Status Epilepticus

Overview and time dependence

Status epilepticus (SE) is generally defined as a seizure lasting more than 5 minutes or recurrent seizures without recovery to baseline. Persistent activity converts a normally self-terminating seizure into a self-sustaining state through interacting synaptic, metabolic, vascular, inflammatory, and cell-death mechanisms. ^[3]D The duration of SE is clinically important because progressive molecular changes increase treatment resistance and amplify the risk of neuronal injury; consequently, time is brain. ^[4]D[5]D Experimental and clinical observations indicate that termination of electrographic seizure activity is itself the simplest neuroprotective intervention, although preservation of neuronal function and prevention of epileptogenesis are not necessarily equivalent to preventing cell loss. ^[6]D

Failure of inhibition and enhancement of excitation

During prolonged SE, synaptic γ-aminobutyric acid type A (GABA_A) receptors are progressively internalized, reducing the effectiveness of GABAergic inhibition and contributing to benzodiazepine resistance. In parallel, glutamatergic N-methyl-D-aspartate (NMDA) and AMPA receptors are trafficked toward the synaptic membrane, increasing excitatory transmission. ^[3]D[5]D Experimental models demonstrate increased surface expression of NMDA receptor NR1 subunits and increased synaptic and extrasynaptic NMDA currents in dentate granule cells during SE. ^[17]D These reciprocal receptor changes help explain why GABAergic treatment becomes less effective as seizure duration increases, whereas strategies that additionally reduce glutamatergic excitation may retain mechanistic relevance. ^[5]D

BDNF–TrkB signaling may further promote hyperexcitability by increasing synaptic accumulation of GluN2B-containing NMDA receptors and altering hippocampal glutamatergic synaptic plasticity during SE. ^[12]D The GluN2B/NMDA receptor system is therefore implicated in both seizure-associated plasticity and excitotoxic signaling; age-dependent effects of the GluN2B antagonist ifenprodil have been examined after SE in immature rats, indicating that developmental stage can modify NMDA-related pharmacology. ^[12]D[13]D Prolonged convulsive SE may also cause GABA signaling to become excitatory, providing a further rationale for combined rather than isolated GABAergic treatment in advanced or high-risk SE. ^[4]D

Calcium overload, mitochondrial injury, and oxidative stress

Increased activation of NMDA and other excitatory pathways produces sustained intracellular calcium accumulation. When calcium influx exceeds mitochondrial buffering capacity, mitochondrial membrane depolarization and mitochondrial injury can become irreversible. ^[3]D Mitochondrial dysfunction compromises energy production and promotes additional cellular stress, while excessive metabolic demand during ictal activity can exceed regional perfusion capacity. ^[1]C[3]D Oxidative stress and downstream molecular injury are among the mechanisms associated with SE-related neuronal damage. ^[3]D

Ion-channel activity also contributes to network persistence. In a pilocarpine model, inhibition of Nav1.6 sodium currents reduced SE severity, supporting a role for persistent sodium-channel-dependent excitability in seizure maintenance. ^[15]D ATP-mediated purinergic signaling may contribute to injury and epileptogenesis: SE selectively increased hippocampal P2X7 receptor expression in mice, particularly in dentate granule neurons, and P2X7-targeted treatment produced seizure-suppressing and neuroprotective effects in the experimental model. ^[18]D

Neurovascular, blood–brain barrier, and regional mechanisms

Ictal activity increases neuronal metabolic demand and can contribute to lesion progression when neurovascular coupling is impaired. Spreading depolarizations produce sustained neuronal and astroglial depolarization, major ion shifts, cytotoxic edema, electrical silencing, and—in some injured brains—inverse neurovascular coupling with severe hypoperfusion. Ictal events may similarly increase metabolic demand, although the relationship between ictal activity and abnormal coupling is incompletely defined. ^[1]C SE is also associated with blood–brain barrier disruption, inflammation, and altered local microenvironments, all of which may intensify neuronal vulnerability. ^[11]D[113]D

Injury is spatially heterogeneous. In a patient with nonconvulsive SE, increased blood flow and persistent cortical MRI abnormalities occurred in the actively involved left cerebrum, whereas a contralateral right cerebellar diffusion abnormality did not progress despite absent increased cerebellar blood flow. The authors attributed this difference to substantially greater excitotoxicity in the cerebrum than in the cerebellum, illustrating that perfusion alone does not determine tissue injury. ^[7]C

Inflammation, proteostasis, and programmed cell death

Experimental SE produces microglial activation and neuronal death in multiple limbic and paralimbic regions, including the hippocampus, amygdala, piriform cortex, and entorhinal cortex. ^[11]D Inflammatory and neurotoxic mediators, including reactive oxygen species, glutamate, and cytokines, are components of the post-SE environment and potential targets of neuroprotective interventions. ^[113]D The ubiquitin–proteasome system, which regulates proteins involved in survival, synaptic plasticity, neurotransmission, and excitability, is inhibited after SE in a spatiotemporal and cell-specific pattern; this response may represent a protective adaptation against hippocampal injury rather than only a pathological failure. ^[14]D

