# Pseudoathetotic Pseudodystonia as a Manifestation of Isolated Medullary Demyelination in Neuromyelitis Optica Spectrum Disorder

## TL;DR

A rare case shows that brainstem demyelination in a specific disorder can cause unusual movement symptoms, which improved with immunotherapy.

## Contribution

This case is the first to link isolated medullary demyelination to pseudoathetotic pseudodystonia in NMOSD.

## Key findings

- Pseudoathetotic movements occurred due to isolated medullary demyelination in a patient with NMOSD.
- The abnormal movements resolved after plasmapheresis and rituximab treatment.
- Sensory-driven hyperkinetic movements can be a rare manifestation of NMOSD.

## Abstract

Pseudoathetosis and pseudodystonia are rare sensory-driven hyperkinetic movement disorders that may mimic primary dystonia. Although these manifestations have been reported in neuromyelitis optica spectrum disorder (NMOSD), they are typically associated with cervical spinal cord lesions, and occurrence due to isolated medullary demyelination is extremely uncommon.

A 32-year-old woman with aquaporin-4-positive NMOSD developed pseudoathetotic movements with dystonic-appearing posturing of both hands following an isolated demyelinating lesion of the medulla with normal spinal cord imaging. The abnormal movements persisted after corticosteroids but resolved completely following plasmapheresis and rituximab.

This case expands the known anatomic spectrum of NMOSD-associated movement disorders by demonstrating isolated medullary demyelination as a rare substrate for pseudoathetotic pseudodystonia and emphasizes the importance of recognizing sensory-driven hyperkinetic movements to ensure timely immunotherapy.