A generalized seizure type: Myoclonic-to-tonic seizure.
Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology
BACKGROUND AND PURPOSE:To test the hypothesis that myoclonic seizures can evolve to tonic seizures, we documented the electroclinical features of this under-recognized seizure type. METHODS:We observed a distinct seizure pattern starting with myoclonus without returning to an interictal state, which subsequently evolved into generalized tonic seizures. The detailed symptomatic and electroencephalographic characteristics of this seizure were extracted, and the clinical manifestations, drug curative responses in patients with this seizure were reviewed and analyzed. RESULTS:The onset of all seizures was characterized by a preceding period of myoclonus and bursts of generalized spike or poly-spike slow wave discharges with high amplitude. This was closely followed by the occurrence of tonic seizures, which were distinguished by bursts of generalized fast activity at 10 Hz or higher frequency. This under-recognized seizure type has been designated as myoclonic-to-tonic (MT) seizure. The number of patients identified with MT seizures in this study was 34. The prevalence rate of MT seizures was found to be higher in males. While MT seizures typically included a tonic component, it should be noted that some patients experiencing this seizure type never presented with isolated tonic seizures. Generalized Epilepsy not further defined (GE) accounted for approximately one-third of the diagnosed cases, followed by Lennox-Gastaut syndrome and Epilepsy with Myoclonic-Atonic seizures. In comparison to other types of epilepsy, GE with MT seizures demonstrated a more favorable prognosis. CONCLUSIONS:The classification of myoclonic-to-tonic seizure represents a novel approach in comprehending the ictogenesis of generalized seizures and can provide valuable assistance to clinicians in epilepsy diagnosis.
10.1016/j.clinph.2024.04.011
Vitamin B6 dependent seizures.
Plecko Barbara,Stöckler Sylvia
The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques
Vitamin B6 is an abundant cofactor in aminoacid- and neurotransmitter metabolism. Physiologic availability depends on dietary supply, intact absorption and conversion of pyridoxamine and pyridoxine into the only active cofactor, pyridoxal-5'-phosphate (PLP) in liver. By now we know of four genetic epilepsies with vitamin B6 dependent seizures. Two are caused by reduced synthesis/availability of PLP (Pyridox(am)in-phosphate oxidase (PNPO) deficiency and infantile hypophosphatasia) and two by increased utilization/inactivation (pyridoxine-dependent epilepsy and hyperprolinemia type II). Aside from hyperprolinemia type II these disorders usually present with therapyresistant (myoclonic) seizures in the neonatal period. The EEG findings may range from burst suppression pattern to unspecific slowing or may even be normal. All four disorders can be diagnosed by reliable biomarkers and be confirmed by molecular analysis of the respective genes. While PLP would benefit all four entities, PNPO patients are typically resistant to pyridoxine and need PLP substitution. Especially in neonatal, therapyresistant seizures, these disorders have to be considered early, to prevent irreversible neurologic damage.
The New Classification of Seizures by the International League Against Epilepsy 2017.
Fisher Robert S
Current neurology and neuroscience reports
PURPOSE OF REVIEW:This review presents the newly developed International League Against Epilepsy (ILAE) 2017 classification of seizure types. RECENT FINDINGS:The fundamental distinction is between seizures that begin focally in one hemisphere of the brain, generalized onset seizures that apparently originate in both hemispheres, and seizures of unknown onset. Focal seizures optionally can be subclassified according to whether awareness (a surrogate marker for consciousness) is intact or impaired. The next level of classification for focal seizures is motor (with subgroups automatisms, atonic, clonic, epileptic spasms, hyperkinetic, myoclonic, tonic), non-motor (with subgroups autonomic, behavior arrest, cognitive, emotional, sensory), and focal to bilateral tonic-clonic. Generalized seizures are categorized as motor (tonic-clonic, clonic, tonic, myoclonic, myoclonic-tonic-clonic, myoclonic-atonic, atonic, epileptic spasms) and non-motor/absence (typical, atypical, myoclonic, eyelid myoclonia). The classification allows new types of focal seizures and a few new generalized seizures, and clarifies terms used to name seizures.
10.1007/s11910-017-0758-6
Structural brain abnormalities in epilepsy with myoclonic atonic seizures.
