Post-traumatic early epilepsy in pediatric age group with emphasis on influential factors

Immune Challenges and Seizures: How Do Early Life Insults Influence Epileptogenesis?

The development of epilepsy, a process known as epileptogenesis, often occurs later in life following a prenatal or early postnatal insult such as cerebral ischemia, stroke, brain trauma, or infection. These insults share common pathophysiological pathways involving innate immune activation including neuroinflammation, which is proposed to play a critical role in epileptogenesis. This review provides a comprehensive overview of the latest preclinical evidence demonstrating that early life immune challenges influence neuronal hyperexcitability and predispose an individual to later life epilepsy. Here, we consider the range of brain insults that may promote the onset of chronic recurrent spontaneous seizures at adulthood, spanning intrauterine insults (e.g. maternal immune activation), perinatal injuries (e.g. hypoxic–ischemic injury, perinatal stroke), and insults sustained during early postnatal life—such as fever-induced febrile seizures, traumatic brain injuries, infections, and environmental stressors. Importantly, all of these insults represent, to some extent, an immune challenge, triggering innate immune activation and implicating both central and systemic inflammation as drivers of epileptogenesis. Increasing evidence suggests that pro-inflammatory cytokines such as interleukin-1 and subsequent signaling pathways are important mediators of seizure onset and recurrence, as well as neuronal network plasticity changes in this context. Our current understanding of how early life immune challenges prime microglia and astrocytes will be explored, as well as how developmental age is a critical determinant of seizure susceptibility. Finally, we will consider the paradoxical phenomenon of preconditioning, whereby these same insults may conversely provide neuroprotection. Together, an improved appreciation of the neuroinflammatory mechanisms underlying the long-term epilepsy risk following early life insults may provide insight into opportunities to develop novel immunological anti-epileptogenic therapeutic strategies.

Contributions of Interleukin-1 Receptor Signaling in Traumatic Brain Injury

Traumatic brain injury (TBI) in various forms affects millions in the United States annually. There are currently no FDA-approved therapies for acute injury or the chronic comorbidities associated with TBI. Acute phases of TBI are characterized by profound neuroinflammation, a process that stimulates the generation and release of proinflammatory cytokines including interleukin-1α (IL-1α) and IL-1β. Both forms of IL-1 initiate signaling by binding with IL-1 receptor type 1 (IL-1R1), a receptor with a natural, endogenous antagonist dubbed IL-1 receptor antagonist (IL-1Ra). The recombinant form of IL-1Ra has gained FDA approval for inflammatory conditions such as rheumatoid arthritis, prompting interest in repurposing these pharmacotherapies for other inflammatory diseases/injury states including TBI. This review summarizes the currently available preclinical and clinical literature regarding the therapeutic potential of inhibiting IL-1-mediated signaling in the context of TBI. Additionally, we propose specific research areas that would provide a greater understanding of the role of IL-1 signaling in TBI and how these data may be beneficial for the development of IL-1-targeted therapies, ushering in the first FDA-approved pharmacotherapy for acute TBI.

In search of antiepileptogenic treatments for post-traumatic epilepsy

Post-traumatic epilepsy (PTE) is diagnosed in 20% of individuals with acquired epilepsy, and can impact significantly the quality of life due to the seizures and other functional or cognitive and behavioral outcomes of the traumatic brain injury (TBI) and PTE. There is no available antiepileptogenic or disease modifying treatment for PTE. Animal models of TBI and PTE have been developed, offering useful insights on the value of inflammatory, neurodegenerative pathways, hemorrhages and iron accumulation, calcium channels and other target pathways that could be used for treatment development. Most of the existing preclinical studies test efficacy towards pathologies of functional recovery after TBI, while a few studies are emerging testing the effects towards induced or spontaneous seizures. Here we review the existing preclinical trials testing new candidate treatments for TBI sequelae and PTE, and discuss future directions for efforts aiming at developing antiepileptogenic and disease-modifying treatments.

Modelling traumatic brain injury and posttraumatic epilepsy in rodents

Posttraumatic epilepsy (PTE) is one of the most debilitating and understudied consequences of traumatic brain injury (TBI). It is challenging to study the effects, underlying pathophysiology, biomarkers, and treatment of TBI and PTE purely in human patients for a number of reasons. Rodent models can complement human PTE studies as they allow for the rigorous investigation into the causal relationship between TBI and PTE, the pathophysiological mechanisms of PTE, the validation and implementation of PTE biomarkers, and the assessment of PTE treatments, in a tightly controlled, time- and cost-efficient manner in experimental subjects known to be experiencing epileptogenic processes. This article will review several common rodent models of TBI and/or PTE, including their use in previous studies and discuss their relative strengths, limitations, and avenues for future research to advance our understanding and treatment of PTE.

