Status epilepticus

Learning objectives

Status epilepticus is defined as more than 30 minutes of either 1) continuous seizure activity or 2) two or more sequential seizures without full recovery of consciousness between seizures
Cerebral damage is more likely if the seizure is prolonged
There are lots of different types of seizures and not all of them involve obvious convulsive activity
Epilepsy can occur at any age but is commonly diagnosed in those aged below 20 or over 65 years
First stage is characterized by an increase in:
- Cerebral metabolism
- Blood flow
- Glucose and lactate concentration
Compensatory mechanisms:
- Massive catecholamine release
- Raised cardiac output
- Hypertension
- Increased central venous pressure
After 30-60 min, compensatory mechanisms fail:
- Hypoxia
- Hypoglycemia
- Increased intracranial pressure
- Cerebral edema
- Hyponatremia
- Potassium imbalance
- Evolving metabolic acidosis
- Consumptive coagulopathy
- Rhabdomyolysis
- Multi-organ failure

Status epilepticus can present in several forms:

Convulsive: unresponsiveness and tonic, clonic, or tonic-clonic movements of the extremities
Non-convulsive: prolonged seizure activity evidenced by epileptiform discharges on EEG, change in behavior or cognition in some patients
Electrographic: commonly used for comatose patients who show electrographic evidence of prolonged seizure activity

Based on history and clinical examination
Often present either actively convulsing or minimal time between clustered seizures

Seizure detection based on EEG and immediate treatment
In patients with a history of well-controlled epilepsy, avoid disruption of antiepileptic medication perioperatively

Rescue benzodiazepines

Medication	Dose range (max dose)	Comments
IV lorazepam	0.05-0.1 mg/kg/dose (2-4 mg)	May repeat dose once
Rectal diazepam	0.2-0.5 mg/kg (20 mg)	Age 6 months - 5 years: 0.5 mg/kg Age 6-12 years: 0.3 mg/kg Age 12+ years: 0.2 mg/kg
Nasal midazolam	0.2-0.3 mg/kg (5-10 mg)	<40 kg: 0.2-0.3 mg/kg >40 kg: give 10 mg (max dose), half the dose in each nostril
IM midazolam	0.2-0.3 mg/kg (5-10 mg)	<13 kg: 0.2-0.3 mg/kg 13-40 kg: give 5 mg >40 kg: give 10 mg (max dose)
IV diazepam	0.15-0.3 mg/kg (10mg)	Shorter duration compared to lorazepam Higher risk for respiratory depression

Tier 2 medications

Medication	Dose range (max dose)	Comments
Fosphenytoin	20 mg PE/kg (1500 mg)	Drug levels quickly available for titration Avoid if known generalized epilepsy or Dravet syndrome Beware of hypotension and bradycardia Tissue extravasation is potentially dangerous
Levetiracetam	60 mg/kg (4500 mg)	Also effective for myoclonic seizures
Valproic acid	40 mg/kg (3000 mg)	Effective in juvenile myoclonic epilepsy, myoclonic status and absence status Caution in patients with liver dysfunction and select metabolic diseases (e.g., POLG1)
Phenobarbital	10-20 mg/kg (1000 mg)	Drug of choice in newborns Beware of hypotension and respiratory depression May use in adults if previously used with status due to missed or held doses
Lacosamide	5-10 mg/kg (400 mg)	Caution with cardiac issues, can prolong PR interval Use if previously used and status due to missed or held doses