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

Paediatric epilepsy and cognition

Cognitive comorbidities are more frequent in children with epilepsy than in the general population. The cognitive function of children with epilepsy should be appropriately screened, and when there is an impairment, it must be diagnosed and managed. Several factors contribute to the occurrence of this comorbidity. The underlying aetiology and epilepsy syndrome are the major risk factors. Other factors also play a role, such as seizure recurrence, antiseizure medication, and interictal abnormalities. Recent evidence also suggested that cognitive involvement is an ongoing process that interacts with the normal maturation of cognitive function in children with epilepsy. Furthermore, some patients experience rapid cognitive deterioration related to epileptic activity, resulting in epileptic encephalopathy. Further research is needed to better understand how to prevent or modify factors that affect cognitive function in children with epilepsy. WHAT THIS PAPER ADDS: Cognitive comorbidities are more frequent in children with epilepsy than in the general population. The risk factors for cognitive impairment are the underlying aetiology/syndrome, seizure recurrence, antiseizure medication, and interictal abnormalities. Advanced genetic and neuroimaging studies are useful tools to better understand cognitive impairment in children with epilepsy.

Interrater and Intrarater Agreement of Epileptic Encephalopathy Among Electroencephalographers for Children with Infantile Spasms Using the Burden of Amplitudes and Epileptiform Discharges (BASED) EEG Grading Scale: Study Design and Statistical Considerations

Background

Infantile spasms are a serious epilepsy syndrome with a poor prognosis. Electroencephalography (EEG) has been a key component in the prognosis and treatment of infantile spasms. This multi-center study protocol is developed to investigate interrater and intrarater agreement of an electroencephalographic grading scale—the Burden of Amplitudes and Epileptiform Discharges (BASED) score among electroencephalographers.

Methods

Thirty children, aged 0–2 years, with infantile spasms who were hospitalized in the Chinese PLA General Hospital will be recruited into this study by stratified sampling. Seven electroencephalographers from different Class A tertiary hospitals will select a 5-min epoch with the most severe epileptiform discharge, score the EEG reports, and provide the basis for the scoring. The 420 (30 × 7 × 2) scoring results provided by electroencephalographers in two rounds can be analyzed statistically using weighted kappa (weighted \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\kappa$$\end{document}κ) statstic, Fless’ kappa (Fless’ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\kappa$$\end{document}κ) statistic, and intraclass correlation coefficient (ICC) to calculate the interrater and intrarater agreement.

Discussion

We will recruit more electroencephalographers than were included in previous studies to assess the interrater and intrarater agreement in the selection of 5-min EEG epochs, the BASED scores, and the basis for scoring. If the BASED score has an adequate interrater and intrarater agreement, the score will have more significance for guiding the clinical management and for predicting the prognosis of patients with infantile spasms.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00382-4.

Novel UBE3A pathogenic variant in a large Georgian family produces non-convulsive status epilepticus responsive to ketogenic diet

PURPOSE

To report the effect of the ketogenic diet (KD) on non-convulsive status epilepticus (NCSE) due to Angelman syndrome (AS) in two members of a large Georgian family affected by a novel frameshift variant in the UBE3A gene (NM_000462.3).

METHODS

We evaluated two members of this family who were affected with clinical and EEG features of AS. Clinical history with special emphasis on development, seizure type, frequency, and treatment was reviewed. Routine and long-term video EEG monitoring were conducted, particularly during NCSE. A non-fasting inpatient KD protocol was implemented using blended food orally with full administration of 4:1 (fat to non-fat) ratio. Urine ketone bodies (KBs), measured with urine ketone acetone strips readings, reached 150 mg/dL in both patients.

RESULTS

Patients had characteristic signs of AS and presented with epilepsy between the age of 2-4 years. As methylation tests were negative, next generation sequencing disclosed a c.2365del variant. For both, NCSE was revealed by cognitive deterioration and did not respond to anti-seizure medication. As recommended, IV pyridoxine, benzodiazepines, and valproic acid were administered, but without success. For both patients, NCSE resolved on the second-third day of KD initiation, before the appearance of ketonuria and resulting in improved communication, mood and sleep.

