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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.

Head CT: Post-Eclamptic Complications

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References