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.     

Characteristic phasic evolution of convulsive seizure in PCDH19‐related epilepsy

PCDH19‐related epilepsy is a genetic disorder that was first described in 1971, then referred to as “epilepsy and mental retardation limited to females”. PCDH19 has recently been identified as the responsible gene, but a detailed characterization of the seizure manifestation based on video‐EEG recording is still limited. The purpose of this study was to elucidate features of the seizure semiology in children with PCDH19‐related epilepsy. To do this, ictal video‐EEG recordings of 26 convulsive seizures in three girls with PCDH19‐related epilepsy were analysed. All seizures occurred in clusters, mainly during sleep accompanied by fever. The motor manifestations consisted of six sequential phases: “jerk”, “reactive”, “mild tonic”, “fluttering”, “mild clonic”, and “postictal”. Some phases were brief or lacking in some seizures, whereas others were long or pronounced. In the reactive phase, the patients looked fearful or startled with sudden jerks and turned over reactively. The tonic and clonic components were less intense compared with those of typical tonic‐clonic seizures in other types of epilepsy. The fluttering phase was characterised initially by asymmetric, less rhythmic, and less synchronous tremulous movement and was then followed by the subtle clonic phase. Subtle oral automatism was observed in the postictal phase. The reactive, mild tonic, fluttering and mild clonic phases were most characteristic of seizures of PCDH19‐related epilepsy. Ictal EEG started bilaterally and was symmetric in some patients but asymmetric in others. It showed asymmetric rhythmic discharges in some seizures at later phases. The electroclinical pattern of the phasic evolution of convulsive seizure suggests a focal onset seizure with secondary generalisation. Based on our findings, we propose that the six unique sequential phases in convulsive seizures suggest the diagnosis of PCDH19‐related epilepsy when occurring in clusters with or without high fever in girls. [Published with video sequences online]     

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.     

Outcome of electroclinical, electrographic, and clinical seizures in the newborn infant

Three seizure types have been described in the neonate: electroclinical, electrographic, and clinical only. Controversy still exists about whether the episodic abnormal movements seen in some infants, which are not accompanied by simultaneous ictal discharges on the EEG, are true seizures. Twenty-four infants with seizures were studied, 17 had purely electrographic and/or electroclinical seizures, seven had clinical-only seizures; six of these seven had clonic seizures, without facial manifestations or autonomic change. The three seizure types were investigated using video-EEG and a Griffiths neurodevelopmental assessment was performed in each seizure group. Of the seven infants with clinical-only seizures, six had clonic seizures with a normal background EEG, neuroimaging studies and neurodevelopmental follow-up assessment were normal in five. In the remaining 17 infants with electrographic and/or electroclinical seizures, seizure discharges were often associated with ocular phenomena, apnoea, or tonic posturing, and the background EEG was abnormal in all but one subject. Neurodevelopmental follow-up assessments revealed a poor outcome (14 of 17) in this group. In otherwise healthy infants, purely clonic seizures involving only the limbs may be a benign phenomenon and an EEG should be obtained to avoid unnecessary treatment. Infants with seizures superimposed on an abnormal background EEG pattern had a poor outcome.     

A progressive sequence of electroencephalographic changes during generalized convulsive status epilepticus

Review of 60 electroencephalograms recorded during episodes of generalized convulsive status epilepticus suggested that there are 5 identifiable EEG patterns which occur in a predictable sequence during the course of generalized convulsive status epilepticus in man: (1) discrete seizures; (2) merging seizures with waxing and waning amplitude and frequency of EEG rhythms; (3) continuous ictal activity; (4) continuous ictal activity punctuated by low voltage 'flat periods'; and (5) periodic epileptiform discharges on a 'flat' background. We confirmed our hypothesis that this sequence represents the natural history of electroencephalographic changes in untreated generalized convulsive status epilepticus by observing the same sequence in the EEGs of rats in which status epilepticus had been induced by 3 different methods: (1) systemic administration of kainic acid, (2) injection of homocysteine thiolactone to cobalt-lesioned rats; and (3) injection of lithium chloride followed 24 h later by injection of pilocarpine.     

