Posterior reversible encephalopathy syndrome — FFICM MCQ

Correct answer: D — MRI brain to assess for posterior reversible encephalopathy syndrome

The correct answer is D, MRI brain to assess for posterior reversible encephalopathy syndrome. This woman has classic eclampsia spectrum disease extending into the postpartum period: severe hypertension, headache, visual disturbance, seizure, thrombocytopenia and deranged ALT, with a normal CT. Vasogenic oedema in PRES is often occipito-parietal and subtle, and CT frequently misses it, so MRI (T2/FLAIR, with DWI to exclude infarction) is the investigation of choice once the airway is secure and blood pressure and seizures are being controlled. Confirming PRES guides continued aggressive blood pressure control and magnesium sulphate seizure prophylaxis, and documents a reversible process rather than an alternative structural cause needing different management. Why the other options are wrong: B. Lumbar puncture before blood pressure control: unsafe and unnecessary here; there is no suggestion of meningitis or subarachnoid haemorrhage, and instrumenting the CSF space before controlling severe hypertension and stabilising the patient risks coning if there is any unrecognised raised intracranial pressure. A. Carotid Doppler ultrasound: assesses extracranial carotid stenosis or dissection, which is not the concern in postpartum eclampsia with a normal CT and multisystem features (thrombocytopenia, transaminitis) pointing to a pre-eclampsia/PRES mechanism, not large vessel disease. E. Routine skull radiograph: has no role in modern neuro-obstetric emergencies; it cannot demonstrate parenchymal oedema and would delay definitive imaging and treatment. C. Elective outpatient EEG: seizures here are explained by eclampsia/PRES and need acute inpatient management, not deferred outpatient electrophysiology; EEG would not change the immediate diagnostic or therapeutic pathway. Key point: In postpartum eclampsia with a normal CT, MRI is required because it is far more sensitive than CT for the vasogenic oedema of PRES, which underlies the seizures and visual disturbance.

Reference: NICE Guideline NG133, Hypertension in pregnancy: diagnosis and management (2019, updated), section on management of severe pre-eclampsia and eclampsia, nice.org.uk/guidance/ng133