If a woman with epilepsy has not required medications for a time before getting pregnant and has a seizure during pregnancy, the best choice of medication may be phenytoin for its advantage in rapid seizure control, or levetiracetam. Exposure of the fetus late in gestation poses few teratogenic risks. If a woman discovers she is pregnant while on an antiepileptic drug, changing medications is unlikely to reduce the chances of birth defects, even for valproate, but this drug retains the risk of lower IQ in the child. The special case of eclamptic seizures is managed by infusion of magnesium as noted below.
Epileptic women of childbearing age who are on an antiepileptic medication, particularly those which induce cytochrome P450, should be advised that higher doses of the estradiol component of birth control agents are required or they may be exposed to the issues of becoming pregnant while antiepileptic medications. Phenytoin, carbamazepine, and topiramate induce hepatic enzymes and most other medications do not have this effect.
Seizures in Eclampsia (See Also Chap. 33)
This syndrome appears during the last trimester of pregnancy or soon after delivery and may announce itself by hypertension and convulsions; the latter are generalized and tend to occur in clusters. The standard practice is to induce labor or perform a cesarean section and manage the seizures as one would manage those of hypertensive encephalopathy (of which this is one type). The administration of magnesium sulfate continues to be the favored treatment by obstetricians for the prevention of eclamptic seizures; two randomized trials have reestablished its value in preventing seizures in preeclamptic women (Lucas et al) and in avoiding a second convulsion once one had occurred (Eclampsia Trial Collaborative Group). Magnesium sulfate, 10 g IM, followed by 5 g every 4 h, proved comparable to standard doses of phenytoin as prophylaxis for seizures. Our colleagues use a regimen of 4 g IV more than 5 to 10 min followed by a maintenance dose of 5 g every 4 h IM or 1 to 2 g/h IV. In nontoxic gestational epilepsy, approximately 25 percent of patients are found to have some disease (neoplastic, vascular, or traumatic) that will persist.
The treatment of epilepsy of all types can be divided into four parts: the use of antiepileptic drugs, the surgical excision of epileptic foci and other surgical measures, the removal of causative and precipitating factors, and the regulation of physical and mental activity.
The goal of drug treatment is to create a seizure-free state if possible and with the fewest side effects. In the past, a few seizures a year had been considered adequate control but with numerous newer medications it is reasonable to eliminate seizures. On the other hand, it is equivalently deleterious to make a patient so mentally dull as to interfere with function at work or school. The choice and dose of medication depends on many factors including sex, age, other medications, and renal or hepatic dysfunction or other medical conditions and psychiatric conditions that might be favorably influenced by a particular agent. As a general rule, starting in the lower dose range and attempting to provide twice daily or daily administration are favored.