Intractable Nausea as the Initial Presentation of Neuromyelitis Optica.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune condition of the central nervous system, primarily involving the optic nerves and spinal cord. Patients typically present with visual disturbance, limb weakness or sensory deficits, and bladder dysfunction. However, atypical and nonspecific presentations may occur, including persistent nausea and vomiting due to involvement of the area postrema. We report the case of a 26-year-old female patient who presented with a one-month history of intractable vomiting, associated with epigastric discomfort (worse prior to vomiting), reduced appetite, and significant weight loss of approximately 7-8 kg over one month. She had been admitted two times prior to presentation, with extensive investigations that were unremarkable. During admission, she also reported blurred vision and was noted to have horizontal nystagmus. Brain MRI demonstrated areas of altered signal intensity involving the brainstem and cervicomedullary junction, along the floor of the fourth ventricle, initially raising concern for Wernicke's encephalopathy. She received intravenous thiamine without clinical improvement. Further evaluation, including whole-spine MRI and autoimmune serology, revealed positivity for aquaporin-4 (AQP4) IgG antibodies, confirming NMOSD. She was treated with intravenous methylprednisolone and tocilizumab, resulting in marked symptomatic improvement. This case highlights NMOSD as an important and often under-recognized cause of intractable nausea and vomiting, which may delay diagnosis and treatment. A thorough neurological history and examination are essential in patients with persistent unexplained vomiting to ensure timely recognition and initiation of appropriate therapy.