Électroencéphalographie dans les états de mal épileptiques : glossaire, protocole et interprétation

Electroencephalography is a useful tool in the diagnosis and management of status epilepticus (SE) and it can also give prognostic information. It can help to confirm that an episode of SE has ended. It can identify the patients who have unsuspected subclinical seizures. There is a wide range of presentations of SE. Nearly all types of seizures have the potential of occurring in a repeated or continuous form. The polymorphic EEG patterns in SE reflect this wide variety. But controversial patterns also exist in the form of periodic epileptiform discharges. While some authors considered these patterns to be interictal or postictal, others postulate that these patterns are ictal. In these cases, clinical features are very important in order to conclude. Generalized convulsive SE is a medical emergency and the EEG is not necessary to make a diagnosis. Convulsive generalized SE requires immediate treatment and in this case, EEG is used in guiding treatment especially in refractory SE that may evolve into subtle SE. In non-convulsive SE, diagnosis is not obvious on the basis of clinical signs and symptoms alone and the diagnosis must be confirmed by urgent EEG. EEG can also be used to distinguish SE from psychogenic seizures, movement disorders and in patients who have causes of persistent loss of consciousness (metabolic encephalopathy, postanoxic encephalopathy). This article proposes a protocol for the use of the EEG in SE, guidelines and simple vocabulary for a good interpretation and comprehension of the EEG.     

Epilepsy-induced behavioral changes during the ictal phase

In epilepsy, experiential phenomena and behavioral manifestations may pose a number of problems in terms of differential diagnosis. From a clinical point of view, ictal psychiatric symptoms represent partial seizures, mainly partial ones. In the majority of cases, they are very brief (lasting from a few seconds to a few minutes), stereotyped, out of context, and frequently associated with subtle or overt automatisms and postictal confusion of variable duration. In some cases, such symptoms are followed by alteration of consciousness as the ictus evolves to a complex partial seizure or a generalized tonic–clonic seizure. This paper reviews clinically relevant behavioral patterns during seizures discussing clinical phenomenology and relevance in terms of lateralizing value.This article is part of a Special Issue entitled Epilepsy and Consciousness.     

Clinical and EEG features of status epilepticus in comatose patients.

We retrospectively evaluated the clinical and EEG features of status epilepticus (SE) in 47 comatose adult patients in whom SE was suspected clinically or because the EEG revealed repetitive electrographic seizures or continuous spike-and-wave activity. Three groups of patients were identified. Group-1 patients (n = 33) had SE both clinically and on EEG. They usually had subtle, clonic movements restricted to the eyes, face, and upper extremities, and the EEG most commonly showed repetitive electrographic seizures or continuous spike-and-wave activity. Group-2 patients (n = 9) also had subtle motor manifestations of seizures, but the EEG was not that of SE, consisting of either irregular slowing with frequent spikes and sharp waves, an irregular mixed-frequency background with episodic accentuation, or diffuse slowing; one patient also had an intermittent burst-suppression pattern. The five patients in Group 3 lacked any clinical signs of seizures, but the EEG showed repetitive electrographic seizures or continuous spike-and-wave activity. There were no significant differences between groups in etiology of SE, response to therapy, or outcome, and there was no obvious relationship between the EEG findings and duration of SE. We conclude that recognition of SE in comatose patients may require both clinical and EEG evaluation since either approach by itself may fail to establish the diagnosis. Furthermore, the EEG findings in established SE do not necessarily progress through the series of defined stages suggested by some authors.     

