Snapshot A 35-year-old woman presents to the emergency department with severe bilateral eye pain. She said that her vision acutely worsened over the course of the day and has experienced eye pain, especially with movements. Her symptoms are associated with mild lower extremity weakness and she endorses having urinary incontinence. Physical examination is notable for 3+ patellar reflexes with 4-/5 power in her bilateral lower extremities. An MRI brain and spine demonstrate signal intensities in the optic nerves and the lumbothoracic spine. She is immediately started on high-dose intravenous methylprednisolone. She is admitted to the hospital and was found to have positive AQP4-IgG antibodies. Introduction Definition a central nervous system inflammatory and demyelinating disorder that predominantly affects the optic nerve and the spinal cord Associated conditions other autoimmune disorders (e.g., sarcoidosis) Epidemiology Incidence more common in women Etiology Idiopathic Pathogenesis Probably secondary to B-cell autoimmunity to aquaporin-4 (AQP4) aquaporin-4 is found in the astrocyte end-feet Presentation Symptoms/physical exam optic neuritis eye pain, which worsens with movement severe vision loss transverse myelitis limb weakness sensory loss bladder dysfunction intractable hiccups, nausea, or vomiting present in lesions involving the area postrema Imaging MRI brain indication imaging modality of choice findings spinal cord longintudinal hyerpintensities involving ≥ 3 vertebral segments optic nerves longitudinal hyperintensities involving the optic nerves brain typically normal (55-84% of cases); however, demyelinating lesions can still be found Studies Serum presence of AQP4-IgG antibodies Differential Multiple sclerosis differentiating factors MRI findings more consistent with multiple sclerosis include lateral ventricle lesions ovoid periventricular lesions ("Dawson fingers") U-fiber juxtacortical lesions Treatment Medical methylprednisolone indication treatment of choice for acute attacks long-term immunosuppression indication to prevent future attacks from occuring medications azathioprine rituximab mycophenolate mofetil Complications Neurogenic respiratory failure