CONCLUSION

KD is safe and effective for the treatment of NCSE due to AS. Resolution before the appearance of ketone bodies points to a possible mechanism of action of KD.

Hypsarrhythmia is associated with widespread, asymmetric cerebral hypermetabolism

PURPOSE

Hypsarrhythmia is the interictal EEG pattern most often associated with infantile spasms. We set out to evaluate the metabolic impact of hypsarrhythmia among patients with infantile spasms by contrasting regional cerebral metabolic activity among children with and without hypsarrhythmia.

METHODS

Patients with video-EEG confirmed infantile spasms who underwent simultaneous interictal EEG and FDG-PET as part of a surgical evaluation were retrospectively identified. Pons-normalized relative cerebral metabolic activity (RCA) was ascertained in 18 cortical and 6 subcortical pre-specified regions of interest (ROIs).

RESULTS

We identified 63 patients with infantile spasms who underwent simultaneous EEG/PET, including children with hypsarrhythmia (n = 9), high-voltage EEG background (n = 20), and multifocal independent spike discharges (MISD) (n = 34). Among them, a putative epileptogenic zone was identified within the left-hemisphere only (n = 27), right-hemisphere only (n = 20), or assumed to be bilateral (n = 16). After adjustment for age at PET, the presence of hypsarrhythmia was associated with hypermetabolism in 11 of 18 cortical ROI's. After adjustment for lateralized epileptogenic zones, the association between hypsarrhythmia and hypermetabolism was generally stronger within the left hemisphere.

CONCLUSION

Hypsarrhythmia is associated with widespread-and curiously left more than right-elevations in pons-normalized RCA, which is not evident on routine clinical review of individual PET studies. This study suggests that hypsarrhythmia may be a quasi-ictal phenomenon based on widespread and usually bilateral cortical hypermetabolism.

Hypsarrhythmia in epileptic spasms: Synchrony in chaos

PURPOSE

Hypsarrhythmia is an electroencephalographic pattern associated with epileptic spasms and West syndrome. West syndrome is a devastating epileptic encephalopathy, originating in infancy. Hypsarrhythmia has been deemed to be the interictal brain activity, while the electrodecremental event associated with the spasms is denoted as the ictal event. Though characterized as chaotic, asynchronous and disorganized based on visual inspection of the EEG, little is known of the dynamics of hypsarrhythmia and how it impacts the developmental arrest of these infants.

METHODS

As an exploratory and feasibility study, we explored the dynamics of both hypsarrhythmia and electrodecremental events with EEG phase synchronization methods, and in a convenience sample of three outpatients with epileptic spasms. As ictal events are associated with prolonged phase synchronization, we hypothesized that if hypsarrhythmia was indeed the interictal brain activity that it would have lower phase synchronization than the electrodecremental event (ictal phase).

RESULTS

We calculated both the phase synchronization index and the temporal variability of the index in three patients with infantile spasms. Two patients had hypsarrhythmia and electrodecremental events and one had hemi-hypsarrhythmia. We found that the hypsarrhythmia pattern was a more synchronized state than the electrodecremental event.

CONCLUSIONS

We have observed that the hypsarrhythmia pattern may represent a more synchronized state than the electrodecremental event in infants with epileptic spasms. However, larger studies are needed to replicate and validate these findings. Additionally, further inquiry is required to determine the impact that increased synchronization may have on developmental outcomes in infants with epileptic spasms.

Randomized, Single-Blind, Parallel Clinical Trial on Efficacy of Oral Prednisolone Versus Intramuscular Corticotropin: A 12-Month Assessment of Spasm Control in West Syndrome

OBJECTIVE

We earlier completed a single-blind, parallel-group, randomized clinical trial to test the null hypothesis that adrenocorticotropic hormone (ACTH) is not superior to high-dose prednisolone for short-term control of West syndrome. We now present long-term follow-up data for spasm control for individuals who completed this earlier trial.