Subclinical focal seizures as a sign of progression in gliomas

Background. Subclinical seizures are ictal electrographic discharges lacking signs of clinical seizures, behavioural alteration or subjective symptoms. The diagnosis and detection of this type of non‐convulsive seizures remain challenging, and information is scarce regarding this electroclinical picture in subjects with gliomas. The aim of this report is to describe two patients with gliomas who, after treatment with surgery and radiotherapy, exhibited subclinical seizures on video‐EEG monitoring, as a manifestation of recurrence or progression of their brain tumour. Methods. Case report and video‐EEG monitoring analysis. Results. Two patients with gliomas were admitted to our neurosurgical unit after a generalized tonic‐clonic seizure. Brain MRI revealed a recurrence of their tumour. The use of video‐EEG monitoring allowed the detection and characterization of subclinical seizures in both patients that otherwise would have gone undetected. In both cases, subclinical seizures arose from the frontal lobe and were not associated with motor manifestations or subjective symptoms. Conclusions. We emphasize that the existence of subclinical seizures in patients with gliomas is likely to be underestimated, and can occur in advanced progressive tumours. It is important to carry out continuous video‐EEG monitoring in brain tumour patients who have had recent clinical seizures in order to be able to detect subclinical seizures and make appropriate diagnosis.     

Characterization and classification of neonatal seizures

To characterize and classify neonatal seizures, we studied 349 neonates, using a portable, cribside EEG/polygraphic/video monitoring system. We recorded 415 clinical seizures in 71 infants; 11 other infants had electrical seizure activity without clinical accompaniments. Each seizure was analyzed in terms of its clinical character and its relationship to the presence of EEG seizure activity. Focal clonic seizures, some forms of myoclonic seizures, and focal tonic seizures were consistently associated with electrical seizure activity. Most "subtle" seizures, all generalized tonic seizures, and some forms of myoclonic seizures were either not associated with EEG seizure activity or had an inconsistent relationship with such activity. Seizures that were consistently and coherently related to focal EEG seizure activity had a high correlation with focal brain lesions and a favorable short-term outcome. Seizures with no relationship or an inconsistent relationship to EEG seizure activity were correlated with diffuse processes such as hypoxic-ischemic encephalopathy and a poor short-term outcome. The clinical and background EEG features of infants whose seizures were not accompanied by EEG seizure activity suggest that these seizures may not be epileptic in character.     

难治性癫痫持续状态患者的脑电图特征

目的 探究难治性癫痫持续状态(RSE)患者的脑电图(EEG)特征.方法 将60例全面惊厥性癫痫持续状态(GCSE)患者根据抗癫痫药物(AEDs)疗效分为RSE和非难治性癫痫持续状态(NRSE),比较两组患者EEG模式的差异.结果 所有患者中,与NRSE组比较,RSE组患者发作期EEG呈持续性放电比例更高,差异具有统计学意义(OR=5.44,95%CI=1.24~23.96,P=0.04).50例EGG呈间歇性演变的患者中,与NRSE组比较,RSE组患者发作间歇期EEG呈周期性放电与痫样放电的比例较高,差异有统计学意义(OR=29.75,4.12;95%CI=3.19~277.32,1.09~15.58;P<0.05);而RSE组患者发作后EEG为正常模式的比例较低,差异具有统计学意义(OR=0.11,95%CI=0.01~0.91,P=0.04).结论 GCSE患者如EEG出现持续性放电、周期性放电、发作间期痫样放电,应引起临床的高度重视,给以强化抗惊厥治疗.     

Convulsive seizures in rats induced by N-methyl-D-aspartate injection into the massa intermedia.

The behavioral and electroencephalographic effects of N-methyl-D-aspartate (NMDA, 25 nmol/1 microliter) injection into the massa intermedia (MI) was examined in rats. The injection caused violent running/jumping and shrill vocalization without evidence of EEG seizure in the hippocampus (HP) and amygdala (AM). Animals with the injection site located in the reuniens nucleus subsequently developed generalized tonic and then clonic seizure, leading to fatal status epilepticus in some animals. Intermittent or continuous EEG discharge in the limbic system was found during clonic seizures. These findings suggest that the NMDA receptor in the reuniens nucleus in the MI participates in the generation and expression of convulsive seizure in rats.     

