Outcomes of children with infantile spasms after perinatal stroke

Neurobehavioral deficits and a progressive ictogenesis in the tetrodotoxin model of epileptic spasms

OBJECTIVE

Our goal was to determine whether animals with a history of epileptic spasms have learning and memory deficits. We also used continuous (24/7) long-term electroencephalographic (EEG) recordings to evaluate the evolution of epileptiform activity in the same animals over time.

METHODS

Object recognition memory and object location memory tests were undertaken, as well as a matching to place water maze test that evaluated working memory. A retrospective analysis was undertaken of long-term video/EEG recordings from rats with epileptic spasms. The frequency and duration of the ictal events of spasms were quantified.

RESULTS

Rats with a history of epileptic spasms showed impairment on the three behavioral tests, and their scores on the object recognition memory and matching to place water maze tests indicated neocortical involvement in the observed impaired cognition. Analysis of EEG recordings unexpectedly showed that the ictal events of spasms and their accompanying behaviors progressively increased in duration over a 2-week period soon after onset, after which spasm duration plateaued. At the same time, spasm frequency remained unchanged. Soon after spasm onset, ictal events were variable in wave form but became more stereotyped as the syndrome evolved.

SIGNIFICANCE

Our EEG findings are the first to demonstrate progressive ictogenesis for epileptic spasms. Furthermore, in demonstrating cognitive deficits in the tetrodotoxin model, we have met a criterion for an animal model of West syndrome. Animal models will allow in-depth studies of spasm progression's potential role in cognitive regression and may elucidate why early treatment is considered essential for improved neurodevelopmental outcomes in children.

A Role for Insulin-like Growth Factor 1 in the Generation of Epileptic Spasms in a murine model

OBJECTIVE

Infantile spasms are associated with a wide variety of clinical conditions, including perinatal brain injuries. We have created a model in which prolonged infusion of tetrodotoxin (TTX) into the neocortex, beginning in infancy, produces a localized lesion and reproduces the behavioral spasms, electroencephalogram (EEG) abnormalities, and drug responsiveness seen clinically. Here, we undertook experiments to explore the possibility that the growth factor IGF-1 plays a role in generating epileptic spasms.

METHODS

We combined long-term video EEG recordings with quantitative immunohistochemical and biochemical analyses to unravel IGF-1's role in spasm generation. Immunohistochemistry was undertaken in surgically resected tissue from infantile spasms patients. We used viral injections in neonatal conditional IGF-1R knock-out mice to show that an IGF-1-derived tripeptide (1-3)IGF-1, acts through the IGF-1 receptor to abolish spasms.

RESULTS

Immunohistochemical methods revealed widespread loss of IGF-1 from cortical neurons, but an increase in IGF-1 in the reactive astrocytes in the TTX-induced lesion. Very similar changes were observed in the neocortex from patients with spasms. In animals, we observed reduced signaling through the IGF-1 growth pathways in areas remote from the lesion. To show the reduction in IGF-1 expression plays a role in spasm generation, epileptic rats were treated with (1-3)IGF-1. We provide 3 lines of evidence that (1-3)IGF-1 activates the IGF-1 signaling pathway by acting through the receptor for IGF-1. Treatment with (1-3)IGF-1 abolished spasms and hypsarrhythmia-like activity in the majority of animals.

INTERPRETATION

Results implicate IGF-1 in the pathogenesis of infantile spasms and IGF-1 analogues as potential novel therapies for this neurodevelopmental disorder. ANN NEUROL 2022;92:45-60.

Patterns of Brain Injury in Perinatal Arterial Ischemic Stroke and the Development of Infantile Spasms

INTRODUCTION

Perinatal arterial ischemic stroke (PAIS) underlies approximately 10% of infantile spasms (IS). We aim to identify patterns of brain injury in ischemic stroke that may predispose infants to infantile spasms.

METHODS

Sixty-four perinatal arterial ischemic stroke patients were identified meeting the following inclusion criteria: term birth, magnetic resonance imaging (MRI) showing ischemic stroke or encephalomalacia in an arterial distribution, and follow-up records. Patients who developed infantile spasms (PAIS-IS) were analyzed descriptively for ischemic stroke injury patterns and were compared to a seizure-free control group (PAIS-only). Stroke injury was scored using the modified pediatric ASPECTS (modASPECTS).