Traumatic Brain Injuries during Development: Implications for Alcohol Abuse

Traumatic brain injuries are strongly related to alcohol intoxication as by some estimates half or more of all brain injuries involve at least one intoxicated individual. Additionally, there is mounting evidence that traumatic brain injuries can themselves serve as independent risk factors for the development of alcohol use disorders, particularly when injury occurs during juvenile or adolescent development. Here, we will review the epidemiological and experimental evidence for this phenomenon and discuss potential psychosocial mediators including attenuation of negative affect and impaired decision making as well as neurochemical mediators including disruption in the glutamatergic, GABAergic, and dopaminergic signaling pathways and increases in inflammation.

Interleukin-1 Receptor in Seizure Susceptibility after Traumatic Injury to the Pediatric Brain

Epilepsy after pediatric traumatic brain injury (TBI) is associated with poor quality of life. This study aimed to characterize post-traumatic epilepsy in a mouse model of pediatric brain injury, and to evaluate the role of interleukin-1 (IL-1) signaling as a target for pharmacological intervention. Male mice received a controlled cortical impact or sham surgery at postnatal day 21, approximating a toddler-aged child. Mice were treated acutely with an IL-1 receptor antagonist (IL-1Ra; 100 mg/kg, s.c.) or vehicle. Spontaneous and evoked seizures were evaluated from video-EEG recordings. Behavioral assays tested for functional outcomes, postmortem analyses assessed neuropathology, and brain atrophy was detected by ex vivo magnetic resonance imaging. At 2 weeks and 3 months post-injury, TBI mice showed an elevated seizure response to the convulsant pentylenetetrazol compared with sham mice, associated with abnormal hippocampal mossy fiber sprouting. A robust increase in IL-1β and IL-1 receptor were detected after TBI. IL-1Ra treatment reduced seizure susceptibility 2 weeks after TBI compared with vehicle, and a reduction in hippocampal astrogliosis. In a chronic study, IL-1Ra-TBI mice showed improved spatial memory at 4 months post-injury. At 5 months, most TBI mice exhibited spontaneous seizures during a 7 d video-EEG recording period. At 6 months, IL-1Ra-TBI mice had fewer evoked seizures compared with vehicle controls, coinciding with greater preservation of cortical tissue. Findings demonstrate this model's utility to delineate mechanisms underlying epileptogenesis after pediatric brain injury, and provide evidence of IL-1 signaling as a mediator of post-traumatic astrogliosis and seizure susceptibility.SIGNIFICANCE STATEMENT Epilepsy is a common cause of morbidity after traumatic brain injury in early childhood. However, a limited understanding of how epilepsy develops, particularly in the immature brain, likely contributes to the lack of efficacious treatments. In this preclinical study, we first demonstrate that a mouse model of traumatic injury to the pediatric brain reproduces many neuropathological and seizure-like hallmarks characteristic of epilepsy. Second, we demonstrate that targeting the acute inflammatory response reduces cognitive impairments, the degree of neuropathology, and seizure susceptibility, after pediatric brain injury in mice. These findings provide evidence that inflammatory cytokine signaling is a key process underlying epilepsy development after an acquired brain insult, which represents a feasible therapeutic target to improve quality of life for survivors.

EEG Monitoring and Antiepileptic Drugs in Children with Severe TBI

BACKGROUND

Traumatic brain injury (TBI) causes substantial morbidity and mortality in US children. Post-traumatic seizures (PTS) occur in 11-42% of children with severe TBI and are associated with unfavorable outcome. Electroencephalographic (EEG) monitoring may be used to detect PTS and antiepileptic drugs (AEDs) may be used to treat PTS, but national rates of EEG and AED use are not known. The purpose of this study was to describe the frequency and timing of EEG and AED use in children hospitalized after severe TBI.

METHODS

Retrospective cohort study of 2165 children at 30 hospitals in a probabilistically linked dataset from the National Trauma Data Bank (NTDB) and the Pediatric Health Information Systems (PHIS) database, 2007-2010. We included children (age <18 years old at admission) with linked NTDB and PHIS records, severe (Emergency Department [ED] Glasgow Coma Scale [GCS] <8) TBI, hospital length of stay >24 h, and non-missing disposition. The primary outcomes were EEG and AED use.

RESULTS

Overall, 31.8% of the cohort had EEG monitoring. Of those, 21.8% were monitored on the first hospital day. The median duration of EEG monitoring was 2.0 (IQR 1.0, 4.0) days. AEDs were prescribed to 52.0% of the cohort, of whom 61.8% received an AED on the first hospital day. The median duration of AED use was 8.0 (IQR 4.0, 17.0) days. EEG monitoring and AED use were more frequent in children with known risk factors for PTS. EEG monitoring and AED use were not related to hospital TBI volume.

CONCLUSION

EEG use is relatively uncommon in children with severe TBI, but AEDs are frequently prescribed. EEG monitoring and AED use are more common in children with known risk factors for PTS.