Denervaud Solange,Korff Christian,Fluss Joël,Kalser Judith,Roulet-Perez Eliane,Hagmann Patric,Lebon Sébastien
Epilepsy research
OBJECTIVE:Epilepsy with myoclonic atonic seizure (EMAS) occurs in young children with previously normal to subnormal development. The outcome ranges from seizure freedom with preserved cognitive abilities to refractory epilepsy with intellectual disability (ID). Routine brain imaging typically shows no abnormalities. We aimed to compare the brain morphometry of EMAS patients with healthy subjects several years after epilepsy onset, and to correlate it to epilepsy severity and cognitive findings. METHODS:Fourteen EMAS patients (4 females, 5-14 years) and 14 matched healthy controls were included. Patients were classified into three outcome groups (good, intermediate, poor) according to seizure control and cognitive and behavioral functioning. Individual anatomical data (T1-weighted sequence) were processed using the FreeSurfer pipeline. Cortical volume (CV), cortical thickness (CT), local gyrification index (LGI), and subcortical volumes were used for group-comparison and linear regression analyses. RESULTS:Morphometric comparison between EMAS patients and healthy controls revealed that patients have 1) reduced CV in frontal, temporal and parietal lobes (p = <.001; 0.009 and 0.024 respectively); 2) reduced CT and LGI in frontal lobes (p = 0.036 and 0.032 respectively); and 3) a neat cerebellar volume reduction (p = 0.011). Neither the number of anti-seizure medication nor the duration of epilepsy was related to cerebellar volume (both p > 0.62). Poor outcome group was associated with lower LGI. Patients in good and intermediate outcome groups had a comparable LGI to their matched healthy controls (p > 0.27 for all lobes). CONCLUSIONS:Structural brain differences were detectable in our sample of children with EMAS, mainly located in the frontal lobes and cerebellum. These findings are similar to those found in patients with genetic/idiopathic generalized epilepsies. Outcome groups correlated best with LGI. Whether these anatomical changes reflect genetically determined abnormal neuronal networks or a consequence of sustained epilepsy remains to be solved with prospective longitudinal studies.
10.1016/j.eplepsyres.2021.106771
Kctd7 deficiency induces myoclonic seizures associated with Purkinje cell death and microvascular defects.
Disease models & mechanisms
Mutations in the potassium channel tetramerization domain-containing 7 (KCTD7) gene are associated with a severe neurodegenerative phenotype characterized by childhood onset of progressive and intractable myoclonic seizures accompanied by developmental regression. KCTD7-driven disease is part of a large family of progressive myoclonic epilepsy syndromes displaying a broad spectrum of clinical severity. Animal models of KCTD7-related disease are lacking, and little is known regarding how KCTD7 protein defects lead to epilepsy and cognitive dysfunction. We characterized Kctd7 expression patterns in the mouse brain during development and show that it is selectively enriched in specific regions as the brain matures. We further demonstrate that Kctd7-deficient mice develop seizures and locomotor defects with features similar to those observed in human KCTD7-associated diseases. We also show that Kctd7 is required for Purkinje cell survival in the cerebellum and that selective degeneration of these neurons is accompanied by defects in cerebellar microvascular organization and patterning. Taken together, these results define a new model for KCTD7-associated epilepsy and identify Kctd7 as a modulator of neuron survival and excitability linked to microvascular alterations in vulnerable regions.
10.1242/dmm.049642
Antiseizure medications for idiopathic generalized epilepsies: a systematic review and network meta-analysis.
Journal of neurology
OBJECTIVES:To compare the efficacy and safety of antiseizure medications (ASMs), both as monotherapies and adjunctive therapies, for idiopathic generalized epilepsies (IGEs) and related entities. METHODS:Two reviewers independently searched PubMed, Embase, and the Cochrane Library for relevant randomized controlled trials from December 2022 to February 2023. Studies on the efficacy and safety of ASM monotherapies or adjunctive therapies for IGEs and related entities-including juvenile myoclonic epilepsy, childhood absence epilepsy (CAE), juvenile absence epilepsy, or generalized tonic-clonic seizures alone (GTCA)-were included. Efficacy outcomes were the proportions of patients remaining seizure free for 1, 3, 6, and 12 months; safety outcomes were the proportions of any treatment-emergent adverse event (TEAE) and TEAEs leading to discontinuation. Network meta-analyses were performed in a random-effects model to obtain odds ratios and 95% confidence intervals. Rankings of ASMs were based on the surface under the cumulative ranking curve (SUCRA). This study is registered with PROSPERO (No. CRD42022372358). RESULTS:Twenty-eight randomized controlled trials containing 4282 patients were included. As monotherapies, all ASMs were more effective than placebo, and valproate and ethosuximide were significantly better than lamotrigine. According to the SUCRA for efficacy, ethosuximide ranked first for CAE, whereas valproate ranked first for other types of IGEs. As adjunctive therapies, topiramate ranked best for GTCA as well as overall for IGEs, while levetiracetam ranked best for myoclonic seizures. For safety, perampanel ranked best (measured by any TEAE). CONCLUSIONS:All of the studied ASMs were more effective than placebo. Valproate monotherapy ranked best overall for IGEs, whereas ethosuximide ranked best for CAE. Adjunctive topiramate and levetiracetam were most effective for GTCA and myoclonic seizures, respectively. Furthermore, perampanel had the best tolerability.
