CSF neopterin and quinolinic acid are biomarkers of neuroinflammation and neurotoxicity in FIRES and other infection-triggered encephalopathy syndromes

Challenges in Management of Febrile Infection-Related Epilepsy Syndrome: Real-World Experience From a Large Cohort of Pediatric Patients

BACKGROUND

Febrile infection-related epilepsy syndrome (FIRES) is a catastrophic neuroinflammatory disorder with refractory status epilepticus. The disease management continues to pose significant challenges.

METHODS

A retrospective observational study of patients with FIRES managed at tertiary care centers in India. The follow-up outcome was assessed using the Clinical Assessment Scale in Autoimmune Encephalitis (CASE).

RESULTS

Forty-one children (27 males) were eligible. The mean presentation age was 7.2 years (range, 2-14). A median of 7 (range, 2-12) antiseizure medications (ASMs) were tried before pharmacologic coma, which was subsequently required in all patients. The pharmacologic coma was induced for a median duration of 11 days (range, 1-125), with midazolam (41) being the most common medication, followed by ketamine (33), thiopentone (18), and isoflurane (13). Only a minority had seizure resolution on pharmacologic coma (ketamine 21%, midazolam 17%, and thiopentone 16.6%). Ninety-seven percent children also concurrently received methylprednisolone (40), 63% intravenous immunoglobulin (26), 32% rituximab (13), 32% cyclophosphamide (13), and 56% ketogenic diet (23). At a median follow-up of 37 months (range, 9-96), 34% (14) children had died. Of the remaining 27, epilepsy was poorly controlled in the majority (18 children, 67%). Also, 14 patients had a CASE score of ≤5 (good outcome) and 13 had a score of >5 (poor outcome). In both groups, there was no statistically significant difference in outcomes with the ketogenic diet, pharmacologic coma, or immunomodulatory therapies.

CONCLUSIONS

The management of FIRES in children is challenging, with limited effectiveness of most currently practiced anesthetic agents and conventional immunomodulatory therapies in seizure control and in altering the outcome in FIRES.

International consensus definitions for infection-triggered encephalopathy syndromes

AIM

To develop standardized diagnostic criteria for 'infection-triggered encephalopathy syndrome (ITES)' and five specific clinical syndromes of ITES.

METHOD

The draft definitions were based on existing criteria, standardized, and discussed by a panel of international experts using nominal group technique over 18 months to achieve consensus. All criteria use the same format: (1) presence of infection/fever; (2) clinical features including encephalopathy; (3) neuroradiological features on magnetic resonance imaging; (4) exclusion of other causes.

RESULTS

We first highlighted differences between ITES and infectious and autoimmune encephalitis, which is the most important differential diagnosis. Consensus was achieved to define five specific ITESs: acute encephalopathy with biphasic seizures and late reduced diffusion; acute necrotizing encephalopathy; mild encephalopathy with a reversible splenial lesion; acute fulminant cerebral oedema; and acute shock with encephalopathy and multiorgan failure. Two further conditions that are currently classified as epilepsy syndromes but have similar features to ITES, namely febrile infection-related epilepsy syndrome and hemiconvulsion-hemiplegia-epilepsy syndrome, are also discussed.

INTERPRETATION

The consensus definition is expected to improve awareness of this disease concept, provide diagnostic framework, and facilitate future international research and clinical trials.

New-Onset Refractory Status Epilepticus With Diffuse Cerebral Restricted Diffusion in Young Children: A Novel Clinical-Radiologic Presentation

BACKGROUND

New-onset refractory status epilepticus (NORSE) is a clinical presentation characterized by explosive-onset refractory status epilepticus (RSE) without evident etiology or active epilepsy, often leading to devastating epilepsy. There is heterogeneity in neuroradiographic findings for NORSE. We encountered a series of young patients with NORSE who had diffuse cerebral restriction in diffusion (DCRD) with similar radiographic appearances as acute encephalopathy with biphasic seizures and late restricted diffusion/acute leukoencephalopathy with restricted diffusion (AESD/ALERD). We explore clinical similarities and proposed pathophysiologic overlaps to highlight a novel clinical-radiologic presentation.

METHODS

Retrospective review was completed for patients younger than five years meeting NORSE criteria and then screened for radiographic evidence of DCRD. Demographic, clinical, and outcome data were collected.

