Types Of Nonconvulsive Status Epilepticus Research Articles

Aphasic status epilepticus in a tertiary referral center in Turkey: Clinical features, etiology, and outcome

ObjectiveAphasic status epilepticus (ASE), although rare, may often remain underdiagnosed. We aimed to report the patients diagnosed with ASE and describe their clinical presentation, etiology, electrophysiological findings, neuroimaging, treatment options, and outcome. MethodsWe retrospectively analyzed a series of 28 patients diagnosed with ASE between January 2010 and August 2019 in our tertiary referral center. We reviewed medical files, patient charts, and short- and long-term intermittent electroencephalogram (EEG) recordings. Demographical, historical, clinical, neuroimaging, electrophysiological parameters, administered antiseizure medications, and prognosis of all patients were recorded. Furthermore, EEGs were re-evaluated according to Salzburg criteria. ResultsMost patients presented with tumors (n = 11) and cerebrovascular disease (CVD) (n = 11), while the rest were diagnosed with hyperglycemia (n = 2), autoimmune encephalitis (n = 1), remote intracranial abscess (n = 1), mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) attack (n = 1), or unknown cause (n = 1). Seventy-one percent of patients had prior history of epilepsy. The most common EEG findings were rhythmic delta activity with fluctuation and epileptiform discharges ≤ 2.5 Hz with spatiotemporal evolution (66 %). Magnetic resonance imaging (MRI) and EEG findings indicated dominant hemisphere involvement in all patients. No casualties occurred; 71 % patients exhibited total recovery, while 29 % had mild-moderate sequela aphasia. None of the patients received aggressive treatment for ASE. SignificanceA relatively higher number of ASE patients could be contributed to the literature through this study. ASE should be considered in patients with prolonged unexplained aphasia, especially with pre-existing risk factors, such as prior history of epilepsy, structural lesion, and metabolic disorders accompanied by concordant EEG findings. Although the underlying cause is a determining prognostic factor, this study shows a significant number of patients with complete remission; thus, the prognosis of ASE may be considered more favorable than other types of nonconvulsive status epilepticus.

Unified EEG terminology and criteria for nonconvulsive status epilepticus

The diagnosis of nonconvulsive status epilepticus (NCSE) relies largely on electroencephalography (EEG) findings. The lack of a unified EEG terminology, and of evidence-based EEG criteria, leads to varying criteria for and ability to diagnose NCSE. We propose a unified terminology and classification system for NCSE, using, as a template, the Standardised Computer-based Organised Reporting of EEG (SCORE). This approach integrates the terminology recently proposed for the rhythmic and periodic patterns in critically ill patients, the electroclinical classification of NCSE (type of NCSE) and the context for the pathologic conditions and age-related epilepsy syndromes. We propose flexible EEG criteria that employ the SCORE system to assemble a database for determining evidence-based EEG criteria for NCSE.

The neurophysiologic types of nonconvulsive status epilepticus:EEGpatterns of different phenotypes

Proceeding from the proposed classification of status epilepticus syndromes by Shorvon in 1994, we performed a systematic search for reports presenting electroencephalography (EEG) patterns of nonconvulsive status epilepticus (NCSE) on all syndromes in the classification, where possible. Using the online medical search engine PubMed for 22 different search strategies, EEG patterns supporting a diagnosis of NCSE were sought. From a total of 4,328 search results, 123 cases with corresponding EEG patterns could be allocated to underlying epilepsy syndromes. Based on the characteristic EEG patterns found for the different NCSE syndromes, we present a synthesis of the significant EEG morphologies and evolutions in the individual NCSE syndromes.

Absence status seen in an adult patient

Absence status epilepticus (ASE) is a type of nonconvulsive status epilepticus in which continuous or recurrent generalized epileptiform discharges are associated with a varying grade of consciousness impairment. Absence status epilepticus may be obtained during progress of many epileptic syndromes, in several metabolic disturbances and related to use of several drugs. Absence status epilepticus is generally seen in childhood; rarely it can be seen in adulthood. In this paper, the case which has never diagnosed until now in spite of many absence seizures for years, applied for absence seizures to our clinic and diagnosed for juvenile absence epilepsy, has been discussed.

