Cerebral Complications of Severe Pre-eclampsia
On this page
Direct answer
Cerebral complications of severe pre-eclampsia are posterior reversible encephalopathy syndrome, intracranial haemorrhage, eclampsia and cortical blindness, all linked to very high blood pressure and failure of cerebral autoregulation. PRES causes headache, visual disturbance and seizures, with vasogenic oedema seen mainly on MRI. Intracranial haemorrhage is the most dangerous, and CT is the first study for a suspected bleed. Definitive treatment is delivery after stabilisation.
What you must remember
- Severe features: Systolic blood pressure of 160 mmHg or more, or diastolic of 110 mmHg or more, or pre-eclampsia with neurological or visual symptoms.
- PRES: Headache, visual disturbance and seizures, with reversible parieto-occipital vasogenic oedema on MRI.
- Intracranial haemorrhage: A serious and often fatal complication, with CT as the first-line investigation.
- Cortical blindness: Bilateral vision loss with normal pupillary reflexes and a normal fundus, from occipital cortex involvement.
- Eclampsia: Generalised seizures in a woman with pre-eclampsia, without another cause.
- Magnesium sulphate: The drug of choice for eclamptic seizures, for both treatment and prophylaxis, and on India's National List of Essential Medicines.
- Blood pressure control: Labetalol, nifedipine or hydralazine lower severe hypertension in a controlled way.
- Definitive treatment: Delivery after maternal stabilisation is the only cure for pre-eclampsia.
A stepwise approach to neurological symptoms in severe pre-eclampsia
A woman at 34 weeks with blood pressure 170/112 mmHg, headache and blurred vision needs urgent action. The steps below set out a standard sequence for managing her.
- Control blood pressure: Give an antihypertensive such as labetalol, nifedipine or hydralazine to bring severe hypertension down in a controlled way.
- Treat or prevent seizures: Start magnesium sulphate, and monitor reflexes, respiratory rate and urine output throughout.
- Examine the neurology: Check consciousness, pupils, fundi and focal signs, since a focal deficit points towards haemorrhage.
- Image the brain: Use CT first for a suspected bleed, and MRI with FLAIR sequences for PRES, which CT often misses.
- Investigate the systemic disease: Check platelets, liver enzymes, creatinine and the coagulation profile for HELLP syndrome and coagulopathy.
- Deliver after stabilisation: Plan delivery once the mother is stable, with fetal assessment guiding the timing.
Neurological improvement after blood pressure control and delivery supports PRES or eclampsia. Persistent deficits after delivery suggest structural damage such as haemorrhage or infarction.
Where the exam tries to catch you
Most questions here test which imaging detects which lesion, and which drug stops the seizures.
- Trap: Excluding brain complications because a plain CT looks normal Correct: CT is often normal in PRES, which needs MRI with FLAIR sequences to show vasogenic oedema.
- Trap: Using diazepam as first-line therapy for eclamptic seizures Correct: Magnesium sulphate is the drug of choice for eclamptic seizures.
- Trap: Attributing cortical blindness to retinal damage Correct: Cortical blindness reflects occipital cortex involvement, so pupillary reflexes are preserved and the fundus looks normal.
Frequently asked questions
Which imaging is most sensitive for posterior reversible encephalopathy syndrome?
MRI with FLAIR sequences is the most sensitive imaging for posterior reversible encephalopathy syndrome. It shows vasogenic oedema in the parietal and occipital white matter. CT is often normal in PRES, so a normal CT does not exclude it.
What is the drug of choice for eclamptic seizures?
Magnesium sulphate is the drug of choice for both treating and preventing eclamptic seizures. It is listed on India's National List of Essential Medicines. Reflexes, respiratory rate and urine output must be monitored during treatment.
Why does cortical blindness occur in severe pre-eclampsia?
Cortical blindness occurs when the occipital visual cortex is affected by oedema or ischaemia from severe hypertension. Pupillary light reflexes are usually preserved, and the fundus looks normal. Vision may recover once blood pressure is controlled.
Is posterior reversible encephalopathy syndrome permanent?
Posterior reversible encephalopathy syndrome is usually reversible, and symptoms and imaging changes often resolve once blood pressure is controlled. Prompt treatment of hypertension and seizures improves the prognosis. Persistent deficits should prompt a search for haemorrhage or infarction.
What does a focal neurological deficit suggest in eclampsia?
A focal deficit after eclampsia suggests intracranial haemorrhage or infarction rather than PRES alone. CT is the first-line study in this setting because it detects acute bleeding quickly. Neurosurgical review is needed if a bleed is confirmed.