# A Case Report of a Rare, but Important, Cause of Delerium Presenting to an Emergency Department

## TL;DR

This case report highlights a rare condition causing sudden mental decline in an emergency setting, linked to a past hypoxia event.

## Contribution

The paper introduces delayed post-hypoxic leukencephalopathy as a diagnosable emergency condition not previously documented in emergency medicine literature.

## Key findings

- A 53-year-old man showed akinetic mutism 14 days after fentanyl overdose recovery.
- MRI revealed symmetric frontoparietal white matter demyelination consistent with delayed post-hypoxic leukencephalopathy.
- The condition can present as altered mental status days to weeks after cerebral hypoxia recovery.

## Abstract

Delayed post-hypoxic leukencephalopathy is a rare cause of acute neuropsychiatric decline diagnosable in the emergency department (ED), but it has not been described in the emergency medical literature. We present a case report of a pathognomonic presentation.

A 53-year-old man developed akinetic mutism 14 days after being discharged from a hospitalization for fentanyl overdose. Magnetic resonance imaging demonstrated symmetric frontoparietal white matter demyelination.

Delayed post-hypoxic leukencephalopathy can present to the ED as altered mental status days to weeks after apparent full recovery from an initial episode of cerebral hypoxia. This report will help emergency physicians avoid missing this diagnosis.