RESULTS

The PAIS-IS (n = 9) group had significantly higher modASPECTS than the PAIS-only (n = 16) group (P = .002, Mann-Whitney). A greater proportion of PAIS-IS patients had injury to deep cerebral structures (67%) than PAIS-only (25%).

CONCLUSION

Infarct size was significantly associated with infantile spasms development. Results support theories implicating deep cerebral structures in infantile spasms pathogenesis. This may help identify perinatal arterial ischemic stroke patients at risk of infantile spasms, facilitating more timely diagnosis.

High-Dose Prednisolone for Treatment of Infantile Spasms After Presumed Perinatal Stroke

ABSTRACT

BACKGROUND: High-dose prednisone and prednisolone have been increasingly studied as a lower-cost alternative to adrenocorticotropic hormone for the treatment of infantile spasms, but this treatment has not been well studied in children with infantile spasms due to perinatal stroke. METHODS: We identified a girl with new-onset infantile spasms due to presumed perinatal left middle cerebral artery stroke seen in our hospital's pediatric stroke clinic in 2019. RESULTS: This girl developed infantile spasms at 9 months old. She had right hemiplegic cerebral palsy due to her perinatal stroke but had been otherwise previously healthy. Modified hypsarrhythmia was confirmed on prolonged video-electroencephalography. High-dose prednisolone at 8 mg/kg per day was initiated on the sixth day of spasms. She was treated with this dose for 2 weeks and then tapered over 5 weeks. The girl became seizure-free after receiving her first dose of prednisolone and experienced no significant adverse effects during therapy. Routine electroencephalography after completion of prednisolone taper confirmed resolution of modified hypsarrhythmia and no epileptiform discharges. She continued to make excellent development progress during and after treatment. CONCLUSION: This case suggests high-dose prednisolone could be considered for first-line therapy for children with infantile spasms due to perinatal stroke; further study is needed.

Neocortical Slow Oscillations Implicated in the Generation of Epileptic Spasms

OBJECTIVE

Epileptic spasms are a hallmark of severe seizure disorders. The neurophysiological mechanisms and the neuronal circuit(s) that generate these seizures are unresolved and are the focus of studies reported here.

METHODS

In the tetrodotoxin model, we used 16-channel microarrays and microwires to record electrophysiological activity in neocortex and thalamus during spasms. Chemogenetic activation was used to examine the role of neocortical pyramidal cells in generating spasms. Comparisons were made to recordings from infantile spasm patients.

RESULTS

Current source density and simultaneous multiunit activity analyses indicate that the ictal events of spasms are initiated in infragranular cortical layers. A dramatic pause of neuronal activity was recorded immediately prior to the onset of spasms. This preictal pause is shown to share many features with the down states of slow wave sleep. In addition, the ensuing interictal up states of slow wave rhythms are more intense in epileptic than control animals and occasionally appear sufficient to initiate spasms. Chemogenetic activation of neocortical pyramidal cells supported these observations, as it increased slow oscillations and spasm numbers and clustering. Recordings also revealed a ramp-up in the number of neocortical slow oscillations preceding spasms, which was also observed in infantile spasm patients.

INTERPRETATION

Our findings provide evidence that epileptic spasms can arise from the neocortex and reveal a previously unappreciated interplay between brain state physiology and spasm generation. The identification of neocortical up states as a mechanism capable of initiating epileptic spasms will likely provide new targets for interventional therapies. ANN NEUROL 2021;89:226-241.

Epileptic Spasms Predict Poor Epilepsy Outcomes After Perinatal Stroke

Perinatal stroke is a significant cause of severe epilepsy, including epileptic spasms. Although epileptic spasms due to underlying structural lesion often respond poorly to treatment and evolve into drug-resistant epilepsy, outcomes are not uniformly poor, and predictors of outcomes are not well described. We performed a single-institution retrospective review of epileptic spasms following perinatal stroke to determine if outcome depended on vascular subtype. We identified 24 children with epileptic spasms due to perinatal ischemic stroke: 11 cases of perinatal arterial stroke and 13 cases of perinatal venous infarct. Initial response to treatment was similar between groups; however, although children with perinatal arterial stroke who responded to epileptic spasms therapy had high rates of seizure freedom, many children with perinatal venous infarct, regardless of initial response, had residual drug-resistant epilepsy. We consider whether the mechanism for epileptogenesis may be different between arterial and venous strokes, and whether these 2 groups should be monitored for epileptic spasms, and subsequent epilepsy, differently.

