Epilepsy in pregnancy

It is Tuesday morning and a 26-year-old with focal epilepsy on lamotrigine walks in eight weeks pregnant. Her seizures have been well-controlled on 200 mg daily for three years. If you do nothing, her lamotrigine clearance will rise by the end of the second trimester and she may seize. If you switch her to levetiracetam, you expose the fetus to a second drug. The fellowship question on epilepsy in pregnancy is almost always about this trade-off — seizure control against AED teratogenicity, with valproate as the worst offender and lamotrigine clearance as the classic exam trap.[1][4]

Overview and definition

Epilepsy in pregnancy is pre-existing seizure disorder managed on antiepileptic drugs (AEDs) or, less commonly, unmedicated. Around 0.3 to 0.7 percent of pregnancies occur in women with epilepsy, and over 90 percent have an uncomplicated pregnancy on appropriate management.[4][9]

The framework is simple and exam-examined:[1][4]

• Preconception: optimise the drug, start folic acid 5 mg, switch off valproate if possible.
• Pregnancy: keep the drug, increase lamotrigine as clearance rises, monitor levels, screen the fetus.
• Peripartum: continue AEDs, avoid pethidine, regional anaesthesia preferred, vitamin K for the neonate.
• Postpartum: reduce lamotrigine rapidly, encourage breastfeeding, address sleep deprivation.[4]

The sentence that anchors every station: the harm of uncontrolled seizures exceeds the marginal benefit of stopping AEDs in pregnancy.[4][9]

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1. [1]Tomson T, Battino D, Bonizzoni E, et al. Comparative risk of major congenital malformations with eight different antiepileptic drugs: a prospective cohort study of the EURAP registry Lancet Neurol, 2018.PMID 29680205
2. [2]Tomson T, Battino D, Bonizzoni E, et al. Dose-dependent teratogenicity of valproate in mono- and polytherapy: an observational study Neurology, 2015.PMID 26085607
3. [3]Tomson T, Battino D, Bonizzoni E, et al. Dose-dependent risk of malformations with antiepileptic drugs: an analysis of data from the EURAP epilepsy and pregnancy registry Lancet Neurol, 2011.PMID 21652013
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5. [5]Harden CL, Pennell PB, Koppel BS, et al. Practice parameter update: management issues for women with epilepsy--focus on pregnancy (an evidence-based review): vitamin K, folic acid, blood levels, and breastfeeding: report of the Quality Standards Subcommittee and Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology and American Epilepsy Society Neurology, 2009.PMID 19398680
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12. [12]Bromley R, Weston J, Adab N, Greenhalgh J, Sanniti A, McKay AJ, Tudur Smith C, Marson AG Treatment for epilepsy in pregnancy: neurodevelopmental outcomes in the child Cochrane Database Syst Rev, 2014.PMID 25354543
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