Neuromyelitis Optica Spectrum Disorder With Hyponatremia as an Initial Presentation: A Case Report.

The diagnosis of neuromyelitis optica spectrum disorder (NMOSD) is easily missed or delayed because of its multiple clinical features, especially at initial presentation. Hyponatremia is an infrequent complication of NMOSD and can present as an initial sign. Hyponatremia in a patient with NMOSD might be caused by autoimmune-related antibodies that attack the hypothalamus, causing inappropriate antidiuretic hormone secretion. Awareness of this pathophysiologic mechanism will help clinicians in the early diagnosis of NMOSD. We report a case of NMOSD with hyponatremia as the initial presentation.