Definition of Eclampsia
Eclampsia is the onset of new generalized tonic-clonic (grand mal) seizures in a pregnant woman with preeclampsia, occurring in the absence of other causative conditions 1, 2, 3.
Etymology and Clinical Presentation
The term "eclampsia" derives from the Greek word meaning "like a flash of lightning," reflecting how these seizures can occur quite abruptly without warning manifestations 4. This dramatic terminology captures the sudden, potentially catastrophic nature of the condition.
Timing and Context
Eclamptic seizures can occur:
- After 20 weeks of gestation (antepartum)
- During labor (intrapartum)
- After delivery (postpartum)
Seizures occurring before 20 weeks are rare and should raise suspicion for gestational trophoblastic disease 3.
Relationship to Preeclampsia
Eclampsia represents a severe complication of preeclampsia, not a separate disease entity 5. While preeclampsia is defined as gestational hypertension with proteinuria and/or maternal organ dysfunction after 20 weeks, eclampsia adds the critical feature of seizure activity to this syndrome 5, 1.
Without magnesium sulfate prophylaxis, approximately 2% of women with severe preeclampsia will develop eclamptic seizures; with magnesium sulfate, this drops to less than 0.6% 2.
Pathophysiology
The underlying mechanism involves blood-brain barrier disruption with passage of fluid, ions, and plasma proteins into brain parenchyma 2. Circulating factors in preeclamptic plasma—including vascular endothelial growth factor, placental growth factor, neurokinin B, inflammatory cytokines, and endothelins—increase blood-brain barrier permeability and alter neuronal excitability 2, 6.
Clinical Significance
Eclampsia is a major cause of maternal and neonatal mortality and morbidity worldwide, with incidence ranging from 1.6-10 per 10,000 deliveries in developed countries to 50-151 per 10,000 in developing countries 2. The condition requires immediate medical intervention and definitive treatment through delivery 1.