RESULTS

Eleven patients met NORSE criteria, of whom seven displayed DCRD. Immunosuppressant management varied. All patients required multiple antiseizure medications and continuous infusions for RSE. Only one had an etiology identified (genetic). All but one patient developed diffuse, global, and progressive cerebral atrophy. Two patients died: one after prolonged seizure three years post-NORSE and another of unknown causes two months post-NORSE. Of five survivors, three have medically refractory epilepsy. Most survivors have severe disability.

CONCLUSIONS

We present a single-center case series of seven patients with NORSE and DCRD, akin to AESD/ALERD. Our patients differed clinically to AESD/ALERD in terms of seizure severity and poorer outcome. There is a need to develop biomarkers for specific NORSE phenotypes. The young child with NORSE and DCRD may represent a novel phenotype with a specific neuroradiographic signature that deserves further attention.

Autoimmune-associated seizure disorders

With the discovery of an expanding number of neural autoantibodies, autoimmune etiologies of seizures have been increasingly recognized. Clinical phenotypes have been identified in association with specific underlying antibodies, allowing an earlier diagnosis. These phenotypes include faciobrachial dystonic seizures with LGI1 encephalitis, neuropsychiatric presentations associated with movement disorders and seizures in NMDA-receptor encephalitis, and chronic temporal lobe epilepsy in GAD65 neurologic autoimmunity. Prompt recognition of these disorders is important, as some of them are highly responsive to immunotherapy. The response to immunotherapy is highest in patients with encephalitis secondary to antibodies targeting cell surface synaptic antigens. However, the response is less effective in conditions involving antibodies binding intracellular antigens or in Rasmussen syndrome, which are predominantly mediated by cytotoxic T-cell processes that are associated with irreversible cellular destruction. Autoimmune encephalitides also may have a paraneoplastic etiology, further emphasizing the importance of recognizing these disorders. Finally, autoimmune processes and responses to novel immunotherapies have been reported in new-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES), warranting their inclusion in any current review of autoimmune-associated seizure disorders.

Brain on Fire: How Brain Infection and Neuroinflammation Drive Worldwide Epilepsy Burden

Roughly 80% of the global burden of epilepsy resides in low- and middle-income countries (LMICs; WHO, 2022). Despite numerous new therapies for the treatment of epilepsy, the number of patients who remain resistant to available medications is unchanged. Additionally, no therapy has yet been clinically proven to prevent or attenuate the development of epilepsy in at-risk individuals. Unfortunately, access to next generation therapies in LMICs is low, the stigma associated with epilepsy remains high, and access to adequate resources is unchanged. Thus, the global epilepsy burden disproportionately falls on LMICs such that strategies to conscientiously integrate global epilepsy risk factors into preclinical research may meaningfully advance 21st century epilepsy therapies. Brain infections are one of the main risk factors for epilepsy in resource-poor settings. Further, both infection- and autoimmune-associated encephalitis contribute to worldwide epilepsy risk and remain relatively understudied. For example, clinical SARS CoV-2 infection can induce rare instances of encephalopathy and acute seizures. Among viruses known to cause acute brain infection, enteroviruses increase risk for encephalitis-induced epilepsy, but are not associated with risk for other neurodevelopmental disorders (eg, autism spectrum or attentional deficit hyperactivity disorders). Naturally occurring models of viral infection-induced epilepsy therefore provide an exquisite opportunity to uncover novel contributors to epileptogenesis. Moreover, the convergent neuroinflammatory pathways that are associated with viral infection-induced encephalitis and autoimmune encephalitis reflect an untapped therapeutic opportunity to meaningfully reduce the global burden of epilepsy. This review summarizes the latest advances in translational research integrating encephalitis-induced seizure and epilepsy models, in tandem with progress in clinical diagnosis of inflammation and virally mediated epilepsy. This improved awareness of the shared biological underpinnings of epileptogenesis following brain infection or autoimmune encephalitis is anticipated to beneficially impact the global burden of epilepsy.

Efficacy and safety of ketamine for pediatric and adolescent super-refractory status epilepticus and the effect of cerebral inflammatory conditions

OBJECTIVE

To investigate the short-term benefits and adverse effects of ketamine in the treatment of pediatric and adolescent super-refractory status epilepticus (SRSE), with a focus on the inflammatory etiology.

