Is Dystonia A Rare Manifestation of Neuromyelitis Optica Spectrum Disorder (NMOSD) - A Case of Varicella-Zoster Virus (VZV) Triggering Aquaporin-4 Antibodies?

NeuromyelitisOptica Spectrum Disorder is an autoimmune disease characterised by demyelination of CNS affecting optic nerve, spinal cord and brain stem region simultaneously or separated by variable period. This case highlights the atypical presentation of NMOSD as dystonia which was triggered by Aquaporin-4 Antibodies due to varicella-zoster virus (VZV) infection. Case Presentation: 42 year old female presented with paroxysmal dystonia, weakness of all 4 limbs and urinary incontinence. Spinal MRI: longitudinally extensive transverse myelitis (Fig. 1). Brain MRI: demyelination in medulla. Visual evoked potential examination abnormal. Serum AQP4-IgG positive, anti-MOG negative. Diagnosis of NMOSD confirmed. Patient improved on pulse methylprednisolone therapy and immunosuppressant Inj. Rituximab and was discharged on tapering dose of corticosteroid. She remained stable on this treatment in her follow up visits. Conclusion: NMOSD can present as movement disorder which can be major cause of disability and often mislabelled or undertreated. And since it is a treatable condition high index of suspicion is required to diagnose and treat this condition.