# Double Seronegative Neuromyelitis Optica Spectrum Disorder with Longitudinally Extensive Transverse Myelitis and Optic Neuritis: A Challenging Case Report

## TL;DR

A 16-year-old girl with double seronegative NMOSD showed optic neuritis and spinal cord issues, highlighting diagnostic challenges and treatment difficulties.

## Contribution

This case report highlights the diagnostic challenges of double seronegative NMOSD and its clinical management complexities.

## Key findings

- The patient showed MRI findings consistent with NMOSD but tested negative for AQP4-IgG and MOG-IgG.
- Despite plasma exchange, the patient continued to experience significant neurological deficits.
- The case emphasizes the difficulty in diagnosing and managing double seronegative NMOSD.

## Abstract

Neuromyelitis optica spectrum disorder (NMOSD) is a rare antibody-mediated neuroinflammatory disease of the central nervous system, typically manifesting in the optic nerves, spinal cord, and other regions of the central nervous system. We hereby report a case of a 16-year-old girl who presented with a six-month history of transverse myelitis with an acute episode of bilateral retrobulbar optic neuritis. MRI revealed patchy contrast enhancements over bilateral retrobulbar intraorbital optic nerves together with long-segment spinal cord hyperintensities (C2 to T2 level). Visual evoked potential testing during the acute presentation showed the absence of P100 bilaterally. However, both serum AQP4-IgG and MOG-IgG were reported to be negative. Despite remarkable improvement in bilateral optic nerve functions, she continued to have disabling bilateral lower limb spasticity, contractures, and loss of bilateral lower limb sensation after five cycles of plasma exchange. This case summarizes the challenges to diagnosing double seronegative NMOSD and its immediate therapeutic significance.