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.     

Chronic bilateral stimulation of the anterior thalamus of kainate-treated rats increases seizure frequency

PURPOSE: Electrical stimulation of the anterior nucleus of the thalamus (ANT) is receiving increased attention as a novel means of controlling intractable epilepsy, and has entered human clinical trial. Animal data supporting the anticonvulsant benefit of ANT stimulation, however, has been obtained from acute chemoconvulsant models of epilepsy rather than models of chronic epilepsy with spontaneous seizures. It is unknown whether ANT stimulation is effective in models of chronic epilepsy. METHODS: Bilateral ANT stimulation was evaluated in rats with chronic epilepsy following acute status epilepticus (SE) produced by systemic kainic acid (KA) administration. The evolution of epilepsy following KA SE and the effects of ANT stimulation were monitored by continuous video-EEG. RESULTS: Following KA SE, most rats have 2-8 seizures per day, and the average seizure rate increases over time, doubling over the course of 14 weeks. Behavioral seizure severity, after the initial development of epilepsy, remains stable. Seizure frequency during ANT stimulation was 2.5 times the baseline seizure frequency. In some cases stimulation triggered seizures were observed. The effects of stimulation were specific to the ANT. Stimulation applied to electrodes placed outside the ANT did not significantly worsen seizure frequency. CONCLUSIONS: ANT stimulation exacerbated seizure frequency in rats with chronic epilepsy following kainate status epilepticus.     

Classification of seizures and epilepsy

The management of seizures and epilepsy begins with forming a differential diagnosis, making the diagnosis, and then classifying seizure type and epileptic syndrome. Classification guides treatment, including ancillary testing, management, prognosis, and if needed, selection of the appropriate antiepileptic drug (AED). Many AEDs are available, and certain seizure types or epilepsy syndromes respond to specific AEDs. The identification of the genetics, molecular basis, and pathophysiologic mechanisms of epilepsy has resulted from classification of specific epileptic syndromes. The classification system used by the International League Against Epilepsy is periodically revised. The proposed revision changes the classification emphasis from the anatomic origin of seizures (focal vs generalized) to seizure semiology (ie, the signs or clinical manifestations). Modified systems have been developed for specific circumstances (eg, neonatal seizures, infantile seizures, status epilepticus, and epilepsy surgery). This article reviews seizure and epilepsy classification, emphasizing new data.     

Pediatric status epilepticus: a perspective from Saudi Arabia

The purpose of this study was to assess risk factors and management of status epilepticus and non–status epilepticus seizures at a community hospital in Saudi Arabia. The research design was a prevalence study of a convenience sample of pediatric seizure episodes admitted to a 350-bed hospital from 1992 to 1997. The mean age at presentation was 2 years, 10 months, 43% of patients had no history of seizures, and 17% were transferred from other hospitals. Fifty-nine (28%) of 212 seizure episodes were status epilepticus (SE). These SE episodes were significantly more likely than non–SE episodes to be associated with a history of seizures, prior antiepileptic drug (AED) therapy, the presence of an acute etiology, and prolonged duration of seizures before hospitalization. SE episodes were also significantly more likely than non–SE episodes to receive an inappropriate AED, to require intensive care unit admission, to suffer morbidity, and to have SE recurrence at follow-up; however, the difference in mortality was not significant. In conclusion, children with SE were more likely than those with non–SE seizures to have a history of seizures and acute brain insults, prolonged seizure duration before hospitalization, and less optimal management and outcomes. Management of SE in this referral population can be improved by more rapid access to appropriate medical care.     

EpiNet study of incidence of status epilepticus in Auckland,New Zealand: Methods and preliminary results

The EpiNet project has been commenced to facilitate investigator‐led collaborative research in epilepsy. A new Web‐based data collection tool has been developed within EpiNet to record comprehensive data regarding status epilepticus and has been used for a study of status epilepticus in Auckland, New Zealand. All patients aged >4 weeks who presented to any of the five public hospitals and the major private hospital within Auckland city (population = 1.61 million) with an episode of status epilepticus between April 6, 2015 and April 5, 2016 were identified using multiple overlapping sources of information. For this study, status epilepticus was defined as any seizure exceeding 10 minutes in duration, or repeated seizures lasting >10 minutes without recovery between seizures. Patients who had either convulsive or nonconvulsive status epilepticus were included. Episodes of status epilepticus were classified according to the 2015 International League Against Epilepsy ILAE status epilepticus classification. A total of 477 episodes in 367 patients were considered as definite or probable status epilepticus; 285 episodes (62%) lasted >30 minutes, which is the duration that has previously been used for epidemiological studies of status epilepticus.     

