A 40-year-old woman who is 34 weeks pregnant, presents to hospital following a generalised tonic/clonic seizure lasting 5 minutes.
- List 6 differential diagnoses
- Briefly discuss the indications for an urgent CT scan in this patient
- List the reasons why pregnant patients may experience worsening of seizure controlList the consequences of seizures on perinatal morbidity and mortality
- Differential diagnoses
- 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
- 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
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."
- 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:
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.