What is eclampsia in a pregnant woman with a history of severe preeclampsia?

Definition of Eclampsia

Eclampsia is defined as new-onset generalized tonic-clonic seizures occurring in a woman with preeclampsia that cannot be attributed to other causes. 1, 2

Core Diagnostic Criteria

Eclampsia represents the convulsive manifestation of preeclampsia, occurring when a woman with preeclampsia (new-onset hypertension ≥140/90 mmHg after 20 weeks gestation with proteinuria or maternal organ dysfunction) develops seizures. 1, 3

Historical Context

• Eclampsia was first described by Celsus in 100 AD as seizures during pregnancy that resolved with delivery, and for 2000 years was considered purely a pregnancy-specific seizure disorder. 1
• The connection between eclampsia and systemic disease was not recognized until the mid-1800s when clinicians noted similarities between eclamptic women and patients with acute glomerulonephritis. 1

Timing of Eclamptic Seizures

Eclamptic seizures can occur at three distinct time periods:

• Antepartum: After 20 weeks of gestation but before delivery 2, 4
• Intrapartum: During labor and delivery 2, 4
• Postpartum: Within 48 hours after delivery (most common postpartum presentation) or as late as 1 month postpartum (late postpartum eclampsia) 2

Critical Pitfall

Up to 10% of maternal deaths from hypertensive disorders occur postpartum, often presenting with neurological symptoms, so vigilance must continue after delivery. 5

Relationship to Preeclampsia

Eclampsia occurs in approximately 0.2% of preeclamptic patients, representing a severe complication of the underlying preeclampsia syndrome. 6

• Preeclampsia is fundamentally a multisystem disorder where hypertension serves as an indicator of widespread endothelial dysfunction rather than the primary pathology. 1
• The acute risks of preeclampsia to mother and baby are substantial, with eclampsia representing one of the most severe manifestations. 1

Pathophysiologic Mechanism

The seizures in eclampsia result from:

• Cerebrovascular dysfunction secondary to the systemic endothelial damage characteristic of preeclampsia 7
• Blood-brain barrier disruption allowing increased permeability and cerebral edema 8
• Neuroinflammation with microglial activation that lowers seizure threshold 8
• Angiogenic imbalance with elevated sFlt-1 and reduced PlGF contributing to CNS complications 2

Distinguishing Features

Key characteristics that define eclampsia:

• Seizures must be new-onset and generalized tonic-clonic in nature 2, 4
• Seizures occur in the setting of preeclampsia (hypertension plus proteinuria or organ dysfunction) 3
• Other causes of seizures must be excluded (epilepsy, cerebral hemorrhage, metabolic derangements) 1, 2
• Associated with severe features including altered mental status, visual disturbances, severe headache, and hyperreflexia 5, 2

Clinical Context for Women with Severe Preeclampsia

In a pregnant woman with a history of severe preeclampsia, eclampsia represents the progression to seizure activity, signaling critical CNS involvement requiring immediate intervention with magnesium sulfate for seizure prophylaxis and control. 9, 2