Clinical and electrophysiological characteristics of startle epilepsy in childhood

ObjectiveStartle epilepsy is one syndrome of reflex epilepsies. We studied its clinical and EEG characteristics.MethodsAnalysis of the clinical and EEG characteristics of startle epilepsy.ResultsOf 11 patients, five were female. Age of onset ranged from 5 months to 7.5 years. Abnormal etiologies were found in seven patients, as a result of perinatal and postnatal factors. Neuroimaging showed abnormalities, commonly focal atrophy, in nine patients. Spontaneous seizures preceded or followed the startle seizures and were present in all patients. Startle seizures experienced included tonic, myoclonic, tonic–myoclonic, tonic–atypical absence, asymmetric tonic motor seizure and tonic–clonic seizure. Diffuse electrodecremental pattern was the most common ictal EEG pattern seen. The triggering stimuli of the startle seizures were sound in seven patients, touch in three and both sound and touch in one. Interictal EEG revealed abnormalities in 10 patients including generalized, multifocal or focal discharges. Many different anti-epileptic drugs were often unsatisfactory.ConclusionStartle epilepsies were often symptomatic reflex epilepsies and there were several types of startle seizure. The ictal EEG often showed a diffuse electrodecremental pattern. This disease has a bad prognosis.SignificanceWe delineated the clinical and EEG characteristics of startle epilepsy in childhood.     

Treatment of seizure emergencies: convulsive and non-convulsive status epilepticus

Status epilepticus (SE), defined as recurrent epileptic seizures without complete recovery between seizures, is one of the most serious manifestations of epilepsy. Generalized convulsive status epilepticus (GCSE) is the most common and most life-threatening form of SE, and aging increases the mortality risk. In a recent study of treatment of GCSE, 226 of 518 evaluable patients (43.6%) were of age 65 or older. In the 157 elderly patients with overt GCSE, phenobarbital was successful as first-line treatment in 71.4%, lorazepam in 63%, diazepam and phenytoin in 53.3%, and phenytoin alone in 41.5%. Phenobarbital and lorazepam were more successful than phenytoin alone. In the 69 elderly patients with subtle GCSE, success as the first treatment was 30.8% for phenobarbital, 14.3% for lorazepam, 11.8% for phenytoin, and 7.7% for diazepam and phenytoin. Overall, the results were similar to those reported for the entire study. Lorazepam, because of ease of use, is probably the best drug for the initial treatment of overt GCSE in the elderly; phenobarbital may be the best drug for subtle GCSE in this group, but more data are needed. The term "nonconvulsive SE" has been used to include complex partial SE and absence SE - both of which present as an "epileptic twilight state" - and SE in comatose patients. The diagnosis can be challenging, particularly in the elderly, as overlapping clinical features and electroencephalogram patterns can be seen in SE and in a variety of encephalopathic conditions. There is a suggestion that aggressive treatment of elderly patients with nonconvulsive SE may worsen prognosis. Clearly, there is a need for more data to better understand management of elderly patients with both convulsive and nonconvulsive SE.     

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.     

Confirmation of nonconvulsive limbic status epilepticus with the sodium amytal test

Summary: Is it a seizure? This question can be difficult for a clinician to answer, and it may be more critical if the possible seizure lasts >30 min. Long‐duration questionable seizure activity changes the question to, “Is it status epilepticus?” Status epilepticus (SE) can be divided into convulsive and nonconvulsive types. Convulsive SE is the most easily recognized, whereas nonconvulsive SE is more clinically variable and controversial. The term nonconvulsive SE is more often applied to patients who are severely obtunded or comatose with minimal or no motor movements, or in a stupor of altered consciousness reflecting generalized ictal activity. Nonconvulsive SE also can be caused by focal seizure activity, sometimes restricted to deep small volumes of brain in which scalp EEG may not be diagnostic. We present the case of a patient who had dominant limbic hippocampal SE, but in whom the diagnosis could not be confirmed until a modified novel use of the sodium amytal test was performed.     

