Status Epilepticus

Status Epilepticus (SE)

ILAE Operational Definition (2015)

Status epilepticus is:

A condition resulting either from failure of seizure termination mechanisms or initiation of mechanisms leading to abnormally prolonged seizures.

Two time points are defined:

t1 (Time to Start Treatment)-When seizure is unlikely to stop spontaneously.
t2 (Time of Potential Neuronal Injury)-When permanent neuronal injury may begin.

Type	t1	t2
Generalized convulsive SE	5 min	30 min
Focal impaired-awareness SE	10 min	>60 min
Absence SE	10–15 min	Unknown

Therefore:

Any generalized tonic-clonic seizure lasting >5 minutes should be treated as status epilepticus.

Classification

Classification According to Clinical Manifestation

Type	Features
Convulsive Status Epilepticus (CSE)	Most common form; generalized tonic-clonic activity with loss of consciousness; true neurological emergency requiring immediate treatment.
Non-Convulsive Status Epilepticus (NCSE)	Persistent seizure activity without obvious convulsions; presents with confusion, delirium, altered behavior, or coma; diagnosis requires EEG confirmation.

Classification According to EEG and Clinical Features

Type	Examples
Generalized Convulsive SE	Generalized tonic-clonic status epilepticus
Focal Motor SE	Epilepsia partialis continua
Myoclonic SE	Post-anoxic myoclonic status epilepticus
Absence SE	Typical or atypical absence status epilepticus
Focal NCSE	Temporal lobe status epilepticus
Comatose NCSE	Electrographic seizures in comatose ICU patients

Modern Treatment-Based Classification

Type	Definition
Early Status Epilepticus	Seizure duration 0–5 minutes.
Established Status Epilepticus	Seizure duration 5–30 minutes; requires prompt benzodiazepine therapy.
Refractory Status Epilepticus (RSE)	Persistence of seizures despite an adequate dose of a benzodiazepine and one appropriately dosed second-line antiseizure medication.
Super-Refractory Status Epilepticus (SRSE)	Seizures continue for ≥24 hours after initiation of anesthetic therapy or recur during anesthetic withdrawal.

Pathophysiology

Initially:

Excess glutamate excitation
Excess NMDA activation
Increased neuronal firing

With prolonged seizure:

Internalization of GABA receptors
Loss of benzodiazepine responsiveness
Increased excitotoxicity
Neuronal injury

This explains why:

Benzodiazepines become less effective as seizure duration increases.

Etiology

Category	Causes of Status Epilepticus
Acute Cerebrovascular Disease	Ischemic stroke, Intracerebral hemorrhage, Subarachnoid hemorrhage
CNS Infections	Meningitis, Encephalitis, Brain abscess, Neurocysticercosis
Metabolic Disorders	Hypoglycemia, Hyperglycemia, Hyponatremia, Hypernatremia, Hypocalcemia, Hypomagnesemia, Uremia, Hepatic encephalopathy
Antiseizure Medication-Related	Non-compliance, Abrupt withdrawal, Subtherapeutic drug levels
Drug and Toxin-Induced	Tramadol, Bupropion, Theophylline, Isoniazid, Cocaine, Amphetamines, Lithium, Cyclosporine, Tacrolimus
Alcohol-Related	Alcohol withdrawal, Alcohol intoxication
Structural Brain Lesions	Brain tumor, Head trauma, AVM, Post-neurosurgical state
Hypoxic-Ischemic Injury	Cardiac arrest, Severe hypoxemia, Near drowning
Autoimmune Disorders	Anti-NMDA receptor encephalitis, LGI1 encephalitis, CASPR2 encephalitis, GAD antibody-associated encephalitis
Systemic Critical Illness	Sepsis-associated encephalopathy, Multiorgan failure, Severe hypertension/PRES
Pregnancy-Related	Eclampsia, Cerebral venous sinus thrombosis
Genetic/Epileptic Syndromes	Known epilepsy, Developmental epileptic encephalopathies
Degenerative Diseases	Alzheimer’s disease, Cortical degenerative disorders
Idiopathic/Cryptogenic	No identifiable cause despite evaluation
NORSE/FIRES	New-onset refractory status epilepticus, Febrile infection-related epilepsy syndrome

Causes in ICU

Hypoxia
Hypercapnia
Sepsis-associated encephalopathy
Electrolyte abnormalities
Drug toxicity
Stroke
CNS infection

Clinical Features

Phase / Type	Clinical Features
Tonic Phase	Generalized stiffening, Jaw clenching
Clonic Phase	Rhythmic jerking movements
Post-Ictal State	Confusion, Agitation, Coma
Subtle Status Epilepticus	Coma, Eyelid twitching, Nystagmus, Facial twitching; convulsions may disappear despite ongoing EEG seizure activity (common ICU trap)

Complications

System	Complications
Neurological	Neuronal death, Cognitive dysfunction, Epilepsy, Cerebral edema
Cardiovascular	Arrhythmias, Myocardial ischemia, Shock
Respiratory	Aspiration, Hypoxemia, Pulmonary edema
Metabolic	Lactic acidosis, Hyperkalemia, Rhabdomyolysis, AKI

Emergency Evaluation

Immediate Bedside

Within minutes.

