Seizure Perpetuation Research Articles

Exploring the association of disease-modifying therapies for multiple sclerosis and BTK inhibitors with epilepsy.

Multiple lines of evidence suggest a role of inflammation in epilepsy. Seizure incidence in patients with multiple sclerosis (MS) is twofold to threefold higher than the age-matched general population. To explore the association of MS disease-modifying therapies (DMTs) and FDA-approved Bruton tyrosine kinase inhibitors (for lymphocytic malignancies) with the occurrence of epilepsy using the US Food and Drug Administration Adverse Event Reporting System (FAERS) database. Secondary analysis of the FAERS database. We conducted a disproportionality analysis of FAERS between 2003-Q4 and 2023-Q3. MS DMTs and the Bruton tyrosine kinase inhibitor, ibrutinib, were included in the analysis. An inverse association was defined by a 95% confidence interval (CI) upper limit of reporting odds ratio (ROR) <1. We found an inverse association of ibrutinib, ocrelizumab, ofatumumab, rituximab, and teriflunomide with epilepsy. The strongest inverse association was seen with ibrutinib (ROR: 0.338; 95% CI: 0.218-0.524). Our findings suggest the possibility of considering these medications for repurposing opportunities in epilepsy and support a potential pathogenic role of leukocyte subsets in seizure perpetuation.

When a Good Cop Turns Bad: The Pro-Ictal Action of Parvalbumin Expressing Interneurons During Seizures.

KCC2 Overexpression Prevents the Paradoxical Seizure-Promoting Action of Somatic Inhibition Magloire, V., Cornford, J., Lieb, A., Kullmann, D. M., and Pavlov, I. Nat. Commun. 10, 1225. doi:10.1038/s41467-019-08933-4. Although cortical interneurons are apparently well-placed to suppress seizures, several recent reports have highlighted a paradoxical role of perisomatic-targeting parvalbumin-positive (PV+) interneurons in ictogenesis. Here, we use an acute in vivo model of focal cortical seizures in awake behaving mice, together with closed-loop optogenetic manipulation of PV+ interneurons, to investigate their function during seizures. We show that photo-depolarization of PV+ interneurons rapidly switches from an anti-ictal to a pro-ictal effect within a few seconds of seizure initiation. The pro-ictal effect of delayed photostimulation of PV+ interneurons was not shared with dendrite-targeting somatostatin-positive (SOM+) interneurons. We also show that this switch can be prevented by overexpression of the neuronal potassium-chloride co-transporter KCC2 in principal cortical neurons. These results suggest that strategies aimed at improving the ability of principal neurons to maintain a trans-membrane chloride gradient in the face of excessive network activity can prevent interneurons from contributing to seizure perpetuation.

KCC2 overexpression prevents the paradoxical seizure-promoting action of somatic inhibition

Although cortical interneurons are apparently well-placed to suppress seizures, several recent reports have highlighted a paradoxical role of perisomatic-targeting parvalbumin-positive (PV+) interneurons in ictogenesis. Here, we use an acute in vivo model of focal cortical seizures in awake behaving mice, together with closed-loop optogenetic manipulation of PV+ interneurons, to investigate their function during seizures. We show that photo-depolarization of PV+ interneurons rapidly switches from an anti-ictal to a pro-ictal effect within a few seconds of seizure initiation. The pro-ictal effect of delayed photostimulation of PV+ interneurons was not shared with dendrite-targeting somatostatin-positive (SOM+) interneurons. We also show that this switch can be prevented by overexpression of the neuronal potassium-chloride co-transporter KCC2 in principal cortical neurons. These results suggest that strategies aimed at improving the ability of principal neurons to maintain a trans-membrane chloride gradient in the face of excessive network activity can prevent interneurons from contributing to seizure perpetuation.

Perampanel in patients with refractory and super-refractory status epilepticus in a neurological intensive care unit: A single-center audit of 30 patients.