Epileptiform EEG activities of the centromedian thalamic nuclei in patients with intractable partial motor, complex partial, and generalized seizures

Centromedian thalamic nuclei (CM) epileptiform EEG activities were recorded in patients with intractable partial motor, complex partial, and generalized seizures through implanted recording-stimulating electrodes, used for seizure control. CM epileptiform activities showed either little or no correlation to focal surface cortical and amygdaloid activities in patients with partial motor and complex partial seizures: CM paroxysmal discharges were correlated to focal epileptiform ictal activities only during the contraversive movements of partial motor and complex partial seizures. In contrast, CM epileptiform activities were consistently correlated to widespread surface cortical activities and clinical symptoms of fully developed nonconvulsive and convulsive tonic-clonic generalized seizures; i.e., unilateral CM double spike-wave complex discharges significantly preceded (p less than 0.001) the contralateral CM and bilateral surface cortical discharges and symptoms of nonconvulsive generalized seizures. Unilateral CM fast-slow-fast paroxysmal discharges significantly preceded (p less than 0.005) those of the contralateral CM and bilateral surface cortical regions and symptoms of the convulsive tonic-clonic generalized seizures. Individual spike-wave complexes from the frontal region preceded (p less than 0.001 and p less than 0.005) those at CM and other cortical regions during the nonconvulsive and clonic generalized attacks. No correlations between CM and cortical epileptiform activities were found, however, in the case of abortive, subclinical thalamocortical EEG discharges.     

Semiological Seizure Classification*

Summary: We propose an epileptic seizure classification based exclusively on ictal semiology. In this semiological seizure classification (SSC), seizures are classified as follows: a. Auras are ictal manifestations having sensory, psychosensory, and experiential symptoms. b. Autonomic seizures are seizures in which the main ictal manifestations are objectively documented autonomic alterations. c. “Dialeptic” seizures have as their main ictal manifestations an alteration of consciousness that is independent of ictal EEG manifestations. The new term “dialeptic” seizure has been coined to differentiate this concept from absence seizures (dialeptic seizures with a generalized ictal EEG) and complex partial seizures (dialeptic seizures with a focal ictal EEG). d. Motor seizures are characterized mainly by motor symptoms and are subclassified as simple or complex. Simple motor seizures are characterized by simple, unnatural movements that can be elicited by electrical stimulation of the primary and supplementary motor area (myoclonic, tonic, clonic and tonic-clonic, versive). Complex motor seizures are characterized by complex motor movements that resemble natural movements but that occur in an inappropriate setting (“automatisms”). e. Special seizures include seizures characterized by “negative” features (atonic, astatic, hypomotor, akinetic, and aphasic seizures). The SSC identifies in detail the somatotopic distribution of the ictal semiology as well as the seizure evolution. The advantages of a pure SSC, as opposed to the current classification of the International League Against Epilepsy (ILAE), which is actually a classification of electroclinical syndromes, are discussed.     

Frontal lobe epilepsy

About one-quarter of patients with refractory focal epilepsies have frontal lobe epilepsy (FLE). The typical seizure semiology for FLE includes unilateral clonic, tonic asymmetric or hypermotor seizures. Interictal electroencephalograms (EEG) usually reveal interictal epileptiform discharges and rhythmical midline theta, which has localizing value. The usefulness of ictal EEG recordings is limited by frequent muscle artifacts in motor seizures and because a large portion of the frontal lobe cortex is “hidden” to scalp electrodes. Ictal single photon emission CT and positron emission tomography are able to localize FLE in about one-third of patients only. A pre-surgical evaluation should include, whenever possible, a subclassification of FLE as dorsolateral frontal, mesial frontal or basal frontal lobe epilepsy to allow a minimal cortical resection. A review of the typical findings of seizure semiology, interictal and ictal EEG regarding the different FLE subtypes is given. Etiology, medical treatment and surgery are also discussed.