Electroclinical Features and Evolution of Grand mal Seizures in Infancy

Abstract: Seizures belonging to primary generalized epilepsy seem to be rare in infancy. Absence seizures are virtually non-existent, although atypical absence is infrequently observed. Most of the apparently generalized tonic-clonic seizures seem to be secondarily generalized partial seizures with initial subtle complex seizure manifestations characterized by motion arrest, staring or blank eyes. Among the generalized motor seizures in the first year, an extremely benign type of epilepsy exists, in which seizures stop before 3 years of age with normal psychomotor development. It is characterized by cryptogenic etiology, normal development before the onset, no neurological abnormality, no evolution into other types of seizures, a normal EEG course and no episodes of status epilepticus. However, it was difficult to differentiate this group from those developing normally but continuing to have seizures beyond 3 years.     

Successful outcome of episodes of status epilepticus after vagus nerve stimulation: a multicenter study

Background and purpose: Vagus nerve stimulation (VNS) has been reported to be a safe and effective treatment for drug-resistant epilepsy. The aim of this study is to describe the effect of VNS in patients with a history of repeated episodes of status epilepticus (SE) before implantation. Methods: From a total of 83 adult patients with drug-resistant epilepsy who had VNS implanted in four tertiary centers in Spain between 2000 and 2010, eight had a previous history of repeated episodes of SE. We performed a retrospective observational study analyzing the outcome of seizures and episodes of SE after implantation. Stimulation was started at the usual settings, and intensity increased according to clinical response and tolerability. Results: Regarding the eight patients with a history of SE, the mean age at time of VNS implantation was 25.1 [14-40] years. Duration of epilepsy until the implantation was 21.7 [7-39.5] years, and they had been treated with a mean of 12 antiepileptic drugs [10-16]. Mean follow-up since implantation was 4.15 [2-7.5] years. Average seizure frequency decreased from 46 to 8.2 per month. Interestingly, four of the eight patients remained free of new episodes of SE after implantation, and in two additional patients, the frequency decreased by >75%. Adverse effects were mild or moderate in intensity and included mainly coughing and dysphonia. Conclusion: In those patients with refractory epilepsy and history of SE who are not surgical candidates, VNS is a safe and effective method to reduce seizure frequency and episodes of SE.     

Autonomic seizures and autonomic status epilepticus peculiar to childhood: diagnosis and management

Autonomic seizures and autonomic status epilepticus in children have a high prevalence, manifest with dramatic clinical symptoms, and have important clinical and management implications. They probably affect approximately 13% of children aged 3-6 years with one or more nonfebrile seizures, or 6% in the age group 1-15. The primary cause is an idiopathic age-dependent epileptogenic susceptibility (Panayiotopoulos syndrome), but 10-20% are due to cerebral pathology. Autonomic seizures and autonomic status epilepticus have been best studied in Panayiotopoulos syndrome, which has been confirmed worldwide in more than 800 cases and recently recognized in the new classification scheme of the International League Against Epilepsy. Seizures start with autonomic symptoms, mainly emesis, while the child is usually fully conscious. Other more conventional seizure manifestations often ensue, but autonomic manifestations commonly predominate to the end of the seizure. Ictal syncope (transient loss of consciousness and postural tone) is an intriguing common symptom. Half of the seizures last longer than 30 minutes, constituting autonomic status epilepticus. Prognosis is invariably excellent except for the symptomatic cases. The interictal EEG shows great variability from normal to severely epileptogenic, often with multifocal spikes. Pathophysiology of Panayiotopoulos syndrome is unknown, but it is likely that they are due to diffuse maturation-related epileptogenicity activating susceptible-for-children emetic centers and the hypothalamus. Thus, Panayiotopoulos syndrome is not occipital epilepsy, with which it is often erroneously equated. Autonomic seizures and autonomic status epilepticus are frequently misdiagnosed and often treated as encephalitis, atypical migraine, cardiogenic syncope, or other unrelated medical conditions such as gastroenteritis. This review examines the existing evidence, provides a means of improving diagnostic yield, and proposes practice parameters and guidelines for the diagnosis and management of autonomic seizures and autonomic status epilepticus in children.     