METHODS

Infants with untreated West syndrome were randomized to receive 14 days of prednisolone (40 to 60 mg/day) or intramuscular long-acting ACTH (40 to 60 IU every other day). They were evaluated at three, six, and 12 months to evaluate long-term spasm control.

RESULTS

The total number of infants treated was 97 (48 prednisolone; 49 ACTH). All completed the treatment course. Eighty-five, 82, and 76 children were available for follow-up at three, six, and 12 months. The number lost to follow-up at each interval was not statistically different. Likelihood of spasm freedom at three months was significantly higher for prednisolone (64.6%) than for ACTH (38.8%) (P = 0.01; odds ratio = 2.9; 95% confidence interval = 1.3 to 6.6). At six months (P = 0.19) and twelve months (P = 0.13), the control of spasms was not statistically different, although a trend in favor of prednisolone was documented at both of these time points (58.3% versus 44.9% for ACTH at six months and 56.2% versus 40.8% with ACTH at 12 months). After initial remission by day 14 (n = 46), the likelihood of a relapse within the next 12 months was not statistically different between the two treatment groups (P = 0.1).

CONCLUSIONS

Control of spasms at three months was significantly better if initially treated with prednisolone. Control of spasms at six and 12 months was not significantly different despite a trend favoring prednisolone. Risk of relapse following initial remission was similar in the two groups.

Epileptic activity is a surrogate for an underlying etiology and stopping the activity has a limited impact on developmental outcome

The concept of epileptic encephalopathy is important in clinical practice, but its relevance to an individual must be assessed in the appropriate context. Except in rare situations, epileptic activity is a surrogate for an underlying etiology, and stopping the activity has a limited impact on developmental outcome. Labeling a group of epilepsies as "the epileptic encephalopathies," risks minimizing the impact of epileptic activity on cognition and behavior more widely in epilepsy. Similarly, describing the encephalopathy associated with many infantile onset epilepsies as "epileptic" may be misleading. Finally, concentrating on the epileptic activity alone and not considering the wider consequences of the underlying etiology on cognitive and behavioral development, may focus research efforts and the search for improved therapies on too narrow a target. Therefore, epileptic encephalopathies should not be considered as a specific group of epilepsies but, rather, the concept of epileptic encephalopathy should be applicable to all types of epilepsies and epilepsy syndromes, whenever it is relevant in the clinical course of a particular individual, at any age.

Infantile spasms syndrome, West syndrome and related phenotypes: what we know in 2013

The current spectrum of disorders associated to clinical spasms with onset in infancy is wider than previously thought; accordingly, its terminology has changed. Nowadays, the term Infantile spasms syndrome (ISs) defines an epileptic syndrome occurring in children younger than 1 year (rarely older than 2 years), with clinical (epileptic: i.e., associated to an epileptiform EEG) spasms usually occurring in clusters whose most characteristic EEG finding is hypsarrhythmia [the spasms are often associated with developmental arrest or regression]. The term West syndrome (WS) refers to a form (a subset) of ISs, characterised by the combination of clustered spasms and hypsarrhythmia on an EEG and delayed brain development or regression [currently, it is no longer required that delayed development occur before the onset of spasms]. Less usually, spasms may occur singly rather than in clusters [infantile spasms single-spasm variant (ISSV)], hypsarrhythmia can be (incidentally) recorded without any evidence of clinical spasms [hypsarrhythmia without infantile spasms (HWIS)] or typical clinical spasms may manifest in absence of hypsarrhythmia [infantile spasms without hypsarrhythmia (ISW)]. There is a growing evidence that ISs and related phenotypes may result, besides from acquired events, from disturbances in key genetic pathways of brain development: specifically, in the gene regulatory network of GABAergic forebrain dorsal-ventral development, and abnormalities in molecules expressed at the synapse. Children with these genetic associations also have phenotypes beyond epilepsy, including dysmorphic features, autism, movement disorders and systemic malformations. The prognosis depends on: (a) the cause, which gives origin to the attacks (the complex malformation forms being more severe); (b) the EEG pattern(s); (c) the appearance of seizures prior to the spasms; and (d) the rapid response to treatment. Currently, the first-line treatment includes the adrenocorticotropic hormone ACTH and vigabatrin. In the near future the gold standard could be the development of new therapies that target specific pathways of pathogenesis. In this article we review the past and growing number of clinical, genetic, molecular and therapeutic discoveries on this expanding topic.