Electroencephalographic criteria for nonconvulsive status epilepticus: Synopsis and comprehensive survey

There have been many attempts at defining the electroencephalography (EEG) characteristics of nonconvulsive status epilepticus (NCSE) without a universally accepted definition. This lack of consensus arises because the EEG expression of NCSE does not exist in isolation, but reflects status epilepticus under the variety of pathologic conditions that occur with age, cerebral development, encephalopathy, and epilepsy syndrome. Current NCSE definitions include "boundary conditions," in which electroencephalographic seizure activity occurs without apparent clinical seizures. Furthermore, what appears to one interpreter as status epilepticus, is not to another reader, reflecting the "art" of EEG interpretation. Seizures and epilepsy syndromes have undergone an evolution that has moved beyond a classification of focal or generalized conditions into a syndromic approach. It seems appropriate to make similar changes in the EEG analysis of the syndromes of NCSE. In effect, the literature on epilepsy classification has progressed to incorporate the different NCSE types with clinical descriptions, but the specific EEG evidence for these types is found largely in individual reports, and often by description only. NCSE classification of EEG patterns should derive from the aggregate of published EEG patterns in the respective clinical subtype, supported by an analysis of these EEG studies. The analysis that follows presents clinical descriptions and EEG patterns of NCSE in the neonatal period, infancy, childhood, adulthood, and late adulthood from a syndromic perspective based on age, encephalopathy, cerebral development, etiology, and syndrome. Proceeding from the proposed classification of status epilepticus syndromes in "Status epilepticus: its clinical features and treatment in children and adults" (published in 1994 by Cambridge University Press, New York), we have performed a systematic search for reports presenting EEG patterns of NCSE using the online medical search engine PubMed for 22 different search strategies. EEG patterns were reviewed by two board-certified epileptologists who reached consensus regarding presence of NCSE. From a total of 4,328 search results, 123 cases with corresponding EEG patterns could be allocated to underlying epilepsy syndromes. Typical characteristic, prominent electrographic patterns, and sequential arrangements are elucidated for the different NCSE syndromes. This compendium of patterns by NCSE syndrome classification with illustration of EEGs, and delineation of electroencephalographic features helps define the characteristics and semiologic borderlines among the types of NCSE.

Cyclic hyperammoniemic encephalopathy and epileptiform triphasic waves: problems in differential diagnosis with nonconvulsive status epilepticus, reply

Dear Editor, We thank Primavera and Audenino for their interest in our case report [1, 2]; in fact, they raise three intriguing issues which deserve some comments. First, we agree with them that our patient experienced one episode of non-convulsive status epilepticus (NCSE); however, this should not be viewed as an alternative diagnosis with respect to metabolic encephalopathy, as Primavera and Audenino seem to imply. In fact, both phenomena may be present in the same patient, especially in case of hepatic encephalopathy [3], with NCSE representing one of its more severe manifestations [4]. Increased ammonia levels may reduce the critical activity threshold in brain, triggering abnormal electric bursts, and possibly resulting in a SE. Consistently, a large spectrum of EEG patterns may be observed in these cases, including TWs with epileptiform characteristics, as Primavera and Audenino wisely remark as a second point in their letter. Thus, we proceeded exactly in the direction suggested by these authors, extensively searching for factors responsible for mental status impairment, and identifying it in a rapidly cycling hyperammoniemic state due to the previous procedure of ureterosigmoidostomy, performed several years before. These are the reasons why we proposed a causal diagnosis of hyatrogenic hyperammoniemic encephalopathy as the solution to this quiz case, whose clinical expression, during the period of hospitalization, cycled from a minimal encephalopathy, to a progressive depression of consciousness, to a full NCSE. Still, a differential diagnosis between these two entities remains of value, especially when thinking to therapeutic options, as Primavera and Audenino correctly raise as their last comment. A causal therapy of the underlying condition may be sufficient for metabolic encephalopathy per se; additional symptomatic treatment is mandatory when metabolic encephalopathy is complicated by SE. Benzodiazepine administration, such as lorazepam, is a well-established firstline therapy, but our patient did not respond to it. For subsequent steps, there are many reasonable options, including intravenous phenytoin, valproate, midazolam, propofol, and barbiturates. Choice depends also on the type of NCSE which includes complex partial (or focal) SE, absence SE, and SE in comatose patients [5]. In particular, treatment algorithms for NCSE in a comatose patient with potentially good prognosis, as it was our case, suggest either IV phenytoin or valproate [6]. Valproate is usually preferred, due to its superior tolerability and ease of use. However, the hyperammoniemic state of our patient represented a contraindication to valproate, given the possibility that this drug might further worsen her metabolic derangement, even in the presence of normal liver-associated enzymes [7, 8]. Thus, we resorted to IV phenytoin, with ECG and blood pressure monitoring, which proved to be safe and effective.