10.1007/s00415-023-11834-8
Antiseizure Medications Withdrawal Seizures in Patients with Juvenile Myoclonic Epilepsy.
The Israel Medical Association journal : IMAJ
BACKGROUND:Patients with juvenile myoclonic epilepsy (JME) are especially prone to having antiseizure medications (ASMs) withdrawal seizures (WS). OBJECTIVES:To clarify whether WS in JME patients are caused by a high tendency of non-adherence from seizure-free patients or by a constitutive increased sensitivity to drug withdrawal. METHODS:Epilepsy patients followed in a tertiary epilepsy clinic between 2010 and 2013 were included in the study. WS prevalence was compared between drug-responsive and drug-resistant JME patients and patients with other types of epilepsy. RESULTS:The study included 23 JME patients (16 drug-responsive and 7 drug-resistant) and 138 patients with other epilepsies (74 drug-responsive and 64 drug-resistant). JME patients were younger and included more women than non-JME patients. Significantly more WS were seen in JME than in non-JME patients (P = 0.01) and in the drug-resistant fraction of JME patients in comparison to drug-resistant non-JME patients (P = 0.02). On logistic regression, the type of epilepsy, but not the patient's sex, was found to significantly predict WS. No significant difference was found in the prevalence of WS between drug-responsive and drug-resistant JME patients. The main ASM discontinued in JME was valproic acid (VPA), especially in women. CONCLUSIONS:Our findings suggest a higher sensitivity of JME patients to withdrawal of medications. It is important to educate JME patients about treatment adherence and to explain to their physicians how to carefully reduce or replace ASMs to mitigate the morbidity and mortality related to ASM withdrawal.
Adjunctive perampanel and myoclonic and absence seizures: Post hoc analysis of data from study 332 in patients with idiopathic generalized epilepsy.
Seizure
PURPOSE:This post hoc analysis assessed the effects of adjunctive perampanel on myoclonic and absence seizure outcomes in patients (aged ≥12 years) with idiopathic generalized epilepsy (IGE) and generalized tonic-clonic seizures during the double-blind (up to 8 mg/day) and open-label extension (OLEx; up to 12 mg/day) phases of Study 332. METHODS:Patients experiencing myoclonic and/or absence seizures during study baseline were included. Assessments for myoclonic and absence seizures included: median percent change in seizure frequency, number of seizure days and seizure-free days (all per 28 days), 50 % and 75 % responder rates, seizure-freedom rates, seizure worsening, and monitoring of treatment-emergent adverse events (TEAEs). RESULTS:During the double-blind phase, myoclonic and/or absence seizures were reported in 47/163 and 60/163 patients, respectively. Median percent reductions in seizure frequency per 28 days from study baseline were 52.5% and 24.5% (myoclonic seizures) and 7.6 % and 41.2 % (absence seizures) for placebo and perampanel, respectively; seizure-freedom rates were 13.0 % and 16.7 % (myoclonic seizures) and 12.1 % and 22.2 % (absence seizures), respectively. During the OLEx phase, 46/138 and 52/138 patients experienced myoclonic and/or absence seizures, respectively. Responses during the double-blind phase were maintained during long-term (>104 weeks) adjunctive perampanel treatment. The frequency/type of TEAEs was consistent with the known safety profile of perampanel. CONCLUSION:In this post hoc analysis, adjunctive perampanel was not associated with any overall worsening of absence seizures. Further research is needed to investigate the effect of adjunctive perampanel in IGE patients with myoclonic and/or absence seizures.
