Forms Of Nonconvulsive Status Epilepticus Research Articles

High-power, frontal-dominant ripples in absence status epilepticus during childhood

ObjectiveAbsence status epilepticus (ASE) is a form of non-convulsive status epilepticus characterized by ongoing or intermittent epileptic activity accompanied by behavioral and cognitive changes. Herein, we assessed high-frequency oscillations in the ripple band in patients with ASE and typical absence seizures. MethodsWe enrolled five patients with ASE, 26 patients with childhood absence epilepsy (CAE), and 15 patients with juvenile absence epilepsy (JAE). We performed time–frequency analysis of electroencephalogram data for ictal absence seizures at each electrode to assess the high frequency activity (HFA) rate, peak frequency, and peak power. ResultsThe average HFA rates were 60.7%, 20.8%, and 12.9% in ASE, CAE, and JAE patients, respectively. The average peak frequencies were 126.4 Hz, 120.9 Hz, and 126.1 Hz in ASE, CAE, and JAE patients, respectively. The average peak power values were 2,388.8 μV2, 120.9 μV2, and 126.1 μV2 in ASE, CAE, and JAE patients, respectively, and all epilepsy groups exhibited frontal-dominant ripple distribution. ConclusionASE patients presented higher power and frontal dominant ripples of absence seizure, compared to CAE and JAE patients. SignificanceFuture studies should utilize scalp-recorded ripples as a biomarker of absence epilepsy. This may aid in the development of novel treatment strategies for ASE.

Cyclic seizures in critically ill patients: Clinical correlates, DC recordings and outcomes

To describe EEG and clinical correlates, DC recordings and prognostic significance of cyclic seizures (CS). We reviewed our prospective continuous EEG database to identify patients with CS, controls with non-cyclic status epilepticus (SE) and controls without seizure matched for age and etiology. EEG was reviewed with DC settings. 39/260 (15%) patients with electrographic seizures presented with CS. These patients were older (62 vs. 54years; p=0.04) and more often had acute or progressive brain injury (77% vs. 52%; p=0.03) than patients with non-cyclic SE and had a lower level of consciousness, were more severely ill, than matched controls. CS almost always had focal onset, often from posterior regions. Patients with CS trended towards worse prognosis. When available (12 patients), DC recordings showed an infraslow cyclic oscillation of EEG baseline synchronized to the seizures in all cases. CS occur mostly in older patients with acute or progressive brain injury, are more likely to be associated with poor outcome than patients with other forms of nonconvulsive SE, and are accompanied by synchronous oscillations of the EEG baseline on DC recordings. CS are a common form of non-convulsive status epilepticus in critically ill patients and provide further insights into the relationship between infraslow activity and seizures; further study on this relationship may shed light on the mechanisms of seizure initiation and termination.

Non Convulsive Status Epilepticus: An Elusive Diagnosis

Absence status is the most common form of non-convulsive status epilepticus and is characterized by confusion with varying degrees of memory loss and cognitive impairment. Patients and Method: Three children were sent to neurological consultation due to behavioral alterations and a prolonged confused state; they were hospitalized and treated with sodium diphenylhydantoinate (DPH) IV at a dose of 10 mg/Kg. Results: The duration of symptoms varied from 6 months to 10 days. All three patients presented with global mental alterations, showing slowness in response and action. The electroencephalogram showed a pattern of slow, generalized stem and poly-stem-wavelengths of 3 - 4 Hz, which were registered for one hour. After the DPH bolus, the attack spontaneously ended in the 3 patients and upon examination all three presented with amnesia of the events occurring during the attack. In the follow-up, two of the patients did not experience further episodes and they showed normal scholastic achievement. The third patient however, after suffering a 6-month status epilepticus, failed the school year and finished his elementary education until the age of 15, experiencing similar difficulties with his secondary education. Discussion: Non-convulsive status epilepticus is more difficult to diagnose mainly because the manifestations are predominantly psychiatric and can be confused with other diseases or with an overdose of anti- convulsive drugs. A prolonged state of mental confusion, with no other explanation, should alert the attending physician to take an electroencephalogram in order to confirm the diagnosis. In our patients, DPH immediately controlled paroxysmal activity. We can therefore conclude that the problem is not in the treatment, but rather in making the correct diagnosis.