In refractory status epilepticus (SE), γ-aminobutyric acidergic drugs become less effective and glutamate plays a major role in seizure perpetuation. Data on the efficacy of perampanel (PER) in treatment of refractory SE in humans are limited. Here, we present a single-center case series of patients with refractory SE who received PER orally in an intensive care unit. We retrospectively analyzed treatment response, outcome, and adverse effects of all patients with refractory SE in our Neurological Intensive Care Unit who received add-on PER between September 2012 and February 2018. Thirty patients with refractory SE (median = 72years, range = 18-91, 77% women) were included. In 14 patients (47%), a high-dose approach was used, with a median initial dose of 24mg (range = 16-32). In five patients (17%), SE could be terminated after PER administration (median dose = 6mg, range = 6-20mg, 2/5 patients in high-dose group). Clinical response was observed after a median of 24hours (range = 8-48hours), whereas electroencephalogram resolved after a median of 60hours (range = 12-72hours). Time to treatment response tended to be shorter in patients receiving high-dose PER (median clinical response = 16hours vs 18hours; electroencephalographic response = 24hours vs 72hours), but groups were too small for statistical analysis. Continuous cardiorespiratory monitoring showed no changes in cardiorespiratory function after "standard" and "high-dose" treatment. Elevated liver enzymes without clinical symptoms were observed after a median of 6days in seven of 30 patients (23%; 57% high dose vs 43% standard dose), of whom six also received treatment with phenytoin (PHT). Outcome was unfavorable (death, persistent vegetative state) in 13 patients (43%; 39% high dose vs 61% standard dose), and good recovery (no significant disability, moderate disability) was achieved in nine patients (56% high dose vs 44% standard dose). Oral PER in loading doses up to 32mg were well tolerated but could terminate SE only in a few patients (5/30; 17%). Long duration of SE, route of administration, and severe underlying brain dysfunction might be responsible for the modest result. An intravenous formulation is highly desired to explore the full clinical utility in the treatment of refractory SE.

Histological Characterization of the Irritative Zones in Focal Cortical Dysplasia Using a Preclinical Rat Model.

Current clinical practice in focal epilepsy involves brain source imaging (BSI) to localize brain areas where from interictal epileptiform discharges (IEDs) emerge. These areas, named irritative zones, have been useful to define candidate seizures-onset zones during pre-surgical workup. Since human histological data are mostly available from final resected zones, systematic studies characterizing pathophysiological mechanisms and abnormal molecular/cellular substrates in irritative zones—independent of them being epileptogenic—are challenging. Combining BSI and histological analysis from all types of irritative zones is only possible through the use of preclinical animal models. Here, we recorded 32-channel spontaneous electroencephalographic data from rats that have focal cortical dysplasia (FCD) and chronic seizures. BSI for different IED subtypes was performed using the methodology presented in Bae et al. (2015). Post-mortem brain sections containing irritative zones were stained to quantify anatomical, functional, and inflammatory biomarkers specific for epileptogenesis, and the results were compared with those obtained using the contralateral healthy brain tissue. We found abnormal anatomical structures in all irritative zones (i.e., larger neuronal processes, glioreactivity, and vascular cuffing) and larger expressions for neurotransmission (i.e., NR2B) and inflammation (i.e., ILβ1, TNFα and HMGB1). We conclude that irritative zones in this rat preclinical model of FCD comprise abnormal tissues disregarding whether they are actually involved in icto-genesis or not. We hypothesize that seizure perpetuation happens gradually; hence, our results could support the use of IED-based BSI for the early diagnosis and preventive treatment of potential epileptic foci. Further verifications in humans are yet needed.

Curcumin attenuates inflammatory response and cognitive deficits in experimental model of chronic epilepsy

Evidence suggests that glial cells play a critical role in inflammation in chronic epilepsy, contributing to perpetuation of seizures and cognitive dysfunctions. The present study was designed to evaluate the beneficial effect of curcumin, a polyphenol with pleiotropic properties, on cognitive deficits and inflammation in chronic epilepsy. Kindled model of epilepsy was induced by administering sub-convulsive dose of pentylenetetrazole (PTZ) at 40 mg/kg, i.p. every alternative day for 30 days to Wistar rats. The animals were assessed for cognitive deficits by Morris water maze and inflammatory response in terms of microglial and astrocyte activation. PTZ treated animals had increased escape latency suggesting impaired cognitive functions. Further, an increased expression of astrocyte (GFAP) and microglial (Iba-1) activation markers were observed in terms of mRNA and protein levels in the PTZ treated animals. Concomitantly, mRNA and protein levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and chemokine (MCP-1) were increased in hippocampus and cortex. Immunoreactivity to anti-GFAP and anti-Iba-1 antibodies was also enhanced in hippocampus and cortex suggesting gliosis in PTZ treated animals. However, curcumin administration at a dose of 100 mg/kg to PTZ animals prevented cognitive deficits. A significant decrease in pro-inflammatory cytokines and chemokine expression was observed in hippocampus and cortex of PTZ treated rats supplemented with curcumin. In addition, curcumin also attenuated increased expression of GFAP and Iba-1 in animals with PTZ induced chronic epilepsy. Moreover, immunohistochemical analysis also showed significant reduction in number of activated glial cells on curcumin administration to PTZ treated animals. Taken together, these findings suggest that curcumin is effective in attenuating glial activation and ameliorates cognitive deficits in chronic epilepsy.

