Double Seronegative Neuromyelitis Optica Spectrum Disorder with Longitudinally Extensive Transverse Myelitis and Optic Neuritis: A Challenging Case Report

双血清阴性视神经脊髓炎谱系疾病伴纵向广泛性横贯性脊髓炎和视神经炎：一例具有挑战性的病例报告