial seizures. Both patients had a febrile illness one week before the onset of seizure. They had reduction of consciousness and repetitive seizures refractory to first-line antiepileptic drugs. Seizure frequency rapidly increased and evolved into status epilepticus. Continuous seizure monitoring with amplitude-integrated EEG revealed frequent subclinical seizures which were missed by direct observation. In addition, the site of origin of seizures was multifocal, and seizure foci shifted from one hemisphere to the other. Their seizures were controlled after an administration of high-dose phenobarbital. Continuous seizure monitoring with amplitude-integrated EEG will contribute to correct estimation of seizure burden and efficacy of antiepileptic drugs in children with acute encephalopathy with refractory, repetitive partial seizures.     

Prolonged confusion following convulsions due to generalized nonconvulsive status epilepticus

Among patients with a prolonged confusional state after convulsive seizure, we diagnosed 8 cases as generalized nonconvulsive status epilepticus. Six had a history of seizures, and 2 had new onset. The convulsive seizures were generalized in 6 and focal in two. The postictal confusion lasted up to 36 hours in the most prolonged case, and a delayed response to anticonvulsant medications occurred in all cases. The clinical symptoms ranged from mild confusion to coma. Psychiatric manifestations or automatisms were rare. The presumed etiology was due to diverse causes, but a withdrawal state was the most common. EEG demonstrated continuous or nearly continuous generalized ictal discharges of variable morphology. These cases call attention to the fact that some prolonged confusional states following convulsive seizures are in fact due to persistent seizure activity that can be diagnosed by EEG.     

Generalized Convulsive Status Epilepticus in the Adult

Summary: Status epilepticus (SE) is denned as recurrent epileptic seizures without full recovery of consciousness before the next seizure begins, or more-or-less continuous clinical and/or electrical seizure activity lasting for more than 30 min whether or not consciousness is impaired. Three presentations of SE are now recognized: recurrent generalized tonic and/or clonic seizures without full recovery of consciousness between attacks, nonconvulsive status where the patient appears to be in a prolonged "epileptic twilight state," and continuous/repetitive focal seizure activity without alteration of consciousness. Generalized convulsive status epilepticus (GCSE) encompasses a broad spectrum of clinical presentations from repeated overt generalized tonic-clonic seizures to subtle convulsive movements in a profoundly comatose patient. Thus, GCSE is a dynamic state that is characterized by paroxysmal or continuous tonic and/or clonic motor activity, which may be symmetrical or asymmetrical and overt or subtle but which is associated with a marked impairment of consciousness and with bilateral (although frequently asymmetrical) ictal discharges on the EEG. Just as there is a progression from overt to increasingly subtle clinical manifestations of GCSE, there is also a predictable sequence of progressive EEG changes during untreated GCSE. A sequence of five patterns of ictal discharges has been observed: discrete electrographic seizures, waxing and waning, continuous, continuous with flat periods, and periodic epileptiform discharges on a relatively flat background. A patient actively having seizures or comatose who exhibits any of these patterns on EEG should be considered to be in GCSE and should be treated aggressively to stop all clinical and electrical seizure activity to prevent further neurological morbidity and mortality.     

Seizures in the elderly: Video/EEG monitoring analysis

OBJECTIVE: Recently there has been a remarkable increase in the number of elderly people with epilepsy due to the growing size of this segment of the population. The literature provides little information on the characteristics of epileptic and nonepileptic events in the elderly. Therefore we report the results of video/EEG recordings in patients aged 60 or older admitted over 2 consecutive years to an epilepsy monitoring unit (EMU). METHODS: We examined the records of all elderly patients admitted to our EMU between December 1999 and December 2001. Fifty-eight patients were older than 60, constituting 17% of the total admissions to the EMU. All patients underwent continuous video/EEG monitoring. On the basis of reasons for admission, video/EEG reports were categorized into (1) diagnosis of events, (2) characterization and localization of seizures, (3) adjustment of medication, and (4) status epilepticus (nonconvulsive). RESULTS: There were 26 women between the ages of 60 and 91 and 32 men between the ages of 60 and 84. The main reasons for admission were diagnosis of events (57% of patients), followed by characterization and localization of events (36% of patients). There were 6 patients with psychogenic nonepileptic seizures (PNES); 5 were women and 4 of them were >70 years of age. All PNES patients presented with motor symptoms, except for an 87-year-old man who presented with abdominal spasm. Two of these six patients were suspected of having PNES before admission. Two patients were admitted with suspicion of status epilepticus, but neither proved to have status epilepticus. The most frequent diagnosis was physiologic nonepileptic seizures (26 patients; 45%), and 27% of these patients were on antiepileptic drugs, which were discontinued after the diagnosis of nonepileptic seizures. Complex partial seizure was the most frequent seizure type, occurring in 23 patients, 6 of whom (27%) had both complex partial seizures and secondarily generalized seizures. CONCLUSION: In the elderly, video/EEG results in a definitive diagnosis in the majority of cases and can assist in the decision whether antiepileptic drugs are necessary. PNES can occur in the elderly, and video/EEG monitoring can facilitate their recognition and management.     

Status epilepticus on the intensive care unit

Status epilepticus occurs on the intensive care unit, either because the patient has been transferred with refractory status epilepticus or as an incidental finding. Management of refractory status epilepticus on the intensive care unit is necessary for adequate treatment of the physiological compromise that occurs in convulsive status epilepticus. In addition, anaesthesia is sometimes necessary for the treatment of status epilepticus, and provided that the potential benefit of anaesthesia offsets the associated morbidity, then such an approach is warranted. In certain instances of nonconvulsive status epilepticus, especially in the elderly, the risks of anaesthesia outweigh the benefits of such aggressive treatment, and thus some caution must be exercised. Status epilepticus is also under-recognised as a cause of persistent coma on the intensive care unit, though the gain from aggressive treatment in this situation is unknown. In most instances, status epilepticus in coma carries such a poor prognosis that aggressive treatment is probably justified. Myoclonic status epilepticus also occurs on the intensive care unit, usually following cardiorespiratory arrest; this does not necessarily represent an agonal event especially if the intial insult was hypoxia related. Received: 11 November 2002, Accepted: 9 December 2002 Correspondence to M. C. Walker