Status epilepticus in stroke: report on a hospital-based stroke cohort

OBJECTIVE: To evaluate occurrence rate, clinical data, and prognostic factors of status epilepticus (SE) after stroke. METHODS: From 1984 to 1994, 3,205 patients were admitted to the Department of Neurology at our institution with first-time strokes. A total of 159 of these patients had first-time poststroke seizures. Among these 159 patients, cases of SE were identified and evaluated. RESULTS: SE was recognized in 31 patients (19%). In 17 patients, SE was the first epileptic symptom (initial SE), and in 4 patients, stroke began with SE (S-SE). In the 14 remaining patients, SE occurred after one or more seizure(s). After a mean follow-up period of 47 months, neurologic deterioration occurred after SE in 15 patients. This deterioration was permanent in two patients. Fifteen patients died; in five patients, death was directly related to SE. Eight of the 17 patients with initial SE and all 14 patients with SE after one or more seizure(s) developed other seizures or SE. S-SE, however, was not a predictive factor for additional seizure(s). CONCLUSIONS: Status epilepticus is common among patients with poststroke seizures. Although the immediate prognosis of patients with status epilepticus is poor, status epilepticus as the presenting sign did not necessarily predict subsequent epilepsy.     

Convulsive Status Epilepticus in Children

Summary: Status epilepticus (SE) occurs most commonly in infancy and childhood. Children with prior neurological abnormalities are most susceptible. More than 90% of cases are convulsive and the majority are generalized. SE may occur in the setting of an acute illness, in patients with established epilepsy or as a first unprovoked seizure. The etiology can be classified as idiopathic, remote symptomatic, febrile, acute symptomatic, or associated with a progressive encephalopathy. The morbidity and mortality of status have dramatically declined in recent years. Overall mortality in recent pediatric series was 3–10%, with almost all fatalities associated with acute central nervous system insults or progressive neurologic disorders. Neurological sequelae in children with idiopathic or febrile status are rare. Neurologically normal children with SE as their first unprovoked seizure have the same risk of experiencing subsequent seizures of any type as children who present with a brief first seizure. The risk of recurrent episodes of convulsive SE approaches 50% in neurologically abnormal children but is very low in neurologically normal children. The favorable outcome of SE in children may be related to advances in therapy and to the resistance of the immature brain to damage from seizures.     

Seizures in the intrahippocampal kainic acid epilepsy model: characterization using long‐term video‐EEG monitoring in the rat

Objective – Intrahippocampal injection of kainic acid (KA) in rats evokes a status epilepticus (SE) and leads to spontaneous seizures. However to date, precise electroencephalographic (EEG) and clinical characterization of spontaneous seizures in this epilepsy model using long‐term video‐EEG monitoring has not been performed. Materials and Methods – Rats were implanted with bipolar hippocampal depth electrodes and a cannula for the injection of KA (0.4 μg/0.2 μl) in the right hippocampus. Video‐EEG monitoring was used to determine habitual parameters of spontaneous seizures such as seizure frequency, severity, progression and day–night rhythms. Results – Spontaneous seizures were detected in all rats with 13 out of 15 animals displaying seizures during the first eight weeks after SE. A considerable fraction (35%) of the spontaneous seizures did not generalize secondarily. Seizure frequency was quite variable and the majority of the KA‐treated animals had less than one seizure per day. A circadian rhythm was observed in all rats that showed sufficient seizures per day. Conclusions – This study shows that the characteristics of spontaneous seizures in the intrahippocampal KA model display many similarities to other SE models and human temporal lobe epilepsy.     

Cyclicity of spontaneous recurrent seizures in pilocarpine model of temporal lobe epilepsy in rat

Pilocarpine administration to rats results in status epilepticus (SE) and after a latency period to the occurrence of spontaneous seizures. The model is commonly used to investigate mechanisms of epileptogenesis as well as the antiepileptic effects of novel compounds. Surprisingly, there have been no video-EEG studies determining the duration of latency period from SE to the appearance of the first spontaneous seizures or the type and frequency of spontaneous seizures at early phase of pilocarpine-induced epilepsy even though such information is critical for design of such studies. To address these questions, we induced SE with pilocarpine in 29 adult male Wistar rats with cortical electrodes. Rats were continuously video-EEG monitored during SE and up to 23 days thereafter. The first spontaneous seizures occurred 7.2+/-3.6 days after SE. During the follow-up, the mean daily seizure frequency was 2.6+/-1.9, the mean seizure duration 47+/-7 s, and the mean behavioral seizure score 3.2+/-0.9. Typically first seizures were partial (score 1-2). Interestingly, spontaneous seizures occurred in clusters with cyclicity, peaking every 5 to 8 days. These data show that in the pilocarpine model of temporal lobe epilepsy the latency period is short. Because many of the early seizures are partial and the seizures occur in clusters, the true phenotype of epilepsy triggered by pilocarpine-induced SE may be difficult to characterize without continuous long-term video-EEG monitoring. Finally, our data suggest that the model can be used for studies aiming at identifying the mechanisms of seizure clustering.     

