# Brainstem Encephalitis Following COVID-19 Vaccination: A Case Report

## TL;DR

A 30-year-old woman developed brainstem encephalitis after receiving an mRNA COVID-19 vaccine, showing symptoms like diplopia and responding to steroid treatment.

## Contribution

This case report adds to the limited literature on rare neurological adverse events following mRNA COVID-19 vaccination.

## Key findings

- The patient exhibited acute diplopia and brainstem inflammation following the second dose of the vaccine.
- Steroid therapy led to rapid improvement in symptoms.
- The case shares similarities with another reported case but differs in symptom onset timing and residual deficits.

## Abstract

Encephalitis is an extremely rare neurological adverse event following vaccination against coronavirus disease 2019 (COVID-19). We report a case of brainstem encephalitis following mRNA COVID-19 vaccination. A 30-year-old Japanese female presented with acute diplopia characterized by recurrent, paroxysmal episodes following the second dose of the vaccine, which resolved spontaneously. Brain magnetic resonance imaging revealed inflammatory changes in the brainstem. The patient responded rapidly to steroid therapy and subsequently improved. This case shares key clinical features with another case, including similarities in symptoms, lesion localization, and steroid responsiveness. However, it differs with respect to the timing of symptom onset and the presence of mild residual deficits. This report makes a contribution to the limited literature on this rare post-vaccination condition by documenting its clinical features.