The efficacy of moderate-to-high dose oral prednisolone versus low-to-moderate dose intramuscular corticotropin for improvement of hypsarrhythmia in West syndrome: a randomized, single-blind, parallel clinical trial

BACKGROUND

The role of therapy on improvement of hypsarrhythmia has not been systematically assessed. This study was performed to assess the efficacy of oral prednisolone and intramuscular adrenocorticotrophin hormone in improving hypsarrhythmia in West syndrome.

METHOD

Children (2 months-2 years), with previously untreated West syndrome, were randomized to receive 40-60 IU every other day of intramuscular adrenocorticotrophin hormone or 40-60 mg/day of oral prednisolone for 14 days. Children with tuberous sclerosis were excluded. Improvement of hypsarrhythmia was assessed blindly using a hypsarrhythmia severity scale before and after completion of therapy. Adverse effects were assessed on day 14 using symptom diary. (Clinical trial registry identifier: SLCTR/2010/010.)

RESULTS

From 92 newly diagnosed West syndrome infants, 48 were randomized to receive prednisolone and 44 to receive adrenocorticotrophin hormone. Eighty infants completed the posttreatment evaluation according to specifications. The hypsarrhythmia severity score, significantly improved with hormonal therapy for 2 weeks (10.45 ± 2.65 vs 3.45 ± 2.67); P < 0.01. When individual treatment arms were compared using mean differences in the improvement of scores, improvement in prednisolone arm (7.95 ± 2.76) was significantly greater than that in the adrenocorticotrophin hormone arm (6.00 ± 2.61); P < 0.01. Both forms of therapy were tolerated well. Frequent crying, irritability, weight gain, increased appetite, and abdominal distension were more common (but not statistically significant) with prednisolone.

CONCLUSIONS

Hypsarrhythmia severity score improved significantly with both hormonal therapies, but this improvement was significantly better with oral prednisolone than intramuscular adrenocorticotrophin hormone. This is the first ever documentation of a superior therapeutic role of oral steroids in West syndrome.

Infantile spasms: treatment challenges

OPINION STATEMENT

Infantile spasms (IS) represent a major therapeutic challenge, as cessation of spasms and normalization of the electroencephalogram (elimination of hypsarrhythmia) are mandatory to prevent cognitive deterioration in previously healthy infants, or to preserve neurocognitive function among those neurologically affected prior to onset of IS. Traditionally, this epilepsy syndrome has been considered a "catastrophic" epilepsy, not only for its frequent refractoriness, but mostly due to its effect on cognition. Nevertheless, a change of attitude among pediatric epileptologists is probably warranted, as enough evidence and clinical experience demonstrate that early, aggressive therapy, especially with adrenocorticotropic hormone (ACTH), may not only lead to cessation of spasms, but often leads to the cure of infants with idiopathic/cryptogenic IS. Some ACTH protocols such as that prescribed in Israel (tetracosactide ACTH) appear to be highly efficacious in guarantying a good or even excellent prognosis in idiopathic IS. Moreover, oral prednisolone is a promising and much less expensive alternative to IM ACTH. Vigabatrin does have a role as a first-line agent, especially for tuberous sclerosis patients, but evidence supports hormonal therapy as the initial treatment. The role of pyridoxine and the ketogenic diet still needs to be established; given the efficacy of a much shorter tetracosactide ACTH protocol, there may be no need for the long-term diet, despite its efficacy. Finally, a very promising drug has been developed (CP-115) that may altogether replace the current therapeutic regimens in the near future.