ABCDE

Airway
Breathing
Circulation
Disability
Exposure

Fingerstick Glucose

Mandatory.Treat immediately if low.

Initial Investigations

Test	Purpose
CBC	Infection
Electrolytes	Na, Ca, Mg
ABG	Acidosis
LFT	Hepatic cause
RFT	Uremia
Toxicology	Drug overdose
Pregnancy test	Women
CK	Rhabdomyolysis
Lactate	Severity

Neuroimaging

CT Brain

CT brain is not mandatory in every patient with status epilepticus, but it is required in many cases to identify a structural cause.

When CT Brain Should Be Performed Urgently

Indication	Reason
First episode of status epilepticus	Rule out structural lesion
New focal neurological deficit	Stroke, hemorrhage, mass lesion
Head trauma	Intracranial bleeding
Persistent altered consciousness	Structural pathology, cerebral edema
Suspected stroke	Ischemic or hemorrhagic stroke
Suspected intracranial hemorrhage	Emergency diagnosis
Immunocompromised patient	CNS infection, abscess
Known malignancy	Brain metastasis
Anticoagulation use	Intracranial bleed

When CT May Not Be Immediately Necessary

Situation	Comments
Known epilepsy with typical breakthrough seizure and clear trigger (e.g., medication non-compliance)	Imaging may not be urgently required if patient returns to baseline
Established epilepsy with recurrent identical seizures and no new neurological findings	Imaging can be deferred
Clear metabolic cause (e.g., severe hypoglycemia, profound hyponatremia) with complete recovery	Imaging may not be immediately needed

MRI Brain

More sensitive.

Detects:

Encephalitis
Autoimmune disease
Tumor
Temporal lobe pathology

EEG

Gold standard.

Indications:

Persistent altered sensorium
Suspected NCSE
Refractory SE
ICU coma

Continuous EEG is preferred.

Management

Step 1: Stabilization

Airway

Intubation if:

GCS ≤8
Ongoing seizures
Aspiration risk
Need for anesthetics

Oxygen

100% oxygen.

IV Access

Two large-bore lines.

Glucose

If glucose unknown:Thiamine 100 mg IV Then Dextrose 25 g IV

Pharmacologic Treatment

First-Line Therapy (0–10 Minutes)-Benzodiazepines

Drug	Dose	Key Points
Lorazepam (Preferred)	0.1 mg/kg IV (maximum 4 mg per dose)	First-line drug for status epilepticus; may repeat once after 5–10 minutes if seizures persist.
Diazepam	0.15–0.2 mg/kg IV (maximum 10 mg per dose)	(may repeat once),Rapid onset but shorter duration due to redistribution; often followed by a longer-acting antiseizure medication.
Midazolam	IM: 10 mg (adults >40 kg) ,5 mg (13–40 kg) IV: 0.2 mg/kg Intranasal/Buccal: 0.2 mg/kg	Preferred when IV access is unavailable; widely used in prehospital and emergency settings.

Second-Line Therapy (10–30 Minutes)-Choose ONE.

Drug	Dose	Important Points
Levetiracetam	60 mg/kg IV (maximum 4.5 g)-Usually infused over 10–15 min (can be given faster in emergencies)	Current ICU favorite; minimal drug interactions,no hepatic enzyme induction, excellent hemodynamic stability, easy administration, no cardiac monitoring required.
Valproate	20–40 mg/kg IV(3–6 mg/kg/min -typically over 5–15 min) Max dose-Usually 3 g (some protocols up to 4 g)	Useful for generalized epilepsy and absence status epilepticus; avoid in severe liver disease, pregnancy, and hyperammonemia.
Fosphenytoin	20 mg PE/kg IV (maximum 1500 mg PE)	Better tolerated than phenytoin; can be infused faster with lower risk of hypotension and tissue injury.
Phenytoin	20 mg/kg IV (infusion rate ≤50 mg/min,≤25 mg/min in elderly/cardiac disease) Max dose-Usually 2 g	Requires ECG and blood pressure monitoring; risks include hypotension, arrhythmias, and extravasation injury.
Phenobarbital	15–20 mg/kg IV(≤50–100 mg/min) Max dose-Usually 1–2 g	Effective when other agents are unavailable or ineffective; may cause significant respiratory depression and hypotension.
Lacosamide	200–400 mg IV loading dose (or 4–10 mg/kg)	PR interval prolongation, bradycardia, AV block, dizziness; caution in known conduction disease, severe cardiac disease, and patients on AV nodal blocking agents

Evidence (ESETT Trial)

The landmark ESETT trial showed:

Levetiracetam
Fosphenytoin
Valproate

have similar efficacy (~45–50%).

