Residency · Residency · Internal Medicine
Status Epilepticus: Emergency Management
Introduction
Status epilepticus (SE) is a neurologic emergency defined as continuous seizure activity lasting 5 minutes or longer, or two or more seizures without return to baseline between episodes. Convulsive SE carries a mortality rate of 10-30% and the risk of permanent neurologic injury increases with each minute of ongoing seizure activity. A structured, time-based protocol with immediate benzodiazepine administration is critical to improving outcomes.
Definitions and Classification
- Convulsive status epilepticus (CSE): continuous generalized tonic-clonic seizure activity >= 5 minutes
- Non-convulsive status epilepticus (NCSE): electrographic seizure activity without prominent motor manifestations; often presents as altered mental status, confusion, or subtle eye movements
- Refractory SE (RSE): seizures persisting despite adequate first-line (benzodiazepine) and second-line antiseizure medication
- Super-refractory SE (SRSE): seizures continuing >= 24 hours after initiation of anesthetic agents, or recurring upon anesthetic withdrawal
- Established SE: seizures lasting >= 30 minutes without treatment; associated with excitotoxic neuronal injury, receptor trafficking (GABA receptor internalization, NMDA receptor externalization), and progressive pharmacoresistance
Etiology
Common Causes in Adults
- Antiseizure medication (ASM) non-adherence or withdrawal: most common cause in known epilepsy patients
- Acute structural lesion: stroke, hemorrhage, traumatic brain injury, brain tumor
- CNS infection: meningitis, encephalitis (HSV), brain abscess
- Metabolic derangements: hypoglycemia, hyponatremia, hypocalcemia, uremia, hepatic encephalopathy
- Toxic exposures: alcohol withdrawal, benzodiazepine withdrawal, drug overdose (sympathomimetics, isoniazid)
- Autoimmune encephalitis: anti-NMDA receptor encephalitis, LGI1 antibody encephalitis
- Anoxic brain injury: post-cardiac arrest
Time-Based Treatment Protocol
Phase 1: Stabilization (0-5 Minutes)
- ABCs: secure airway, suction secretions, position in lateral decubitus, supplemental oxygen
- IV access: obtain two large-bore IVs
- Fingerstick glucose: administer dextrose 50% (25-50 mL IV) if hypoglycemic
- Thiamine 100 mg IV before or with dextrose (if alcoholism or malnutrition suspected)
- Labs: BMP, CBC, calcium, magnesium, ASM levels, toxicology screen, ABG
- Do NOT: place objects in the mouth, restrain the patient forcefully
Phase 2: First-Line Therapy -- Benzodiazepines (5-20 Minutes)
| Agent | Route | Dose | Notes |
|---|---|---|---|
| Lorazepam | IV | 0.1 mg/kg (max 4 mg), repeat x1 in 5 min | Preferred IV agent |
| Midazolam | IM | 10 mg (>40 kg) | Preferred if no IV access (RAMPART) |
| Diazepam | IV | 0.15 mg/kg (max 10 mg) | If lorazepam unavailable |
| Midazolam | Intranasal | 5 mg per nostril | Alternative non-IV route |
| Diazepam | Rectal | 0.2 mg/kg | Alternative non-IV route |
- IV lorazepam: 0.1 mg/kg (max 4 mg), repeat once in 5 minutes if seizures continue
- IM midazolam: 10 mg IM (> 40 kg) if no IV access; RAMPART trial demonstrated IM midazolam non-inferior to IV lorazepam with faster time-to-treatment in the prehospital setting
- IV diazepam: 0.15 mg/kg (max 10 mg) if lorazepam unavailable
- Rectal diazepam or intranasal midazolam: alternatives when IV/IM access is not available
- Benzodiazepines terminate seizures in approximately 65% of cases when given promptly
Phase 3: Second-Line Therapy -- Urgent Control (20-40 Minutes)
If seizures persist after adequate benzodiazepine doses:
| Agent | Dose | Infusion Rate | Avoid If |
|---|---|---|---|