SE activates programmed cell-death pathways. Seizures rapidly increase p53, and p53-dependent induction of the proapoptotic protein Puma contributes to hippocampal damage in experimental models. Pharmacological inhibition of p53 or genetic absence of Puma reduces seizure-associated neuronal injury. ^[19]D[110]D However, p53 deficiency can prolong electrographic seizures and worsen the later epileptic phenotype despite altering acute neuronal death, emphasizing that seizure duration, cell death, and epileptogenesis are mechanistically related but not interchangeable outcomes. ^[19]D[6]D

Structural and long-term consequences

Prolonged or super-refractory SE can cause neuronal death, network reorganization, and progressive cortical and subcortical atrophy. Serial MRI observations in super-refractory SE documented measurable progressive brain atrophy over time. ^[16]D Post-SE plasticity is regionally variable and extends beyond the hippocampus; chronic temporal lobe epilepsy models show altered corticostriatal synaptic communication and changes in long-term potentiation, indicating disruption of extralimbic network function. ^[20]D Aberrant neurogenesis, inflammation, neuronal loss, and network reorganization may contribute to later spontaneous recurrent seizures and cognitive dysfunction. ^[111]D[113]D

Endogenous responses can be protective or harmful depending on timing, intensity, and cellular context. For example, ERK1/2 signaling may support neuronal survival or promote neuronal death, while later inhibition of apoptotic pathways and early NMDA-receptor antagonism have distinct therapeutic rationales. ^[6]D Systemic complications of refractory SE—including cardiopulmonary injury, hemodynamic collapse, and multisystem failure—can impose additional secondary insults on the brain and increase overall mortality. ^[2]D

Overview

Status epilepticus (SE) is a final common pathway produced by diverse structural, infectious, inflammatory/autoimmune, genetic, metabolic, toxic, vascular, and medication-related processes. The etiologic evaluation should therefore be pursued in parallel with seizure termination, because identifying a reversible cause may alter acute treatment and prognosis.^[138] In a prospective multicenter ICU registry, the predefined investigation included brain CT/MRI, laboratory testing, lumbar puncture, toxicology screening, antiseizure-medication assays, and paraneoplastic testing, reflecting the breadth of potentially actionable causes.^[138]

Structural, vascular, and infectious triggers

Acute cerebrovascular disease is an important precipitant. In a pediatric ischemic-stroke cohort, 30 of 137 children with acute seizures had SE, demonstrating that SE may occur as an early symptomatic complication of pediatric stroke.^[139] In adults with acute stroke monitored with point-of-care EEG, early post-stroke SE was specifically evaluated during the first 72 hours after admission; the reported incidence of SE after acute stroke is approximately 1.5%.^[122] Stroke can also be mimicked by nonconvulsive SE: ictal paresis may present with hemiparesis or isolated limb weakness, sensory symptoms, mutism, or hemianopia, and EEG may show an ictal-interictal continuum.^[140]C Consequently, acute focal deficits should not be attributed automatically to ischemia without electroclinical assessment.^[140]C

Infection, particularly encephalitis, is a major trigger of refractory SE. In a cohort of severe viral encephalitis, seizures occurred in 55.2% of patients and 18.9% developed refractory SE; mortality was 20% among those with refractory SE compared with 5.5% in the overall cohort.^[114] Cerebrospinal-fluid and serum cytokine abnormalities differed between patients with severe viral encephalitis who had no seizures, controlled seizures, or refractory SE, supporting an inflammatory contribution to seizure refractoriness.^[114] Febrile infection-related epilepsy syndrome (FIRES) is a catastrophic infection-associated neuroinflammatory presentation characterized by refractory SE; in a 41-child cohort, all patients required pharmacologic coma after a median of seven antiseizure medications had been tried.^[115]C

Autoimmune and inflammatory causes

Autoimmune encephalitis is an important cause of new-onset refractory status epilepticus (NORSE). Anti-NMDA-receptor encephalitis commonly includes seizures, and a Mayo Clinic series characterized electroclinical features and factors associated with SE during the acute encephalitic phase.^[116]C Among patients with autoimmune encephalitis presenting with NORSE, persistent seizures despite adequate immunotherapy and resolution of active inflammation defined autoimmune-associated epilepsy; the DAME score was developed to predict this outcome after at least 24 months of follow-up.^[33]D In adult and pediatric NORSE, early immunotherapy was defined as first-line treatment within 7 days of admission and second-line treatment within 30 days, allowing evaluation of treatment timing in relation to functional outcome.^[38]D

