Question 20

College Answer

• Differential diagnoses

1. • Eclampsia
   • Idiopathic epilepsy including non-compliance, or subtherapeutic anticonvulsant levels
   • Intracerebral haemorrhage – including, venous thrombosis
   • Infection – meningitis, encephalitis
   • Space occupying lesion – abscess, tumour
   • Metabolic disorders – hypoglycaemia, hyponatremia
   • Hepatic encephalopathy- fatty liver of pregnancy
   • Hypertensive encephalopathy
   • Cerebral vasculitis.
   • Use of elicit drugs – Amphetamines, Cocaine
   • Reversible posterior leukoencephalopathy syndrome

• Indications for CT scan
  • It is probably unnecessary in those with a clear diagnosis (e.g. known epilepsy or being treated for pregnancy induced hypertension), and who wake quickly without focal neurological deficit.
  • In patients without a clear cause for the seizure, and in particular those who are at risk for focal intracranial pathology (ie. Persistent altered level of consciousness and focal neurological signs) a CT scan may be warranted with appropriate shielding of the baby
  • It may be indicated imaging is thought warranted and urgent MRI is unavailable or not feasible (patient unstable)

• Seizure control in pregnancy
  • Psychological stress
  • Altered Vd
  • Increased hepatic metabolism
  • Poor compliance because of fears of teratogenecity
  • Sleep deprivation

• Seizures and perinatal morbidity and mortality
  • • Risk of fetal hypoxia and acidosis
    • Fetal intracranial haemorrhage
    • Stillbirth
    • Fetal bradycardia
    • Neonatal haemorrhagic disorder secondary to deficient Vit K dependent clotting factors induced by AEDs
    • Maternal death
    • Maternal trauma leading to premature rupture of membranes, placental abruption, fetal death

Discussion

Organised into a familiar patern, the differentials for seizures in pregnancy look like this:

• Stroke, cerebral aneurysm, eclampsia, sinus thrombosis
• Menignitis / encephalitis
• Intracranial neoplasm
• Cocaine toxicity, poor antiepileptic drug compliance
• SLE encephalitis, CNS vasculitis
• Traumatic injury in context of coagulopathy or thrombocytopenia
• Hepatic encephalopathy, hypoglycaemia, hyponatremia

As far as the CT goes... When would you expose a pregnant woman to radiation?

• Failure to wake up after the seizure
• Focal neurological signs
• No obvious extracranial (eg. metabolic) cause for the seizure
• Suspicion of intracranial hypertension

In any case, this authoritative body states that

" Teratogenesis is not a major concern after diagnostic CT studies of the pelvis in pregnancy, because the radiation dose is generally too low to cause such effects."

Reasons an epileptic might have more seziures during pregnancy:

• Poor compliance
• Anxiety regarding teratogenicity, and cessation of drugs on those grounds
• Increased clearance of the drug
• Increased volume of distribution
• Stress and sleep deprivation

Weirdly, progensterone has an antiepileptic effect, and its levels are wildly elevated in pregnancy

Consequences to the foetus:

• maternal hypoxia = foetal hypoxia
• maternal acidosis = foetal acidosis
• Transient foetal bradycardia during the seizure
• Uterine haemorrhage and foetal loss
• Vitamin K deficiency due to antiepileptic use, leading to coagulopathy

 

Beach, Robert L., and Peter W. Kaplan. "Seizures in pregnancy: diagnosis and management." International review of neurobiology 83 (2008): 259-271.

Walker, S. P., M. Permezel, and S. F. Berkovic. "The management of epilepsy in pregnancy." BJOG: An International Journal of Obstetrics & Gynaecology116.6 (2009): 758-767.

Chen, Yi-Hua, et al. "Affect of seizures during gestation on pregnancy outcomes in women with epilepsy." Archives of neurology 66.8 (2009): 979-984.

Otani, Koichi. "Risk factors for the increased seizure frequency during pregnancy and puerperium." Psychiatry and Clinical Neurosciences 39.1 (1985): 33-42.

Teramo, K., et al. "Fetal heart rate during a maternal grand mal epileptic seizure." Journal of Perinatal Medicine-Official Journal of the WAPM 7.1 (1979): 3-6.

LaJoie, Josiane, and Solomon L. Moshé. "Effects of seizures and their treatment on fetal brain." Epilepsia 45.s8 (2004): 48-52.

Klein, Pave, and Andrew G. Herzog. "Hormonal effects on epilepsy in women."Epilepsia 39.s8 (1998): S9-S16.