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

Background: 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. Case Report: 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. Discussion: 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.