← Back to Browse
Ask AleraHome
CT
HeadDemonstration data

Head CT: Post-Eclamptic Complications

Neuroimaging in the peripartum period is used to investigate seizures, persistent depressed consciousness or focal deficits complicating eclampsia. Non-contrast CT is the fast, widely available first-line study to exclude intracranial haemorrhage, while MRI better characterises posterior reversible encephalopathy syndrome (PRES) and cerebral venous sinus thrombosis. Most eclamptic encephalopathy is reversible with blood-pressure control and supportive care, but haemorrhage and infarction can be catastrophic.

Indications

  • Eclamptic seizures, especially atypical, focal, recurrent or refractory to magnesium
  • Persistent altered consciousness or failure to recover after seizure control
  • Focal neurological deficit or new visual loss (cortical blindness)
  • Thunderclap or severe persistent headache post-partum
  • Suspected intracranial haemorrhage or cerebral venous sinus thrombosis
  • Seizure onset beyond 48-72 hours post-partum or presentation atypical for eclampsia

Contraindications & Cautions

  • No absolute contraindication to non-contrast CT; justify radiation against clinical need
  • MRI preferred when stable and available (no ionising radiation, superior for PRES and venous thrombosis)
  • Iodinated or gadolinium contrast: assess renal function; caution with concurrent acute kidney injury or HELLP
  • Gadolinium crosses the placenta - avoid antenatally unless essential; post-partum use with lactation is acceptable per current guidance
  • MRI: screen for pacemakers and incompatible implants

Patient Preparation

  • Stabilise the airway and control seizures with magnesium sulphate and blood pressure before transfer
  • Continuous monitoring of oxygen saturation and blood pressure during scanning
  • Supine positioning with head immobilised; sedation may be required for agitation
  • Obtain consent from patient or next of kin; proceed under emergency provision if obtunded
  • Confirm renal function before contrast administration where possible
  • For MRI, remove all ferromagnetic items and complete a safety checklist

Technique & Parameters

  • Non-contrast helical head CT from skull base to vertex, 120 kVp with dose modulation, 4-5 mm axial reconstructions and multiplanar reformats
  • Review on brain, subdural and bone windows
  • CT venography (or MR venography) if cerebral venous sinus thrombosis is suspected
  • MRI protocol: T1, T2, FLAIR, DWI/ADC, and susceptibility-weighted or GRE for haemorrhage
  • FLAIR and DWI/ADC differentiate vasogenic PRES oedema from cytotoxic infarction
  • Add MRA/MRV and, where indicated, post-contrast sequences for vasculopathy or thrombosis

Systematic Review

  • Assess parieto-occipital and watershed white matter for symmetric vasogenic oedema (PRES)
  • Search for parenchymal, subarachnoid, subdural or intraventricular haemorrhage
  • Evaluate dural venous sinuses for dense clot (cord/dense triangle sign) or filling defect on venography
  • Look for restricted diffusion indicating infarction or malignant PRES
  • Assess ventricular size, mass effect and midline shift
  • Review the posterior circulation and brainstem for atypical PRES involvement
  • Inspect for reversible cerebral vasoconstriction features on angiographic sequences

Key Findings & Significance

  • PRES: symmetric subcortical vasogenic oedema, predominantly parieto-occipital, high on FLAIR with facilitated diffusion
  • Lobar or deep intracerebral haemorrhage from severe hypertension or eclampsia
  • Subarachnoid haemorrhage, occasionally convexity SAH accompanying PRES or RCVS
  • Cerebral venous sinus thrombosis: dense sinus, empty delta sign on contrast, venous infarction with haemorrhage
  • Cytotoxic oedema/restricted diffusion signalling infarction or irreversible injury
  • Often normal CT early despite florid clinical encephalopathy - MRI more sensitive

Differential Considerations

  • Posterior white matter oedema: PRES versus posterior circulation infarction versus demyelination
  • Post-partum thunderclap headache: RCVS, venous thrombosis, SAH, pituitary apoplexy
  • Seizure with focal deficit: haemorrhage, venous infarction, arterial stroke, PRES
  • Convexity SAH: RCVS, PRES, cortical vein thrombosis
  • Encephalopathy without haemorrhage: PRES, metabolic (hepatic in HELLP), infective
  • Dense sinus sign: true thrombosis versus high haematocrit or partial-volume artefact

Pearls & Pitfalls

  • PRES is frequently reversible - imaging appearance may lag both onset and resolution of symptoms
  • A normal CT does not exclude PRES; obtain MRI when the patient is stable
  • Restricted diffusion within PRES lesions suggests infarction and poorer reversibility
  • Always consider cerebral venous sinus thrombosis in post-partum headache and seizure - use venography
  • PRES can be atypical (frontal, brainstem, cerebellar) - do not dismiss non-occipital oedema
  • Correlate with blood pressure, HELLP labs and magnesium therapy; RCVS may coexist with PRES

Structured Report

  • State modality, coverage and contrast/venography performed
  • Describe distribution and character of any oedema and whether it fits PRES
  • Report presence, location and volume of haemorrhage and any mass effect
  • Comment on dural venous sinus patency and any venous infarction
  • Note diffusion status distinguishing vasogenic oedema from infarction
  • Impression: give the most likely diagnosis, flag reversibility, and recommend MRI/MRV follow-up and blood-pressure control

References

  • ACR Appropriateness Criteria: Seizures and Epilepsy / Headache
  • Bartynski WS, Posterior Reversible Encephalopathy Syndrome (AJNR review)
  • RCOG/NICE NG133: Hypertension in pregnancy
  • Osborn's Brain: Imaging, Pathology, and Anatomy (PRES and venous thrombosis)

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.