Epilepsy, cognition and behavior.

Epilepsy is defined as two or more unprovoked seizures. Epileptic patients have intellectual disability and behavioral co-morbidities to the tune of up to 25 and 75% respectively. Various factors like underlying etiology, socioeconomic environment at home, age at onset, seizure semiology, seizure descriptors like duration, severity and frequency, therapy related adverse effects secondary to antiepileptic drugs and epilepsy surgery have been implicated for the causation of cognitive and behavioral impairment in epilepsy. Cognitive epilepsy has emerged as a specific entity. This may manifest as a transient behavioral or cognitive change, insidous onset subacute to chronic encephalopathy or more catastrophic in the form of nonconvulsive status epilepticus. Cognitive impairment seen in epileptic children include difficulties in learning, memory, problem solving as well as concept formation. Anxiety, depression and attention deficit hyperkinetic disorders are the most common psychiatric co-morbidities seen. Investigating a child with epilepsy for cognitive and behavioral impairment is difficult as these tests would require cooperation from the patient's side to a significant extent. A rational approach towards treatment would be judicious selection of antiepileptic drugs, treatment of underlying cause, appropriate management of behavioral co-morbidities including psychopharmacotherapy and a trial of immunotherapy (particularly in cognitive epilepsies), wherever appropriate.

Non‐convulsive status epilepticus of frontal origin as the first manifestation of Hashimoto's encephalopathy

Hashimoto's encephalopathy is an often misdiagnosed, life threatening, condition which improves promptly with steroid therapy. Since clinical manifestations are heterogeneous and non-specific, the diagnosis is often difficult. Several case reports of Hashimoto's encephalopathy presenting with partial or generalised seizures are described, but only a few have focused on status epilepticus as the first clinical manifestation. We report two patients presenting with repetitive and prolonged seizures characterised by progressive reduction in contact and reactivity associated with frontal/diffuse polyspike-and-wave activities. This condition, which can be interpreted as a form of non-convulsive status epilepticus (NCSE) of frontal origin, was refractory to antiepileptic drugs but responded promptly to high doses of intravenous steroid treatment. In cases of unexplained encephalopathy with EEG documentation of NCSE, the early recognition and treatment of Hashimoto's encephalopathy may lead to a favourable prognosis. [Published with video sequences].

Rhythmic delta activity represents a form of nonconvulsive status epilepticus in anti-NMDA receptor antibody encephalitis

Anti-NMDA receptor antibody encephalitis is a limbic encephalitis with psychiatric manifestations, abnormal movements, coma, and seizures. The coma and abnormal movements are not typically attributed to seizure activity, and slow activity is the most common EEG finding. We report drug-resistant nonconvulsive status epilepticus as the basis for coma in a 19-year-old woman with anti-NMDA receptor antibodies and a mediastinal teratoma. The EEG showed generalized rhythmic delta activity, with evolution in morphology, frequency, and field typical of nonconvulsive status epilepticus. The status was refractory to antiepileptic drugs, repeated drug-induced coma, resection of the tumor, intravenous steroids, rituximab, and plasmapheresis. She awoke after the addition of felbamate, and the rhythmic delta activity ceased. The rhythmic delta activity described with coma in anti-NMDA receptor antibody encephalitis may represent a pattern of status epilepticus in some patients. Felbamate, which has NMDA receptor antagonist activity, should be studied as a therapeutic agent in this condition.