DOOR syndrome concomitant with non-convulsive status epilepticus and hyperintense cerebellar cortex on T2-weighted imaging

We report a case study of an 11-year-old Japanese boy with complex partial status epilepticus, a type of non-convulsive status epilepticus, concomitant with DOOR syndrome. To our knowledge, this is the first report of this type of epilepsy concomitant with DOOR syndrome. Magnetic resonance (MR) imaging showed diffuse atrophy of the cerebellar cortex. The cerebellar cortex was hyperintense on T2-weighted imaging. This finding of MR imaging is rare and has been considered pathognomonic for infantile neuroaxonal dystrophy and Marinesco–Sjogren syndrome which are in the entity of metabolic disease. So this lesion may be the result of a metabolic defect occurring in conjunction with DOOR syndrome.

Non-convulsive status epilepticus in adults - an overview

Status epilepticus (SE) is the most frequent neurological emergency requiring admission on the intensive care unit (ICU). The classification of status epilepticus may be dichotomised into the and the form. Whereas the diagnosis of generalised convulsive status epilepticus (GCSE) is easily made in view of the evident manifestation, the diagnosis of non-convulsive status epilepticus (NCSE) may become very difficult according to its non-spectacular and protean presentation. Non-convulsive status epilepticus is a common cause of altered mental status and delirium; and a substantial number of comatose patients in the intensive care unit may suffer from NCSE. The most important part of making a diagnosis of NCSE is to think of it at all. The definite diagnosis of NCSE is dependent on electroencephalographic (EEG) confirmation. Repetitive or, optimally, continuous EEG recording may help to closely monitor seizure activity and to guide the therapy in order to protect the patient from under- and/or over-treatment. The interpretation of EEG recordings of NCSE may become challenging because of numerous artifacts caused by the patient, caregivers and devices, and because of trace elements of ambiguous significance and of waveforms mimicking epileptic activity. Non-convulsive status epilepticus was historically subdivided into the groups of complex-partial status epilepticus (focal; CPSE) and absence status (generalised; AS). Most recently, a classification proposed by the International League Against Epilepsy (ILAE) has subdivided focal NCSE into aura continua (non-convulsive simple partial with maintained consciousness) and into dys-cognitive (with impaired consciousness) of mesial temporal or neocortical origin. Several patients with focal NCSE or AS were known for pre-existing epilepsy. In addition, other types of NCSE have been reported, like subtle where convulsions in patients with GCSE clinically stop, but the continuous epileptic activity electroencephalographically still persists. Another variant belongs to those patients with critical illness where the serious disorder and/or medications may trigger an acute, prolonged and all too often very-hard-to-treat epileptic condition (critical illness SE [CISE]). The majority of these patients will never have had seizures before. Of note, none of the currently proposed classifications has gained broad acceptance and official approval. Since the need for immediate and intensive treatment of GCSE is beyond debate, the insidiously calm presentation of NCSE may mislead to a much less aggressive therapeutic approach. However, experimental and clinical data suggest that continuous epileptic activity in the brain during NCSE associated with consecutive (glutamatergic) hyperexcitation triggers neurotoxicity and proapoptotic mechanisms which eventually may lead to irreversible brain damage and the onset of a chronic epileptic disorder or to an irreversible neurological deficit. Thus, recent national and international guidelines and reviews recommend immediate and intensive treatment for NCSE as well as for GCSE. With a few exceptions, the first drug is an intravenous benzodiazepine, mainly lorazepam; intravenous phenytoin or valproate should be started without delay. Persistence of NCSE after administration of these two classes of drugs heralds refractory (RSE) where single or combinations of drugs in anaesthetic dosages requiring intubation and enteral antiepileptics may be added except for the cases of AS or an underlying terminal disease. The outcome of NCSE is mainly determined by the type, duration, cause and the severity of concomitant diseases.

