Maternal Medicine - Epilepsy

Course during pregnancy

  • About a third worsen, improve or remain the same.
  • Severe epilepsy tends to worsen.
  • Worsening is often due to cessation/reduction of drugs by mother/nervous doctors.

Drug safety

  • Major congenital malformation rates:
    • Background population - 0.5%
    • Epileptic mothers on no drugs - 4%
    • Lamotrigine - 3-4%
    • Carbamazepine - 4%
    • Sodium valproate - 9%
    • Rates increase with multi-drug therapy, especially with valproate
  • Valproate during pregnancy also associated with lower IQ in offspring (NEJM Meador et al 2009)
  • Stopping medication on discovering pregnancy is probably detrimental: neural tube development is complete by 21 days, and major organogenesis by 56 days, so in most cases it will be too late to achieve any reduction in malformations, but exposes to a risk of severe epilepsy.

Management

  • Continue folate 5mg od through pregnancy if taking a folate antagonist (pheyntoin, carbamazepine, sodium valproate).
  • More screening scans than usual.
  • Ensure continuation of usual meds through labour (time of greatest risk for seizures).
  • Use slow-release anticonvulsant if possible to avoids peaks and troughs.
  • Consider gradual withdrawal of anticonvulsant if seizure-free: if remains so, restart drugs after 1st trimester. NB should not drive while dose reduced or for 6 months after stopping.