creation date: 2025-07-21 19:05
tags: Pathologies
Eclampsia
Background
Definitions
Eclampsia refers to occurence of new-onset, generalized, tonic-clonic seizures or coma in a patient with preeclampsia or gestational hypertension. It is considered a manifestation of preeclampsia and on the severe end of the preeclampsia spectrum.
This condition is part of a group of disorders known as hypertensive disorders of pregnancy, which consist of:
- Chronic hypertension with or without superimposed pre-eclampsia/eclampsia
- Gestational hypertension
- Preeclampsia
- Hemolysis, elevated liver enzyme, and low platelet count (HELLP) syndrome
- Eclampsia
These conditions presents a significant risk of morbidity to both mother and fetus, with the primary concern being the progression to preeclampsia/eclampsia and HELLP syndrome.
Etiology and Pathogenesis
The cause of eclamptic seizures is not well understood. Two suggested hypotheses are:
- Hypertension causes dysfunction of autoregulatory system of cerebral circulation resulting in hyperperfusion, endothelial dysfunction and edema.
- Hypertension causes activation of autoregulatory system resulting in vasoconstriction and thus hypoperfusion, localized ischemia, endothelial dysfunction, and edema.
As eclampsia is considered a manifestation of preeclampsia, the pathogenesis of preeclampsia is found in its respective page.
Eclampsia can occur antepartum (60%), intrapartum (20%), and postpartum (20%). Approximately 20% of cases occur between 20 to 30 weeks of gestation. Of postpartum cases, 90% occur within one week of delivery.
Clinical Presentation
Signs & Symptoms
Most common antecedent signs and symptoms are:
- Hypertension
- Headache
- Visual disturbances
- Right upper quadrant or epigastric pain
- Neurologic findings (brisk deep tendon reflexes, altered mental status, cranial nerve deficits)
In 25% of cases, patients may be asymptomatic prior to seizure.
Eclamptic seizures present as:
- Self-limited generalized tonic-clonic
- Tonic phase: abrupt loss of consciousness and stiffening of muscles in the arms, legs, chest, and back; may appear cynaotic
- Clonic phase (~1 min after tonic): muscles jerk and twitch for 1-2 minutes, tongue biting, frothy and bloody sputum
- Postictal: initially appears like sleeping with gradual regain of consciousness; may report of headache; responsiveness after 10-20 minutes without focal neurologic deficits
Very rarely, focal or multifocal seizures or coma may occur.
Fetal response generally consist of fetal bradycardia for 3-5 minutes followed by fetal tachycardia with loss of FHR variability.
History & Physical Exam
History should evaluate for risk factors and presence of prior or currently diagnosed preeclampsia or gestational hypertension.
Neurological exam should be performed for persistent neurological deficits which will guide workup and triage.
Risk factors
Peak incidence is bimodal, within the adolescence/early twenties group and greater than age 35 group.
Risk factors mirror those of preeclampsia.
Diagnosis
Criteria
Eclampsia is a clinical diagnosis made on occurrence of new-onset tonic-clonic seizures in absence of other causative conditions in a patient with a hypertensive disorder of pregnancy.
In rare cases, focal or multifocal seizures or coma may be the presenting condition. Additionally, if the patient was not diagnosed with a hypertensive disorder of pregnancy, clinical features and neuroimaging findings of reversible posterior leukoencephalopathy syndrome (RPLS) is sufficient for diagnosis.
Work-up
Work-up is generally not required in typical cases of eclampsia (preexisting preeclampsia with generalized tonic-clonic seizure without persistent neurologic deficit).
Consider the following laboratory tests for metabolic abnormalities:
- Electrolytes and creatinine
- Glucose
- Calcium
- Magnesium
- CBC
- Toxicity screen
For patients with any of the following atypical features, further workup (generally, neuroimaging) and referral to neurologist is recommended:
- Does not meet diagnosis for preeclampsia, HELLP syndrome, or gestational hypertension
- Persistent neurological deficits
- Prolonged loss of consciousness
- Onset of seizure >48 hours after giving birth
- Onset of seizures before 20 weeks of gestation
- Seizures despite adequate magnesium sulfate therapy
Differential
The evaluation of eclampsia requires ruling out new-onset seizures that are incidental to the pregnant state or were exacerbated by the pregnancy.