Cryptogenic NORSE may still have an immune-mediated biological substrate despite negative conventional testing. Whole-genome sequencing in 31 patients with cryptogenic NORSE found increased polygenic risk scores for autoimmune diseases, enrichment of variants in genes expressed in the central nervous system and lymphocytes, and associations between autoimmune polygenic risk and selected clinical phenotypes.^[118] Altered fecal microbiomes have also been reported in NORSE and conventional SE compared with chronic epilepsy, with longitudinal analyses examining relationships between microbiota and cytokines; these findings are associative and do not establish the microbiome as a confirmed cause.^[36]D

Genetic and metabolic causes

Genetic etiologies are particularly relevant in children with epilepsy complicated by SE. A multicenter Italian pediatric cohort was designed to characterize confirmed or presumed genetic causes and identify clinical features associated with genetic epilepsy complicated by SE.^[30]D POLG-related mitochondrial disease is a notable example: among 195 genetically confirmed patients, 130 had epilepsy and SE was identified in 97 of 126 evaluable patients; SE was the presenting manifestation in 40 of 93 affected individuals, with a median age of onset of 7 years.^[119]C These findings support consideration of mitochondrial and other genetic disorders when SE is recurrent, unusually severe, early-onset, or accompanied by multisystem features.^[30]D[119]C

Metabolic disease is an important but relatively infrequent explanation for adult NORSE. In a single-centre evaluation of 42 suspected adult NORSE cases, 62% were classified as cryptogenic and 38% as symptomatic; despite 100 metabolic-related tests, no inherited metabolic disorder was identified as the cause in that cohort.^[35]D A negative metabolic screen therefore reduces, but does not eliminate, the possibility of an inherited metabolic disorder, particularly when clinical features remain suggestive.^[35]D

NORSE and cryptogenic presentations

NORSE occurs in individuals without active epilepsy or a pre-existing neurologic disorder and without a rapidly identified structural, toxic, metabolic, or other cause.^[21][36]D In a 72-patient adult cohort, the most common classification was cryptogenic NORSE (54%), followed by viral encephalitis (25%); 51.3% progressed to super-refractory SE and overall mortality was 27.8%.^[32]D The high proportion of cryptogenic cases underscores that “cryptogenic” is a diagnostic category rather than proof that no trigger exists.^{[32]D[35]D[118]}

Toxic, medication-related, and systemic precipitants

Toxic exposure and antiseizure-medication factors should be assessed early because toxicology screening and serum antiseizure-medication assays are included in structured etiologic protocols for SE.^[138] Medication nonadherence, withdrawal, drug interactions, and inadequate drug exposure are clinically plausible precipitants, but the supplied studies do not quantify their relative contribution. Systemic infection and fever may act as proximate triggers, particularly in FIRES and viral encephalitis.^[114][115]C

Age- and phenotype-related considerations

Etiology varies with age and seizure phenotype. Pediatric SE cohorts emphasize stroke, FIRES, genetic epilepsy, mitochondrial disease, and autoimmune encephalitis.^{[30]D[115]C[119]C[139]} In older adults, myoclonic SE has been studied as a near-continuous myoclonus syndrome with epileptiform EEG abnormalities; its etiologies and prognosis were evaluated in patients older than 60 years, with duration and underlying cause assessed in relation to outcome.^[123]C Crossed cerebellar diaschisis may accompany SE from multiple etiologies and has been described using MRI, PET, or SPECT; it is an imaging phenomenon rather than an independent cause.^[26] Similarly, cytokine abnormalities, microbiome changes, and genetic risk profiles may provide mechanistic clues but should not replace evaluation for treatable structural, infectious, autoimmune, toxic, metabolic, or genetic causes.^{[26][36]D[114][118]}

Practical etiologic approach

A systematic evaluation should be guided by age, seizure semiology, fever or systemic illness, focal neurologic findings, medication exposure, immune or cancer history, and evidence of multisystem disease.^[138] Initial testing generally encompasses urgent neuroimaging, metabolic and laboratory studies, medication concentrations, toxicology, EEG, and lumbar puncture when infection or inflammation is suspected; autoimmune, paraneoplastic, genetic, and metabolic testing should be selected according to the clinical phenotype.^[138] Early recognition of autoimmune or inflammatory NORSE is particularly important because immunotherapy timing is associated with outcome-focused clinical assessment.^[38]D

Recognize status epilepticus as a time-critical emergency

Status epilepticus (SE) is a major neurological emergency in adults, and mortality remains substantial despite advances in acute neurological care; delays may result from a persistent gap between clinical-practice-guideline recommendations and bedside implementation. ^[40] Recognition should therefore trigger simultaneous resuscitation, seizure characterization, cause assessment, treatment preparation, and escalation planning rather than a sequential diagnostic process. ^[40]