Tracking of neurocognitive outcomes over time in children with perinatal stroke and associated complex medical conditions: a case series

Neurocognitive outcomes in children with perinatal stroke are complicated by additional neurological/medical factors. The main objective of this study was to retrospectively examine long-term neurocognitive outcomes in five children with perinatal stroke with increasingly complex comorbidities; ages 5-7 at first evaluation. Results revealed that intelligence and academic skills were significantly decreased in cases with combined perinatal stroke and comorbidities. Early language development was particularly vulnerable to disruption over time in children with increasing medical complexity. The delayed emergence of neurocognitive deficits emphasizes the need for serial assessment of neurocognitive development to identify early services and interventions.

West syndrome in three patients with brain injury and a benign course

Infants with West Syndrome and underlying structural pathology typically experience persistent symptomatic focal seizures and intellectual disability. We performed a retrospective case review of 84 patients with West Syndrome evaluated at one institution between 1990 and 2013. From this group we identified three patients with West syndrome and congenital hemiplegia who later developed genetic epilepsy features and had normal intellectual development. This outcome is highly unusual and raises important questions about the relationship and possible influence of genetic epilepsy in patients with pre-existent West Syndrome and brain injury.

Mechanisms of perinatal arterial ischemic stroke

The incidence of perinatal stroke is high, similar to that in the elderly, and produces a significant morbidity and severe long-term neurologic and cognitive deficits, including cerebral palsy, epilepsy, neuropsychological impairments, and behavioral disorders. Emerging clinical data and data from experimental models of cerebral ischemia in neonatal rodents have shown that the pathophysiology of perinatal brain damage is multifactorial. These studies have revealed that, far from just being a smaller version of the adult brain, the neonatal brain is unique with a very particular and age-dependent responsiveness to hypoxia-ischemia and focal arterial stroke. In this review, we discuss fundamental clinical aspects of perinatal stroke as well as some of the most recent and relevant findings regarding the susceptibility of specific brain cell populations to injury, the dynamics and the mechanisms of neuronal cell death in injured neonates, the responses of neonatal blood-brain barrier to stroke in relation to systemic and local inflammation, and the long-term effects of stroke on angiogenesis and neurogenesis. Finally, we address translational strategies currently being considered for neonatal stroke as well as treatments that might effectively enhance repair later after injury.

Genetic and biologic classification of infantile spasms

Infantile spasms constitute an age-dependent epilepsy, highly associated with cognitive impairment, autism, and movement disorders. Previous classification systems focused on a distinction between symptomatic and cryptogenic etiologies, and have not kept pace with recent discoveries of mutations in genes in key pathways of central nervous system development in patients with infantile spasms. Children with certain genetic syndromes are much likelier to manifest infantile spasms, and we review the literature to propose a genetic classification of these disorders. Children demonstrating genetic associations with infantile spasms also manifest phenotypes beyond epilepsy that may be explained by recent advances in the understanding of underlying biological mechanisms. Therefore we propose a biologic classification of genes highly associated with infantile spasms, and articulate models for infantile spasms pathogenesis based on those data. The two best described pathways of pathogenesis involve abnormalities in the gene regulatory network of gamma-aminobutyric acidergic forebrain development and abnormalities in molecules expressed at the synapse. These genetic and biologic classifications are flexible, and they should encourage much needed progress in syndrome recognition, clinical genetic testing, and the development of new therapies targeting specific pathways of pathogenesis.

Outcomes of perinatal arterial ischemic stroke and cerebral sinovenous thrombosis

Perinatal stroke can result in cerebral palsy, cognitive impairment, epilepsy, and sensory deficits. While some children only experience one type of disability, severe disabilities often cluster together. Death associated with perinatal stroke is rare, and often associated with other comorbidities. Clinical and radiographic factors can help predict outcome, but additional as-yet unknown factors appear to contribute to outcome as well. Rehabilitation can ameliorate deficits, and advances in rehabilitation technology and in adult stroke rehabilitation offer promise to pediatric perinatal stroke patients.