Status epilepticus in the course of epilepsy in children and adolescents

Status epilepticus (SP) is defined as a single seizure or recurrent seizures of over 30 min. duration, without regaining full consciousness. In approximately 50% of cases SE is related to epilepsy. The International League Against Epilepsy has recently proposed a new SE classification (2001). The purpose of this prospective study is to evaluate SE incidence in children and adolescents in relation to their age and type of epilepsy, as well as to determine usefulness of the new classification of SE. A group of 600 children and adolescents with epilepsy was observed prospectively. The inclusion criteria were: recently diagnosed epilepsy in children aged under 15 years, and long-term treatment and observations (mean = 5 years, SD = 3.2). Out of the 600 children and adolescents with epilepsy 39 (6.1%) had one or more episodes during the observation period. Two factors were correlated with SE: age at the onset of epilepsy (under 5 years), and the type of epileptic syndrome (the Lennox-Gastaut syndrome, myoclonic-astatic epilepsy, symptomatic and cryptogenic partial epilepsy, progressive myoclonic epilepsy, and the Kojevnikov syndrome). Only in a fourth of the patients the cause of SP was related to a known factor, such as e.g. infection or sudden discontinuation of anti-epileptic medication. The currently used classification of SP (by Appelton and Gibbs) was found to be more useful than the one newly proposed by ILAE, because the former is better suited to the evaluation of SE in children.     

Status epilepticus and seizures induced by iopamidol myelography.

PURPOSE: To report that iopamidol myelography can induce status epilepticus (SE) in patients carrying the diagnosis of symptomatic epilepsy and to estimate the incidence of seizures in patients undergoing iopamidol myelography. METHODS: We retrospectively identified all patients with seizures/SE associated with 1350 iopamidol myelographies during the last 5 years at our institution. The impact of cervical versus lumbar myelography was analysed. RESULTS: Induced by iopamidol myelography two non-epileptic patients suffered from first generalised tonic-clonic seizures and a 67-year-old women with symptomatic epilepsy after a remote ischemic stroke developed a generalised tonic-clonic seizure evolving into a dialeptic and right nystagmus SE (i.e. complex focal status) of 5-hour duration. The incidence of seizures in non-epileptic patients was 0.15%. The incidence of seizure induction for lumbar myelography was lower than for myelographies that included the cervical subarachnoid space. CONCLUSIONS: Iopamidol myelography (especially if cervical) is associated with a risk of seizures in non-epileptic individuals and can induce SE in patients with epilepsy. Patients should be informed about the risk of seizure induction.     

Nonconvulsive status epilepticus precipitated by carbamazepine presenting as dissociative and affective disorders in adolescents

Nonconvulsive status epilepticus can be confused with psychiatric disorders. Inappropriate drug treatment can represent a precipitating factor. We describe two patients with idiopathic generalized epilepsy in whom nonconvulsive status epilepticus, aggravated by carbamazepine, was misdiagnosed as psychiatric disorder. A 14-year-old girl experienced a tonic-clonic seizure at age 12 years preceded by monthly episodes of confusion with awkward behavior since age 9 years. She was treated with carbamazepine, and the episodes of confusion became more frequent, leading to a diagnosis of dissociative disorder. An electroencephalogram during one of these episodes revealed nonconvulsive status epilepticus. Substitution of carbamazepine with valproic acid controlled the episodes of status epilepticus. A 23-year-old woman presented at age 16 years with a tonic-clonic seizure. Since early adolescence, she had had episodes of depressive mood, worsening of school performances, and facial tics. Carbamazepine treatment caused worsening of the depressive episodes and facial tics. An electroencephalogram during a typical episode revealed nonconvulsive status epilepticus. Carbamazepine substitution with valproate led to seizure freedom and behavioral improvement. Nonconvulsive status epilepticus should be suspected and searched for in patients with epileptic seizures and ictal or fluctuating behavioral disorders.     