Convulsive SE is usually apparent from ongoing or recurrent convulsive activity, but motor manifestations may diminish or stop while electrographic seizures continue. Nonconvulsive SE (NCSE) should be suspected in patients with otherwise unexplained altered mental status, persistent impaired awareness after convulsive seizures, prolonged postictal deficits, or unexplained focal neurological findings. ^{[124]C[128]C[137]} A prolonged postictal deficit lasting more than 1 hour can represent either uncomplicated Todd’s palsy or ongoing/recurrent nonconvulsive seizure activity; clinical examination alone may not reliably distinguish these conditions. ^[137]

Immediate triage and parallel assessment

Patients with suspected SE require emergency assessment of airway, breathing, circulation, consciousness, seizure activity, glucose, temperature, and likely precipitants while antiseizure treatment and definitive monitoring are arranged. The supplied guideline systematic review supports use of formal SE management pathways, although the abstract does not provide a single universal triage algorithm or treatment threshold. ^[40] Under-recognition and benzodiazepine underdosing are clinically important hazards: the available emergency-department study specifically addresses frequent administration below guideline-recommended doses and the concern that respiratory or cardiovascular complications may lead clinicians to undertreat, despite the greater complication burden associated with untreated SE. ^[125]C

EMS dispatch and prehospital systems should treat suspected SE as a high-acuity neurological emergency. Dispatch algorithms are intended to identify seizure-related emergencies and allocate appropriate EMS resources, but their accuracy and effect on resource allocation remain active areas of investigation. ^[141] Community-level social vulnerability may influence out-of-hospital identification and the quality of EMS care for neurological emergencies, including SE, and should be considered when evaluating delays or disparities in access. ^[127]

Identify nonconvulsive seizures rapidly

NCSE is commonly overlooked among emergency-department patients presenting with acute or unexplained mental-status changes. ^[124]C EEG is essential for diagnosis, and a standard EEG may be unavailable or delayed, particularly outside regular working hours or in resource-constrained settings. ^{[41][128]C[129]} Rapid-response or limited EEG can provide earlier bedside assessment, but automated or artificial-intelligence interpretation should supplement—not replace—qualified clinical and EEG review. ^[124]C[130]

Point-of-care EEG is a potential triage tool when conventional EEG is not immediately available. A pediatric systematic review identified six studies using simplified montages, with cohorts ranging from 20 to 242 patients, and concluded that point-of-care EEG is feasible for acute assessment while emphasizing important evidence gaps. ^[41] A pediatric quality-improvement program used a rapid, low-cost two-channel device for children with altered mental status, including children recovering from convulsive seizures without visible ongoing seizure activity. ^[128]C A related implementation study analyzed 62 pediatric point-of-care EEG recordings and evaluated feasibility and concordance with standard interpretation, although implementation evidence remains limited. ^[129]

Arrange continuous EEG when risk persists

Patients with persistent impaired consciousness, suspected NCSE, recurrent seizures, or high risk of electrographic seizures should undergo urgent EEG and, when clinically indicated, continuous EEG monitoring. In critically ill patients at risk for nonconvulsive seizures or NCSE, a multicenter randomized study compared 24–72 hours of tele-continuous EEG with a 30-minute tele-routine EEG; the trial was designed to compare seizure detection, mortality, and functional outcomes. ^[42] Pediatric ICU data indicate that electrographic seizures after SE occur in approximately 26–57% of critically ill children, usually within 48 hours of onset, and are associated with adverse neurological outcomes. ^[126]C Fever-associated SE represents approximately 40–49% of pediatric SE in the cited literature, making continued EEG vigilance particularly relevant in this group. ^[126]C

Interpret EEG findings within the clinical context. The Salzburg EEG criteria are proposed consensus criteria for NCSE, but their diagnostic accuracy requires independent clinical validation and may vary according to the reference standard and reader expertise. ^[132]C Emergency EEG studies demonstrate that clinically relevant seizures and SE are detected in a minority—but meaningful proportion—of referred patients: one tertiary emergency-department series found SE-related seizures in 5.40% of emergency EEGs and seizures without SE in 3.05%. ^[133]

Triage severity and prognosis

Prognostic scores can support—not replace—clinical judgment, treatment escalation, or goals-of-care discussions. STESS, EMSE-EACE, and END-IT have been evaluated in neurology ICU populations requiring continuous EEG, while the modified END-IT tool was developed to provide individualized prediction of 3-month functional outcome after convulsive SE. ^[44][23] STESS and qSOFA are also being studied as rapidly applicable prehospital tools for predicting early and in-hospital mortality and the need for mechanical ventilation. ^[95] These tools should not be used to withhold urgent treatment solely because a predicted outcome is unfavorable. ^[23][44][95]

In refractory or prolonged SE, early transfer to an ICU or center with continuous EEG, neurocritical care, and anesthetic-management capability is appropriate. Contemporary registries emphasize that evidence remains limited for third-line anesthetic treatment and many NCSE management questions, including the prognostic significance of distinct EEG patterns. ^[136] Pediatric ICU monitoring studies similarly evaluate seizure detection, treatment changes, NCSE, and longer-term epilepsy outcomes, reinforcing the need for specialty escalation when electrographic seizures persist. ^[135]C

