Delayed visual improvement in a pediatric patient with anti-AQP4 antibody-positive neuromyelitis optica spectrum disorder after acute immunomodulatory treatment: A case report

Neuromyelitis optica spectrum disorder (NMOSD) requires early therapeutic intervention to prevent relapse and further complications. Studies in adult patients with steroid-resistant NMOSD have indicated that the duration between disease onset and plasma exchange (PE) initiation significantly impacts prognosis, and that symptoms resolve within one month after PE in most cases. However, research assessing the prognostic factors of pediatric NMOSD is limited. We report a 14-year-old boy presenting with progressive visual loss in the left eye and diagnosed with anti-aquaporin-4 antibody-positive NMOSD four months after symptom onset. As the patient proved steroid resistant, PE was performed seven times per month over a three-month period. Although his vision initially continued to deteriorate, magnetic resonance imaging indicated optic nerve lesion regression by the third month of PE. Gradual improvement in visual acuity was observed following combined maintenance treatment with prednisolone and satralizumab from three months after completing acute-phase treatment. Despite the delayed initiation of PE and lack of initial response, acute-phase treatment can contribute to the recovery of visual acuity, which has significant implications, particularly in pediatric NMOSD cases.