A case of acute encephalitis with refractory, repetitive partial seizures, presenting autoantibody to glutamate receptor Gluepsilon2

Japanese guidelines for treatment of pediatric status epilepticus - 2023

The updated definition of status epilepticus (SE) by the International League Against Epilepsy in 2015 included two critical time points (t1: at which the seizure should be regarded as an "abnormally prolonged seizure"; and t2: beyond which the ongoing seizure activity can pose risk of long-term consequences) to aid in diagnosis and management and highlights the importance of early treatment of SE more clearly than ever before. Although Japan has witnessed an increasing number of pre-hospital drug treatment as well as first- and second-line treatments, clinical issues have emerged regarding which drugs are appropriate. To address these clinical concerns, a revised version of the "Japanese Guidelines for the Treatment of Pediatric Status Epilepticus 2023" (GL2023) was published. For pre-hospital treatment, buccal midazolam is recommended. For in-hospital treatment, if an intravenous route is unobtainable, buccal midazolam is also recommended. If an intravenous route can be obtained, intravenous benzodiazepines such as midazolam, lorazepam, and diazepam are recommended. However, the rates of seizure cessation were reported to be the same among the three drugs, but respiratory depression was less frequent with lorazepam than with diazepam. For established SE, phenytoin/fosphenytoin and phenobarbital can be used for pediatric SE, and levetiracetam can be used in only adults in Japan. Coma therapy is recommended for refractory SE, with no recommended treatment for super-refractory SE. GL2023 lacks adequate recommendations for the treatment of nonconvulsive status epilepticus (NCSE). Although electrographic seizure and electrographic SE may lead to brain damages, it remains unclear whether treatment of NCSE improves outcomes in children. We plan to address this issue in an upcoming edition of the guideline.

The value of hypothermia as a neuroprotective and antiepileptic strategy in patients with status epilepticus: an update of the literature

INTRODUCTION

Status epilepticus represents a significant neurological emergency, with high morbidity and mortality rates. In addition to standard care, the identification of adjuvant strategies is essential to improve the outcome.

AREAS COVERED

The authors conducted a narrative review to provide an update on the value of hypothermia as an antiseizure and neuroprotective treatment in status epilepticus.

EXPERT OPINION

The use of targeted temperature management in the treatment of hypothermia in patients with status epilepticus represents a potentially promising adjuvant strategy, supported by a substantial body of experimental evidence. However, further clinical data demonstrating its efficacy are necessary before it can be recommended for routine use in targeted patient populations, such as those with refractory or super-refractory status epilepticus.

Hypothermia as a treatment in status epilepticus: A narrative review

Status epilepticus (SE) is associated with high mortality and morbidity rates, notably in its refractory and super-refractory forms. This narrative review discusses recent data on the potential benefits of targeted temperature management. In studies of patients with cerebral injury due to various factors, therapeutic hypothermia had variable effects on survival and functional outcomes. Sources of this variability may include the underlying etiology, whether hypothermia was used for prophylaxis or treatment, the degree and duration of hypothermia, and the hypothermia application modalities. Data from animal studies strongly suggest benefits from therapeutic hypothermia in SE. In humans, beneficial effects have been described in anecdotal case reports and small case series, but the level of evidence is low. A randomized controlled trial found no evidence that moderate hypothermia (32-34 °C) was neuroprotective in critically ill patients with convulsive SE. Nevertheless, some promising effects were noted, suggesting that therapeutic hypothermia might have a role as an adjuvant to anticonvulsant drug therapy in patients with refractory or super-refractory SE. This article is part of a Special Issue entitled "Status Epilepticus". This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Therapeutic Hypothermia for Refractory Status Epilepticus

BACKGROUND

Our goal was to perform a systematic review of the literature on the use of therapeutic hypothermia for refractory status epilepticus (RSE) and its impact on seizure control.

METHODS

All articles from MEDLINE, BIOSIS, EMBASE, Global Health, HealthStar, Scopus, Cochrane Library, the International Clinical Trials Registry Platform (inception to May 2014), reference lists of relevant articles, and gray literature were searched. The strength of evidence was adjudicated by two independent reviewers, using both the Oxford and GRADE methodology.