Outcomes of epileptic spasms in patients aged less than 3 years: single-center United States experience

Retrospective review was performed of children aged <3 years with epileptic spasms at our center from 2004-2010. Short-term (<6 months) and long-term (≥6 months) outcomes were assessed. We included 173 children (104 boys; median age of onset, 6.8 months) with epileptic spasms of known (62%) and unknown (38%) etiology. Treatments included adrenocorticotropic hormone (n = 103), vigabatrin (n = 82), phenobarbital (n = 34), and other agents (n = 121). Short-term treatment with adrenocorticotropic hormone and vigabatrin provided better epileptic spasm control in groups with known and unknown etiology than other agents. At follow-up (6-27 months), 54% of children manifested seizures, and 83% manifested developmental delay. Known etiology was a predictor of poor developmental outcome (P = 0.006), whereas bilateral/diffuse brain lesions predicted both poor development and seizures (P = 0.001 and 0.005, respectively). Initial presentations of epileptic spasms with hypotonia or developmental delay most strongly predicted both seizures and neurodevelopmental outcomes (P < 0.001). In a child presenting with epileptic spasms with developmental delay or hypotonia, no specific treatment may offer superior benefit.

Resting-state activity in development and maintenance of normal brain function

One of the most intriguing recent discoveries concerning brain function is that intrinsic neuronal activity manifests as spontaneous fluctuations of the blood oxygen level-dependent (BOLD) functional MRI signal. These BOLD fluctuations exhibit temporal synchrony within widely distributed brain regions known as resting-state networks. Resting-state networks are present in the waking state, during sleep, and under general anesthesia, suggesting that spontaneous neuronal activity plays a fundamental role in brain function. Despite its ubiquitous presence, the physiological role of correlated, spontaneous neuronal activity remains poorly understood. One hypothesis is that this activity is critical for the development of synaptic connections and maintenance of synaptic homeostasis. We had a unique opportunity to test this hypothesis in a 5-y-old boy with severe epileptic encephalopathy. The child developed marked neurologic dysfunction in association with a seizure disorder, resulting in a 1-y period of behavioral regression and progressive loss of developmental milestones. His EEG showed a markedly abnormal pattern of high-amplitude, disorganized slow activity with frequent generalized and multifocal epileptiform discharges. Resting-state functional connectivity MRI showed reduced BOLD fluctuations and a pervasive lack of normal connectivity. The child underwent successful corpus callosotomy surgery for treatment of drop seizures. Postoperatively, the patient's behavior returned to baseline, and he resumed development of new skills. The waking EEG revealed a normal background, and functional connectivity MRI demonstrated restoration of functional connectivity architecture. These results provide evidence that intrinsic, coherent neuronal signaling may be essential to the development and maintenance of the brain's functional organization.

Neurodevelopmental and epilepsy outcomes in a North American cohort of patients with infantile spasms

Studies have suggested disparate variables affecting long-term outcomes in patients with infantile spasms. Using a retrospective chart review, the authors identified 109 patients who had follow-up data for at least 1 year since the onset of spasms. Patient and treatment variables were recorded, in addition to neurodevelopmental and seizure outcomes. Etiology was strongly associated with motor and cognitive status but not with long-term seizure control. Lag time to initiation of treatment was not predictive of any outcome, nor for need to use a second agent to resolve spasms, even when controlling for etiology. However, patients who responded to the first medication achieved superior seizure and cognitive outcomes. The delayed impact of individual medications could not be analyzed because many patients received multiple agents. While etiology and response to first medication predict better outcomes, the majority of patients with infantile spasms continue to have epilepsy with long-term motor and cognitive disabilities.

Interictal cerebral blood flow abnormality in cryptogenic West syndrome

PURPOSE

To elucidate the abnormality of interictal regional cerebral blood flow (rCBF) of West syndrome at the onset.

METHODS

Quantitative measurement of rCBF with an autoradiography method using N-isopropyl-((123)I) p-iodoamphetamine single photon emission computed tomography (SPECT) was performed on 14 infants with cryptogenic West syndrome. Regions of interest (ROIs) for rCBF were placed automatically using an automated ROI analysis software (three-dimensional stereotactic ROI template), and were grouped into 12 segments: callosomarginal, precentral, central, parietal, angular, temporal, posterior cerebral, pericallosal, lenticular nucleus, thalamus, hippocampus, and cerebellum. We compared rCBF between the patients and seven age-matched infants with cryptogenic focal epilepsy as a control group. The patients were divided into two groups according to the duration from onset to SPECT, to compare rCBF.