Absence status epilepticus in monozygotic twins with Jeavons syndrome

As a generalized form of nonconvulsive status epilepticus (NCSE), absence status epilepticus is the most common form. It manifests as prolonged, confusional states of varying severity, and continuous or repetitive generalized discharges of spikes, multiple spikes, and slow waves on EEG. Jeavons syndrome (JS) is a new type of epilepsy syndrome. Hitherto, only four sets of monozygotic twin with JS have been reported. Absence status epilepticus occurring in monozygotic twins with JS have not been reported. Here we report on monozygotic male twins of Chinese origin with JS. Both of them presented with status epilepticus with eyelid myoclonia and absences.

Is hypsarrhythmia a form of non-convulsive status epilepticus in infants?

Hypsarrhythmia is generally associated with infantile spasms, a combination referred to as West syndrome. It is debatable whether hypsarrhythmia is usefully regarded as a form of non-convulsive status epilepticus (NCSE). The earliest English language description of hypsarrhythmia reported an almost continuous EEG pattern, although later studies showed a degree of state dependence. Its principal features are very high amplitude and irregular slow waves with superimposed multifocal epileptiform discharges. Paroxysms of spasms are clearly overt seizure events, and there are variable EEG patterns associated with this ictus. There remains a debate about the definitional boundaries of hypsarrhythmia, and about the defining characteristics of NCSE. There is evidence that hypsarrhythmia is an age-dependent EEG pattern that evolves, sometimes independently of clinical features. Frequently, hypsarrhythmia is associated with delay in or regression of neuro-developmental skills, and recent studies have reported that a longer lead time to diagnosis and effective treatment is associated with poorer long-term neuro-developmental outcomes. Recent consensus definitions and classifications of NCSE have suggested boundaries that permit inclusion of hypsarrhythmia as an EEG pattern of NCSE. In practice, adopting the idea that hypsarrhythmia is a form of NCSE might lead to earlier appropriate investigation of infants with subtle developmental delay or regression, hence avoiding treatment delays and potentially preserving developmental potential.

Nonconvulsive Status Epilepticus and Neurodevelopmental Delay

Nonconvulsive status epilepticus is characterized by continuous or near continuous epileptiform discharges on electroencephalography without overt motor or sensory phenomena. It is a symptomatic condition related to a disease such as epileptic encephalopathy or a metabolic disorder. Children with isolated nonconvulsive status epilepticus rarely present with global neurodevelopmental delay. This report describes an 18-month-old male who presented with global neurodevelopmental delay and decreased alertness in whom electrical status epilepticus during sleep, which is a form of nonconvulsive status epilepticus, was determined. Metabolic investigations and cranial magnetic resonance imaging were normal. He began to achieve developmental milestones after treatment with valproic acid. Although rare, pediatric neurologists and pediatricians must be aware of this condition in making the differential diagnosis of global neurodevelopmental delay and decreased alertness.

