Case Report

Double-Seronegative Neuromyelitis Optica Spectrum Disorder Presenting with Acute Flaccid Paraplegia and Bilateral Optic Neuritis

Sabyasachi Chowdhury.¹ Vaibhav Agarwal.² Jemima Islam.³ Md. Karimulla Mondal.⁴ Anup Kumar Datta.⁵

• ¹Post Graduate Resident, Department of General Medicine, Institute of Post Graduate Medical Education and Research and SSKM Hospital, Kolkata, West Bengal, India 
• ²Post Graduate Resident, Department of General Medicine, Institute of Post Graduate Medical Education and Research and SSKM Hospital, Kolkata, West Bengal, India 
• ³Post Graduate Resident, Department of General Medicine, Institute of Post Graduate Medical Education and Research and SSKM Hospital, Kolkata, West Bengal, India 
• ⁴Senior Resident, Department of General Medicine, Institute of Post Graduate Medical Education and Research and SSKM Hospital, Kolkata, West Bengal, India 
• ⁵Assistant Professor, Department of General Medicine, Institute of Post Graduate Medical Education and Research and SSKM Hospital, Kolkata, West Bengal, India
•  

Correspondence: Sabyasachi Chowdhury, Post Graduate Resident, Department of General Medicine, Institute of Post Graduate Medical Education and Research and SSKM Hospital, Kolkata, West Bengal, India. Email [email protected]

Received: November 25, 2025                                                           Published: December 19, 2025

Citation: Sabyasachi Ch. Double-Seronegative Neuromyelitis Optica Spectrum Disorder Presenting With Acute Flaccid Paraplegia and Bilateral Optic Neuritis. AOJ Emerg and Int Med. 2025;1(3):45–50.

Copyright: ©2025 Sabyasachi. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially.

Abstract 

Neuromyelitis optica (NMO) is an autoimmune, demyelinating inflammatory disorder of the central nervous system primarily targeting the optic nerves and spinal cord. The 2015 International Consensus criteria classify patients based on aquaporin-4 antibody (AQP4-IgG) status, with seronegative cases posing diagnostic difficulty because of overlap with other inflammatory and demyelinating conditions. Early recognition is essential, as untreated disease may lead to irreversible neurological disability. 

A 30-year-old woman with no comorbidities presented with 15 days of progressive bilateral lower-limb weakness, low back pain, and abdominal distention due to acute urinary retention requiring catheterization. Examination revealed hypotonia of both lower limbs, absent deep tendon reflexes, bilateral extensor plantar responses, and Medical Research Council (MRC) grade 0/5 power throughout. Routine laboratory investigations—including liver and kidney function tests, electrolytes, inflammatory markers, serum proteins, vitamin B12, folate, and urinalysis—were within normal limits. 

MRI dorsolumbar spine with whole-spine screening demonstrated longitudinally extensive transverse myelitis. MRI brain and orbit revealed demyelinating changes in the bilateral posterior optic nerves near the chiasm and in the pons. Visual evoked potentials showed prolonged P100 latency, compatible with conduction block. CSF analysis demonstrated lymphocytic pleocytosis, elevated protein, and negative oligoclonal bands. Anti-AQP4 and anti-MOG antibodies were negative. CNS infections, autoimmune encephalitides, systemic autoimmune diseases, sarcoidosis, and paraneoplastic syndromes were excluded based on clinical, biochemical, and radiologic findings. 

She received high-dose intravenous methylprednisolone for five days without improvement, followed by seven alternate-day plasma exchange sessions, which led to gradual motor and bladder recovery. She was discharged on tapering oral prednisolone with mycophenolate mofetil. 

Seronegative NMOSD may follow a relapsing course with significant long-term disability. Early diagnosis and timely initiation of immunomodulatory therapy are essential to reduce recurrence and improve neurological outcomes. Further refinement of diagnostic modalities is required for better identification of seronegative disease. 

Keywords: Neuromyelitis optica spectrum disorder; Longitudinally extensive transverse myelitis; Optic neuritis; Seronegative NMOSD; Demyelinating disorders

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