Snapshot A 25-year-old woman presents to the emergency department for poor vision on the left eye. She reports that her symptoms began approximately 1 week ago and it has progressively worsened. Her visual deficit is associated with eye pain with movement. She denies having these symptoms in the past but recalls having urinary incontinence that self-resolved. Physical examination is only remarkable for a significant visual deficit solely affecting the left eye. The rest of the neurological examination is normal. An MRI of the brain and spinal cord enhanced with gadolinium demonstrate a hyperintense lesion affecting her left optic nerve. There is also enhancing and nonenhancing hyperintense lesions in the spinal cord, suggestive of demyelinating lesions of different ages. She is admitted to the hospital and is started on 3 days of intravenous methylprednisolone. Introduction Definition login to view 1 more bullet Associated conditions login to view 1 more bullet Epidemiology Incidence login to view 1 more bullet Risk factors login to view 7 more bullets Pathogenesis Believed to be due to a trigger (e.g., infection in a susceptible patient) that results in the migration of autoreactive lymphocytes to affect the central nervous system leading to login to view 4 more bullets Presentation Clinical presentation depends on where demyelinating plaques are located login to view 25 more bullets Imaging MRI brain and spinal cord with gadolinium login to view 4 more bullets Studies Diagnosis is made based on McDonald 2017 criteria login to view 10 more bullets Cerebrospinal fluid analysis login to view 7 more bullets Differential Neuromyelitis optica login to view 2 more bullets Treatment Medical login to view 18 more bullets Complications Increased risk of infection due to being on immunosuppressants Disability