Idiopathic Generalized Epilepsies: A Review and Modern Approach

Idiopathic Generalized Epilepsies: A Review and Modern Approach

Status Epilepticus in Idiopathic Generalized Epilepsy

Status epilepticus (SE) can take various forms in idiopathic generalized epilepsy (IGE), some of which forms also occur in symptomatic or focal epilepsies. Although the clinical semiology of the SE episodes may be similar in these different epilepsies, the frequency, response to treatment and prognosis differ. (a) Convulsive SE is surprisingly uncommon in IGE and much less common than in the secondarily generalized or partial epilepsies. Also, when it does occur, it usually responds rapidly to treatment. (b) Typical absence SE occurs only in patients with IGE (the subcategories with typical absence seizures) and also in the syndrome of de novo absence SE of late onset. This form of nonconvulsive SE should be differentiated from atypical absence SE, which occurs in the secondarily generalized epilepsy encephalopathies, and from complex partial SE which occurs in focal epilepsy. The clinical symptoms of these three types overlap but the prognosis and response to treatment are different. The mechanisms underlying absence SE are uncertain and may include both genetic and environmental factors. The termination of absence seizures has been hypothesized to be due to persistent activation of a depolarizing current in thalamocortical neurons that inactivates T-type calcium channels. SE could thus result from dysfunction of this channel or mechanisms that hyperpolarize thalamocortical neurons-these include decreased cortical inhibition, increased reticular thalamic neuronal activity or increased thalamocortical neuron GABA(B)-receptor activation. (c) Generalized electrographic SE is encountered in IGE in the syndrome of phantom absence with GTCS. It also occurs in ESES and in the Landau-Kleffner syndrome. The seizure phenomenology overlaps with the focal SE of temporal or frontal lobe epilepsy. (d) Myoclonic SE is also uncommon in IGE but occurs in juvenile myoclonic epilepsy. It is more commonly encountered in progressive myoclonic epilepsies, myoclonic-astatic epilepsy and in the Dravet syndrome. (e) Autonomic status occurs largely in the Panayiotopoulos syndrome. It is included here under the rubric of IGE, although the epilepsy has focal as well as generalized features and its nosological position is controversial. Fifty percent of seizures in this syndrome could be classified as status epilepticus. There is no doubt that convulsive SE can result in cerebral damage. In animal models of focal SE, nonconvulsive forms can also result in cerebral damage, but cerebral damage is not observed in animal models of absence SE. Similarly, cerebral damage seems not to occur in the forms of nonconvulsive SE in human IGE.

Diagnosis and Treatment of Nonconvulsive Status Epilepticus in an Intensive Care Unit Setting.

Nonconvulsive status epilepticus (NCSE) in adults is a heterogeneous epileptic emergency and includes absence status (AS), complex-partial status epilepticus (CPSE), and the status epilepticus of epileptic encephalopathy (SEEE). The latter seems to be strikingly frequent among patients in intensive care units (ICU). Diagnosis of NCSE is difficult, but has to be made quickly. It relies on clinical signs and a confirmation electroencephalography (EEG). According to the different etiologies and outcomes of AS, CPSE, and SEEE, treatment has to be individually adapted, but needs to follow some basic principles--treatment should take place in the ICU and be monitored by continuous EEG. With a few exceptions, the first drug is an intravenous benzodiazepine, mainly lorazepam. Intravenous fosphenytoin or phenytoin or valproate may follow next. If some forms of NCSE are resistant to first- and second-line treatments, single or combinations of anesthetics and enteral antiepileptic drugs (AEDs) may be added. This opinion is not evidence-based, and randomized controlled prospective trials to evaluate optimal treatment of NCSE are of first priority.

Status epilepticus: risk factors and complications.

Status epilepticus is common and associated with significant mortality and complications. It affects approximately 50 patients per 100,000 population annually and recurs in >13%. History of epilepsy is the strongest single risk factor for generalized convulsive status epilepticus. More than 15% of patients with epilepsy have at least one episode of status epilepticus and low antiepileptic drug levels are a potentially modifiable risk factor. Other risks include young age, genetic predisposition, and acquired brain insults. Fever is a very common risk in children, as is stroke in adults. Mortality rates are 15% to 20% in adults and 3% to 15% in children. Acute complications result from hyperthermia, pulmonary edema, cardiac arrhythmias, and cardiovascular collapse. Long-term complications include epilepsy (20% to 40%), encephalopathy (6% to 15%), and focal neurologic deficits (9% to 11%). Neuronal injury leading to temporal lobe epilepsy is probably mediated by excess excitation via activation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors and consequent elevated intracellular calcium that causes acute necrosis and delayed apoptotic cell death. Some forms of nonconvulsive status epilepticus may also lead to neuronal injury by this mechanism, but others may not. Based on clinical and experimental observations, complex partial status epilepticus is more likely to result in neuronal injury similar to generalized convulsive status epilepticus. Absence status epilepticus is much less likely to result in neuronal injury, and complications because it may be mediated primarily through excess inhibition. Future research strategies to prevent complications of status epilepticus include the study of new drugs (including NMDA antagonists, new drug delivery systems, and drug combinations) to stop seizure activity and prevent acute and delayed neuronal injury that leads to the development of epilepsy.