| Levetiracetam | 60 mg/kg (max 4500 mg) | Over 10 min | Few contraindications |
| Fosphenytoin | 20 mg PE/kg | 150 mg PE/min | Cardiac conduction disease, bradycardia |
| Valproate | 40 mg/kg (max 3000 mg) | Over 10 min | Pregnancy, hepatic failure, mitochondrial disease |
- IV levetiracetam: 60 mg/kg (max 4500 mg) infused over 10 minutes; fewest drug interactions, no hemodynamic effects
- IV fosphenytoin: 20 mg PE/kg at 150 mg PE/min; monitor for hypotension and arrhythmia; avoid in known cardiac conduction disease
- IV valproate: 40 mg/kg (max 3000 mg) infused over 10 minutes; avoid in pregnancy, hepatic failure, mitochondrial disease, pancreatitis
- ESETT trial: levetiracetam, fosphenytoin, and valproate are equally effective as second-line agents (seizure cessation in approximately 45% each); choice should be based on patient-specific factors
Phase 4: Refractory SE -- Third-Line Therapy (> 40 Minutes)
- Intubation and continuous IV anesthetic infusion:
- Midazolam: 0.2 mg/kg bolus, then 0.1-2 mg/kg/hour infusion
- Propofol: 2 mg/kg bolus, then 30-200 mcg/kg/min; monitor for propofol infusion syndrome (metabolic acidosis, rhabdomyolysis, cardiac failure) if > 48 hours or > 5 mg/kg/hour
- Pentobarbital: 5 mg/kg bolus, then 1-5 mg/kg/hour; most potent but greatest hemodynamic compromise
- Continuous EEG (cEEG) monitoring: mandatory to guide anesthetic titration; target burst suppression or seizure suppression
- Maintain anesthetic infusion for 24-48 hours, then slowly wean while monitoring for seizure recurrence
Non-Convulsive Status Epilepticus
- Suspect in any patient with unexplained altered mental status, particularly after convulsive seizures
- Diagnosis requires continuous EEG monitoring
- Common in the ICU: up to 20% of comatose ICU patients have NCSE
- Treat with the same stepwise protocol, though urgency may be slightly less than in convulsive SE
- Post-cardiac arrest: electrographic seizures common but treatment decisions are complex; avoid aggressive anesthetic therapy if prognosis is poor
Special Considerations
- Isoniazid toxicity: treat with pyridoxine (vitamin B6) gram-for-gram replacement (5 g IV if dose unknown)
- Eclampsia: magnesium sulfate is the agent of choice (not benzodiazepines)
- Alcohol withdrawal seizures: typically self-limited; benzodiazepines are first-line; phenobarbital is an effective alternative
- Anti-NMDA receptor encephalitis: immunotherapy (steroids, IVIG, plasmapheresis) alongside ASMs
Key Clinical Pearls
- Give benzodiazepines IMMEDIATELY; every minute of delay reduces the probability of seizure termination
- IM midazolam is as effective as IV lorazepam and can be administered faster when IV access is not established (RAMPART trial)
- Levetiracetam, fosphenytoin, and valproate are equally effective second-line agents (ESETT trial); choose based on comorbidities and drug interactions
- Always obtain continuous EEG monitoring in refractory SE and in any patient who does not return to baseline mental status after seizure cessation
References
- Glauser T, Shinnar S, Gloss D, et al. Evidence-Based Guideline: Treatment of Convulsive Status Epilepticus in Children and Adults (AAN/AES). Epilepsy Curr. 2016;16(1):48-61.
- Kapur J, Elm J, Chamberlain JM, et al. Randomized Trial of Three Anticonvulsant Medications for Status Epilepticus (ESETT). N Engl J Med. 2019;381(22):2103-2113.
- Silbergleit R, Durkalski V, Lowenstein D, et al. Intramuscular versus Intravenous Therapy for Prehospital Status Epilepticus (RAMPART). N Engl J Med. 2012;366(7):591-600.
- Brophy GM, Bell R, Claassen J, et al. Guidelines for the Evaluation and Management of Status Epilepticus. Neurocrit Care. 2012;17(1):3-23.