Multiple intracranial tuberculomas associated with partial status epilepticus and refractory infantile spasms

We report the case of a 10 month-old girl presenting with multiple intracranial tuberculomas associated with partial status epilepticus and cerebrovascular accident in the left sylvian territory. She later developed paradoxical enlargement of the tuberculomas during antituberculous treatment and severe neurological sequelae with refractory infantile spasms. The development of infantile spasms in this context is particularly remarkable, and this case is illustrative of the complex interrelationship between intracranial lesions, partial status epilepticus, and infantile spasms. It also highlights the difficult diagnosis of cerebral tuberculomas in infants and further supports the need for continued vigilance in industrialized countries.

Neuropsychologic outcomes in a case series of twins discordant for perinatal stroke

Perinatal stroke may affect cognitive development, but few studies have addressed the details of cognitive function after perinatal stroke. The present study was designed to compare the neuropsychologic features of five sets of twins discordant for perinatal stroke. All of the affected children had unilateral middle cerebral artery infarction (two left, three right); four of the five infarcts were large-branch, affecting the entire M1 territory. Three of the five affected children had comorbid epilepsy. Measures of intelligence, memory, language, attention, executive function, visual-motor integration, and fine motor skills were administered to children at a median age of 5 years (range, 5-8 years). Relative to their unaffected co-twins, the twins with perinatal stroke exhibited lower levels of full scale (p=0.005), verbal (p=0.006), and nonverbal (p=0.005) intelligence. Children with perinatal stroke also showed significant deficits on tests of verbal memory (p=0.041), receptive language (p=0.011), verbal fluency (p=0.019), and visual attention (p=0.011), compared with their unaffected co-twins. Twin gestation may be a risk factor for poor cognitive outcome after perinatal stroke. Large infarct size and comorbid epilepsy may have contributed to some of the poor cognitive outcomes in this cohort.

Time interval from a brain insult to the onset of infantile spasms

The temporal latency between an encephalopathic event and the onset of infantile spasms cannot be determined in the majority of symptomatic cases (e.g. genetic conditions, cerebral malformations). However, we can measure this interval when a previously normal infant sustains brain injury followed by infantile spasms. This information has implications for understanding the underlying pathophysiologic basis for infantile spasms and, also, is germane to allegations that a close temporal relationship between vaccination and the onset of this seizure disorder establishes causation. We identified 19 published cases with sufficient information. The interval between brain injury and the onset of infantile spasms ranged from 6 weeks to 11 months (mean = 5.1 months). A similar temporal latency occurs in children with perinatal cerebral infarction and infantile spasms. We conclude that infantile spasms do not occur acutely following an encephalopathic event. This interval of weeks to months is consistent with prior studies indicating temporal latency between brain injury and the onset of other types of epilepsy, as well as with the previously proposed developmental desynchronization hypothesis. The findings refute claims that a close temporal association between an immunization and the onset of infantile spasms establishes causation.

Perinatal stroke and the risk of developing childhood epilepsy

OBJECTIVES

To describe the prevalence of epilepsy after 6 months of age in children with perinatal stroke and examine whether perinatal data predict epilepsy onset and resolution.

STUDY DESIGN

A retrospective review of 64 children with perinatal stroke. In children with at least 6 months of follow-up data, Kaplan-Meier curves, univariate log-rank tests, and Cox proportional hazards models were used to examine predictors of time to development of seizures, and time to resolution of seizures in children with epilepsy. The association of risk factors with the presence of epilepsy at any time after 6 months of age was examined using Fisher's exact test.

RESULTS

Forty-one of the 61 children with at least 6 months of follow-up data (67%) had epilepsy between 6 months of age and last follow-up, but in 13 of 41, seizures eventually resolved and anticonvulsants were discontinued. Infarct on prenatal ultrasonography (P = .0065) and family history of epilepsy (P = .0093) were significantly associated with time to development of seizures after 6 months of age in the univariate analysis. No assessed variables were associated with time to resolution of epilepsy or with the presence of epilepsy after 6 months of age.

CONCLUSIONS

Childhood epilepsy is frequent after perinatal stroke. Evidence of infarction on prenatal ultrasonography and a family history of epilepsy predict earlier onset of active seizures.