Perampanel in patients with refractory and super-refractory status epilepticus in a neurological intensive care unit.

In refractory status epilepticus (SE), because of subcellular maladaptive changes, GABAergic drugs are no longer effective, and the excitatory neurotransmitter glutamate (Glu) plays a major role in seizure perpetuation. Perampanel (PER, licensed since 09/2012) is the first orally active noncompetitive AMPA receptor antagonist for adjunctive treatment of refractory focal epilepsy. We analyzed treatment response, seizure outcome, and adverse effects of add-on treatment with perampanel in patients with refractory status epilepticus in the Neurological Intensive Care Unit (NICU), Salzburg, Austria between 09/2012 and 11/2014 by retrospective chart review. Twelve patients (75% women) with refractory status epilepticus were treated with PER administered per nasogastric tube between 09/2012 and 11/2014. Median age was 75 years [range: 60-91]. The most frequent SE type was nonconvulsive SE (NCSE) with (5/12, 42%) and without coma (6/12, 50%). In seven patients (58%), SE arose de novo, with an acute symptomatic cause in five patients (42%). Cerebrovascular diseases (4/12, 33%) and cerebral tumors (4/12, 33%) were the most common etiologies. Perampanel was given after a median number of four antiepileptic drugs [range: 2-7] and a median time of 1.5 days [range: 0.8-18.3]. In one patient (8%), clinical improvement was observed within 24h and EEG improvement within 60 h after administration of PER, while in another patient (8%), clinical and EEG improvement was observed more than 48 h after administration. Median initial dose was 4 mg [range: 2-12; SD: 4.11], titrated up to a median of 12 mg [range: 4-12] in steps of 2 to 4 mg per day. No adverse effects were reported regarding cardiorespiratory changes or laboratory parameters. Outcomes after SE were moderate disability in five patients (42%), death in three patients (25%), and persistent vegetative state in two patients (17%). Though glutamate plays a major role in seizure perpetuation, the noncompetitive AMPA receptor antagonist PER could only ameliorate seizure activity in a few patients with refractory SE. The long duration of SE before the administration of PER via nasogastric tube, as well as relatively low doses of PER, might be responsible for the modest result. Perampanel was well tolerated, and no adverse events were reported. This article is part of a Special Issue entitled Status Epilepticus.

Modulation of Immunity and the Inflammatory Response: A New Target for Treating Drug-resistant Epilepsy

Until recently, epilepsy medical therapy is usually limited to anti-epileptic drugs (AEDs). However, approximately 1/3 of epilepsy patients, described as drug-resistant epilepsy (DRE) patients, still suffer from continuous frequent seizures despite receiving adequate AEDs treatment of sufficient duration. More recently, with the remarkable progress of immunology, immunity and inflammation are considered to be key elements of the pathobiology of epilepsy. Activation of inflammatory processes in brain tissue has been observed in both experimental seizure animal models and epilepsy patients. Anti-inflammatory and immunotherapies also showed significant anticonvulsant properties both in clinical and in experimental settings. The above emerging evidence indicates that modulation of immunity and inflammatory processes could serve as novel specific targets to achieve potential anticonvulsant effects for the patients with epilepsy, especially DRE. Herein we review the recent evidence supporting the role of inflammation in the development and perpetuation of seizures, and also discuss the recent achievements in modulation of inflammation and immunotherapy applied to the treatment of epilepsy. Apart from medical therapy, we also discuss the influences of surgery, ketogenic diet, and electroconvulsive therapy on immunity and inflammation in DRE patients. Taken together, a promising perspective is suggested for future immunomodulatory therapies in the treatment of patients with DRE.

