Michael Levy, MD, PhD, Massachusetts General Hospital and Harvard Medical School, Boston, MA, discusses the variance and challenges of diagnosing multiple sclerosis (MS). Neuromyelitis optica spectrum disorder (NMOSD) is an alternative diagnosis of MS and distinguishing between them is critical; treatments are different and, thus, can be harmful if incorrect. Access to aquaporin 4 antibodies is an important and challenging factor in the diagnostic process. The detection of those antibodies requires a cell-based assay not available worldwide. A process that consists in drying a patient’s drop of blood on filter paper to subsequently transport the blood over long distances without losing the ability to detect antibodies is currently being tested in locations that lack access to cell-based assays. This interview took place at the American Academy of Neurology 2022 Congress in Seattle, WA.