RESULTS

Overall, 13 studies were identified, with 10 manuscripts and 3 meeting abstracts. A total of 40 patients were treated. The common target temperature was 33 degrees Celsius, sustained for a median 48 hours. Patients displayed a 62.5%, 15% and 22.5% rate of seizure cessation, seizure reduction, and failure of treatment respectively. External cooling was utilized in the majority of cases. Deep venous thrombosis, coagulopathy and infections were the commonly reported complications. Two ongoing clinical trials were identified.

CONCLUSIONS

Oxford level 4, GRADE D evidence exists to support the use of therapeutic hypothermia to control seizures in RSE. Further prospective study is warranted.

Causes of CNS inflammation and potential targets for anticonvulsants

Inflammation is one of the most important endogenous defence mechanisms in an organism. It has been suggested that inflammation plays an important role in the pathophysiology of a number of human epilepsies and convulsive disorders, and there is clinical and experimental evidence to suggest that inflammatory processes within the CNS may either contribute to or be a consequence of epileptogenesis. This review discusses evidence from human studies on the role of inflammation in epilepsy and highlights potential new targets in the inflammatory cascade for antiepileptic drugs. A number of mechanisms have been shown to be involved in CNS inflammatory reactions. These include an inflammatory response at the level of the blood-brain barrier (BBB), immune-mediated damage to the CNS, stress-induced release of inflammatory mediators and direct neuronal dysfunction or damage as a result of inflammatory reactions. Mediators of inflammation in the CNS include interleukin (IL)-1β, tumour necrosis factor-α, nuclear factor-κB and toll-like receptor-4 (TLR4). IL-1β, BBB and high-mobility group box-1-TLR4 signalling appear to be the most promising targets for anticonvulsant agents directed at inflammation. Such agents may provide effective therapy for drug-resistant epilepsies in the future.

A Boy with Non-Herpes Simplex Acute Limbic Encephalitis and Antiglutamate Receptor Antibodies

This report concerns a 12-year-old male with intractable seizures over a long period. The case fulfilled the diagnostic criteria for nonherpetic acute limbic encephalitis. He had frequent convulsions starting with a partial seizure at the left angle of the mouth and progressing to secondary generalized seizures. He was treated with several anticonvulsants, combined with methylprednisolone and γ-globulin under mechanical ventilation. However, his convulsions reappeared after tapering of the barbiturate. His magnetic resonance imaging showed a high intensity area in the hippocampus by FLAIR and diffusion. After five months he recovered without serious sequelae. Virological studies, including for herpes simplex virus, were all negative. He was transiently positive for antiglutamate receptor antibodies in cerebrospinal fluid and serum.

Amplitude-integrated electroencephalography in patients with acute encephalopathy with refractory, repetitive partial seizures

We report amplitude-integrated EEG findings in two children with acute encephalopathy with refractory, repetitive partial seizures. Both patients had a febrile illness one week before the onset of seizure. They had reduction of consciousness and repetitive seizures refractory to first-line antiepileptic drugs. Seizure frequency rapidly increased and evolved into status epilepticus. Continuous seizure monitoring with amplitude-integrated EEG revealed frequent subclinical seizures which were missed by direct observation. In addition, the site of origin of seizures was multifocal, and seizure foci shifted from one hemisphere to the other. Their seizures were controlled after an administration of high-dose phenobarbital. Continuous seizure monitoring with amplitude-integrated EEG will contribute to correct estimation of seizure burden and efficacy of antiepileptic drugs in children with acute encephalopathy with refractory, repetitive partial seizures.

The growing recognition of immunotherapy-responsive seizure disorders with autoantibodies to specific neuronal proteins

PURPOSE OF REVIEW

The concept of epilepsy and seizure disorders caused by autoantibodies to specific neuronal membrane proteins has developed significantly during the past few years.

RECENT FINDINGS

Antibodies to cell-surface membrane proteins such as voltage-gated potassium channels or N-methyl-D-aspartate receptors, or to glutamic acid decarboxylase, are found in patients with different forms of limbic encephalitis, and in a few patients with epilepsy as their main or only condition. Many of these patients do not show a good response to conventional antiepileptic drugs, but respond to immunotherapies. By contrast, studies of other antibodies in idiopathic forms of epilepsy, or epilepsy associated with systemic lupus erythematosus or coeliac disease, have not in general disclosed consistent, clinically helpful results.

