Eclampsia
Eclampsia is the onset of seizures in a pregnant woman with pre-eclampsia. Pre-eclampsia is a hypertensive disorder of pregnancy that presents with three main features: new onset of high blood pressure, large amounts of protein in the urine or other organ dysfunction, and edema. If left untreated, pre-eclampsia can result in long-term consequences for the pregnant woman, namely increased risk of cardiovascular diseases and associated complications. In more severe cases, it may be fatal for both the pregnant woman and the fetus.
The diagnostic criterion for pre-eclampsia is high blood pressure, occurring after 20 weeks gestation or during the second half of pregnancy. Most often it occurs during the 3rd trimester of pregnancy and may occur before, during, or after delivery. The seizures are of the tonic–clonic type and typically last about a minute. Following the seizure, there is either a period of confusion or coma. Other complications include aspiration pneumonia, cerebral hemorrhage, kidney failure, pulmonary edema, HELLP syndrome, coagulopathy, placental abruption and cardiac arrest.
Low dose aspirin is recommended to prevent pre-eclampsia and eclampsia in those at high risk. Other preventative recommendations include calcium supplementation in areas with low calcium intake and treatment of prior hypertension with anti-hypertensive medications. Exercise during pregnancy may also be useful. The use of intravenous or intramuscular magnesium sulfate improves outcomes in those with severe pre-eclampsia and eclampsia and is generally safe. Treatment options include blood pressure medications such as hydralazine and emergency delivery of the baby either vaginally or by cesarean section.
Pre-eclampsia is estimated to globally affect about 5% of deliveries while eclampsia affects about 1.4% of deliveries. In the developed world eclampsia rates are about 1 in 2,000 deliveries due to improved medical care whereas in developing countries it can impact 10–30 times as many women. Hypertensive disorders of pregnancy are one of the most common causes of death in pregnancy. They resulted in 46,900 deaths in 2015. Maternal mortality due to eclampsia occurs at a rate of approximately 0–1.8% of cases in high-income countries and up to 15% of cases in low- to middle- income countries. The word eclampsia is from the Greek term for lightning. The first known description of the condition was by Hippocrates in the 5th century BC.
Signs and symptoms
Eclampsia is a disorder of pregnancy characterized by seizures in the setting of pre-eclampsia. Most women have premonitory signs/symptoms in the hours before the initial seizure. Typically the mother develops hypertension before the onset of a convulsion. Other signs and symptoms include:- Long-lasting frontal, occipital, or thunderclap headaches
- Visual disturbance
- Photophobia
- Abdominal pain, often in the epigastric region or in the right upper quadrant of the abdomen
- Altered mental status
Other cerebral signs that may precede the convulsion include nausea, vomiting, headaches, and cortical blindness. If the complication of multi-organ failure ensues, signs and symptoms of those failing organs will appear, such as abdominal pain, jaundice, shortness of breath, and diminished urine output.
Onset
The seizures of eclampsia typically present during pregnancy and prior to delivery, but may also occur during labor and delivery or after the baby has been delivered. If postpartum seizures develop, it is most likely to occur within the first 48 hours after delivery. However, late postpartum seizures of eclampsia may occur as late as 4 weeks after delivery.Characteristics
Eclamptic seizure is typically described as a tonic–clonic seizure which may cause an abrupt loss of consciousness at onset. This is often associated with a shriek or scream followed by stiffness of the muscles of the arms, legs, back and chest. During the tonic phase, the mother may begin to appear cyanotic. This presentation lasts for about a minute, after which the muscles begin in jerk and twitch for an additional one to two minutes. Other signs include tongue biting, frothy and bloody sputum coming out of the mouth.Complications
There are risks to both the mother and the fetus when eclampsia occurs. The fetus may grow more slowly than normal within the womb of a woman with eclampsia, which is termed intrauterine growth restriction and may result in the child appearing small for gestational age or being born with low birth weight. Eclampsia may also cause problems with the placenta. The placenta may bleed or begin to separate early from the wall of the uterus. It is normal for the placenta to separate from the uterine wall during delivery, but it is abnormal for it to separate prior to delivery; this condition is called placental abruption and can be dangerous for the fetus. Placental insufficiency may also occur, a state in which the placenta fails to support appropriate fetal development because it cannot deliver the necessary amount of oxygen or nutrients to the fetus. During an eclamptic seizure, the beating of the fetal heart