Therefore current guidelines allow any of these as second-line therapy.

Refractory Status Epilepticus

Failure of:Benzodiazepine PLUS One second-line agent

Intubate and initiate continuous EEG.neurologist consult

A common ICU mistake is to assume that if the motor activity stops after paralysis, the seizure has stopped. Neuromuscular blockers do not treat seizures. They only abolish the motor manifestations while electrographic seizure activity may continue unabated.

Guideline Position

Major guidelines from the:

Neurocritical Care Society
American Epilepsy Society

do not recommend neuromuscular blockers as antiepileptic therapy. Seizure treatment must be with benzodiazepines, antiseizure medications, and anesthetic agents.

Continuous Anesthetic Infusions

Anesthetic Agent	Dose	Important Points
Midazolam	Loading: 0.2 mg/kg IV Infusion: 0.05–2 mg/kg/hr	Most common first anesthetic for refractory status epilepticus; rapid onset and easy titration.Tachyphylaxis present
Propofol	Loading: 1–2 mg/kg IV Infusion: 20–200 µg/kg/min	Rapid onset and rapid offset; monitor for Propofol Infusion Syndrome (PRIS)—metabolic acidosis, hyperkalemia, rhabdomyolysis, and cardiac failure.
Ketamine	Loading: 1–5 mg/kg IV Infusion: 1–10 mg/kg/hr	Increasingly favored; NMDA receptor antagonist, causes less hypotension, particularly useful in super-refractory status epilepticus.
Pentobarbital / Thiopentone	Pentobarbital Loading: 5–15 mg/kg IV (followed by continuous infusion 0.5–5 mg/kg/hr) Thiopentone Loading 2–5 mg/kg,Infusion 1–5 mg/kg/hr	Reserved for severe refractory cases; major complications include profound hypotension, immunosuppression, and ileus.

EEG Targets During Anesthetic Therapy

Common targets:

Seizure suppression
Burst suppression
Complete EEG suppression

No clear superiority of one strategy.

Maintenance Antiseizure Therapy

Even while on anesthetic infusions, multiple antiseizure drugs are continued.

Common combinations:

Levetiracetam + Valproate
Levetiracetam + Lacosamide
Levetiracetam + Fosphenytoin
Triple therapy in difficult cases

How Long Should EEG Suppression Be Maintained?

Most guidelines recommend:

24–48 Hours of: No electrographic seizuresbefore attempting weaning.

Common ICU practice:

Maintain seizure freedom for 24 hours
Longer (48 hours) if SRSE

What If Seizures Recur During Weaning?

This is very common.

Patient now effectively has:Super-Refractory Status Epilepticus

Actions:

Re-establish Control

Increase anesthetic back to effective dose.

Super-Refractory Status Epilepticus

Persisting >24 hours despite anesthetic therapy.

Additional Therapies

Ketogenic Diet-4:1 fat-to-carbohydrate/protein ratio

Particularly useful in:

NORSE
FIRES

Immunotherapy

If autoimmune encephalitis suspected.

Methylprednisolone-1 g/day × 3–5 days
IVIG-0.4 g/kg/day × 5 days
Plasma Exchange-5–7 exchanges

Useful in antibody-mediated disease.

Biologic Therapy

Selected cases:

Rituximab
Cyclophosphamide
Tocilizumab
Anakinra

Neuromodulation

Vagus Nerve Stimulation (VNS)

May help persistent SRSE.

Usually considered:

After medical failure

Deep Brain Stimulation

Rare rescue therapy.

Electroconvulsive Therapy (ECT)

Occasionally effective.

Used only in extreme SRSE.

Surgical Therapy

Consider when focal epileptogenic lesion identified.

Options:

Focal resection
Lobectomy
Hemispherectomy (rare)

Particularly useful:

Tumors
Cortical dysplasia
Focal encephalitis

NORSE(New-Onset Refractory Status Epilepticus)

Definition:

Refractory SE occurring in a person without previous epilepsy and without obvious acute cause.

Commonly autoimmune.

FIRES(Febrile Infection-Related Epilepsy Syndrome)

A subtype of NORSE.

Typically:

Previously healthy
Viral-like illness
Explosive refractory seizures

High mortality.