Epilepsy is the most common neurological disease in pregnant women and a risk factor for increased maternal mortality. The condition may be idiopathic or secondary to intracranial insult, such as previous surgery or tumour. Convulsions may develop for the first time in pregnancy and cause a problem in differential diagnosis.
Problems and special considerations
It is generally thought that pre-existing epilepsy is affected by the hormonal changes of pregnancy, and that the frequency of seizures may increase in 14-32% of women during pregnancy. However, in an equal proportion of women, the symptoms improve. Lack of pre-pregnancy advice and the woman’s anxiety over the teratogenic effects of antiepileptics may lead to poor compliance with medication. In addition, the pharmacodynamics and pharmacokinetics of antiepileptic drugs may be affected by the physiological changes of pregnancy. Hyperventilation, dehydration and the pain and stress of labour may lower the threshold for convulsions.
In recent reports of the Confidential Enquiries into Maternal Deaths, epilepsy (especially poorly controlled) has been a major factor in deaths from neurological disease. The majority of the reported deaths were classed as sudden unexpected death in epilepsy (SUDEP) or were associated with drowning.
Convulsions occurring during labour, delivery, and the early postpartum period may be particularly hazardous to maternal and fetal health. Immediate problems include aortocaval compression, hypoxaemia, stroke, aspiration of gastric contents and trauma. In addition, the differential diagnosis may include a number of conditions both related and unrelated to pregnancy (see Chapter 127, Convulsions).
Management options
Ideally, the woman with diagnosed epilepsy should have had pre-conception counselling to discuss the management of her epilepsy during pregnancy, with the aim of simplifying the drug regimen. Medication may be stopped in a woman who has been convulsion-free for a long time. Assessing the risks and benefits of changing the treatment requires specialist advice for each individual.
During pregnancy, normal medication should be maintained. This may necessitate alternative routes of administration when gastric absorption is affected. Regular monitoring of drug levels during pregnancy is not routinely recommended but may be warranted in some cases. Antiepileptic medication should be continued through labour and delivery, and women at high risk of developing peripartum seizures may require additional anticonvulsants during this period.
When carefully managed, women with epilepsy do not usually experience problems during pregnancy, and most can be offered any form of pain relief that they wish. Pethidine is not recommended, as its active metabolite norpethidine has epileptogenic potential; diamorphine may be a more suitable alternative. A woman with poorly controlled epilepsy will benefit from epidural analgesia to reduce the stress of labour and hyperventilation. General anaesthesia is not associated with increased risk in women with epilepsy in comparison with pregnant women without epilepsy, and thiopental remains a good anticonvulsant. Alfentanil has greater proconvulsant properties than other opioids, and avoidance in these patients has been suggested.
Convulsions are managed in the standard way, taking into account the risk of aortocaval compression and aspiration of gastric contents (see Chapter 127, Convulsions).
Key points
• Epilepsy is the commonest neurological disease in pregnancy and a risk factor for poor maternal outcomes.
• Eclampsia is not the only cause of convulsions in pregnancy.
• Epilepsy may become poorly controlled in pregnancy.
• Management of women whose epilepsy is well controlled is as for normal women.
Further reading
Hart LA, Sibai BM. Seizures in pregnancy: epilepsy, eclampsia and stroke. Semin Perinatol 2013; 37: 207-24.
Kelso A, Wills A, on behalf of the MBRRACE-UK neurology chapter writing group. Learning from neurological complications. In Knight M, Kenyon S, Brocklehurst P, et al.; MBRRACE- UK. Saving Lives, Improving Mothers’ Care: Lessons learned to inform future maternity care from the UK and Ireland Confidential Enquiries into Maternal Deaths and Morbidity 2009-12. Oxford: National Perinatal Epidemiology Unit, University of Oxford, 2014, pp. 73-9.
Royal College of Obstetricians and Gynaecologists. Epilepsy in Pregnancy. Green-top Guideline 68.
London: RCOG, 2016. www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg68 (accessed December 2018).