10.1016/j.seizure.2020.06.011
A systematic review of the efficacy of perampanel as treatment for myoclonic seizures and symptomatic myoclonus
Epileptic disorders : international epilepsy journal with videotape
Epileptic myoclonus or myoclonic seizures can occur in idiopathic generalized epilepsy (IGE) and progressive myoclonus epilepsy (PME). However, symptomatic myoclonus which is stimulus-sensitive and provoked by movement is typically seen in PME and Lance-Adams syndrome. Symptomatic myoclonus is not always associated with epileptiform discharges on the electroencephalogram. Therapeutic interventions such as anti-seizure medications (ASMs), the ketogenic diet and vagus nerve stimulation are not always effective. There is emerging evidence that perampanel (PER), an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, may be effective for the treatment of myoclonic seizures and symptomatic myoclonus. We performed a systematic review of the literature to assess the efficacy of PER as treatment for myoclonic seizures and symptomatic myoclonus. Twenty-seven studies with a total sample size of 260 patients were included. The efficacy of PER was analysed separately for myoclonic seizures and symptomatic myoclonus. In the group with myoclonic seizures, 50% responder, 75% responder and seizure freedom rates were reported as 74.3% (101/ 136), 60.3% (82/136) and 57.4% (78/136), respectively, with a follow-up duration of 6-12 months. However, in one post-hoc analysis of data from patients with IGE, the efficacy of PER as treatment for myoclonic seizures during the double-blind phase showed no significant difference compared to placebo. The efficacy of PER for symptomatic myoclonus was reported in a total of 119 patients. Four studies (n=88 patients) reported the efficacy of PER as a decrease in myoclonus score/scale. In the remaining 31 patients, symptomatic myoclonus resolved in three patients, decreased in 21 patients and seven patients showed no improvement. We also analysed the number of patients who were already on levetiracetam (LEV) or valproic acid (VPA) at the time of PER initiation; these data were available for 153 patients. Of these, 56.8% were on LEV and 75.1% were on VPA when PER was initiated. This systematic review suggests that PER maybe effective as treatment for drug-resistant myoclonic seizures and symptomatic myoclonus. It may also be effective in patients who have already failed to respond to LEV and VPA. These findings are preliminary yet encouraging. This study has several limitations, particularly given the scarcity of high-quality randomized controlled trials and marked heterogeneity regarding the type and results of the studies. Hence, the findings of this review should be viewed with considerable reservation.
10.1684/epd.2022.1439
Epilepsy with myoclonic-atonic seizures, also known as Doose syndrome: Modification of the diagnostic criteria.
European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society
PURPOSE:The aim of this review is to propose the updated diagnostic criteria of epilepsy with myoclonic-atonic seizures (EMAS), which is a recent subject of genetic studies. Although EMAS has been well known as Doose syndrome, it is often difficult to diagnose due to a lack of consensus regarding some of the inclusion criteria. Along with progress in molecular genetic study on the syndrome, it becomes important to recruit electroclinical homogeneous EMAS patients, hence the validity of the clinical criteria should be verified based on recent clinical researches. At present, the most updated ILAE diagnostic manual of EMAS includes: (1) normal development and cognition before the onset of epilepsy; (2) onset of epilepsy between 6 months and 6 years of age (peak: 2-4 years); (3) myoclonic-atonic seizures (MAS) are mandatory (4) presence of generalized spike-wave discharges at 2-3 Hz without persistent focal spike discharges; and (5) exclusion of other myoclonic epilepsy syndromes. In the criteria, we should emphasize that the age at onset of MAS is between 2-5 years in (2), presence of myoclonic-atonic, atonic or myoclonic-flexor seizures (MASs) causing drop attacks associated with generalized spike-wave discharges is mandatory in (3), and epileptic spasms causing drop attacks must be excluded in (5). In the modified criteria, I propose that EMAS is redesignated as genetic generalized epilepsy with MASs, consistent with the familial genetic study conducted by Doose and the recent identification of candidate genes. It should also be noted that EMASs evolves to transient or long-lasting epileptic encephalopathy.
10.1016/j.ejpn.2021.11.009
Non-convulsive seizures and non-convulsive status epilepticus in neuro-intensive care unit.
Acta neurologica Scandinavica
Most seizures in critical ill patients are non-convulsive, and some patients may develop non-convulsive status epilepticus (NCSE), a state of continuous or repetitive seizures without convulsions. With the growing use of continuous electroencephalogram (EEG) monitoring in neuro-intensive care units, non-convulsive seizure (NCS) and NCSE are increasingly diagnosed in patients with impaired consciousness, and progress has been made in identifying various EEG characteristics of NCS/NCSE. Epidemiological studies have contributed to a better understanding of etiologies and risk factors for NCS and NCSE. However, sufficient clinical trials about the treatment of NCS and NCSE are still lacking. The appropriate level of aggressiveness in the treatment of NCSE is still debated, particularly with regard to the use of anesthetics in patients with refractory NCSE. In this review, we summarize the EEG, clinical, epidemiological, diagnostic and therapeutic knowledge of NCS and NCSE in the neuro-intensive care setting in detail.
