BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease that causes severe demyelination, especially in the optic nerve and spinal cord with typical clinical manifestations of acute optic neuritis and transverse myelitis. The symptoms can occur simultaneously or separated by a variable period. NMOSD is associated with serum aquaporin antibodies 4 immunoglobulin G (AQP4-IgG). CASE PRESENTATION: We report a case of a 22-year-old male with complaints of weakness of all four limbs, impaired vision, urinary incontinence, and dyspnea. The Expanded Disability Status Scale (EDSS) was nine. Spinal magnetic resonance imaging (MRI) showed longitudinal extensive transversal myelitis. The brain MRI showed a normal impression, whereas the brain magnetic resonance spectroscopy (MRS) examination showed a description of the mild demyelination process. The serum antibody AQP4 (AQP4-IgG) results were seronegative, the cerebrospinal fluid examination was normal, and the oligoclonal band was negative. The ophthalmoscopic examination found bilateral papillary atrophy but optical coherence tomography (OCT) was still normal. Somatosensory evoked potential and visual evoked potential examinations were abnormal. The patient was diagnosed with NMOSD and was given combination immunosuppressant therapy, corticosteroids, and therapeutic plasma exchange. The patient experienced significant improvement with EDSS decreased to six. CONCLUSION: In the case of relapsing NMOSD patient, combination therapy of immunosuppressants, corticosteroids, and TPE was used. There were significant improvements from EDSS nine to six.