Status Epilepticus

Introduction and Definitions

• Status epilepticus is defined by continuous seizure activity or recurrent seizures without return to baseline consciousness.
• The seizure duration threshold for status epilepticus is ≥5 minutes for convulsive status epilepticus or ≥10 minutes for non-convulsive status epilepticus.
• Convulsive status epilepticus typically includes tonic–clonic seizures, whereas non-convulsive status epilepticus involves ongoing electrographic seizure activity without motor findings, though subtle findings such as nystagmus or fixed gaze deviation may be present.
• Refractory status epilepticus (RSE) persists despite first- and second-line therapy, and super-refractory status epilepticus (SRSE) continues >24 hours after anesthetic therapy initiation.¹

Epidemiology and Etiology

• The annual incidence approximates 20 cases per 100,000 adults.
• Common precipitants include withdrawal of antiseizure medications, acute cerebrovascular events, traumatic brain injury, infection, hypoxia, metabolic derangements, and toxic ingestions.
• Anesthetic and perioperative triggers include hypoglycemia, hyponatremia, local-anesthetic toxicity, and inadequate anticonvulsant coverage in epilepsy patients.¹

Pathophysiology

• The pathophysiology of status epilepticus arises from sustained epileptiform activity, which produces neuronal hyperexcitability through NMDA-mediated excitation and failure of GABAergic inhibition.
• Prolonged seizure activity leads to excitotoxicity, cerebral edema, and systemic complications such as metabolic acidosis and cardiovascular instability.
• From an anesthetic perspective, sustained cerebral and muscle activity increases oxygen consumption and CO_₂ production, necessitating early airway control and mechanical ventilation.¹

Anesthetic Evaluation, Management, and Considerations

Initial Evaluation

• When there is suspicion of seizure activity, one should assess the patient’s ability to maintain airway and respiratory function. Hemodynamic compromise should be addressed promptly, with ACLS protocols initiated as necessary. Intubation should be considered for patients with a Glasgow Coma Scale ≤ 8, obtunded patients, hypoventilating patients, or patients at risk of aspiration.
• It is vital to assess for reversible causes, including hypoglycemia, electrolyte disturbances, and toxin ingestion.
• Initiate electroencephalogram (EEG) monitoring if seizure activity persists beyond benzodiazepine administration.
• Recommend obtaining a non-contrast CT head, metabolic panel, toxicology screen, and checking antiseizure drug levels.

Pharmacologic Management^1,3,4,5

Anesthetic Considerations

• Anticipate a potentially difficult intubation due to trismus or secretions, and consider rapid-sequence induction with an agent appropriate for the patient’s hemodynamic status.
• Manage vasoplegia and myocardial depression secondary to infusions and titrate vasopressors as needed.
• Aggressively control temperature as hyperthermia worsens neuronal injury.
• Maintain normocapnia and avoid severe hypocapnia, which could potentially exacerbate neuronal injury through cerebral ischemia.
• Manage intracranial pressure by treating edema with head elevation, osmotic therapy, and normothermia.^1-3,5,6

Critical Care and Perioperative Management

• In severe cases, consider targeting burst suppression on the EEG.
• Monitor for acidosis, propofol infusion syndrome, and renal dysfunction, often secondary to rhabdomyolysis. Weaning anesthetics should be gradual after 24–48 h of control.
• Identify and treat the underlying etiology.
• Coordinate with OR/ICU teams for timing of interventions once seizures are stabilized.^2,4,5,7

Prognosis

• Mortality in adult status epilepticus ranges from 10–30%. Poor prognostic factors include patients older than 65, acute symptomatic etiology, delayed treatment, and prolonged RSE duration.^1,2,4,7