Refractory status epilepticus (RSE) is defined as seizure activity that persists despite the administration of a first-line benzodiazepine and at least one appropriately dosed second-line non-sedating intravenous (IV) antiseizure medication (ASM) ^[60][66]D. Approximately 10% to 40% of pediatric status epilepticus cases progress to RSE ^[54]. Super-refractory status epilepticus (SRSE) occurs when seizures continue or recur 24 hours or more after the initiation of anesthetic therapy, including instances where seizures return during the weaning of anesthetic infusions ^{[55][63]D[71]C}. Management requires rapid escalation to continuous intravenous anesthetic drugs (CIVADs) to prevent neuronal injury and systemic complications ^[64]D[66]D.

Step 1: Initial Assessment and Severity Classification

Upon failure of second-line ASMs (e.g., levetiracetam , fosphenytoin , or valproate ), the patient must be classified as having RSE and immediately transitioned to an intensive care unit (ICU) for continuous hemodynamic and electroencephalography (EEG) monitoring ^[60][66]D. Clinicians must decide between adding a second non-sedating IV ASM or proceeding directly to anesthetic induction. While equipoise exists, rapid sedation is often preferred in convulsive RSE to halt systemic metabolic exhaustion ^[58]C. For non-convulsive status epilepticus (NCSE), the FAST trial suggests comparing high-dose IV ASMs against rapid ICU sedation to determine if the risks of intubation outweigh the benefits of immediate seizure suppression ^[57].

Step 2: Induction of Continuous Intravenous Anesthetic Drugs (CIVADs)

Administer Midazolam 0.2 mg/kg IV bolus, followed by a continuous infusion of 0.05–2.0 mg/kg/hr ^[61]. Midazolam is often the preferred initial CIVAD due to its rapid onset and familiar safety profile ^[64]D. In pediatric populations, a dose threshold of 0.8 mg/kg/hr has been identified; exceeding this dose may be associated with diminishing returns in seizure cessation and increased risk of treatment failure ^[61]. Alternatively, Propofol 1–2 mg/kg IV bolus followed by 20–100 μg/kg/min may be used ^[60]. A multicenter study found no significant difference in efficacy between midazolam and propofol for RSE control, though propofol requires caution regarding propofol-related infusion syndrome (PRIS) during prolonged use ^[60].

Step 3: Integration of NMDA Antagonism (Ketamine)

Administer Ketamine 1–2 mg/kg IV bolus, followed by an infusion of 1–5 mg/kg/hr ^[54][67]D. As status epilepticus persists, GABA-A receptors are internalized and become less responsive to benzodiazepines and barbiturates, while N-methyl-D-aspartate (NMDA) receptors are upregulated ^[64]D[67]D. Ketamine, a non-competitive NMDA receptor antagonist, targets this mechanism and is increasingly used as an advanced second-line or early third-line agent ^[67]D[75]C. Unlike other anesthetics, ketamine does not significantly suppress respiratory drive, potentially allowing for seizure management without endotracheal intubation in select cases of NCSE ^[73]C[74]C. Prehospital administration of ketamine for benzodiazepine-refractory SE has also shown promise in terminating seizures before ICU arrival ^[65]D[72]C.

Step 4: Monitoring and Titration

Continuous EEG (cEEG) is mandatory to guide titration, especially as clinical convulsions may cease while electrographic seizures persist (electromechanical dissociation) ^[66]D. The therapeutic goal is typically the cessation of all electrographic seizures or the achievement of a burst-suppression pattern ^[66]D. When using ketamine, EEG monitoring may reveal increased beta-frequency activity, which has been suggested as a potential marker for treatment response ^[70]. Clinicians should monitor for drug-specific adverse effects, such as hypotension with midazolam or propofol, and metabolic acidosis or bradycardia with propofol ^[60].

Step 5: Resolution, Weaning, and Transition

Anesthetic weaning should only be attempted after at least 24 hours of electrographic seizure control ^[63]D. Weaning must be gradual to prevent rebound SE. For patients who fail repeated weaning attempts (SRSE), adjunctive therapies may be required. Memantine 20 mg/day (oral NMDA antagonist) has been used off-label to facilitate weaning from ketamine infusions in refractory cases ^[71]C. In cases with suspected neuroinflammatory components, Tocilizumab 8 mg/kg IV (max 800 mg) may be considered; a randomized trial indicated that adding tocilizumab to standard anesthetic regimens may improve outcomes in RSE by modulating inflammatory cytokines ^[59].

