PRES in pre-eclampsia tracks with transaminases and platelets

Design

systematic review and random-effects meta-analysis of 28 studies, PRISMA 2020

Population

women with pre-eclampsia or eclampsia assessed for PRES

Primary outcome

pooled incidence of PRES, with associated laboratory and imaging factors

Effect

incidence 38.68% (95% CI 29.63-48.59), I squared 98.5%; ALT +35.9 IU/L, AST +48.7 IU/L, platelets -31.2 x 10^9/L in PRES

Twenty-eight studies were pooled to describe posterior reversible encephalopathy syndrome in pre-eclampsia and eclampsia. The pooled incidence was 38.7% (95% CI 29.6 to 48.6) - among women imaged in these cohorts, not among all women with pre-eclampsia, and with heterogeneity of 98.5%, which is as high as it gets.

The biochemical signal is the usable part. Women with PRES had alanine transaminase higher by 35.9 IU/L and aspartate transaminase by 48.7 IU/L on average, with platelet counts lower by 31.2 x 10^9/L and raised total bilirubin. Maternal mortality was numerically higher (relative risk 4.06) but did not reach significance; stillbirth and preterm birth showed no association. Imaging involvement was frontal in 43.1% and temporal in 20.3%, which is worth knowing because the parieto-occipital pattern the name implies is not the only one.

In a district hospital without ready MRI access, this points the assessment at the laboratory results already being sent for HELLP screening. Deranged liver enzymes and falling platelets in a woman with pre-eclampsia and any neurological symptom should raise PRES specifically, and should push towards imaging and towards magnesium and blood pressure control rather than towards an antiepileptic escalation.

• Read the transaminases and platelet count as neurological information in a woman with pre-eclampsia and headache or visual symptoms
• Do not expect a parieto-occipital pattern - frontal involvement was commonest in these cohorts
• Control blood pressure and give magnesium; PRES is not primarily an epilepsy problem
• Arrange imaging where available, but do not delay obstetric management waiting for it
• Reassess vision and conscious level after delivery - the syndrome is usually reversible, and failure to reverse means reconsidering the diagnosis

Why it matters

It ties a neurological complication to two laboratory values that are already being measured in every pre-eclampsia admission.

Don't overread it

These are associations in imaged cohorts - the pooled incidence is not the risk in an unselected woman with pre-eclampsia.

The statistics, in plain English

An I squared of 98.5% means the 28 studies were measuring populations so different that pooling their incidence produces a number belonging to none of them - read the 38.7% as evidence that PRES is common in imaged cohorts, not as a rate for your unit. The biochemical differences are means across studies rather than a validated threshold, so there is no cut-off here to apply. And the mortality relative risk of 4.06 without statistical significance means exactly that: a worrying direction on too few events to rely on.

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