may become slower than normal. If any of these complications occurs, fetal distress may develop. Treatment of the mother's seizures may also manage fetal bradycardia. If the risk to the health of the fetus or the mother is high, the definitive treatment for eclampsia is delivery of the baby. Delivery by cesarean section may be necessary, especially if the instance of fetal bradycardia does not resolve after 10 to 15 minutes of resuscitative interventions. It may be safer to deliver the infant preterm than to wait for the full 40 weeks of fetal development to finish, and as a result prematurity is also a potential complication of eclampsia.In the mother, changes in vision may occur as a result of eclampsia, and these changes may include blurry vision, one-sided blindness, or cortical blindness, which affects the vision from both eyes. There are also potential complications in the lungs. The person may have fluid slowly collecting in the lungs in a process known as pulmonary edema. During an eclamptic seizure, it is possible for a person to vomit the contents of the stomach and to inhale some of this material in a process known as aspiration. If aspiration occurs, the mother may experience difficulty breathing immediately or could develop an infection in the lungs later, called aspiration pneumonia. It is also possible that during a seizure breathing will stop temporarily or become inefficient, and the amount of oxygen reaching the mother's body and brain will be decreased. If it becomes difficult for the mother to breathe, she may need to have her breathing temporarily supported by an assistive device in a process called mechanical ventilation. In some severe eclampsia cases, the mother may become weak and sluggish or even comatose. These may be signs that the brain is swelling or bleeding.
Risk factors
Eclampsia, like pre-eclampsia, tends to occur more commonly in first pregnancies than subsequent pregnancies. Women who have long term high blood pressure before becoming pregnant have a greater risk of pre-eclampsia. Women who have gestational hypertension and pre-eclampsia have an increased risk of eclampsia. Furthermore, women with other pre-existing vascular diseases or thrombophilia disease such as the antiphospholipid syndrome are at higher risk to develop pre-eclampsia and eclampsia. Having a placenta that is enlarged by multiple gestation or hydatidiform mole also increases risk of eclampsia. In addition, there is a genetic component: a person whose mother or sister had the condition is at higher risk than otherwise. Women who have experienced eclampsia are at increased risk for pre-eclampsia/eclampsia in a later pregnancy. The occurrence of pre-eclampsia was 5% in White, 9% in Hispanic, and 11% in African American patients and this may reflect disproportionate risk of developing pre-eclampsia among ethnic groups. Additionally, Black women were also shown to have a disproportionately higher risk of dying from eclampsia.Mechanism
The mechanisms of eclampsia and preeclampsia are not definitively understood. The presence of a placenta is required, and eclampsia resolves if it is removed. Reduced blood flow to the placenta may be a key feature of the process. It is typically accompanied by increased sensitivity of the maternal vasculature to agents which cause constriction of the small arteries, leading to reduced blood flow to multiple organs. Vascular dysfunction-associated maternal conditions such as Lupus, hypertension, and renal disease, or obstetric conditions that increase placental volume without an increase in placental blood flow may increase risk for pre-eclampsia. Also, activation of the coagulation cascade can lead to microthrombi formation, which may further impair blood flow. Thirdly, increased vascular permeability results in the shift of extracellular fluid from the blood to the interstitial space which reduces blood flow and causes edema. These events can lead to hypertension, renal dysfunction, pulmonary dysfunction, hepatic dysfunction, and cerebral edema with cerebral dysfunction and convulsions. In clinical context, increased platelet and endothelial activation may be detected before symptoms appear.Hypoperfusion of the placenta is associated with abnormal modelling of the fetal–maternal placental interface that may be immunologically mediated. The pathogenesis of pre-eclampsia is poorly understood and may be attributed to factors related to the pregnant person and placenta since pre-eclampsia is seen in molar pregnancies absent of a fetus or fetal tissue. The placenta normally produces the potent vasodilator adrenomedullin but it is reduced in pre-eclampsia and eclampsia. Other vasodilators, including prostacyclin, thromboxane A2, nitric oxide, and endothelins, are reduced in eclampsia and may lead to vasoconstriction.
Eclampsia is associated with hypertensive encephalopathy in which cerebral vascular resistance is reduced, leading to increased blood flow to the brain, cerebral edema and resultant convulsions. An eclamptic convulsion usually does not cause chronic brain damage unless intracranial haemorrhage occurs.