The diagnosis of status epilepticus (SE) is a time-sensitive neuro-emergency that requires a parallel approach: stabilizing the patient while simultaneously identifying the seizure type and underlying etiology ^[83]D[84]D. Because prolonged seizure activity leads to progressive changes in neurotransmission—specifically the internalization of GABA receptors and the mobilization of NMDA receptors—prompt recognition is vital to prevent the transition to refractory states ^[84]D. The diagnostic process is guided by the International League Against Epilepsy (ILAE) framework, which classifies SE across four axes: semiology, EEG correlates, etiology, and age ^[89]D.

Diagnostic Criteria

Formal diagnosis relies on the ILAE two-timepoint definition. Timepoint 1 (t1) represents the duration beyond which a seizure is unlikely to self-terminate (typically 5 minutes for generalized tonic-clonic SE), while Timepoint 2 (t2) represents the duration beyond which there is a significant risk of long-term consequences, including neuronal injury and death ^[84]D[89]D.

• Required Features: Continuous seizure activity or recurrent seizures without a return to clinical baseline between episodes ^[84]D[88]D.
• Supportive Features: For nonconvulsive status epilepticus (NCSE), supportive features include fluctuating mental status, subtle motor twitches (e.g., nystagmus, perioral twitching), or a response to antiseizure medications (ASMs) accompanied by EEG improvement ^[83]D[90]D.
• Exclusion Criteria: Clinicians must exclude mimics such as psychogenic non-epileptic seizures (PNES), syncope, or movement disorders. Notably, in patients with Creutzfeldt-Jakob disease (CJD), periodic sharp wave complexes (PSWCs) may respond to benzodiazepines without clinical improvement; this should not be misdiagnosed as NCSE ^[46]D.

Laboratory Tests

Laboratory evaluation should be initiated immediately to identify reversible metabolic triggers and systemic complications of prolonged muscle activity.

• Fingerstick Glucose: Must be performed immediately in all patients to rule out hypoglycemia as a reversible cause ^[88]D.
• Comprehensive Metabolic Panel: To assess for hyponatremia, hypocalcemia , and renal or hepatic failure which may lower the seizure threshold ^[88]D.
• Toxicology Screen: Essential for identifying sympathomimetic toxicity or withdrawal states (e.g., alcohol or benzodiazepine withdrawal) ^[88]D.
• Pregnancy Test: Mandatory for all women of reproductive age to guide ASM selection and screen for eclampsia ^[88]D.
• Cerebrospinal Fluid (CSF) Analysis: Indicated if there is clinical suspicion of meningitis, encephalitis, or autoimmune epilepsy, particularly after the acute phase is stabilized ^[89]D.

Imaging

Neuroimaging is used to identify acute structural brain injuries that may be the primary cause of SE, such as hemorrhage, tumor, or stroke ^[78]D.

• Non-contrast CT Head : The emergent modality of choice to rule out large intracranial hemorrhages or masses ^[78]D.
• MRI Brain: Superior for detecting subtle cortical dysplasia, encephalitis, or posterior reversible encephalopathy syndrome (PRES). Specific findings in SE include Crossed Cerebellar Diaschisis (CCD), a phenomenon where supratentorial seizure activity causes functional deafferentation and metabolic depression in the contralateral cerebellar hemisphere ^[26].
• Special Considerations: In patients receiving amyloid-targeting therapies (e.g., aducanumab), clinicians should look for Amyloid-Related Imaging Abnormalities (ARIA), which can trigger fatal super-refractory SE ^[87]C.

Electrodiagnostic Studies

Electroencephalography (EEG) is the gold standard for diagnosing NCSE and monitoring treatment response in refractory SE ^[90]D.

• Continuous EEG (cEEG): Recommended in the ICU for patients with unexplained altered mental status or those who do not wake up within 10–20 minutes of seizure cessation ^[78]D[83]D. A seizure burden of >12 minutes per hour (20%) is often used to define SE in the critical care setting ^[78]D.
• Point-of-Care EEG (pocEEG): Utilizes simplified montages for rapid bedside assessment in the emergency department. It is highly feasible in pediatric populations for the early detection of NCSE ^[41].
• AI-Integrated EEG: Emerging AI platforms offer a sensitivity of 95% and specificity of 83% for detecting nonconvulsive seizures, potentially reducing unnecessary ASM administration ^[86].
• EEG-EMG Monitoring: Combined monitoring is useful in the ICU to differentiate between epileptic myoclonus and non-epileptic movement disorders like postanoxic myoclonus or tremors ^[82]D.

Diagnostic Algorithm

1. Step 1: Clinical Suspicion: Identify prolonged motor activity (>5 min) or persistent altered mental status without recovery ^[84]D[88]D.
2. Step 2: Immediate Metabolic Screen: Check fingerstick glucose and electrolytes ^[88]D.
3. Step 3: Emergent EEG: Order EEG (pocEEG or routine) within 30–60 minutes if the patient remains encephalopathic to rule out NCSE ^[41][83]D.
4. Step 4: Neuroimaging: Perform CT head once the patient is stabilized; follow with MRI if the etiology remains unknown ^[26][78]D.
5. Step 5: Etiological Workup: Conduct targeted testing (CSF, toxicology, or autoimmune panels) based on clinical context ^[89]D.