RESULTS

Quantitative analysis revealed cerebral hypoperfusion in cryptogenic West syndrome with normal SPECT images under visual inspection. In bilateral central, posterior cerebral, pericallosal, lenticular nucleus, and hippocampus, and in the left parietal, temporal, and cerebellum, and in the right angular and thalamus segments there were statistical differences (p < 0.05). Compared with the duration from onset to SPECT, there were no significant differences of rCBF in all segments.

DISCUSSION

Broad cerebral hypoperfusion with posterior predominance involving the hippocampus and lenticular nucleus implies that even cryptogenic West syndrome has a widespread cerebral dysfunction at least transiently, which would correspond to clinical manifestations of hypsarrhythmia and epileptic spasms. Hippocampal hypoperfusion suggests the dysfunction of hippocampal circuitry in the brain adrenal axis, and may contribute to subsequent cognitive impairment of cryptogenic West syndrome.

Nonconvulsive status epilepticus and coma

Nonconvulsive status epilepticus (NCSE) in a comatose patient cannot be diagnosed without electroencephalography (EEG). In many advanced coma stages, the EEG exhibits continuous or periodic EEG abnormalities, but their causal role in coma remains unclear in many cases. To date there is no consensus on whether to treat NCSE in a comatose patient in order to improve the outcome or to retract from treatment, as these EEG patterns might reflect the end stages of a dying brain. On the basis of EEG, NCSE in comatose patients may be classified as generalized or lateralized. This review aims to summarize the ongoing debate of NCSE and coma and to critically reassess the available literature on coma with epileptiform EEG pattern and its prognostic and therapeutic implications. The authors suggest distinguishing NCSE proper and comatose NCSE, which includes coma with continuous lateralized discharges or generalized epileptiform discharges (coma-LED, coma-GED). Although NCSE proper is accompanied by clinical symptoms suggestive of status epilepticus and mild impairment of consciousness, such as in absence status or complex focal status epilepticus, coma-LED and coma-GED represent deep coma of various etiology without any clinical motor signs of status epilepticus but with characteristic epileptiform EEG pattern. Hence coma-LED and coma-GED can be diagnosed with EEG only. Subtle or stuporous status epilepticus and epilepsia partialis continua-like symptoms in severe acute central nervous system (CNS) disorders represent the borderland in this biologic continuum between NCSE proper and comatose NCSE (coma-LED/GED). This pragmatic differentiation could act as a starting point to solve terminologic and factual confusion.

Long-term weekly ACTH therapy for relapsed West syndrome

Adrenocorticotrophic hormone (ACTH) therapy is an established treatment for West syndrome. However, some patients may relapse after this therapy, for whom there is no established treatment. We describe 3 patients with symptomatic West syndrome and multiple, poor prognostic factors who relapsed after initial ACTH therapy. They were treated with a second round of ACTH therapy, i.e., daily intramuscular injection for 2-3 weeks and subsequent withdrawal, alternative days for 1 or 2 weeks, every 3 days for 1 or 2 weeks, followed by weekly or biweekly for >/=1 year. Clinical seizures and hypsarrhythmia resolved in all 3 patients within 4 weeks, and these clinical improvements continued through a second round of ACTH therapy. Two patients developed other types of seizures and aggravation of paroxysms on electroencephalography, but no hypsarrhythmia, soon after termination of ACTH therapy. In the other patient, although electroencephalographic findings remained normal during weekly ACTH therapy, focal sharp waves with irregular slow waves appeared after the injection interval became biweekly. After a second round of ACTH therapy, all patients exhibited developmental progress, particularly in gross motor development and visual functions. No serious adverse events occurred during treatment. Long-term weekly ACTH therapy is a potentially effective treatment option for relapsed West syndrome.