SUMMARY

There are a growing number of specific antibodies associated with new onset epilepsy. These patients are likely to have an immune-mediated disorder that may benefit from immunotherapies. In autoimmune diseases such as systemic lupus erythematosus or coeliac disease, antibodies to specific membrane targets may also prove to be important in the future.

Acute encephalitis with refractory, repetitive partial seizures (AERRPS): a peculiar form of childhood encephalitis

OBJECTIVE

We conducted a nationwide multicenter study in Japan to elucidate the clinical and laboratory characteristics of acute encephalitis with refractory, repetitive partial seizures (AERRPS).

MATERIALS AND METHODS

Clinical and laboratory features, treatment, and outcome were assessed using a structured questionnaire.

RESULTS

Twenty-nine children were enrolled in the study. Refractory and repetitive partial seizures accompanied by fever were the cardinal clinical features. Partial seizures consisted principally of eye deviation or facial twitching, being periodically repeated during the acute phase. These seizures were refractory to conventional anticonvulsants and were only suppressed by high-dose intravenous barbiturate administration. Rhythmic activities on electroencephalography and non-specific cerebral atrophy on neuroimaging were common. Serum or cerebrospinal antibodies against GluRepsilon2 were positive in six patients. General prognosis was unfavorable due to intractable epilepsy and cognitive deficits.

CONCLUSION

Based on the peculiar and homogenous features, AERRPS can be regarded as a distinct clinical entity.

Epileptic encephalopathy in children possibly related to immune-mediated pathogenesis

Severe epilepsy in the paediatric population negatively influences neurological and cognitive development. Different etiological factors could be responsible of these severe epilepsies, and an early diagnosis could change, in some cases, the neurological and cognitive development. Immune mechanisms have been reported in epilepsy. Epilepsy has been associated with systemic lupus erythematosus, with the presence of anti-phospholipid antibodies (aPL), anti-cardiolipin antibodies, anti-nuclear antibodies, Beta2-glycoprotein antibodies, and anti-glutamic acid decarboxylase (anti-GAD) antibodies. CNS inflammation and markers of adaptive immunity have been, also, associated with some epileptic syndromes, such as West syndrome, temporal lobe epilepsy, febrile seizures, tonic-clonic seizures, and tuberous sclerosis. Inflammation and blood-brain barrier (BBB) disruption could be one of the mechanisms responsible for seizure recurrence. Recently clinical entities, characterized by severe epilepsy with a febrile, acute or sub-acute onset, sometimes associated with status epilepticus, followed by drug-resistant, partial epilepsy have been described. Some of these publications also suggested acronyms for the condition described: Acute Encephalitis with Refractory, Repetitive Partial Seizures (AERRPS) reported by Japanese authors, Devastating Epileptic Encephalopathy in School-aged Children (DESC) reported by French authors. Among children with acquired symptomatic severe epilepsy, we identified a group of previously normal children who had developed severe partial epilepsy after an acute/sub-acute illness resembling encephalitis. The etiological factors for those patients seems to remain unknown, and a possible immune-mediating or inflammatory process as pathogenesis of the disease could be hypothesized. More studies need to be addressed to finally define this peculiar epileptic entity.

Acute encephalitis with refractory, repetitive partial seizures

Acute encephalitis with refractory, repetitive partial seizures (AERRPS) represents a peculiar form of encephalitis mainly affecting children. They usually present abruptly with seizure or impaired consciousness as well as high-grade fever following antecedent infection. Seizures in AERRPS are almost exclusively of localized origin, whose semiology includes eye deviation, hemifacial twitching, hemiclonic convulsion, and autonomic manifestations. Partial seizures are brief, but repeat with increasing frequency and develop status epilepticus at nadir. They are extremely pharmaco-resistant and are only suppressed by intravenous administration of high-dose barbiturates. Although acute seizures are hardly controlled, patients gradually recover with decreasing seizure frequency and continuously evolve into post-encephalitic epilepsy without latent period. Residual cognitive impairment is common. Electroencephalograms in active stage demonstrate electrical seizure activities and interictal periodic discharges. Magnetic resonance imaging reveals late cerebral atrophy with limited signal abnormality. Persistent fever during active stage, cerebrospinal fluid (CSF) pleocytosis, and up-regulation of neopterin raise the hypothesis that inflammatory process is involved in this condition. Furthermore, early production of autoantibody against NMDA receptor 2B in serum and CSF, although its disease specificity is still in controversy, is suggestive of autoimmune etiology. Exploration for definite clinical marker is currently in progress.

