Eclampsia overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Assosciate Editor(s)-In-Chief: Navneet Kaur M.B.,B.S.
Overview
Eclampsia, an acute and life-threatening complication of pregnancy, is characterized by the appearance of tonic-clonic seizures in a patient who had developed preeclampsia; rarely does eclampsia occur without preceding preeclamptic symptoms. Hypertensive disorder of pregnancy and toxemia of pregnancy are terms used to encompass both preeclampsia and eclampsia. Seizures and coma that happen during pregnancy but are due to preexisting or organic brain disorders are not eclampsia.
Eclamptic convulsions may appear in the last trimester (rarely before), during labour, and in the first two days postpartum; it would be highly unusual to see eclampsia later than 48 hours after delivery.[1]
Historical Perspective
The importance of historical perspective lies in the fact that our current understanding of pathophysiology, classifications and management strategies is influenced by past hypotheses and scientific contributions, which have also shaped our current practice trends. The term is derived from Greek and refers to a flash, a term used by Hippocrates to designate a fever of sudden onset. Various theories have been proposed from time to time such as the theory of four humours, wet and dry theory, wandering womb theory during ancient times; dominant humour theory and Mauriceau’s suppressed lochia flow theory during the middle ages; During the 18th and the 19th century, physicians started noting the association of various symptoms such as headache, body edema, short term loss of vision, severe pain in the stomach, etc. during later months of pregnancy and the development of convulsions. Smith’s theory of toxic elements came during the same period. Extensive advancements in uncovering the pathophysiological changes were made in the 20th century, such as the trophoblastic shallow invasion theory and endothelial disorder theory. Various treatments were offered from time to time depending upon the theories proposed such as purging, bloodletting, altered diets, getting rid of toxic elements, placing the patient in a warm bath, opiates, etc. during the 20th century increased focus was placed on routine prenatal care and early recognition of warning signs and symptoms. In the early 20th century the use of magnesium sulphate was popularised and safety was established which still guides our treatment protocols.
Pathophysiology
Eclampsia is severe form of pre-eclampsia and all the changes that happen in pre-eclampsia are further intensified. It is associated with abnormal or defective spiral artery remodelling, that is, high-resistance, low-flow blood vessels are unable to convert to low-resistance, high-flow blood vessels, hypoperfusion of the fetoplacental unit, and chronic placental ischemia which result in oxidative stress and formation of reactive oxygen species. There is an imbalance between vasodilator agents such as prostaglandins and nitric oxide and vasoconstrictor agents such as thromboxane-II (TXA-2) amd angiotensin II. Also there is increased production of endothelin-1 which also acts as a vasoconstrictor. Enhanced expression of antiangiogenic factors like sFlt-1 and soluble endoglin (sEng) are also responsible for deranged cell signalling and inhibition of VEGF and TGF-beta. The oxidative stress results in various organ system damages and can ultimately lead to cerebral edema, cerebral anoxia, cerebral autoregulation failure and excess of excitatory neurotransmitters, which can result in convulsions.
Epidemiology and demographics
Hypertensive disorders of pregnancy (HDP), defined as a sex-specific cardiovascular disease, is one of the leading causes of maternal and fetal morbidity and mortality globally and a critical threat to maternal and infant health. Preeclampsia is a pregnancy-related hypertensive disorder occurring usually after 20 weeks of gestation and if left untreated, it progresses to eclampsia. Preeclampsia and eclampsia are not distinct disorders but the manifestation of the spectrum of clinical symptoms of the same condition. Although preeclampsia prevails to be a significant public health threat in both developed and developing nations bringing maternal and perinatal morbidity and mortality worldwide, the impact of the disease is witnessed to be harsher in the developing countries, where, unlike other more prevalent causes of maternal mortality (such as haemorrhage and sepsis), medical interventions may be ineffective due to late presentation of cases. The problem is confounded by the continued ambivalence of the aetiology and the unpredictable behavior of the disease. According to WHO, the incidence of preeclampsia is seven times higher in developing countries (2.8% of live births) than in developed countries (0.4%). In developing countries the prevalence of preeclampsia, the precursor of eclampsia, ranges from 1.8% to 16.7% and from 1990 to 2019, the incidence, prevalence, death and YLDs were highest in populations aged 25–29 years.
Risk Factors
The various risk factors associated with the development of eclampsia encompass a personal or family history of pre-eclampsia/eclampsia, nulliparity, primigravida, long interpregnancy intervals, conditions with a large placenta such as multiple gestations(twins or triplets) and H Mole, women with preexisting conditions such as chronic hypertension, history of gestational hypertension in the previous pregnancy, renal diseases, diabetes, gestational diabetes, obesity, certain thrombophilic diseases (such as the antiphospholipid antibody syndrome, protein C deficiency, protein S deficiency, anti-thrombin deficiency), connective tissue disorders, SLE and genetics.
Prevention
Detection and management of preeclampsia is critical to reduce the risk of eclampsia. Appropriate management of patients with preeclampsia generally involves the use of magnesium sulfate as an agent to prevent convulsions, and thus preventing eclampsia.
References
- ↑ Chesley LC. Hypertensive Disorders in Pregnancy, in Williams Obstetrics, 14th Edition. Appleton Century Crofts, New York (1971), page 700.