METHODS

This retrospective observational cohort study included a consecutive series of 18 pediatric to adolescent patients with SRSE admitted between 2008 and 2023 and treated with ketamine. Seizure frequency per hour before and after ketamine administration and response rate were calculated. Neurological decline, catecholamine administration, and adverse effects were also assessed. The patients were divided into inflammatory and non-inflammatory etiology groups.

RESULTS

The median age at SRSE onset was 1 year 5 months (range: 11 days-24 years), and 78% of the patients were male individuals. The median duration of treatment was 7.5 days (interquartile range: 2.8-15.5 days). Fifteen (83%) patients achieved >50% seizure reduction. The median seizure frequency before and after ketamine treatment was 5.9 and 0.9, respectively, showing a significant reduction in seizure frequency (p < 0.0001). Ten patients had inflammatory etiologies including bacterial meningitis (n = 2), viral encephalitis (n = 3), and febrile infection related epilepsy syndrome (n = 5). The inflammatory etiology group required a longer treatment duration (p = 0.0453) and showed lower seizure reduction (p = 0.0264), lower response rate (p = 0.0044), and higher neurological decline (p = 0.0003) than the non-inflammatory etiology group. Three (17%) patients experienced transient adverse events requiring intervention within 24 h of initiating ketamine administration.

CONCLUSIONS

Ketamine administration was associated with fewer serious adverse events and a reduced seizure frequency. Additionally, inflammatory conditions may weaken the efficacy of ketamine in patients with SRSE.

Metabolomic changes in adults with status epilepticus: A human case-control study

OBJECTIVE

Status epilepticus (SE) is a life-threatening prolonged epileptic seizure that affects ~40 per 100 000 people yearly worldwide. The persistence of seizures may lead to excitotoxic processes, neuronal loss, and neuroinflammation, resulting in long-term neurocognitive and functional disabilities. A better understanding of the pathophysiological mechanisms underlying SE consequences is crucial for improving SE management and preventing secondary neuronal injury.

METHODS

We conducted a comprehensive untargeted metabolomic analysis, using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), on plasma and cerebrospinal fluid (CSF) samples from 78 adult patients with SE and 107 control patients without SE, including 29 with CSF for both groups. The metabolomic fingerprints were compared between patients with SE and controls. Metabolites with differences in relative abundances that could not be attributed to treatment or nutrition provided in the intensive care unit were isolated. Enrichment analysis was performed on these metabolites to identify the most affected pathways.

RESULTS

We identified 76 metabolites in the plasma and 37 in the CSF that exhibited differential expression in patients with SE compared to controls. The enrichment analysis revealed that metabolic dysregulations in patients with SE affected primarily amino acid metabolism (including glutamate, alanine, tryptophan, glycine, and serine metabolism), pyrimidine metabolism, and lipid homeostasis. Specifically, patients with SE had elevated levels of pyruvate, quinolinic acid, and keto butyric acid levels, along with lower levels of arginine, N-acetylaspartylglutamate (NAAG), tryptophan, uracil, and uridine. The tryptophan kynurenine pathway was identified as the most significantly altered in SE, resulting in the overproduction of quinolinic acid, an N-methyl-d-aspartate (NMDA) receptor agonist with pro-inflammatory properties.

SIGNIFICANCE

This study has identified several pathways that may play pivotal roles in SE consequences, such as the tryptophan kynurenine pathway. These findings offer novel perspectives for the development of neuroprotective therapeutics.

RANBP2 evolution and human disease

Ran-binding protein 2 (RANBP2)/Nup358 is a nucleoporin and a key component of the nuclear pore complex. Through its multiple functions (e.g., SUMOylation, regulation of nucleocytoplasmic transport) and subcellular localizations (e.g., at the nuclear envelope, kinetochores, annulate lamellae), it is involved in many cellular processes. RANBP2 dysregulation or mutation leads to the development of human pathologies, such as acute necrotizing encephalopathy 1, cancer, neurodegenerative diseases, and it is also involved in viral infections. The chromosomal region containing the RANBP2 gene is highly dynamic, with high structural variation and recombination events that led to the appearance of a gene family called RANBP2 and GCC2 Protein Domains (RGPD), with multiple gene loss/duplication events during ape evolution. Although RGPD homoplasy and maintenance during evolution suggest they might confer an advantage to their hosts, their functions are still unknown and understudied. In this review, we discuss the appearance and importance of RANBP2 in metazoans and its function-related pathologies, caused by an alteration of its expression levels (through promotor activity, post-transcriptional, or post-translational modifications), its localization, or genetic mutations.