10.1111/ane.13718
Assessment of the Validity of the 2HELPS2B Score for Inpatient Seizure Risk Prediction.
Struck Aaron F,Tabaeizadeh Mohammad,Schmitt Sarah E,Ruiz Andres Rodriguez,Swisher Christa B,Subramaniam Thanujaa,Hernandez Christian,Kaleem Safa,Haider Hiba A,Cissé Abbas Fodé,Dhakar Monica B,Hirsch Lawrence J,Rosenthal Eric S,Zafar Sahar F,Gaspard Nicholas,Westover M Brandon
JAMA neurology
Importance:Seizure risk stratification is needed to boost inpatient seizure detection and to improve continuous electroencephalogram (cEEG) cost-effectiveness. 2HELPS2B can address this need but requires validation. Objective:To use an independent cohort to validate the 2HELPS2B score and develop a practical guide for its use. Design, Setting, and Participants:This multicenter retrospective medical record review analyzed clinical and EEG data from patients 18 years or older with a clinical indication for cEEG and an EEG duration of 12 hours or longer who were receiving consecutive cEEG at 6 centers from January 2012 to January 2019. 2HELPS2B was evaluated with the validation cohort using the mean calibration error (CAL), a measure of the difference between prediction and actual results. A Kaplan-Meier survival analysis was used to determine the duration of EEG monitoring to achieve a seizure risk of less than 5% based on the 2HELPS2B score calculated on first- hour (screening) EEG. Participants undergoing elective epilepsy monitoring and those who had experienced cardiac arrest were excluded. No participants who met the inclusion criteria were excluded. Main Outcomes and Measures:The main outcome was a CAL error of less than 5% in the validation cohort. Results:The study included 2111 participants (median age, 51 years; 1113 men [52.7%]; median EEG duration, 48 hours) and the primary outcome was met with a validation cohort CAL error of 4.0% compared with a CAL of 2.7% in the foundational cohort (P = .13). For the 2HELPS2B score calculated on only the first hour of EEG in those without seizures during that hour, the CAL error remained at less than 5.0% at 4.2% and allowed for stratifying patients into low- (2HELPS2B = 0; <5% risk of seizures), medium- (2HELPS2B = 1; 12% risk of seizures), and high-risk (2HELPS2B, ≥2; risk of seizures, >25%) groups. Each of the categories had an associated minimum recommended duration of EEG monitoring to achieve at least a less than 5% risk of seizures, a 2HELPS2B score of 0 at 1-hour screening EEG, a 2HELPS2B score of 1 at 12 hours, and a 2HELPS2B score of 2 or greater at 24 hours. Conclusions and Relevance:In this study, 2HELPS2B was validated as a clinical tool to aid in seizure detection, clinical communication, and cEEG use in hospitalized patients. In patients without prior clinical seizures, a screening 1-hour EEG that showed no epileptiform findings was an adequate screen. In patients with any highly epileptiform EEG patterns during the first hour of EEG (ie, a 2HELPS2B score of ≥2), at least 24 hours of recording is recommended.
10.1001/jamaneurol.2019.4656
Seizures, Status Epilepticus, and Continuous EEG in the Intensive Care Unit.
Continuum (Minneapolis, Minn.)