Seizures in Children With Severe Traumatic Brain Injury

OBJECTIVE

Traumatic brain injury causes substantial morbidity and mortality in children. Posttraumatic seizures may worsen outcomes after traumatic brain injury. Posttraumatic seizures risk factors are not completely understood. Our objective was to clarify posttraumatic seizures risk factors in a large cohort of children with severe traumatic brain injury.

DESIGN

Retrospective cohort study of a probabilistically linked dataset from the National Trauma Data Bank and the Pediatric Health Information Systems database, 2007-2010.

SETTING

Twenty-nine U.S. children's hospitals.

PATIENTS

A total of 2,122 children (age, < 18 yr old at admission) with linked National Trauma Data Bank and Pediatric Health Information Systems records, severe (emergency department Glasgow Coma Scale, < 8) traumatic brain injury, hospital length of stay more than 24 hours, and nonmissing disposition.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The outcome was posttraumatic seizures, identified using validated International Classification of Diseases, 9th Revision, Clinical Modification diagnosis codes. Prespecified candidate predictors of posttraumatic seizures included age, injury mechanism, emergency department Glasgow Coma Scale, intracranial hemorrhage type, hypoxia, hypotension, and cardiac arrest. Posttraumatic seizures were diagnosed in 25.2% of children with severe traumatic brain injury. In those without abuse/assault or subdural hemorrhage, the posttraumatic seizures rate varied between 36.6% in those less than 2 years old and 16.4% in those 14-17 years old. Age, abusive mechanism, and subdural hemorrhage are each significant predictors of posttraumatic seizures. The risk of posttraumatic seizures has a complex relationship with these predictors. The estimated odds of posttraumatic seizures decrease with advancing age, odds ratio equal to 0.929 (0.905-0.954) per additional year of age with no abuse/assault and no subdural hemorrhage; odds ratio equal to 0.820 (0.730-0.922) per additional year of age when abuse and subdural hemorrhage are present. An infant with accidental traumatic brain injury and subdural hemorrhage has approximately the same estimated probability of posttraumatic seizures as an abused infant without subdural hemorrhage (47% [95% CI, 39-55%] vs 50% [95% CI, 41-58%]; p = 0.69). The triad of young age, injury by abuse/assault, and subdural hemorrhage confers the greatest estimated probability for posttraumatic seizures (60% [95% CI, 53-66%]).

CONCLUSIONS

Posttraumatic seizures risk in children with severe traumatic brain injury is greatest with a triad of younger age, injury by abuse/assault, and subdural hemorrhage. However, posttraumatic seizures are common even in the absence of these factors.

Pediatric head injury: a pain for the emergency physician?

The prompt diagnosis and initial management of pediatric traumatic brain injury poses many challenges to the emergency department (ED) physician. In this review, we aim to appraise the literature on specific management issues faced in the ED, specifically: indications for neuroimaging, choice of sedatives, applicability of hyperventilation, utility of hyperosmolar agents, prophylactic anti-epileptics, and effect of hypothermia in traumatic brain injury. A comprehensive literature search of PubMed and Embase was performed in each specific area of focus corresponding to the relevant questions. The majority of the head injured patients presenting to the ED are mild and can be observed. Clinical prediction rules assist the ED physician in deciding if neuroimaging is warranted. In cases of major head injury, prompt airway control and careful use of sedation are necessary to minimize the chance of hypoxia, while avoiding hyperventilation. Hyperosmolar agents should be started in these cases and normothermia maintained. The majority of the evidence is derived from adult studies, and most treatment modalities are still controversial. Recent multicenter trials have highlighted the need to establish common platforms for further collaboration.

Posttraumatic seizures in children with severe traumatic brain injury

PURPOSE

Traumatic brain injury (TBI) remains a leading cause of childhood death and disability worldwide. Seizures are a common complication of TBI and they are particularly common in pediatric populations. The proper management of children sustaining severe TBI is still controversial. Our study aims to share our experience contributing to build evidence for better care.

METHODS

Retrospective chart review was performed on individuals ages 0 to <18 who presented to a level 1 trauma center during a 10-year period with the diagnosis of severe TBI. Data analyzed included patient's demographics, event information, clinical and radiological presentation, management, and midterm follow-up. Presence of seizures was tracked through EEG monitoring, staff witnessing, or guardian referral.

RESULTS

The incidence of early posttraumatic seizures (EPTS) observed in our population (19 %) exceeds those previously reported. Such findings likely reflect the importance of close monitoring including EEG. An association between the presence of EPTS and the development of late posttraumatic seizures (LPTS) was evidenced (p=0.001; 95 % CI 2.2, 16.5), while this association should not be assumed as a measure of causality, it should be considered for the management of patients presenting EPTS. Non-accidental trauma and young age were identified as independent predictors for the development of seizures.

CONCLUSIONS

Seizures are a common complication of severe TBI among children aged 0-3 years. Given the detrimental effects that seizures produce on the injured brain, close observation and appropriate monitoring with EEG are essential for the management of children sustaining severe TBI.