Prior to 20 weeks gestation (rare for eclampsia to occur this early):
- Molar pregnancy
- Seizure unrelated to pregnancy
Persistent neurologic deficits suggests anatomical abnormality, of which eclampsia may be concurrent:
- Stroke
- Intracranial hemorrhage
- Brain mass lesion
- Toxic and metabolic encephalopathies
- Reversible cerebral vasoconstriction syndrome
- Thrombotic thrombocytopenic purpura
- Central nervous system infection
Seizures without neurologic deficits may be due to metabolic abnormalities:
- Hypocalcemia
- Hyponatremia
- Hypoglycemia
- Toxins (drugs or alcohol withdrawal or intoxication)
- Infection (meningitis, encephalitis, sepsis)
- Anatomical abnormality
Pregnancy may have also precipitated seizure in conditions such as:
- Thrombotic thrombocytopenic purpura
- Hemolytic uremic syndrome
Red Flags / Complications
Maternal and neonatal complications occur frequently:
- Placental abruption
- Disseminated intravascular coagulation
- Pulmonary edema
- Acute kidney failure
- Aspiration pneumonia
- Cardiopulmonary arrest
- Liver hematoma
- HELLP syndrome
- Perinatal death
- Preterm birth
Management
General Management
Prevention of maternal hypoxia
Due to hypoxemia fro hypoventilation during seizure.
- Place patient on left side
- Supplemental oxygen (8-10 L/min) via nonrebreather
Treatment of hypertension
Antihypertensive therapy is generally indicated if SBP ≥160 or DBP ≥110 for stroke prevention. Options include:
- Labetalol 20 mg IV over 2 minutes (most predictable)
- Hydralazine 5 mg IV over 1-2 minutes
Termination of seizure and prevention of recurrence
If the patient actively seizes for >5 minutes, the one of the following can be used to terminate the seizure:
- Lorazepam 4 mg IV at maximum rate of 2 mg/min, repeat at 3-5 min if seizure continues
- Diazepam 5 mg IV at max rate of 5 mg/min, repeat at 3-5 min interval to max dose of 30 mg
- Midazolam 10mg IM (if IV lines not placed yet)
Once the tonic-clonic phase of an eclamptic seizure resolves, prevention of recurrent seizures:
- Loading dose: magnesium sulfate 6 g IV over 15-20 minutes
- Maintenance dose: magnesium sulfate 2 g/hr IV infusion (if kidney function is good; consult nephrology if not)
If seizures persist despite magnesium sulfate therapy,:
- Additional bolus of magnesium sulfate 2-4 g IV over 5 minutes
- Therapeutic Mg level is considered 1.9-3.5 mmol/L; check if recurrent seizure or concern for toxicity (toxicity counteracted with calcium gluconate)
Fetal resuscitation
While maternal interventions typically stabilizes the fetus, nonimprovement of the fetal heart rate tracking with 10-15 minutes following interventions, emergency delivery may be indicated.
Delivery
The only definitive treatment for eclampsia is prompt delivery, however, eclampsia is not an absolute contraindication to continued expectant management.
For patients at least 32-34 weeks of gestation or earlier with a favourable Bishop score, induction with a planned end point (eg. within 24 hours) for c-section is reasonable.
For patients <32-34 weeks of gestation with unfavourable cervix, induction is not recommended but c-section is an option following recovery from seizure.
Postpartum Care
Seizures due to eclampsia always resolve postpartum within few hours to days. Diuresis (>4 L/day) is the most accurate indicator of resolution.
Generally:
- Magnesium sulfate is continued for 24-48 hours postpartum
- Antihypertensive therapy continued for 3-4 weeks or transition to oral hypertensive depending on blood pressure at assessment
Consider neurologist followup in patients with atypical features.