Epilepsy in pregnancy

Scenario

A 33 year old woman had had occasional myoclonic jerks in the mornings since the age of 15, usually after sleep deprivation. Two years later, after her first generalised tonic-clonic seizure, she was diagnosed with juvenile myoclonic epilepsy, an idiopathic generalised epilepsy. After her second tonic-clonic seizure she was prescribed valproate. During the next two years, she had a few more tonic-clonic seizures until the dosage of valproate was increased to 500 mg twice daily. On this medication, she was free from seizures for 11 years and only had isolated myoclonic jerks—years apart—always after sleep deprivation.

Two years ago, her medication was changed from valproate to lamotrigine in response to her plans for pregnancy and the concern that valproate could be teratogenic. This conversion was uneventful. She has remained free from tonic-clonic seizures, but her myoclonic jerks have been slightly more frequent despite a lamotrigine dose of 150 mg twice daily.

The pregnancy was planned together with her neurologist. She was followed more closely during pregnancy, with clinical check-ups and monitoring of lamotrigine plasma concentrations every second month. The dosage of lamotrigine was gradually increased to 250 mg twice daily during the second half of pregnancy in response to an increased frequency of myoclonic jerks caused by a fall in lamotrigine plasma concentrations to less than half of the prepregnancy values. She had an uneventful delivery without seizures and gave birth to a healthy child. The lamotrigine dosage was gradually decreased to 150 mg twice daily within three days of delivery.