Diagnosis and treatment of nonconvulsive status epilepticus.

Nonconvulsive status epilepticus (SE) is not uncommon and comprises at least one-third of all cases of SE. However, nonconvulsive SE consists of very different syndromes, a common feature being the difficulty in making the diagnosis. In this review, nonconvulsive SE is divided into typical absence SE, complex partial SE, nonconvulsive SE in patients with learning difficulties (including electrical SE during sleep, atypical absence SE and tonic SE), and nonconvulsive SE in coma. These conditions have different prognoses and treatments. The diagnosis of these conditions is critically dependent on EEG. When the EEG demonstrates typical ictal patterns, the diagnosis is usually straightforward. However, in many circumstances the EEG has to be differentiated from encephalopathic patterns, and this differentiation can prove troublesome, although the clinical and electrographic response to treatment can prove helpful. Nonconvulsive SE in patients with learning difficulties possibly provides the greatest diagnostic difficulty; the clinical presentation can be subtle resulting in the diagnosis being frequently missed. Whether the neuronal damage that occurs in convulsive SE and in animal models of limbic SE also occurs in nonconvulsive SE in humans is still a matter of debate. There are critical differences between the animal models and the human condition. Indeed, the prognosis of nonconvulsive SE is usually dependent on the underlying aetiology rather than the persistence of electrographic discharges. Because of these doubts, a more conservative approach to the treatment of particular types of nonconvulsive SE (those with a better prognosis) has been taken in this article. Thus, in most instances, oral benzodiazepines for the treatment of typical absence SE and complex partial SE are recommended. In some circumstances intravenous medication is necessary, but in neither condition is anaesthetic coma recommended. This contrasts with nonconvulsive SE in coma in which a more aggressive approach is suggested. Until there are more relevant animal models, and controlled trials of conservative versus more aggressive treatment, treatment regimens for nonconvulsive SE will remain largely speculative.

Prognosis in nonconvulsive status epilepticus

ABSTRACT Determining the prognosis in nonconvulsive status epilepticus (NCSE) is complicated by several factors: under‐recognition of NCSE with its spontaneous resolution (thus decreasing the “denominator” of total cases that will have a poor outcome); incorrect diagnosis of NCSE based on misinterpretation of EEG “epileptiform” activity; mis‐classification of certain EEG patterns as NCSE ( e.g. PLEDs; triphasic waves); and grouping of different populations that have markedly different co‐morbidities (ambulatory patients with NCSE together with comatose patients with electrographic seizure activity on EEG). There are almost no prospective studies with premorbid neuropsychometric studies, and retrospective studies typically include isolated cases, or case series that include conditions in which the cause of NCSE itself causes cognitive morbidity. To summarize available data, absence status (ambulatory generalized non‐convulsive status epilepticus) would appear to carry no lasting morbidity. Complex partial status epilepticus in ambulatory patients rarely results in measurable permanent neurologic deficit, although rarely, short or longstanding deficits may clearly occur. Because intensive treatment with intravenous anticonvulsants ( e.g. benzodiazepines or phenytoin) can confer morbidity, the equation has not yet been made as to whether the morbidity of such intensive treatment for all cases of NCSE exceeds the morbidity of the disease itself. Larger, prospective studies will be needed to truly determine the prognosis in the different types of NCSE, stratified according to associated degrees of impairment (minimally impaired, moderately obtunded, comatose).

Nonconvulsive status epilepticus with continuous diffuse spike-and-wave discharges during sleep in childhood.

On three epileptic conditions with common characteristics of almost continuous diffuse spike-and-wave discharges during sleep in EEG, clinical and electroencephalographic studies were undertaken to elucidate their pathophysiologies and interrelationships; namely on five cases of epilepsy with electrical status epilepticus during slow sleep (ESES), seven cases of a peculiar type of nonconvulsive status epilepticus in childhood (PNSE) and three cases of atypical benign partial epilepsy (ABPE). The dominant seizure types were absences and/or GTC in ESES, whereas they were focal motor seizures in PNSE and ABPE with more focalized epileptic discharges on EEGs than those in ESES. All the three conditions showed both features of generalized and partial epilepsies, although the former features were more prominent in ESES and the latter in PNSE and ABPE.