Management of status epilepticus (SE) requires significant modification when encountered in specific patient cohorts. Physiological variations, altered pharmacokinetics, and distinct etiologic profiles necessitate a departure from standard adult protocols to optimize outcomes and minimize iatrogenic harm ^[88]D[97]D.

Pediatrics

In the pediatric population, SE is a common neurological emergency where rapid intervention is critical to prevent long-term developmental and cognitive sequelae ^[99]D. The Established Status Epilepticus Treatment Trial (ESETT) included patients as young as 2 years old, demonstrating that second-line management with Levetiracetam (60 mg/kg, max 4500 mg), Fosphenytoin (20 mg PE/kg, max 1500 mg PE), or Valproic acid (40 mg/kg, max 3000 mg) shows comparable efficacy in benzodiazepine-refractory convulsive SE ^[91].

Diagnostic considerations in children must prioritize metabolic disturbances and infection. In cases of New-Onset Refractory Status Epilepticus (NORSE), which can occur in previously healthy children, the prognosis is often guarded, and clinicians must aggressively investigate for autoimmune or paraneoplastic etiologies ^[21][32]D. For pediatric patients with super-refractory SE (SRSE), adjunctive therapies such as Vagus Nerve Stimulation (VNS) have emerged as safe options, with some evidence suggesting they may assist in SE resolution when anesthetic weaning fails ^[93][94].

Pediatric Monitoring Protocol:

1. Step 1: Immediate stabilization and administration of weight-based benzodiazepines (e.g., Midazolam 0.2 mg/kg IM or Lorazepam 0.1 mg/kg IV).
2. Step 2: If seizures persist at 5–10 minutes, initiate a second-line ASM (Levetiracetam, Fosphenytoin, or Valproate) ^[91].
3. Step 3: Early transition to continuous EEG (cEEG). In pediatric SE, monitoring should ideally persist for 36.8 hours after the last seizure to ensure the risk of recurrence is reduced below 5% ^[106]D.

Pregnancy

SE in pregnancy represents a dual-emergency involving both the mother and the fetus. The primary clinical challenge is differentiating SE from eclampsia , as the treatments differ fundamentally ^[88]D. While SE is managed with standard ASMs, eclampsia requires Magnesium sulfate (4–6 g IV loading dose followed by 1–2 g/h infusion).

Physiological changes in pregnancy, such as increased glomerular filtration and volume of distribution, often lead to subtherapeutic ASM levels. Furthermore, the risk of fetal hypoxia during prolonged maternal seizures is high, necessitating continuous fetal heart rate monitoring if the fetus is viable (typically >24 weeks gestation) ^[88]D.

Management of SE in Pregnancy:

• Teratogenicity: While Valproate is highly effective, it is generally avoided in pregnancy due to significant teratogenic risks (neural tube defects). Levetiracetam (60 mg/kg) or Fosphenytoin (20 mg PE/kg) are preferred second-line agents ^[91].
• Delivery Planning: SE is not an absolute indication for immediate Cesarean section unless there is evidence of fetal distress that does not resolve with maternal seizure control.
• Breastfeeding : Most ASMs are compatible with breastfeeding, though infants should be monitored for sedation if the mother is receiving high-dose benzodiazepines or phenobarbital.

Elderly

Patients aged ≥60 years represent the demographic with the highest incidence of SE, reaching 89.6 per 100,000 person-years in women ^[97]D. Mortality in this group increases nearly fourfold compared to younger adults, often due to the underlying etiology such as acute ischemic stroke , intracranial hemorrhage, or neuro-oncological complications ^[97]D[105]D.

Pharmacokinetic changes in the elderly, including reduced hepatic metabolism and renal clearance, increase the risk of drug-induced toxicity. Clinicians must be vigilant against underdosing, which is a frequent cause of treatment failure in the emergency department ^[98]. However, the use of highly protein-bound drugs (e.g., Phenytoin) is complicated by age-related hypoalbuminemia, which increases the free (active) fraction of the drug, potentially leading to toxicity even with "normal" total serum levels ^[97]D.

Elderly Prognostic Stratification: Prognostic scores like the Status Epilepticus Severity Score (STESS) and qSOFA are utilized to predict mortality, though their performance in the elderly can be limited by the complexity of comorbidities ^[95]. Structured EEG reporting is increasingly recognized as a vital tool for predicting length of stay and mortality in this population ^[101]D. Biomarkers such as Neurofilament light-chain (Nf-L) in the CSF or serum may also serve as indicators of neuroaxonal injury following SE ^[102]D.

