Definition of Status Epilepticus
Status epilepticus is defined as a seizure lasting 5 minutes or longer, or recurrent seizures without return to baseline consciousness between episodes. 1
Evolution of the Definition
The definition of status epilepticus has evolved significantly over time, reflecting improved understanding of seizure pathophysiology and treatment urgency:
Traditional definition: Status epilepticus was historically defined as unremitting convulsive seizure activity lasting 20 minutes or more, or intermittent seizures without regaining full consciousness between episodes. 2
Current operational definition: Modern clinical guidelines now use a 5-minute threshold, recognizing that generalized convulsive seizures lasting this duration should prompt immediate treatment as status epilepticus. 2, 1
Rationale for the shorter timeframe: Once a seizure has lasted 5-10 minutes, it is unlikely to cease spontaneously, and the longer seizure activity continues, the more difficult it becomes to control. 3
Clinical Characteristics
Status epilepticus is a life-threatening neurological emergency characterized by:
Prolonged seizure activity or recurrent seizures without full recovery of consciousness between episodes 1, 4
High risk of permanent neurological impairment if inadequately treated 4
Mortality rates of 5-22% in general cases, increasing to 65% in refractory cases 1
Age-Related Considerations
Patient age is a major determinant of prognosis in status epilepticus. 2
Pediatric population: The incidence peaks in children, with febrile seizures being a major etiology. 5 However, the safety of lorazepam in pediatric patients has not been established, and there are insufficient data to support dosage recommendations for patients less than 18 years of age. 4
Elderly patients: The incidence also peaks in older adults, with stroke being a predominant etiology. 5 Patients over 50 years may experience more profound and prolonged sedation with treatment. 4
Overall epidemiology: Up to 5% of adults with epilepsy will experience at least one episode of status epilepticus in their lifetime. 2
Common Etiologies
The underlying causes vary by population and geographic region:
Infections: A common cause of status epilepticus, particularly central nervous system infections in developing countries 2, 6
Ischemic stroke: A major etiology requiring investigation, especially in elderly patients 2, 6
Head injury: Particularly prevalent in developing countries 6
Withdrawal syndromes: Can trigger status epilepticus, emphasizing need for comprehensive assessment 2
Metabolic derangements: Status epilepticus may result from correctable acute causes such as hypoglycemia, hyponatremia, or other metabolic or toxic derangements that must be immediately sought and corrected 4
Critical Action Thresholds
First aid providers and EMS should be activated for: 2
- Seizures lasting >5 minutes
- Multiple seizures without return to baseline mental status
- Failure to return to baseline within 5-10 minutes after seizure activity stops
Special Considerations
Nonconvulsive status epilepticus: EEG monitoring is crucial for detecting this form, especially in patients with persistent altered consciousness. 1 Consider emergent EEG in patients suspected of nonconvulsive status epilepticus, those who have received long-acting paralytics, or patients in drug-induced coma. 1
Refractory status epilepticus: Defined as status epilepticus persisting despite sufficient doses of benzodiazepines and at least one antiepileptic drug, occurring in 23-48% of patients. 6
Super-refractory status epilepticus: Defined as status epilepticus continuing for 24 hours or more after anesthetic therapy, or recurring on weaning of anesthetic agents, occurring in approximately 22% of patients. 6