PURPOSE OF REVIEW:This article discusses the evolving definitions of seizures and status epilepticus in the critical care environment and the role of critical care EEG in both diagnosing seizure activity and serving as a predictive biomarker of clinical trajectory. RECENT FINDINGS:Initial screening EEG has been validated as a tool to predict which patients are at risk of future seizures. However, accepted definitions of seizures and nonconvulsive status epilepticus encourage a treatment trial when the diagnosis on EEG is indeterminate because of periodic or rhythmic patterns or uncertain clinical correlation. Similarly, recent data have demonstrated the diagnostic utility of intracranial EEG in increasing the yield of seizure detection. EEG has additionally been validated as a diagnostic biomarker of covert consciousness, a predictive biomarker of cerebral ischemia and impending neurologic deterioration, and a prognostic biomarker of coma recovery and status epilepticus resolution. A recent randomized trial concluded that patients allocated to continuous EEG had no difference in mortality than those undergoing intermittent EEG but could not demonstrate whether this lack of difference was because of studying heterogeneous conditions, examining a monitoring tool rather than a therapeutic approach, or examining an outcome measure (mortality) perhaps more strongly associated with early withdrawal of life-sustaining therapy than to a sustained response to pharmacotherapy. SUMMARY:Seizures and status epilepticus are events of synchronous hypermetabolic activity that are either discrete and intermittent or, alternatively, continuous. Seizures and status epilepticus represent the far end of a continuum of ictal-interictal patterns that include lateralized rhythmic delta activity and periodic discharges, which not only predict future seizures but may be further classified as status epilepticus on the basis of intracranial EEG monitoring or a diagnostic trial of antiseizure medication therapy. In particularly challenging cases, neuroimaging or multimodality neuromonitoring may be a useful adjunct documenting metabolic crisis. Specialized uses of EEG as a prognostic biomarker have emerged in traumatic brain injury for predicting language function and covert consciousness, cardiac arrest for predicting coma recovery, and subarachnoid hemorrhage for predicting neurologic deterioration due to delayed cerebral ischemia.
10.1212/CON.0000000000001012
Electroencephalogram in the intensive care unit: a focused look at acute brain injury.
Intensive care medicine
Over the past decades, electroencephalography (EEG) has become a widely applied and highly sophisticated brain monitoring tool in a variety of intensive care unit (ICU) settings. The most common indication for EEG monitoring currently is the management of refractory status epilepticus. In addition, a number of studies have associated frequent seizures, including nonconvulsive status epilepticus (NCSE), with worsening secondary brain injury and with worse outcomes. With the widespread utilization of EEG (spot and continuous EEG), rhythmic and periodic patterns that do not fulfill strict seizure criteria have been identified, epidemiologically quantified, and linked to pathophysiological events across a wide spectrum of critical and acute illnesses, including acute brain injury. Increasingly, EEG is not just qualitatively described, but also quantitatively analyzed together with other modalities to generate innovative measurements with possible clinical relevance. In this review, we discuss the current knowledge and emerging applications of EEG in the ICU, including seizure detection, ischemia monitoring, detection of cortical spreading depolarizations, assessment of consciousness and prognostication. We also review some technical aspects and challenges of using EEG in the ICU including the logistics of setting up ICU EEG monitoring in resource-limited settings.
10.1007/s00134-022-06854-3
Pathophysiology of status epilepticus.
Walker Matthew C
Neuroscience letters
Status epilepticus (SE) is the maximal expression of epilepsy with a high morbidity and mortality. It occurs due to the failure of mechanisms that terminate seizures. Both human and animal data indicate that the longer a seizure lasts, the less likely it is to stop. Recent evidence suggests that there is a critical transition from an ictal to a post-ictal state, associated with a transition from a spatio-temporally desynchronized state to a highly synchronized state, respectively. As SE continues, it becomes progressively resistant to drugs, in particular benzodiazepines due partly to NMDA receptor-dependent internalization of GABA(A) receptors. Moreover, excessive calcium entry into neurons through excessive NMDA receptor activation results in activation of nitric oxide synthase, calpains, and NADPH oxidase. The latter enzyme plays a critical part in the generation of seizure-dependent reactive oxygen species. Calcium also accumulates in mitochondria resulting in mitochondrial failure (decreased ATP production), and opening of the mitochondrial permeability transition pore. Together these changes result in status epilepticus-dependent neuronal death via several pathways. Multiple downstream mechanisms including inflammation, break down of the blood-brain barrier, and changes in gene expression can contribute to later pathological processes including chronic epilepsy and cognitive decline.
10.1016/j.neulet.2016.12.044
Status Epilepticus: Definition, Classification, Pathophysiology, and Epidemiology.
Johnson Emily L,Kaplan Peter W
Seminars in neurology
Status epilepticus (SE) is the state of continuous or repetitive seizures, which can occur with or without convulsions. Evolving definitions of SE take into account the concept that neuronal injury may occur at different times in different types of SE.SE that does not respond to initial treatment may become refractory or even super-refractory. Nonconvulsive SE is increasingly recognized in comatose patients in critical care units, with the growing use of continuous electroencephalogram monitoring. SE is a neurologic emergency that carries a high risk of mortality and morbidity.
10.1055/s-0040-1718722