États de mal épileptiques : épidémiologie, définitions et classifications

The annual incidence of status epilepticus based on the definitions of the International League Against Epilepsy (1993) ranges from 10.3 to 41 per 100,000 inhabitant. Half of the cases of status epilepticus concern epileptic patients. In all studies, incidence is higher in epileptic patients, young children and the elderly. It is estimated that 13% of patients with status epilepticus will experience recurrence during the two first years. The three leading etiologies are low-dose antiepileptic drugs, non-acute brain lesions and acute stroke. Seizures are generalized in 9 to 33% of patients and focal in 25 to 75%. Secondary generalized seizures can be observed in 19 to 66% of patients. Mortality ranges from 7.6 to 39% and varies as a function of inclusion of postanoxic encephalopathies and difference in initial care. The definition retained and the classification adopted for status epilepticus also affect mortality estimates. Status epilepticus is defined as the existence of a prolonged seizure or a series of seizures during which the patient does not recover, or incompletely recovers, consciousness. The duration parameter used to distinguish status epilepticus from a seizure remains controversial. At the present time, there is general agreement in the literature distinguishing two definitions based on different durations according to the clinical type of status epilepticus and its potential severity: (i) a status epilepticus is defined by a seizure lasting more than 30 minutes or recurrent seizures without recovery of consciousness over a period of 30 minutes; (ii) considering its severity, tonic-clonic status epilepticus has a specific definition leading to earlier therapeutic management. This operational definition is continuous, generalized, convulsive seizure lasting more than five minutes or two or more seizures during which the patient does not return to baseline consciousness. Several types of background can be used to establish a classification for status epilepticus: clinical manifestations, prognostic and therapeutic course, epidemiological data, pathophysiological mechanisms… At the present time, the classifications most commonly used in France for status epilepticus are derived from the syndromic epileptic classification, the seizure classification or the classification proposed by the French consensus workshop on status epilepticus. For routine clinical practice, an operational classification can be used to adopt therapeutic strategies adapted to probable prognosis: short-term life-threatening, mid-term life-threatening, not life-threatening.     

ECT in the treatment of status epilepticus

INTRODUCTION: Owing to its potent anticonvulsant actions, electroconvulsive therapy (ECT) has been proposed as an intervention for treatment-resistant seizure disorders. METHOD: We review the literature on the use of ECT in treatment-resistant epilepsy and status epilepticus (SE) and present a case of a patient who was in nonconvulsive SE for 26 days and then treated with ECT after all standard pharmacological strategies were exhausted. Because of skull defects, a novel electrode placement was used. RESULTS: Owing to massively elevated seizure threshold attributable to concomitant anticonvulsant medications, extraordinarily high electrical dosage was needed for ECT to elicit generalized seizures. Status was terminated after three successful ECT-induced seizures. However, the long-term functional outcome of the patient was poor. DISCUSSION: The role of ECT in the treatment algorithm for SE is discussed.     

Clinical and EEG analysis of initial status epilepticus during infancy in patients with mesial temporal lobe epilepsy

This study investigated the clinical and EEG characteristics of initial status epilepticus (SE) during infancy in patients with mesial temporal lobe epilepsy (MTLE). The subjects were six patients who had been brought to our emergency clinic and treated for their initial SE between 1977 and 1988, and later developed MTLE. We reviewed the medical records and laboratory findings at the time of the initial SE, and the clinical evolution up to the development of MTLE. The six patients included four females and two males. The initial SE developed at ages ranging from 7 months to 2 years and 9 months with a mean of 1 year and 2 months. These episodes were characterized by an elevated temperature of more than 38 degrees C (4/6 cases), clusters of prolonged seizures during one episode of SE (4/6 cases), long-lasting SE (120-380 min, mean 227 min, 6/6 cases), postictal prolonged loss of consciousness (median 5 h, 6/6 cases), and the presence of Todd's paralysis (3/6 cases). The lateralization of the ictal or postictal EEGs of the SE in five of the six cases was identical to that of the hippocampal atrophy later confirmed by MRI. Follow-up EEG examinations at a 6 month interval demonstrated temporal spike discharges appearing only after the onset of complex partial seizures. Two patients, who had no fever at the initial SE, were characterized by a very early appearance of epileptic EEG abnormality and a short interval between the initial SE and the development of complex partial seizures, suggesting that the SE was the first epileptic manifestation. The result of this study showed that SE progressing to MTLE tends to have complicated clinical manifestations characterized by clusters of unilateral or generalized SE followed by prolonged postictal unconsciousness, generalized clinical manifestations despite lateralized ictal EEG discharges, and the Todd's paresis in addition to the prolonged seizure duration.     

Epileptic prodromal manifestations and episodic affective symptoms: nonspecific complaints or non-convulsive status epilepticus?

Subjective unspecific complaints presage in some patients with epilepsy a following overt epileptic seizure. It has to be considered whether these epileptic prodromal states are simple partial seizures (epileptic aura) or a status epilepticus non convulsivus. Three patients with epilepsy of different classification and etiology were studied. Their interictally occurring unspezific complaints, the clinical examination and EEG with simultaneous videorecording were documented. In these three cases the results led to the conclusion that the epileptic prodromal states were the expression of a status epilepticus non convulsivus. The management and possible therapeutic intervention are discussed.