Eclampsia

Managing Seizures During Pregnancy

Seizures Opens in new window can occur during pregnancy as part of an established epileptic process, as new seizures, or induced by pregnancy. The most significant situations are eclampsia and generalized convulsive status epilepticus. At all times the management is directed at both mother and baby, with the realization that the best treatment for the baby will relate to optimal maternal care.

In previously diagnosed epileptics there is an increased risk of seizures during pregnancy of 17%. Anticonvulsant levels are influenced by reduced protein binding, increased drug binding and reduced absorption of varying degrees. The final effect on free drug levels is unpredictable and is most variable around the time of delivery. Careful clinical monitoring is essential, and monitoring of free drug levels rather than total serum levels may be necessary in selected patients. Anticonvulsants also interfere with the metabolism of vitamins D, K and folic acid. Supplementation is advisable.

Isolated simple seizures place both mother and fetus at increased danger of injury, but are otherwise generally well tolerated. Generalized seizures during labor cause transient fetal hypoxia and bradycardia of uncertain significance. Generalized convulsive SE is life-threatening to both mother and fetus at any stage of pregnancy.

All of the anticonvulsants cross the placenta and are potentially teratogenic. The risk of neural tube defects associated with valproate and carbamazepine. Prenatal screening for such defects is advised in patients who become pregnant while taking these agents. The risk from uncontrolled seizures greatly outweighs the risk from prophylactic medication in patients with good seizure control.

The management of seizures in pregnant patients is along the same lines as for non-pregnant patients. After 20 weeks’ gestation the patient should have a wedge placed under the right hip to prevent supine hypotension, and eclampsia must be considered. Investigation will include an assessment of fetal wellbeing by heart rate, ultrasound and/or tocography, as indicated. Management and disposition should be decided in consultation with neurology and obstetric services.

Eclampsia is the occurrence of seizures in patients with pregnancy-induced toxaemia occurring after the 20th week of pregnancy, and consists of a triad of hypertension, oedema and proteinuria. One in 300 women with pre-eclampsia progresses to eclampsia. Seizures are typically brief, self-terminating, usually preceded by headache and visual disturbances, and tend to occur without warning.

Treatment is directed at controlling the seizures and hypertension, and expedient delivery of the baby. Magnesium sulphate is effective in seizure control and is associated with a better outcome for both mother and baby than standard anticonvulsant and antihypertensive therapy. The mechanism of action is unclear.

Management of SE in pregnancy includes consideration of eclampsia, positioning in the left lateral position, and assessment and monitoring of fetal wellbeing. Urgent control of seizures is essential for both mother and baby. Phenobarbital may reduce the incidence of intraventricular haemorrhage in premature infants, and should be considered in place of phenytoin in this circumstance. Early involvement of obstetric and neurology services is essential.