Modulation of Immunity and the Inflammatory Response: A New Target for Treating Drug-resistant Epilepsy

Until recently, epilepsy medical therapy is usually limited to anti-epileptic drugs (AEDs). However, approximately 1/3 of epilepsy patients, described as drug-resistant epilepsy (DRE) patients, still suffer from continuous frequent seizures despite receiving adequate AEDs treatment of sufficient duration. More recently, with the remarkable progress of immunology, immunity and inflammation are considered to be key elements of the pathobiology of epilepsy. Activation of inflammatory processes in brain tissue has been observed in both experimental seizure animal models and epilepsy patients. Anti-inflammatory and immunotherapies also showed significant anticonvulsant properties both in clinical and in experimental settings. The above emerging evidence indicates that modulation of immunity and inflammatory processes could serve as novel specific targets to achieve potential anticonvulsant effects for the patients with epilepsy, especially DRE. Herein we review the recent evidence supporting the role of inflammation in the development and perpetuation of seizures, and also discuss the recent achievements in modulation of inflammation and immunotherapy applied to the treatment of epilepsy. Apart from medical therapy, we also discuss the influences of surgery, ketogenic diet, and electroconvulsive therapy on immunity and inflammation in DRE patients. Taken together, a promising perspective is suggested for future immunomodulatory therapies in the treatment of patients with DRE. Keywords: Immunity, Inflammation, Drug-Resistant Epilepsy, Auto-antibodies, Cytokines

Inflammation in epilepsy: Clinical observations

Over the past decade, an increasing number of observations indicate that activation of inflammatory processes occurs in variety of focal epilepsies. Understanding the feature and consequences of neuroinflammation, including the contribution to development and perpetuation of seizures, as well as to mood or cognitive dysfunction, is a major requisite for delineating its role in epilepsy. The present article discusses the most recent observations supporting the involvement of the inflammatory response in human focal epilepsy. It also evaluates emerging evidence concerning the possibility to identify epilepsy-associated inflammatory biomarkers in cerebrospinal fluid and serum, as well as the potential application of neuroimaging approaches to study the inflammatory reactions in chronic epilepsy patients in vivo, aiming to improve the recognition of appropriate patient populations who might benefit from antiinflammatory or immunomodulatory therapies.

Activation of toll-like receptor, RAGE and HMGB1 signalling in malformations of cortical development

Recent evidence in experimental models of seizures and in temporal lobe epilepsy support an important role of high-mobility group box 1 and toll-like receptor 4 signalling in the mechanisms of hyperexcitability leading to the development and perpetuation of seizures. In this study, we investigated the expression and cellular distribution of toll-like receptors 2 and 4, and of the receptor for advanced glycation end products, and their endogenous ligand high-mobility group box 1, in epilepsy associated with focal malformations of cortical development. Immunohistochemistry showed increased expression of toll-like receptors 2 and 4 and receptor for advanced glycation end products in reactive glial cells in focal cortical dysplasia, cortical tubers from patients with the tuberous sclerosis complex and in gangliogliomas. Toll-like receptor 2 was predominantly detected in cells of the microglia/macrophage lineage and in balloon cells in focal cortical dysplasia, and giant cells in tuberous sclerosis complex. The toll-like receptor 4 and receptor for advanced glycation end products were expressed in astrocytes, as well as in dysplastic neurons. Real-time quantitative polymerase chain reaction confirmed the increased receptors messenger RNA level in all pathological series. These receptors were not detected in control cortex specimens. In control cortex, high-mobility group box 1 was ubiquitously detected in nuclei of glial and neuronal cells. In pathological specimens, protein staining was instead detected in the cytoplasm of reactive astrocytes or in tumour astrocytes, as well as in activated microglia, predictive of its release from glial cells. In vitro experiments in human astrocyte cultures showed that nuclear to cytoplasmic translocation of high-mobility group box 1 was induced by interleukin-1β. Our findings provide novel evidence of intrinsic activation of these pro-inflammatory signalling pathways in focal malformations of cortical development, which could contribute to the high epileptogenicity of these developmental lesions.