Acute encephalitis with refractory, repetitive partial seizures

BACKGROUND

Acute encephalitis with refractory, repetitive partial seizures (AERRPS) is a new epileptic syndrome described by Sakuma in Japan in 2001. The clinical manifestations, neuroimaging findings and outcome of AERRPS in Taiwan have not been reported.

METHODS

From 2000 to 2006, we collected cases that fulfilled the diagnostic criteria of AERRPS and analyzed the clinical course, virology, medication, electroencephalographic findings, neuroimaging characters and prognosis retrospectively.

RESULTS

Fourteen children aged from 1 year and 2 months to 15 years and 6 months were enrolled. They presented with prodromic symptoms including fever (n=13, 92.9%), upper respiratory tract infection symptoms (n=12, 85.7%) and gastrointestinal tract discomfort (n=6, 42.9%). Seizures occurred 3-14 days after antecedent symptoms with patterns of generalized tonic-clonic seizures, focal seizures or myoclonic seizures. The seizures were refractory to combinations of antiepileptic drugs (AEDs). Prolonged fever (n=14, 100.0%), hypersensitivity to AEDs (n=11, 78.6%) and liver function impairment (n=8, 57.1%) were noted during the period of hospitalization. The follow-up EEG findings were similar to those of initial findings including epileptiform discharges and/or generalized background slow waves. Initial brain MRI scans were normal but later showed focal or multifocal abnormal signal intensity followed by generalized brain atrophy in more than 50% of cases. The general prognosis was poor with variable psychomotor retardation and persistence of refractory epileptic seizures.

CONCLUSIONS

The similarities of the clinical features support AERRPS as a new epileptic syndrome. More study is needed to specify the etiology of the syndrome as the first step for more effective treatment.

Chronic myoclonia of subcortical origin with antiglutamate receptor antibodies

We report a 10-year-old girl with chronic nonprogressive continuous myoclonia with mild muscle weakness and dissociated sensory impairment of the ipsilateral side of myoclonic jerks. Irregular myoclonic jerks continuously appeared in the right upper limb. The jerk-locked back averaging of electroencephalographic activity failed to show any activity preceded by the muscle contraction. Magnetic resonance imaging of the brain and cervical spine revealed no abnormal findings. Single photon emission computed tomography showed an increased blood perfusion in the left thalamus. (18)F-deoxyglucose-positron emission tomography (PET) also showed a slight high density in the posterior region of the left thalamus. Antiglutamate receptor epsilon2 and delta2 antibodies were detected in the serum and cerebrospinal fluid. The patient's symptoms have now been stable with clonazepam treatment for 2 years. The left thalamus was suspected to have been the region at least partly responsible for the patient's symptoms.

Acute encephalitis with refractory, repetitive partial seizures: case reports of this unusual post-encephalitic epilepsy

We report on three acute encephalitis patients with refractory, repetitive partial seizures (AERRPS). All three suffered acute febrile episodes associated with status epilepticus, which necessitated high-dose barbiturate therapy under artificial ventilation for several weeks. Electroencephalography (EEG) revealed a predominance of diffuse epileptiform discharges initially, subsequently developing into periodic bursts of these discharges. Reduction of the barbiturate dosage resulted in clinical and subclinical partial seizures appearing repetitively in clusters. Prolonged fever persisted for 2-3 months, even several weeks after normalization of cell counts in the cerebrospinal fluid. The EEG showed an improvement after resolution of this fever, and seizures became less frequent, although still intractable. Oral administration of high-dose barbiturate and benzodiazepines were partially effective during the acute phase, and a barbiturate dependency, lasting for years, was noted in one patient. Steroid administration was effective in stopping the febrile episodes in one patient, with concurrent improvement in seizure control. Magnetic resonance imaging showed enhancement of bitemporal cortical areas in one patient, and high signal intensity on T2 weighted image in the bilateral claustrum in another patient. Diffuse cortical atrophy appeared within two months after the onset of encephalitis in all patients. The evolution of the seizures and EEG findings suggested a high degree of cortical excitability in AERRPS. In this report, we propose a tentative therapeutic regimen for seizure control in this condition. We also hypothesize that a prolonged inflammatory process exists in the cerebral cortex with AERRPS, and may be pivotal in the epileptogenesis.