Immunocompromised Patients

In immunocompromised individuals (e.g., HIV/AIDS, post-transplant, or those on chemotherapy), SE is frequently the result of opportunistic CNS infections or progressive multifocal leukoencephalopathy ^[88]D. These patients are at higher risk for nonconvulsive status epilepticus (NCSE), which may present subtly as altered mental status or "brain fog" rather than overt motor activity.

Management must include a low threshold for lumbar puncture and broad-spectrum antimicrobial coverage while awaiting culture results. Clinicians must also account for significant drug-drug interactions between ASMs (especially enzyme-inducers like Carbamazepine or Phenytoin) and immunosuppressant medications (e.g., calcineurin inhibitors), which can lead to graft rejection or increased ASM toxicity.

Clinical practice guidelines for status epilepticus (SE) emphasize a time-sensitive, tiered approach to management . Because SE is a neurological emergency with high morbidity, standardized protocols are essential to reduce institutional variability and improve patient outcomes ^[107]. The primary objectives of all major guidelines are the rapid termination of clinical and electrographic seizure activity and the prevention of seizure recurrence.

Neurocritical Care Society (NCS) 2012 Guidelines

The 2012 NCS guidelines provide a comprehensive framework for the evaluation and management of SE in critically ill patients ^[107]. These guidelines utilize the GRADE system to categorize recommendations based on the quality of evidence and the balance between benefits and risks. A central tenet of the NCS approach is the categorization of treatment into three distinct phases: Emergent, Urgent, and Refractory.

Emergent Initial Therapy (0–5 Minutes)

The goal of the emergent phase is the immediate cessation of seizure activity. Benzodiazepines are the established first-line agents due to their rapid onset of action. The NCS recommends the following protocols:

1. Step 1: Stabilization — Assess airway, breathing, and circulation (ABCs). Initiate cardiac monitoring and pulse oximetry . Perform a rapid finger-stick glucose check to rule out hypoglycemia.
2. Step 2: Pharmacological Intervention — Administer a rapid-acting benzodiazepine.
   • Lorazepam: 0.1 mg/kg IV (up to 4 mg per dose), may repeat once.
   • Midazolam: 10 mg IM (for patients without IV access) or 0.2 mg/kg IV.
   • Diazepam: 0.15 mg/kg IV (up to 10 mg per dose).

Urgent Control Therapy (5–20 Minutes)

If seizures persist after the initial benzodiazepine dose, the patient enters the urgent control phase. The goal is to achieve long-term seizure control using non-sedating antiepileptic drugs (AEDs). The NCS highlights that the choice of agent often depends on the patient's comorbidities and the side-effect profile of the drug ^[107].

• Fosphenytoin: 20 mg PE/kg IV (max 1500 mg/dose) at a rate of 150 mg PE/min.
• Valproate Sodium: 20–40 mg/kg IV at a rate of 3–6 mg/kg/min.
• Levetiracetam: 1000–3000 mg IV over 15 minutes.

Refractory Status Epilepticus (RSE)

Refractory SE is defined as continued seizures despite the administration of an emergent and an urgent agent. The NCS recommends moving to continuous intravenous infusions (cIVIs) with anesthetic agents. This stage requires intensive care monitoring and often endotracheal intubation ^[107].

• Midazolam Infusion: Loading dose of 0.2 mg/kg followed by a maintenance infusion of 0.05–2.0 mg/kg/hr.
• Propofol: Loading dose of 1–2 mg/kg followed by 20–200 mcg/kg/min.
• Pentobarbital: Loading dose of 5–15 mg/kg followed by 0.5–5.0 mg/kg/hr.

Management in Special Populations: Pregnancy

The American Academy of Neurology (AAN) and the American Epilepsy Society (AES) provided a practice parameter update regarding women with epilepsy (WWE) and pregnancy ^[108][109]. While SE during pregnancy is a life-threatening event for both the mother and the fetus, the guidelines offer reassurance regarding general obstetrical risks for WWE.

Key findings from the AAN/AES update include:

• Obstetrical Complications: For WWE taking AEDs, there is probably no substantially increased risk (defined as > 2 times the expected rate) of cesarean delivery or late pregnancy bleeding ^[108].
• Labor and Delivery: There is probably no moderately increased risk (defined as > 1.5 times the expected rate) of premature contractions or premature labor and delivery ^[109].
• Seizure Frequency: While the risk of SE remains a concern, many women remain seizure-free throughout pregnancy. Monitoring AED serum levels is recommended to maintain therapeutic thresholds as physiological changes in pregnancy can alter drug metabolism.

Monitoring and Evaluation

The NCS guidelines emphasize the role of Electroencephalography (EEG) in the management of SE, particularly for identifying non-convulsive status epilepticus (NCSE) ^[107]. Continuous EEG (cEEG) should be initiated within 1 hour of SE onset if seizures continue or if the patient does not return to clinical baseline. This is critical because clinical cessation of motor activity does not always correlate with the cessation of electrographic seizure activity, a phenomenon known as electromechanical dissociation.