# Posterior reversible encephalopathy syndrome in dengue virus infection with concurrent encephalitis and ischemic stroke: a case report

## TL;DR

A 90-year-old woman with dengue developed neurological issues including PRES and stroke, showing dengue can cause complex brain complications.

## Contribution

This case report highlights the rare occurrence of PRES alongside dengue encephalitis and stroke.

## Key findings

- Neuroimaging showed PRES with vasogenic edema and focal hemorrhage.
- The patient also had small acute infarcts in brain regions.
- Follow-up imaging showed near-complete resolution of PRES with clinical improvement.

## Abstract

Dengue is hyperendemic in Singapore and typically presents as an acute febrile illness. Neurological complications, such as dengue encephalitis and encephalopathy, are increasingly recognized; however, dengue-associated posterior reversible encephalopathy syndrome (PRES) remains rare.

We report a 90-year-old woman with primary dengue virus serotype 3 infection who developed persistent altered mental status during the critical phase of illness. Neuroimaging revealed bilateral asymmetric parieto-occipital vasogenic edema with focal hemorrhage, consistent with PRES, together with small acute infarcts in the deep watershed and left middle cerebral artery territories. Cerebrospinal fluid analysis demonstrated mildly elevated protein without pleocytosis; dengue IgM and IgG were positive, while dengue PCR was negative. She was managed with supportive care with close neurological monitoring. Follow-up imaging at two months showed near-complete radiological resolution accompanied by significant clinical improvement.

This case highlights two important considerations. First, altered mental status in elderly patients with dengue should not be attributed solely to delirium, and prompt neurological evaluation is essential. Second, dengue infection may be associated with overlapping neurological manifestations, including dengue encephalitis, PRES and ischemic stroke. Recognition of such overlap is important for accurate diagnosis and management of dengue-related central nervous system involvement.

Not applicable.