From the Guidelines
Eclampsia is a severe complication of preeclampsia, characterized by seizures, and its pathophysiology is rooted in abnormal placentation, leading to placental ischemia, oxidative stress, and the release of anti-angiogenic factors into maternal circulation. The pathophysiology of eclampsia begins with inadequate placental implantation, where trophoblast cells fail to adequately invade maternal spiral arteries, leading to placental hypoxia, oxidative stress, and inflammation 1. This triggers the release of anti-angiogenic factors like soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin into maternal circulation, which antagonize vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) 1.
The resulting widespread endothelial dysfunction causes systemic vasoconstriction, increased vascular permeability, and activation of the coagulation cascade. In the brain specifically, these changes lead to disruption of the blood-brain barrier, cerebral edema, and vasogenic edema. The posterior cerebral circulation is particularly vulnerable, explaining the visual disturbances often seen. Autoregulation of cerebral blood flow becomes impaired, making the brain susceptible to hyperperfusion when blood pressure rises, which can cause hemorrhage or further edema.
Key factors involved in the pathophysiology of eclampsia include:
- Abnormal placentation and placental ischemia
- Release of anti-angiogenic factors (sFlt-1 and soluble endoglin)
- Endothelial dysfunction
- Systemic vasoconstriction and increased vascular permeability
- Activation of the coagulation cascade
- Disruption of the blood-brain barrier and cerebral edema
The most recent and highest quality study 1 highlights the complexity of preeclampsia and eclampsia, emphasizing the need for further research into the underlying biological mechanisms and the development of targeted prevention and treatment strategies. Understanding the pathophysiology of eclampsia is crucial for the development of effective prevention and treatment strategies, and current research suggests that a multifaceted approach, including the use of low-dose aspirin and other therapies, may be necessary to prevent and treat this condition.
From the FDA Drug Label
Magnesium prevents or controls convulsions by blocking neuromuscular transmission and decreasing the amount of acetylcholine liberated at the end-plate by the motor nerve impulse. The pathophysiology of eclampsia is not directly addressed in the provided drug label.
- The label discusses the mechanism of action of magnesium sulfate in preventing or controlling convulsions, but does not provide information on the underlying pathophysiology of eclampsia itself 2.
From the Research
Pathophysiology of Eclampsia
The pathophysiology of eclampsia is complex and involves multiple systems. Key aspects include:
- Cerebral hemodynamics and perfusion play a crucial role in the development of eclampsia 3
- The condition is characterized by new-onset seizures in the setting of preeclampsia, which is a multisystem disorder involving the central nervous system 4
- Preeclampsia is considered a pregnancy-specific disorder caused by the placenta and cured only by delivery 5
- The release of antiangiogenic factors by the placenta is thought to be an adaptive response to improve uterine perfusion, but can become maladaptive and lead to damage of target organs 5
Clinical Features and Diagnosis
Clinical features of eclampsia include:
- New-onset seizures in pregnancy or within 10 days of delivery, accompanied by hypertension, proteinuria, thrombocytopenia, or raised aspartate amino transferase 6
- Neurologic signs and symptoms such as hyperreflexia, headaches, visual disturbance, seizures, and cerebral hemorrhage 4
- Diagnosis is based on the presence of these clinical features, and optimal emergency management of seizures, hypertension, fluid balance, and subsequent safe transfer is essential to minimize morbidity and mortality 6
Treatment and Management
Treatment of eclampsia aims to stop seizures and prevent reoccurrence of convulsions and complications. Key aspects include:
- Magnesium sulfate is the drug of first choice used in the treatment of eclampsia seizure 7
- Antihypertensive drugs and proper blood pressure control are also crucial in reducing the risk of deaths or acute complications and poor pregnancy outcomes 7
- The most urgent part of the treatment is the lifesaving procedure involving airways patency assessment, maintenance of breathing and blood circulation of the mother, securing an adequate oxygen level of the mother and thereby of the fetus, and prevention of injuries 7