RT Journal Article SR Electronic T1 Multiple Sclerosis Followed by Neuromyelitis Optica Spectrum Disorder JF Neurology - Neuroimmunology Neuroinflammation JO Neurol Neuroimmunol Neuroinflamm FD Lippincott Williams & Wilkins SP e200037 DO 10.1212/NXI.0000000000200037 VO 10 IS 1 A1 Carolyn Goldschmidt A1 Steven L. Galetta A1 Robert P. Lisak A1 Laura J. Balcer A1 Andrew Hellman A1 Michael K. Racke A1 Amy E. Lovett-Racke A1 Roberto Cruz A1 Matthew S. Parsons A1 Neda Sattarnezhad A1 Lawrence Steinman A1 Scott S. Zamvil A1 Elliot M. Frohman A1 Teresa C. Frohman YR 2023 UL http://nn.neurology.org/content/10/1/e200037.abstract AB A woman presented at age 18 years with partial myelitis and diplopia and experienced multiple subsequent relapses. Her MRI demonstrated T2 abnormalities characteristic of multiple sclerosis (MS) (white matter ovoid lesions and Dawson fingers), and CSF demonstrated an elevated IgG index and oligoclonal bands restricted to the CSF. Diagnosed with clinically definite relapsing-remitting MS, she was treated with various MS disease-modifying therapies and eventually began experiencing secondary progression. At age 57 years, she developed an acute longitudinally extensive transverse myelitis and was found to have AQP4 antibodies by cell-based assay. Our analysis of the clinical course, radiographic findings, molecular diagnostic methods, and treatment response characteristics support the hypothesis that our patient most likely had 2 CNS inflammatory disorders: MS, which manifested as a teenager, and neuromyelitis optica spectrum disorder, which evolved in her sixth decade of life. This case emphasizes a key principle in neurology practice, which is to reconsider whether the original working diagnosis remains tenable, especially when confronted with evidence (clinical and/or paraclinical) that raises the possibility of a distinctively different disorder.DMT=disease-modifying therapy; MS=multiple sclerosis; NMOSD=neuromyelitis optica spectrum disorder; RRMS=relapsing-remitting MS; S-1-P=sphingosine-1-phosphate; SPMS=secondary progressive MS; UTI=urinary tract infection